feat: add display UI with splash screen, dashboard, and RSSI sparkline

Implement full SSD1306 OLED display support:
- Splash screen on boot (1.5s) with project name, version, board
- Dashboard showing radio state, config, counters, RSSI/SNR
- RSSI history sparkline (64-sample ring buffer, 2px-wide bars)
- DisplayOn/DisplayOff host commands routed via dedicated channel
- Pure render functions against generic DrawTarget (no hardware coupling)
- Display on/off control bypasses radio task entirely

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vendor/toml_parser/src/debug.rs

@@ -0,0 +1,140 @@
+use crate::ErrorSink;
+use crate::Span;
+use crate::decoder::Encoding;
+
+pub(crate) struct DebugDepth(core::sync::atomic::AtomicUsize);
+
+impl DebugDepth {
+    pub(crate) fn enter_unchecked(&self) -> usize {
+        self.0.fetch_add(1, core::sync::atomic::Ordering::SeqCst)
+    }
+
+    pub(crate) fn exit_unchecked(&self) {
+        let _ = self.0.fetch_sub(1, core::sync::atomic::Ordering::SeqCst);
+    }
+
+    pub(crate) fn depth(&self) -> usize {
+        self.0.load(core::sync::atomic::Ordering::SeqCst)
+    }
+}
+
+static DEBUG_DEPTH: DebugDepth = DebugDepth(core::sync::atomic::AtomicUsize::new(0));
+
+fn render_event(span: impl Into<Option<Span>>, text: &str, style: anstyle::Style) {
+    #![allow(unexpected_cfgs)] // HACK: fixed in newer versions
+    let span = span.into();
+    let depth = DEBUG_DEPTH.depth().min(20);
+    anstream::eprintln!("{:depth$}{style}{text}: {span:?}{style:#}", "");
+}
+
+pub(crate) struct DebugErrorSink<'s> {
+    sink: &'s mut dyn ErrorSink,
+}
+
+impl<'s> DebugErrorSink<'s> {
+    pub(crate) fn new(sink: &'s mut dyn ErrorSink) -> Self {
+        Self { sink }
+    }
+}
+
+impl ErrorSink for DebugErrorSink<'_> {
+    fn report_error(&mut self, error: crate::ParseError) {
+        render_event(
+            error.unexpected(),
+            &format!("{error:?}"),
+            anstyle::AnsiColor::Red.on_default(),
+        );
+        self.sink.report_error(error);
+    }
+}
+
+pub(crate) struct DebugEventReceiver<'r> {
+    receiver: &'r mut dyn crate::parser::EventReceiver,
+}
+
+impl<'r> DebugEventReceiver<'r> {
+    pub(crate) fn new(receiver: &'r mut dyn crate::parser::EventReceiver) -> Self {
+        Self { receiver }
+    }
+}
+
+impl crate::parser::EventReceiver for DebugEventReceiver<'_> {
+    fn std_table_open(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.std_table_open(span, error);
+        render_event(span, "[", anstyle::Style::new() | anstyle::Effects::DIMMED);
+        DEBUG_DEPTH.enter_unchecked();
+    }
+    fn std_table_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.std_table_close(span, error);
+        DEBUG_DEPTH.exit_unchecked();
+        render_event(span, "]", anstyle::Style::new() | anstyle::Effects::DIMMED);
+    }
+    fn array_table_open(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.array_table_open(span, error);
+        render_event(span, "[[", anstyle::Style::new() | anstyle::Effects::DIMMED);
+        DEBUG_DEPTH.enter_unchecked();
+    }
+    fn array_table_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.array_table_close(span, error);
+        DEBUG_DEPTH.exit_unchecked();
+        render_event(span, "]]", anstyle::Style::new() | anstyle::Effects::DIMMED);
+    }
+    fn inline_table_open(&mut self, span: Span, error: &mut dyn ErrorSink) -> bool {
+        let allowed = self.receiver.inline_table_open(span, error);
+        render_event(span, "{", anstyle::Style::new() | anstyle::Effects::DIMMED);
+        DEBUG_DEPTH.enter_unchecked();
+        allowed
+    }
+    fn inline_table_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.inline_table_close(span, error);
+        DEBUG_DEPTH.exit_unchecked();
+        render_event(span, "}", anstyle::Style::new() | anstyle::Effects::DIMMED);
+    }
+    fn array_open(&mut self, span: Span, error: &mut dyn ErrorSink) -> bool {
+        let allowed = self.receiver.array_open(span, error);
+        render_event(span, "[", anstyle::Style::new() | anstyle::Effects::DIMMED);
+        DEBUG_DEPTH.enter_unchecked();
+        allowed
+    }
+    fn array_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.array_close(span, error);
+        DEBUG_DEPTH.exit_unchecked();
+        render_event(span, "]", anstyle::Style::new() | anstyle::Effects::DIMMED);
+    }
+    fn simple_key(&mut self, span: Span, encoding: Option<Encoding>, error: &mut dyn ErrorSink) {
+        self.receiver.simple_key(span, encoding, error);
+        render_event(span, "<key>", anstyle::AnsiColor::Magenta.on_default());
+    }
+    fn key_sep(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.key_sep(span, error);
+        render_event(span, ".", anstyle::Style::new() | anstyle::Effects::DIMMED);
+    }
+    fn key_val_sep(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.key_val_sep(span, error);
+        render_event(span, "=", anstyle::Style::new() | anstyle::Effects::DIMMED);
+    }
+    fn scalar(&mut self, span: Span, encoding: Option<Encoding>, error: &mut dyn ErrorSink) {
+        self.receiver.scalar(span, encoding, error);
+        render_event(span, "<scalar>", anstyle::AnsiColor::Green.on_default());
+    }
+    fn value_sep(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.value_sep(span, error);
+        render_event(span, ",", anstyle::Style::new() | anstyle::Effects::DIMMED);
+    }
+    fn whitespace(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.whitespace(span, error);
+        render_event(span, "<whitespace>", anstyle::AnsiColor::Cyan.on_default());
+    }
+    fn comment(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.comment(span, error);
+        render_event(span, "<comment>", anstyle::AnsiColor::Cyan.on_default());
+    }
+    fn newline(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.newline(span, error);
+        render_event(span, "<newline>", anstyle::AnsiColor::Cyan.on_default());
+    }
+    fn error(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.error(span, error);
+        render_event(span, "<error>", anstyle::AnsiColor::Red.on_default());
+    }
+}

vendor/toml_parser/src/decoder/mod.rs

@@ -0,0 +1,117 @@
+//! Decode [raw][crate::Raw] TOML values into Rust native types
+//!
+//! See
+//! - [`Raw::decode_key`][crate::Raw::decode_key]
+//! - [`Raw::decode_scalar`][crate::Raw::decode_scalar]
+//! - [`Raw::decode_whitespace`][crate::Raw::decode_whitespace]
+//! - [`Raw::decode_comment`][crate::Raw::decode_comment]
+//! - [`Raw::decode_newline`][crate::Raw::decode_newline]
+
+#[cfg(feature = "alloc")]
+use alloc::borrow::Cow;
+#[cfg(feature = "alloc")]
+use alloc::string::String;
+
+pub(crate) mod scalar;
+pub(crate) mod string;
+pub(crate) mod ws;
+
+pub use scalar::IntegerRadix;
+pub use scalar::ScalarKind;
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+#[repr(u8)]
+pub enum Encoding {
+    LiteralString = crate::lexer::APOSTROPHE,
+    BasicString = crate::lexer::QUOTATION_MARK,
+    MlLiteralString = 1,
+    MlBasicString,
+}
+
+impl Encoding {
+    pub const fn description(&self) -> &'static str {
+        match self {
+            Self::LiteralString => crate::lexer::TokenKind::LiteralString.description(),
+            Self::BasicString => crate::lexer::TokenKind::BasicString.description(),
+            Self::MlLiteralString => crate::lexer::TokenKind::MlLiteralString.description(),
+            Self::MlBasicString => crate::lexer::TokenKind::MlBasicString.description(),
+        }
+    }
+}
+
+pub trait StringBuilder<'s> {
+    fn clear(&mut self);
+    #[must_use]
+    fn push_str(&mut self, append: &'s str) -> bool;
+    #[must_use]
+    fn push_char(&mut self, append: char) -> bool;
+}
+
+impl<'s> StringBuilder<'s> for () {
+    fn clear(&mut self) {}
+    fn push_str(&mut self, _append: &'s str) -> bool {
+        true
+    }
+    fn push_char(&mut self, _append: char) -> bool {
+        true
+    }
+}
+
+impl<'s> StringBuilder<'s> for &'s str {
+    fn clear(&mut self) {
+        *self = &self[0..0];
+    }
+    fn push_str(&mut self, append: &'s str) -> bool {
+        if self.is_empty() {
+            *self = append;
+            true
+        } else {
+            false
+        }
+    }
+    fn push_char(&mut self, _append: char) -> bool {
+        false
+    }
+}
+
+#[cfg(feature = "alloc")]
+impl<'s> StringBuilder<'s> for Cow<'s, str> {
+    fn clear(&mut self) {
+        match self {
+            Cow::Borrowed(s) => {
+                s.clear();
+            }
+            Cow::Owned(s) => s.clear(),
+        }
+    }
+    fn push_str(&mut self, append: &'s str) -> bool {
+        match self {
+            Cow::Borrowed(s) => {
+                if !s.push_str(append) {
+                    self.to_mut().push_str(append);
+                }
+            }
+            Cow::Owned(s) => s.push_str(append),
+        }
+        true
+    }
+    fn push_char(&mut self, append: char) -> bool {
+        self.to_mut().push(append);
+        true
+    }
+}
+
+#[cfg(feature = "alloc")]
+impl<'s> StringBuilder<'s> for String {
+    fn clear(&mut self) {
+        self.clear();
+    }
+    fn push_str(&mut self, append: &'s str) -> bool {
+        self.push_str(append);
+        true
+    }
+    fn push_char(&mut self, append: char) -> bool {
+        self.push(append);
+        true
+    }
+}

vendor/toml_parser/src/decoder/scalar.rs

@@ -0,0 +1,772 @@
+use winnow::stream::ContainsToken as _;
+use winnow::stream::FindSlice as _;
+use winnow::stream::Offset as _;
+use winnow::stream::Stream as _;
+
+use crate::ErrorSink;
+use crate::Expected;
+use crate::ParseError;
+use crate::Raw;
+use crate::Span;
+use crate::decoder::StringBuilder;
+
+const ALLOCATION_ERROR: &str = "could not allocate for string";
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub enum ScalarKind {
+    String,
+    Boolean(bool),
+    DateTime,
+    Float,
+    Integer(IntegerRadix),
+}
+
+impl ScalarKind {
+    pub fn description(&self) -> &'static str {
+        match self {
+            Self::String => "string",
+            Self::Boolean(_) => "boolean",
+            Self::DateTime => "date-time",
+            Self::Float => "float",
+            Self::Integer(radix) => radix.description(),
+        }
+    }
+
+    pub fn invalid_description(&self) -> &'static str {
+        match self {
+            Self::String => "invalid string",
+            Self::Boolean(_) => "invalid boolean",
+            Self::DateTime => "invalid date-time",
+            Self::Float => "invalid float",
+            Self::Integer(radix) => radix.invalid_description(),
+        }
+    }
+}
+
+#[derive(Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub enum IntegerRadix {
+    #[default]
+    Dec,
+    Hex,
+    Oct,
+    Bin,
+}
+
+impl IntegerRadix {
+    pub fn description(&self) -> &'static str {
+        match self {
+            Self::Dec => "integer",
+            Self::Hex => "hexadecimal",
+            Self::Oct => "octal",
+            Self::Bin => "binary",
+        }
+    }
+
+    pub fn value(&self) -> u32 {
+        match self {
+            Self::Dec => 10,
+            Self::Hex => 16,
+            Self::Oct => 8,
+            Self::Bin => 2,
+        }
+    }
+
+    pub fn invalid_description(&self) -> &'static str {
+        match self {
+            Self::Dec => "invalid integer number",
+            Self::Hex => "invalid hexadecimal number",
+            Self::Oct => "invalid octal number",
+            Self::Bin => "invalid binary number",
+        }
+    }
+
+    fn validator(&self) -> fn(char) -> bool {
+        match self {
+            Self::Dec => |c| c.is_ascii_digit(),
+            Self::Hex => |c| c.is_ascii_hexdigit(),
+            Self::Oct => |c| matches!(c, '0'..='7'),
+            Self::Bin => |c| matches!(c, '0'..='1'),
+        }
+    }
+}
+
+pub(crate) fn decode_unquoted_scalar<'i>(
+    raw: Raw<'i>,
+    output: &mut dyn StringBuilder<'i>,
+    error: &mut dyn ErrorSink,
+) -> ScalarKind {
+    let s = raw.as_str();
+    let Some(first) = s.as_bytes().first() else {
+        return decode_invalid(raw, output, error);
+    };
+    if !first.is_ascii_digit() && s.contains(" ") {
+        // Only datetimes can have a space
+        return decode_invalid(raw, output, error);
+    }
+    match first {
+        // number starts
+        b'+' | b'-' => {
+            let value = &raw.as_str()[1..];
+            decode_sign_prefix(raw, value, output, error)
+        }
+        // Report as if they were numbers because its most likely a typo
+        b'_' => decode_datetime_or_float_or_integer(raw.as_str(), raw, output, error),
+        // Date/number starts
+        b'0' => decode_zero_prefix(raw.as_str(), false, raw, output, error),
+        b'1'..=b'9' => decode_datetime_or_float_or_integer(raw.as_str(), raw, output, error),
+        // Report as if they were numbers because its most likely a typo
+        b'.' => {
+            let kind = ScalarKind::Float;
+            let stream = raw.as_str();
+            if ensure_float(stream, raw, error) {
+                decode_float_or_integer(stream, raw, kind, output, error)
+            } else {
+                kind
+            }
+        }
+        b't' | b'T' => {
+            const SYMBOL: &str = "true";
+            let kind = ScalarKind::Boolean(true);
+            let expected = &[Expected::Literal(SYMBOL)];
+            decode_symbol(raw, SYMBOL, kind, expected, output, error)
+        }
+        b'f' | b'F' => {
+            const SYMBOL: &str = "false";
+            let kind = ScalarKind::Boolean(false);
+            let expected = &[Expected::Literal(SYMBOL)];
+            decode_symbol(raw, SYMBOL, kind, expected, output, error)
+        }
+        b'i' | b'I' => {
+            const SYMBOL: &str = "inf";
+            let kind = ScalarKind::Float;
+            let expected = &[Expected::Literal(SYMBOL)];
+            decode_symbol(raw, SYMBOL, kind, expected, output, error)
+        }
+        b'n' | b'N' => {
+            const SYMBOL: &str = "nan";
+            let kind = ScalarKind::Float;
+            let expected = &[Expected::Literal(SYMBOL)];
+            decode_symbol(raw, SYMBOL, kind, expected, output, error)
+        }
+        _ => decode_invalid(raw, output, error),
+    }
+}
+
+fn decode_sign_prefix<'i>(
+    raw: Raw<'i>,
+    value: &'i str,
+    output: &mut dyn StringBuilder<'i>,
+    error: &mut dyn ErrorSink,
+) -> ScalarKind {
+    let Some(first) = value.as_bytes().first() else {
+        return decode_invalid(raw, output, error);
+    };
+    match first {
+        // number starts
+        b'+' | b'-' => {
+            let start = value.offset_from(&raw.as_str());
+            let end = start + 1;
+            error.report_error(
+                ParseError::new("redundant numeric sign")
+                    .with_context(Span::new_unchecked(0, raw.len()))
+                    .with_expected(&[])
+                    .with_unexpected(Span::new_unchecked(start, end)),
+            );
+
+            let value = &value[1..];
+            decode_sign_prefix(raw, value, output, error)
+        }
+        // Report as if they were numbers because its most likely a typo
+        b'_' => decode_datetime_or_float_or_integer(value, raw, output, error),
+        // Date/number starts
+        b'0' => decode_zero_prefix(value, true, raw, output, error),
+        b'1'..=b'9' => decode_datetime_or_float_or_integer(value, raw, output, error),
+        // Report as if they were numbers because its most likely a typo
+        b'.' => {
+            let kind = ScalarKind::Float;
+            let stream = raw.as_str();
+            if ensure_float(stream, raw, error) {
+                decode_float_or_integer(stream, raw, kind, output, error)
+            } else {
+                kind
+            }
+        }
+        b'i' | b'I' => {
+            const SYMBOL: &str = "inf";
+            let kind = ScalarKind::Float;
+            if value != SYMBOL {
+                let expected = &[Expected::Literal(SYMBOL)];
+                let start = value.offset_from(&raw.as_str());
+                let end = start + value.len();
+                error.report_error(
+                    ParseError::new(kind.invalid_description())
+                        .with_context(Span::new_unchecked(0, raw.len()))
+                        .with_expected(expected)
+                        .with_unexpected(Span::new_unchecked(start, end)),
+                );
+                decode_as(raw, SYMBOL, kind, output, error)
+            } else {
+                decode_as_is(raw, kind, output, error)
+            }
+        }
+        b'n' | b'N' => {
+            const SYMBOL: &str = "nan";
+            let kind = ScalarKind::Float;
+            if value != SYMBOL {
+                let expected = &[Expected::Literal(SYMBOL)];
+                let start = value.offset_from(&raw.as_str());
+                let end = start + value.len();
+                error.report_error(
+                    ParseError::new(kind.invalid_description())
+                        .with_context(Span::new_unchecked(0, raw.len()))
+                        .with_expected(expected)
+                        .with_unexpected(Span::new_unchecked(start, end)),
+                );
+                decode_as(raw, SYMBOL, kind, output, error)
+            } else {
+                decode_as_is(raw, kind, output, error)
+            }
+        }
+        _ => decode_invalid(raw, output, error),
+    }
+}
+
+fn decode_zero_prefix<'i>(
+    value: &'i str,
+    signed: bool,
+    raw: Raw<'i>,
+    output: &mut dyn StringBuilder<'i>,
+    error: &mut dyn ErrorSink,
+) -> ScalarKind {
+    debug_assert_eq!(value.as_bytes()[0], b'0');
+    if value.len() == 1 {
+        let kind = ScalarKind::Integer(IntegerRadix::Dec);
+        // No extra validation needed
+        decode_float_or_integer(raw.as_str(), raw, kind, output, error)
+    } else {
+        let radix = value.as_bytes()[1];
+        match radix {
+            b'x' | b'X' => {
+                if value.contains(" ") {
+                    // Only datetimes can have a space
+                    return decode_invalid(raw, output, error);
+                }
+                if signed {
+                    error.report_error(
+                        ParseError::new("integers with a radix cannot be signed")
+                            .with_context(Span::new_unchecked(0, raw.len()))
+                            .with_expected(&[])
+                            .with_unexpected(Span::new_unchecked(0, 1)),
+                    );
+                }
+                if radix == b'X' {
+                    let start = value.offset_from(&raw.as_str());
+                    let end = start + 2;
+                    error.report_error(
+                        ParseError::new("radix must be lowercase")
+                            .with_context(Span::new_unchecked(0, raw.len()))
+                            .with_expected(&[Expected::Literal("0x")])
+                            .with_unexpected(Span::new_unchecked(start, end)),
+                    );
+                }
+                let radix = IntegerRadix::Hex;
+                let kind = ScalarKind::Integer(radix);
+                let stream = &value[2..];
+                if ensure_radixed_value(stream, raw, radix, error) {
+                    decode_float_or_integer(stream, raw, kind, output, error)
+                } else {
+                    kind
+                }
+            }
+            b'o' | b'O' => {
+                if value.contains(" ") {
+                    // Only datetimes can have a space
+                    return decode_invalid(raw, output, error);
+                }
+                if signed {
+                    error.report_error(
+                        ParseError::new("integers with a radix cannot be signed")
+                            .with_context(Span::new_unchecked(0, raw.len()))
+                            .with_expected(&[])
+                            .with_unexpected(Span::new_unchecked(0, 1)),
+                    );
+                }
+                if radix == b'O' {
+                    let start = value.offset_from(&raw.as_str());
+                    let end = start + 2;
+                    error.report_error(
+                        ParseError::new("radix must be lowercase")
+                            .with_context(Span::new_unchecked(0, raw.len()))
+                            .with_expected(&[Expected::Literal("0o")])
+                            .with_unexpected(Span::new_unchecked(start, end)),
+                    );
+                }
+                let radix = IntegerRadix::Oct;
+                let kind = ScalarKind::Integer(radix);
+                let stream = &value[2..];
+                if ensure_radixed_value(stream, raw, radix, error) {
+                    decode_float_or_integer(stream, raw, kind, output, error)
+                } else {
+                    kind
+                }
+            }
+            b'b' | b'B' => {
+                if value.contains(" ") {
+                    // Only datetimes can have a space
+                    return decode_invalid(raw, output, error);
+                }
+                if signed {
+                    error.report_error(
+                        ParseError::new("integers with a radix cannot be signed")
+                            .with_context(Span::new_unchecked(0, raw.len()))
+                            .with_expected(&[])
+                            .with_unexpected(Span::new_unchecked(0, 1)),
+                    );
+                }
+                if radix == b'B' {
+                    let start = value.offset_from(&raw.as_str());
+                    let end = start + 2;
+                    error.report_error(
+                        ParseError::new("radix must be lowercase")
+                            .with_context(Span::new_unchecked(0, raw.len()))
+                            .with_expected(&[Expected::Literal("0b")])
+                            .with_unexpected(Span::new_unchecked(start, end)),
+                    );
+                }
+                let radix = IntegerRadix::Bin;
+                let kind = ScalarKind::Integer(radix);
+                let stream = &value[2..];
+                if ensure_radixed_value(stream, raw, radix, error) {
+                    decode_float_or_integer(stream, raw, kind, output, error)
+                } else {
+                    kind
+                }
+            }
+            b'd' | b'D' => {
+                if value.contains(" ") {
+                    // Only datetimes can have a space
+                    return decode_invalid(raw, output, error);
+                }
+                if signed {
+                    error.report_error(
+                        ParseError::new("integers with a radix cannot be signed")
+                            .with_context(Span::new_unchecked(0, raw.len()))
+                            .with_expected(&[])
+                            .with_unexpected(Span::new_unchecked(0, 1)),
+                    );
+                }
+                let radix = IntegerRadix::Dec;
+                let kind = ScalarKind::Integer(radix);
+                let stream = &value[2..];
+                error.report_error(
+                    ParseError::new("redundant integer number prefix")
+                        .with_context(Span::new_unchecked(0, raw.len()))
+                        .with_expected(&[])
+                        .with_unexpected(Span::new_unchecked(0, 2)),
+                );
+                if ensure_radixed_value(stream, raw, radix, error) {
+                    decode_float_or_integer(stream, raw, kind, output, error)
+                } else {
+                    kind
+                }
+            }
+            _ => decode_datetime_or_float_or_integer(value, raw, output, error),
+        }
+    }
+}
+
+fn decode_datetime_or_float_or_integer<'i>(
+    value: &'i str,
+    raw: Raw<'i>,
+    output: &mut dyn StringBuilder<'i>,
+    error: &mut dyn ErrorSink,
+) -> ScalarKind {
+    let Some(digit_end) = value
+        .as_bytes()
+        .offset_for(|b| !(b'0'..=b'9').contains_token(b))
+    else {
+        let kind = ScalarKind::Integer(IntegerRadix::Dec);
+        let stream = raw.as_str();
+        if ensure_no_leading_zero(value, raw, error) {
+            return decode_float_or_integer(stream, raw, kind, output, error);
+        } else {
+            return kind;
+        }
+    };
+
+    #[cfg(feature = "unsafe")] // SAFETY: ascii digits ensures UTF-8 boundary
+    let rest = unsafe { &value.get_unchecked(digit_end..) };
+    #[cfg(not(feature = "unsafe"))]
+    let rest = &value[digit_end..];
+
+    if rest.starts_with("-") || rest.starts_with(":") {
+        decode_as_is(raw, ScalarKind::DateTime, output, error)
+    } else if rest.contains(" ") {
+        decode_invalid(raw, output, error)
+    } else if is_float(rest) {
+        let kind = ScalarKind::Float;
+        let stream = raw.as_str();
+        if ensure_float(value, raw, error) {
+            decode_float_or_integer(stream, raw, kind, output, error)
+        } else {
+            kind
+        }
+    } else if rest.starts_with("_") {
+        let kind = ScalarKind::Integer(IntegerRadix::Dec);
+        let stream = raw.as_str();
+        if ensure_no_leading_zero(value, raw, error) {
+            decode_float_or_integer(stream, raw, kind, output, error)
+        } else {
+            kind
+        }
+    } else {
+        decode_invalid(raw, output, error)
+    }
+}
+
+/// ```abnf
+/// ;; Float
+///
+/// float = float-int-part ( exp / frac [ exp ] )
+///
+/// float-int-part = dec-int
+/// frac = decimal-point zero-prefixable-int
+/// decimal-point = %x2E               ; .
+/// zero-prefixable-int = DIGIT *( DIGIT / underscore DIGIT )
+///
+/// exp = "e" float-exp-part
+/// float-exp-part = [ minus / plus ] zero-prefixable-int
+/// ```
+#[must_use]
+fn ensure_float<'i>(mut value: &'i str, raw: Raw<'i>, error: &mut dyn ErrorSink) -> bool {
+    let mut is_valid = true;
+
+    is_valid &= ensure_dec_uint(&mut value, raw, false, "invalid mantissa", error);
+
+    if value.starts_with(".") {
+        let _ = value.next_token();
+        is_valid &= ensure_dec_uint(&mut value, raw, true, "invalid fraction", error);
+    }
+
+    if value.starts_with(['e', 'E']) {
+        let _ = value.next_token();
+        if value.starts_with(['+', '-']) {
+            let _ = value.next_token();
+        }
+        is_valid &= ensure_dec_uint(&mut value, raw, true, "invalid exponent", error);
+    }
+
+    if !value.is_empty() {
+        let start = value.offset_from(&raw.as_str());
+        let end = raw.len();
+        error.report_error(
+            ParseError::new(ScalarKind::Float.invalid_description())
+                .with_context(Span::new_unchecked(0, raw.len()))
+                .with_expected(&[])
+                .with_unexpected(Span::new_unchecked(start, end)),
+        );
+        is_valid = false;
+    }
+
+    is_valid
+}
+
+#[must_use]
+fn ensure_dec_uint<'i>(
+    value: &mut &'i str,
+    raw: Raw<'i>,
+    zero_prefix: bool,
+    invalid_description: &'static str,
+    error: &mut dyn ErrorSink,
+) -> bool {
+    let mut is_valid = true;
+
+    let start = *value;
+    let mut digit_count = 0;
+    while let Some(current) = value.chars().next() {
+        if current.is_ascii_digit() {
+            digit_count += 1;
+        } else if current == '_' {
+        } else {
+            break;
+        }
+        let _ = value.next_token();
+    }
+
+    match digit_count {
+        0 => {
+            let start = start.offset_from(&raw.as_str());
+            let end = start;
+            error.report_error(
+                ParseError::new(invalid_description)
+                    .with_context(Span::new_unchecked(0, raw.len()))
+                    .with_expected(&[Expected::Description("digits")])
+                    .with_unexpected(Span::new_unchecked(start, end)),
+            );
+            is_valid = false;
+        }
+        1 => {}
+        _ if start.starts_with("0") && !zero_prefix => {
+            let start = start.offset_from(&raw.as_str());
+            let end = start + 1;
+            error.report_error(
+                ParseError::new("unexpected leading zero")
+                    .with_context(Span::new_unchecked(0, raw.len()))
+                    .with_expected(&[])
+                    .with_unexpected(Span::new_unchecked(start, end)),
+            );
+            is_valid = false;
+        }
+        _ => {}
+    }
+
+    is_valid
+}
+
+#[must_use]
+fn ensure_no_leading_zero<'i>(value: &'i str, raw: Raw<'i>, error: &mut dyn ErrorSink) -> bool {
+    let mut is_valid = true;
+
+    if value.starts_with("0") {
+        let start = value.offset_from(&raw.as_str());
+        let end = start + 1;
+        error.report_error(
+            ParseError::new("unexpected leading zero")
+                .with_context(Span::new_unchecked(0, raw.len()))
+                .with_expected(&[])
+                .with_unexpected(Span::new_unchecked(start, end)),
+        );
+        is_valid = false;
+    }
+
+    is_valid
+}
+
+#[must_use]
+fn ensure_radixed_value(
+    value: &str,
+    raw: Raw<'_>,
+    radix: IntegerRadix,
+    error: &mut dyn ErrorSink,
+) -> bool {
+    let mut is_valid = true;
+
+    let invalid = ['+', '-'];
+    let value = if let Some(value) = value.strip_prefix(invalid) {
+        let pos = raw.as_str().find(invalid).unwrap();
+        error.report_error(
+            ParseError::new("unexpected sign")
+                .with_context(Span::new_unchecked(0, raw.len()))
+                .with_expected(&[])
+                .with_unexpected(Span::new_unchecked(pos, pos + 1)),
+        );
+        is_valid = false;
+        value
+    } else {
+        value
+    };
+
+    let valid = radix.validator();
+    for (index, c) in value.char_indices() {
+        if !valid(c) && c != '_' {
+            let pos = value.offset_from(&raw.as_str()) + index;
+            error.report_error(
+                ParseError::new(radix.invalid_description())
+                    .with_context(Span::new_unchecked(0, raw.len()))
+                    .with_unexpected(Span::new_unchecked(pos, pos)),
+            );
+            is_valid = false;
+        }
+    }
+
+    is_valid
+}
+
+fn decode_float_or_integer<'i>(
+    mut stream: &'i str,
+    raw: Raw<'i>,
+    kind: ScalarKind,
+    output: &mut dyn StringBuilder<'i>,
+    error: &mut dyn ErrorSink,
+) -> ScalarKind {
+    output.clear();
+
+    let underscore = "_";
+
+    let stream_start = stream.offset_from(&raw.as_str());
+    while !stream.is_empty() {
+        let sep_pos = stream.find_slice(underscore);
+        let sep_start = sep_pos
+            .clone()
+            .map(|r| r.start)
+            .unwrap_or_else(|| stream.len());
+
+        let part_start = stream.offset_from(&raw.as_str());
+        let part_end = part_start + sep_start;
+        let part = stream.next_slice(sep_start);
+
+        if sep_pos.is_some() {
+            let _ = stream.next_slice(underscore.len());
+
+            let mut is_invalid_sep = false;
+            if let Some(last_pos) = sep_start.checked_sub(1) {
+                let last_byte = raw.as_bytes()[part_start + last_pos];
+                if !is_any_digit(last_byte, kind) {
+                    is_invalid_sep = true;
+                }
+            } else if part_start == stream_start {
+                is_invalid_sep = true;
+            }
+
+            if let Some(next_byte) = stream.as_bytes().first() {
+                if !is_any_digit(*next_byte, kind) {
+                    is_invalid_sep = true;
+                }
+            } else if stream.is_empty() {
+                is_invalid_sep = true;
+            }
+
+            if is_invalid_sep {
+                let start = part_end;
+                let end = start + underscore.len();
+                error.report_error(
+                    ParseError::new("`_` may only go between digits")
+                        .with_context(Span::new_unchecked(0, raw.len()))
+                        .with_expected(&[])
+                        .with_unexpected(Span::new_unchecked(end - underscore.len(), end)),
+                );
+            }
+        }
+
+        if !part.is_empty() && !output.push_str(part) {
+            error.report_error(
+                ParseError::new(ALLOCATION_ERROR)
+                    .with_unexpected(Span::new_unchecked(part_start, part_end)),
+            );
+        }
+    }
+
+    kind
+}
+
+fn is_any_digit(b: u8, kind: ScalarKind) -> bool {
+    if kind == ScalarKind::Float {
+        is_dec_integer_digit(b)
+    } else {
+        is_any_integer_digit(b)
+    }
+}
+
+fn is_any_integer_digit(b: u8) -> bool {
+    (b'0'..=b'9', b'a'..=b'f', b'A'..=b'F').contains_token(b)
+}
+
+fn is_dec_integer_digit(b: u8) -> bool {
+    (b'0'..=b'9').contains_token(b)
+}
+
+fn is_float(raw: &str) -> bool {
+    raw.as_bytes().find_slice((b'.', b'e', b'E')).is_some()
+}
+
+fn decode_as_is<'i>(
+    raw: Raw<'i>,
+    kind: ScalarKind,
+    output: &mut dyn StringBuilder<'i>,
+    error: &mut dyn ErrorSink,
+) -> ScalarKind {
+    let kind = decode_as(raw, raw.as_str(), kind, output, error);
+    kind
+}
+
+fn decode_as<'i>(
+    raw: Raw<'i>,
+    symbol: &'i str,
+    kind: ScalarKind,
+    output: &mut dyn StringBuilder<'i>,
+    error: &mut dyn ErrorSink,
+) -> ScalarKind {
+    output.clear();
+    if !output.push_str(symbol) {
+        error.report_error(
+            ParseError::new(ALLOCATION_ERROR).with_unexpected(Span::new_unchecked(0, raw.len())),
+        );
+    }
+    kind
+}
+
+fn decode_symbol<'i>(
+    raw: Raw<'i>,
+    symbol: &'static str,
+    kind: ScalarKind,
+    expected: &'static [Expected],
+    output: &mut dyn StringBuilder<'i>,
+    error: &mut dyn ErrorSink,
+) -> ScalarKind {
+    if raw.as_str() != symbol {
+        if raw.as_str().contains(" ") {
+            return decode_invalid(raw, output, error);
+        } else {
+            error.report_error(
+                ParseError::new(kind.invalid_description())
+                    .with_context(Span::new_unchecked(0, raw.len()))
+                    .with_expected(expected)
+                    .with_unexpected(Span::new_unchecked(0, raw.len())),
+            );
+        }
+    }
+
+    decode_as(raw, symbol, kind, output, error)
+}
+
+fn decode_invalid<'i>(
+    raw: Raw<'i>,
+    output: &mut dyn StringBuilder<'i>,
+    error: &mut dyn ErrorSink,
+) -> ScalarKind {
+    if raw.as_str().ends_with("'''") {
+        error.report_error(
+            ParseError::new("missing opening quote")
+                .with_context(Span::new_unchecked(0, raw.len()))
+                .with_expected(&[Expected::Literal(r#"'''"#)])
+                .with_unexpected(Span::new_unchecked(0, 0)),
+        );
+    } else if raw.as_str().ends_with(r#"""""#) {
+        error.report_error(
+            ParseError::new("missing opening quote")
+                .with_context(Span::new_unchecked(0, raw.len()))
+                .with_expected(&[Expected::Description("multi-line basic string")])
+                .with_expected(&[Expected::Literal(r#"""""#)])
+                .with_unexpected(Span::new_unchecked(0, 0)),
+        );
+    } else if raw.as_str().ends_with("'") {
+        error.report_error(
+            ParseError::new("missing opening quote")
+                .with_context(Span::new_unchecked(0, raw.len()))
+                .with_expected(&[Expected::Literal(r#"'"#)])
+                .with_unexpected(Span::new_unchecked(0, 0)),
+        );
+    } else if raw.as_str().ends_with(r#"""#) {
+        error.report_error(
+            ParseError::new("missing opening quote")
+                .with_context(Span::new_unchecked(0, raw.len()))
+                .with_expected(&[Expected::Literal(r#"""#)])
+                .with_unexpected(Span::new_unchecked(0, 0)),
+        );
+    } else {
+        error.report_error(
+            ParseError::new("string values must be quoted")
+                .with_context(Span::new_unchecked(0, raw.len()))
+                .with_expected(&[Expected::Description("literal string")])
+                .with_unexpected(Span::new_unchecked(0, raw.len())),
+        );
+    }
+
+    output.clear();
+    if !output.push_str(raw.as_str()) {
+        error.report_error(
+            ParseError::new(ALLOCATION_ERROR).with_unexpected(Span::new_unchecked(0, raw.len())),
+        );
+    }
+    ScalarKind::String
+}

vendor/toml_parser/src/decoder/ws.rs

@@ -0,0 +1,76 @@
+use core::ops::RangeInclusive;
+
+use winnow::stream::ContainsToken as _;
+
+use crate::ErrorSink;
+use crate::Expected;
+use crate::ParseError;
+use crate::Raw;
+use crate::Span;
+use crate::lexer::COMMENT_START_SYMBOL;
+
+/// Parse comment
+///
+/// ```abnf
+/// ;; Comment
+///
+/// comment-start-symbol = %x23 ; #
+/// non-ascii = %x80-D7FF / %xE000-10FFFF
+/// non-eol = %x09 / %x20-7E / non-ascii
+///
+/// comment = comment-start-symbol *non-eol
+/// ```
+pub(crate) fn decode_comment(raw: Raw<'_>, error: &mut dyn ErrorSink) {
+    let s = raw.as_bytes();
+
+    if s.first() != Some(&COMMENT_START_SYMBOL) {
+        error.report_error(
+            ParseError::new("missing comment start")
+                .with_context(Span::new_unchecked(0, raw.len()))
+                .with_expected(&[Expected::Literal("#")])
+                .with_unexpected(Span::new_unchecked(0, 0)),
+        );
+    }
+
+    for (i, b) in s.iter().copied().enumerate() {
+        if !NON_EOL.contains_token(b) {
+            error.report_error(
+                ParseError::new("invalid comment character")
+                    .with_context(Span::new_unchecked(0, raw.len()))
+                    .with_expected(&[Expected::Description("printable characters")])
+                    .with_unexpected(Span::new_unchecked(i, i)),
+            );
+        }
+    }
+}
+
+// non-ascii = %x80-D7FF / %xE000-10FFFF
+// - ASCII is 0xxxxxxx
+// - First byte for UTF-8 is 11xxxxxx
+// - Subsequent UTF-8 bytes are 10xxxxxx
+pub(crate) const NON_ASCII: RangeInclusive<u8> = 0x80..=0xff;
+
+// non-eol = %x09 / %x20-7E / non-ascii
+pub(crate) const NON_EOL: (u8, RangeInclusive<u8>, RangeInclusive<u8>) =
+    (0x09, 0x20..=0x7E, NON_ASCII);
+
+/// Parse newline
+///
+/// ```abnf
+///;; Newline
+///
+/// newline =  %x0A     ; LF
+/// newline =/ %x0D.0A  ; CRLF
+/// ```
+pub(crate) fn decode_newline(raw: Raw<'_>, error: &mut dyn ErrorSink) {
+    let s = raw.as_str();
+
+    if s == "\r" {
+        error.report_error(
+            ParseError::new("carriage return must be followed by newline")
+                .with_context(Span::new_unchecked(0, raw.len()))
+                .with_expected(&[Expected::Literal("\n")])
+                .with_unexpected(Span::new_unchecked(raw.len(), raw.len())),
+        );
+    }
+}

vendor/toml_parser/src/error.rs

@@ -0,0 +1,102 @@
+use crate::Span;
+
+pub trait ErrorSink {
+    fn report_error(&mut self, error: ParseError);
+}
+
+impl<F> ErrorSink for F
+where
+    F: FnMut(ParseError),
+{
+    fn report_error(&mut self, error: ParseError) {
+        (self)(error);
+    }
+}
+
+impl ErrorSink for () {
+    fn report_error(&mut self, _error: ParseError) {}
+}
+
+impl ErrorSink for Option<ParseError> {
+    fn report_error(&mut self, error: ParseError) {
+        self.get_or_insert(error);
+    }
+}
+
+#[cfg(feature = "alloc")]
+#[allow(unused_qualifications)]
+impl ErrorSink for alloc::vec::Vec<ParseError> {
+    fn report_error(&mut self, error: ParseError) {
+        self.push(error);
+    }
+}
+
+#[derive(Clone, PartialEq, Eq, Debug)]
+#[non_exhaustive]
+pub struct ParseError {
+    context: Option<Span>,
+    description: ErrorStr,
+    expected: Option<&'static [Expected]>,
+    unexpected: Option<Span>,
+}
+
+impl ParseError {
+    pub fn new(description: impl Into<ErrorStr>) -> Self {
+        Self {
+            context: None,
+            description: description.into(),
+            expected: None,
+            unexpected: None,
+        }
+    }
+
+    pub fn with_context(mut self, context: Span) -> Self {
+        self.context = Some(context);
+        self
+    }
+
+    pub fn with_expected(mut self, expected: &'static [Expected]) -> Self {
+        self.expected = Some(expected);
+        self
+    }
+
+    pub fn with_unexpected(mut self, unexpected: Span) -> Self {
+        self.unexpected = Some(unexpected);
+        self
+    }
+
+    pub fn context(&self) -> Option<Span> {
+        self.context
+    }
+    pub fn description(&self) -> &str {
+        &self.description
+    }
+    pub fn expected(&self) -> Option<&'static [Expected]> {
+        self.expected
+    }
+    pub fn unexpected(&self) -> Option<Span> {
+        self.unexpected
+    }
+
+    pub(crate) fn rebase_spans(mut self, offset: usize) -> Self {
+        if let Some(context) = self.context.as_mut() {
+            *context += offset;
+        }
+        if let Some(unexpected) = self.unexpected.as_mut() {
+            *unexpected += offset;
+        }
+        self
+    }
+}
+
+#[cfg(feature = "alloc")]
+type ErrorStr = alloc::borrow::Cow<'static, str>;
+#[cfg(not(feature = "alloc"))]
+type ErrorStr = &'static str;
+
+#[derive(Copy, Clone, PartialEq, Eq, Debug)]
+#[non_exhaustive]
+pub enum Expected {
+    Literal(&'static str),
+    Description(&'static str),
+}

vendor/toml_parser/src/lexer/mod.rs

@@ -0,0 +1,638 @@
+//! Lex TOML tokens
+//!
+//! To get started, see [`Source::lex`][crate::Source::lex]
+
+#[cfg(test)]
+#[cfg(feature = "std")]
+mod test;
+mod token;
+
+#[cfg(feature = "alloc")]
+use alloc::vec::Vec;
+
+use winnow::stream::AsBStr as _;
+use winnow::stream::ContainsToken as _;
+use winnow::stream::FindSlice as _;
+use winnow::stream::Location;
+use winnow::stream::Stream as _;
+
+use crate::Span;
+
+pub use token::Token;
+pub use token::TokenKind;
+
+/// Lex TOML [tokens][Token]
+///
+/// To get started, see [`Source::lex`][crate::Source::lex]
+pub struct Lexer<'i> {
+    stream: Stream<'i>,
+    eof: bool,
+}
+
+impl<'i> Lexer<'i> {
+    pub(crate) fn new(input: &'i str) -> Self {
+        let mut stream = Stream::new(input);
+        if input.as_bytes().starts_with(BOM) {
+            let offset = BOM.len();
+            #[cfg(feature = "unsafe")] // SAFETY: only called when next character is ASCII
+            unsafe {
+                stream.next_slice_unchecked(offset)
+            };
+            #[cfg(not(feature = "unsafe"))]
+            stream.next_slice(offset);
+        }
+        Lexer { stream, eof: false }
+    }
+
+    #[cfg(feature = "alloc")]
+    pub fn into_vec(self) -> Vec<Token> {
+        #![allow(unused_qualifications)] // due to MSRV of 1.66
+        let capacity = core::cmp::min(
+            self.stream.len(),
+            usize::MAX / core::mem::size_of::<Token>(),
+        );
+        let mut vec = Vec::with_capacity(capacity);
+        vec.extend(self);
+        vec
+    }
+}
+
+impl Iterator for Lexer<'_> {
+    type Item = Token;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let Some(peek_byte) = self.stream.as_bstr().first() else {
+            if self.eof {
+                return None;
+            } else {
+                self.eof = true;
+                let start = self.stream.current_token_start();
+                let span = Span::new_unchecked(start, start);
+                return Some(Token::new(TokenKind::Eof, span));
+            }
+        };
+        Some(process_token(*peek_byte, &mut self.stream))
+    }
+}
+
+const BOM: &[u8] = b"\xEF\xBB\xBF";
+
+pub(crate) type Stream<'i> = winnow::stream::LocatingSlice<&'i str>;
+
+fn process_token(peek_byte: u8, stream: &mut Stream<'_>) -> Token {
+    let token = match peek_byte {
+        b'.' => lex_ascii_char(stream, TokenKind::Dot),
+        b'=' => lex_ascii_char(stream, TokenKind::Equals),
+        b',' => lex_ascii_char(stream, TokenKind::Comma),
+        b'[' => lex_ascii_char(stream, TokenKind::LeftSquareBracket),
+        b']' => lex_ascii_char(stream, TokenKind::RightSquareBracket),
+        b'{' => lex_ascii_char(stream, TokenKind::LeftCurlyBracket),
+        b'}' => lex_ascii_char(stream, TokenKind::RightCurlyBracket),
+        b' ' => lex_whitespace(stream),
+        b'\t' => lex_whitespace(stream),
+        b'#' => lex_comment(stream),
+        b'\r' => lex_crlf(stream),
+        b'\n' => lex_ascii_char(stream, TokenKind::Newline),
+        b'\'' => {
+            if stream.starts_with(ML_LITERAL_STRING_DELIM) {
+                lex_ml_literal_string(stream)
+            } else {
+                lex_literal_string(stream)
+            }
+        }
+        b'"' => {
+            if stream.starts_with(ML_BASIC_STRING_DELIM) {
+                lex_ml_basic_string(stream)
+            } else {
+                lex_basic_string(stream)
+            }
+        }
+        _ => lex_atom(stream),
+    };
+    token
+}
+
+/// Process an ASCII character token
+///
+/// # Safety
+///
+/// - `stream` must be UTF-8
+/// - `stream` must be non-empty
+/// - `stream[0]` must be ASCII
+fn lex_ascii_char(stream: &mut Stream<'_>, kind: TokenKind) -> Token {
+    debug_assert!(!stream.is_empty());
+    let start = stream.current_token_start();
+
+    let offset = 1; // an ascii character
+    #[cfg(feature = "unsafe")] // SAFETY: only called when next character is ASCII
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+
+    let end = stream.previous_token_end();
+    let span = Span::new_unchecked(start, end);
+    Token::new(kind, span)
+}
+
+/// Process Whitespace
+///
+/// ```abnf
+/// ;; Whitespace
+///
+/// ws = *wschar
+/// wschar =  %x20  ; Space
+/// wschar =/ %x09  ; Horizontal tab
+/// ```
+///
+/// # Safety
+///
+/// - `stream` must be UTF-8
+/// - `stream` must be non-empty
+fn lex_whitespace(stream: &mut Stream<'_>) -> Token {
+    debug_assert!(!stream.is_empty());
+    let start = stream.current_token_start();
+
+    let offset = stream
+        .as_bstr()
+        .offset_for(|b| !WSCHAR.contains_token(b))
+        .unwrap_or(stream.eof_offset());
+    #[cfg(feature = "unsafe")] // SAFETY: WSCHAR ensures `offset` will be at UTF-8 boundary
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+
+    let end = stream.previous_token_end();
+    let span = Span::new_unchecked(start, end);
+    Token::new(TokenKind::Whitespace, span)
+}
+
+/// ```abnf
+/// wschar =  %x20  ; Space
+/// wschar =/ %x09  ; Horizontal tab
+/// ```
+pub(crate) const WSCHAR: (u8, u8) = (b' ', b'\t');
+
+/// Process Comment
+///
+/// ```abnf
+/// ;; Comment
+///
+/// comment-start-symbol = %x23 ; #
+/// non-ascii = %x80-D7FF / %xE000-10FFFF
+/// non-eol = %x09 / %x20-7E / non-ascii
+///
+/// comment = comment-start-symbol *non-eol
+/// ```
+///
+/// # Safety
+///
+/// - `stream` must be UTF-8
+/// - `stream[0] == b'#'`
+fn lex_comment(stream: &mut Stream<'_>) -> Token {
+    let start = stream.current_token_start();
+
+    let offset = stream
+        .as_bytes()
+        .find_slice((b'\r', b'\n'))
+        .map(|s| s.start)
+        .unwrap_or_else(|| stream.eof_offset());
+    #[cfg(feature = "unsafe")] // SAFETY: newlines ensure `offset` is along UTF-8 boundary
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+
+    let end = stream.previous_token_end();
+    let span = Span::new_unchecked(start, end);
+    Token::new(TokenKind::Comment, span)
+}
+
+/// ```abnf
+/// comment-start-symbol = %x23 ; #
+/// ```
+pub(crate) const COMMENT_START_SYMBOL: u8 = b'#';
+
+/// Process Newline
+///
+/// ```abnf
+/// ;; Newline
+///
+/// newline =  %x0A     ; LF
+/// newline =/ %x0D.0A  ; CRLF
+/// ```
+///
+/// # Safety
+///
+/// - `stream` must be UTF-8
+/// - `stream[0] == b'\r'`
+fn lex_crlf(stream: &mut Stream<'_>) -> Token {
+    let start = stream.current_token_start();
+
+    let mut offset = '\r'.len_utf8();
+    let has_lf = stream.as_bstr().get(1) == Some(&b'\n');
+    if has_lf {
+        offset += '\n'.len_utf8();
+    }
+
+    #[cfg(feature = "unsafe")] // SAFETY: newlines ensure `offset` is along UTF-8 boundary
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+    let end = stream.previous_token_end();
+    let span = Span::new_unchecked(start, end);
+
+    Token::new(TokenKind::Newline, span)
+}
+
+/// Process literal string
+///
+/// ```abnf
+/// ;; Literal String
+///
+/// literal-string = apostrophe *literal-char apostrophe
+///
+/// apostrophe = %x27 ; ' apostrophe
+///
+/// literal-char = %x09 / %x20-26 / %x28-7E / non-ascii
+/// ```
+///
+/// # Safety
+///
+/// - `stream` must be UTF-8
+/// - `stream[0] == b'\''`
+fn lex_literal_string(stream: &mut Stream<'_>) -> Token {
+    let start = stream.current_token_start();
+
+    let offset = 1; // APOSTROPHE
+    #[cfg(feature = "unsafe")] // SAFETY: only called when next character is ASCII
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+
+    let offset = match stream.as_bstr().find_slice((APOSTROPHE, b'\n')) {
+        Some(span) => {
+            if stream.as_bstr()[span.start] == APOSTROPHE {
+                span.end
+            } else {
+                span.start
+            }
+        }
+        None => stream.eof_offset(),
+    };
+    #[cfg(feature = "unsafe")]
+    // SAFETY: `APOSTROPHE`/newline ensure `offset` is along UTF-8 boundary
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+
+    let end = stream.previous_token_end();
+    let span = Span::new_unchecked(start, end);
+    Token::new(TokenKind::LiteralString, span)
+}
+
+/// ```abnf
+/// apostrophe = %x27 ; ' apostrophe
+/// ```
+pub(crate) const APOSTROPHE: u8 = b'\'';
+
+/// Process multi-line literal string
+///
+/// ```abnf
+/// ;; Multiline Literal String
+///
+/// ml-literal-string = ml-literal-string-delim [ newline ] ml-literal-body
+///                     ml-literal-string-delim
+/// ml-literal-string-delim = 3apostrophe
+/// ml-literal-body = *mll-content *( mll-quotes 1*mll-content ) [ mll-quotes ]
+///
+/// mll-content = literal-char / newline
+/// mll-quotes = 1*2apostrophe
+/// ```
+///
+/// # Safety
+///
+/// - `stream` must be UTF-8
+/// - `stream.starts_with(ML_LITERAL_STRING_DELIM)`
+fn lex_ml_literal_string(stream: &mut Stream<'_>) -> Token {
+    let start = stream.current_token_start();
+
+    let offset = ML_LITERAL_STRING_DELIM.len();
+    #[cfg(feature = "unsafe")] // SAFETY: only called when next character is ASCII
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+
+    let offset = match stream.as_bstr().find_slice(ML_LITERAL_STRING_DELIM) {
+        Some(span) => span.end,
+        None => stream.eof_offset(),
+    };
+    #[cfg(feature = "unsafe")]
+    // SAFETY: `ML_LITERAL_STRING_DELIM` ensure `offset` is along UTF-8 boundary
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+
+    if stream.as_bstr().peek_token() == Some(APOSTROPHE) {
+        let offset = 1;
+        #[cfg(feature = "unsafe")] // SAFETY: `APOSTROPHE` ensure `offset` is along UTF-8 boundary
+        unsafe {
+            stream.next_slice_unchecked(offset)
+        };
+        #[cfg(not(feature = "unsafe"))]
+        stream.next_slice(offset);
+
+        if stream.as_bstr().peek_token() == Some(APOSTROPHE) {
+            let offset = 1;
+            #[cfg(feature = "unsafe")]
+            // SAFETY: `APOSTROPHE` ensure `offset` is along UTF-8 boundary
+            unsafe {
+                stream.next_slice_unchecked(offset)
+            };
+            #[cfg(not(feature = "unsafe"))]
+            stream.next_slice(offset);
+        }
+    }
+
+    let end = stream.previous_token_end();
+    let span = Span::new_unchecked(start, end);
+    Token::new(TokenKind::MlLiteralString, span)
+}
+
+/// ```abnf
+/// ml-literal-string-delim = 3apostrophe
+/// ```
+pub(crate) const ML_LITERAL_STRING_DELIM: &str = "'''";
+
+/// Process basic string
+///
+/// ```abnf
+/// ;; Basic String
+///
+/// basic-string = quotation-mark *basic-char quotation-mark
+///
+/// quotation-mark = %x22            ; "
+///
+/// basic-char = basic-unescaped / escaped
+/// basic-unescaped = wschar / %x21 / %x23-5B / %x5D-7E / non-ascii
+/// escaped = escape escape-seq-char
+///
+/// escape = %x5C                   ; \
+/// escape-seq-char =  %x22         ; "    quotation mark  U+0022
+/// escape-seq-char =/ %x5C         ; \    reverse solidus U+005C
+/// escape-seq-char =/ %x62         ; b    backspace       U+0008
+/// escape-seq-char =/ %x65         ; e    escape          U+001B
+/// escape-seq-char =/ %x66         ; f    form feed       U+000C
+/// escape-seq-char =/ %x6E         ; n    line feed       U+000A
+/// escape-seq-char =/ %x72         ; r    carriage return U+000D
+/// escape-seq-char =/ %x74         ; t    tab             U+0009
+/// escape-seq-char =/ %x78 2HEXDIG ; xHH                  U+00HH
+/// escape-seq-char =/ %x75 4HEXDIG ; uHHHH                U+HHHH
+/// escape-seq-char =/ %x55 8HEXDIG ; UHHHHHHHH            U+HHHHHHHH
+/// ```
+///
+/// # Safety
+///
+/// - `stream` must be UTF-8
+/// - `stream[0] == b'"'`
+fn lex_basic_string(stream: &mut Stream<'_>) -> Token {
+    let start = stream.current_token_start();
+
+    let offset = 1; // QUOTATION_MARK
+    #[cfg(feature = "unsafe")] // SAFETY: only called when next character is ASCII
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+
+    loop {
+        // newline is present for error recovery
+        match stream.as_bstr().find_slice((QUOTATION_MARK, ESCAPE, b'\n')) {
+            Some(span) => {
+                let found = stream.as_bstr()[span.start];
+                if found == QUOTATION_MARK {
+                    let offset = span.end;
+                    #[cfg(feature = "unsafe")]
+                    // SAFETY: `QUOTATION_MARK` ensure `offset` is along UTF-8 boundary
+                    unsafe {
+                        stream.next_slice_unchecked(offset)
+                    };
+                    #[cfg(not(feature = "unsafe"))]
+                    stream.next_slice(offset);
+                    break;
+                } else if found == ESCAPE {
+                    let offset = span.end;
+                    #[cfg(feature = "unsafe")]
+                    // SAFETY: `ESCAPE` / newline ensure `offset` is along UTF-8 boundary
+                    unsafe {
+                        stream.next_slice_unchecked(offset)
+                    };
+                    #[cfg(not(feature = "unsafe"))]
+                    stream.next_slice(offset);
+
+                    let peek = stream.as_bstr().peek_token();
+                    match peek {
+                        Some(ESCAPE) | Some(QUOTATION_MARK) => {
+                            let offset = 1; // ESCAPE / QUOTATION_MARK
+                            #[cfg(feature = "unsafe")]
+                            #[cfg(feature = "unsafe")]
+                            // SAFETY: `ESCAPE` / newline ensure `offset` is along UTF-8 boundary
+                            unsafe {
+                                stream.next_slice_unchecked(offset)
+                            };
+                            #[cfg(not(feature = "unsafe"))]
+                            stream.next_slice(offset);
+                        }
+                        _ => {}
+                    }
+                    continue;
+                } else if found == b'\n' {
+                    let offset = span.start;
+                    #[cfg(feature = "unsafe")]
+                    // SAFETY: newline ensure `offset` is along UTF-8 boundary
+                    unsafe {
+                        stream.next_slice_unchecked(offset)
+                    };
+                    #[cfg(not(feature = "unsafe"))]
+                    stream.next_slice(offset);
+                    break;
+                } else {
+                    unreachable!("found `{found}`");
+                }
+            }
+            None => {
+                stream.finish();
+                break;
+            }
+        }
+    }
+
+    let end = stream.previous_token_end();
+    let span = Span::new_unchecked(start, end);
+    Token::new(TokenKind::BasicString, span)
+}
+
+/// ```abnf
+/// quotation-mark = %x22            ; "
+/// ```
+pub(crate) const QUOTATION_MARK: u8 = b'"';
+
+/// ```abnf
+/// escape = %x5C                   ; \
+/// ```
+pub(crate) const ESCAPE: u8 = b'\\';
+
+/// Process multi-line basic string
+///
+/// ```abnf
+/// ;; Multiline Basic String
+///
+/// ml-basic-string = ml-basic-string-delim [ newline ] ml-basic-body
+///                   ml-basic-string-delim
+/// ml-basic-string-delim = 3quotation-mark
+/// ml-basic-body = *mlb-content *( mlb-quotes 1*mlb-content ) [ mlb-quotes ]
+///
+/// mlb-content = basic-char / newline / mlb-escaped-nl
+/// mlb-quotes = 1*2quotation-mark
+/// mlb-escaped-nl = escape ws newline *( wschar / newline )
+/// ```
+///
+/// # Safety
+///
+/// - `stream` must be UTF-8
+/// - `stream.starts_with(ML_BASIC_STRING_DELIM)`
+fn lex_ml_basic_string(stream: &mut Stream<'_>) -> Token {
+    let start = stream.current_token_start();
+
+    let offset = ML_BASIC_STRING_DELIM.len();
+    #[cfg(feature = "unsafe")] // SAFETY: only called when next character is ASCII
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+
+    loop {
+        // newline is present for error recovery
+        match stream.as_bstr().find_slice((ML_BASIC_STRING_DELIM, "\\")) {
+            Some(span) => {
+                let found = stream.as_bstr()[span.start];
+                if found == QUOTATION_MARK {
+                    let offset = span.end;
+                    #[cfg(feature = "unsafe")]
+                    // SAFETY: `QUOTATION_MARK` ensure `offset` is along UTF-8 boundary
+                    unsafe {
+                        stream.next_slice_unchecked(offset)
+                    };
+                    #[cfg(not(feature = "unsafe"))]
+                    stream.next_slice(offset);
+                    break;
+                } else if found == ESCAPE {
+                    let offset = span.end;
+                    #[cfg(feature = "unsafe")]
+                    // SAFETY: `ESCAPE` ensure `offset` is along UTF-8 boundary
+                    unsafe {
+                        stream.next_slice_unchecked(offset)
+                    };
+                    #[cfg(not(feature = "unsafe"))]
+                    stream.next_slice(offset);
+
+                    let peek = stream.as_bstr().peek_token();
+                    match peek {
+                        Some(ESCAPE) | Some(QUOTATION_MARK) => {
+                            let offset = 1; // ESCAPE / QUOTATION_MARK
+                            #[cfg(feature = "unsafe")]
+                            // SAFETY: `QUOTATION_MARK`/`ESCAPE` ensure `offset` is along UTF-8 boundary
+                            unsafe {
+                                stream.next_slice_unchecked(offset)
+                            };
+                            #[cfg(not(feature = "unsafe"))]
+                            stream.next_slice(offset);
+                        }
+                        _ => {}
+                    }
+                    continue;
+                } else {
+                    unreachable!("found `{found}`");
+                }
+            }
+            None => {
+                stream.finish();
+                break;
+            }
+        }
+    }
+    if stream.as_bstr().peek_token() == Some(QUOTATION_MARK) {
+        let offset = 1;
+        #[cfg(feature = "unsafe")]
+        // SAFETY: `QUOTATION_MARK` ensure `offset` is along UTF-8 boundary
+        unsafe {
+            stream.next_slice_unchecked(offset)
+        };
+        #[cfg(not(feature = "unsafe"))]
+        stream.next_slice(offset);
+        if stream.as_bstr().peek_token() == Some(QUOTATION_MARK) {
+            let offset = 1;
+            #[cfg(feature = "unsafe")]
+            // SAFETY: `QUOTATION_MARK` ensure `offset` is along UTF-8 boundary
+            unsafe {
+                stream.next_slice_unchecked(offset)
+            };
+            #[cfg(not(feature = "unsafe"))]
+            stream.next_slice(offset);
+        }
+    }
+
+    let end = stream.previous_token_end();
+    let span = Span::new_unchecked(start, end);
+    Token::new(TokenKind::MlBasicString, span)
+}
+
+/// ```abnf
+/// ml-basic-string-delim = 3quotation-mark
+/// ```
+pub(crate) const ML_BASIC_STRING_DELIM: &str = "\"\"\"";
+
+/// Process Atom
+///
+/// This is everything else
+///
+/// # Safety
+///
+/// - `stream` must be UTF-8
+/// - `stream` must be non-empty
+fn lex_atom(stream: &mut Stream<'_>) -> Token {
+    let start = stream.current_token_start();
+
+    // Intentionally leaves off quotes in case the opening quote was missing
+    const TOKEN_START: &[u8] = b".=,[]{} \t#\r\n";
+    let offset = stream
+        .as_bstr()
+        .offset_for(|b| TOKEN_START.contains_token(b))
+        .unwrap_or_else(|| stream.eof_offset());
+    #[cfg(feature = "unsafe")] // SAFETY: `TOKEN_START` ensure `offset` is along UTF-8 boundary
+    unsafe {
+        stream.next_slice_unchecked(offset)
+    };
+    #[cfg(not(feature = "unsafe"))]
+    stream.next_slice(offset);
+
+    let end = stream.previous_token_end();
+    let span = Span::new_unchecked(start, end);
+    Token::new(TokenKind::Atom, span)
+}

vendor/toml_parser/src/lexer/token.rs

@@ -0,0 +1,106 @@
+//! Lexed TOML tokens
+
+use super::APOSTROPHE;
+use super::COMMENT_START_SYMBOL;
+use super::QUOTATION_MARK;
+use super::Span;
+use super::WSCHAR;
+use crate::decoder::Encoding;
+
+/// An unvalidated TOML Token
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub struct Token {
+    pub(super) kind: TokenKind,
+    pub(super) span: Span,
+}
+
+impl Token {
+    pub(super) fn new(kind: TokenKind, span: Span) -> Self {
+        Self { kind, span }
+    }
+
+    #[inline(always)]
+    pub fn kind(&self) -> TokenKind {
+        self.kind
+    }
+
+    #[inline(always)]
+    pub fn span(&self) -> Span {
+        self.span
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+#[repr(u8)]
+pub enum TokenKind {
+    /// Either for dotted-key or float
+    Dot = b'.',
+    /// Key-value separator
+    Equals = b'=',
+    /// Value separator
+    Comma = b',',
+    /// Either array or standard-table start
+    LeftSquareBracket = b'[',
+    /// Either array or standard-table end
+    RightSquareBracket = b']',
+    /// Inline table start
+    LeftCurlyBracket = b'{',
+    /// Inline table end
+    RightCurlyBracket = b'}',
+    Whitespace = WSCHAR.0,
+    Comment = COMMENT_START_SYMBOL,
+    Newline = b'\n',
+    LiteralString = APOSTROPHE,
+    BasicString = QUOTATION_MARK,
+    MlLiteralString = 1,
+    MlBasicString,
+
+    /// Anything else
+    Atom,
+
+    Eof,
+}
+
+impl TokenKind {
+    pub const fn description(&self) -> &'static str {
+        match self {
+            Self::Dot => "`.`",
+            Self::Equals => "`=`",
+            Self::Comma => "`,`",
+            Self::LeftSquareBracket => "`[`",
+            Self::RightSquareBracket => "`]`",
+            Self::LeftCurlyBracket => "`{`",
+            Self::RightCurlyBracket => "`}`",
+            Self::Whitespace => "whitespace",
+            Self::Comment => "comment",
+            Self::Newline => "newline",
+            Self::LiteralString => "literal string",
+            Self::BasicString => "basic string",
+            Self::MlLiteralString => "multi-line literal string",
+            Self::MlBasicString => "multi-line basic string",
+            Self::Atom => "token",
+            Self::Eof => "end-of-input",
+        }
+    }
+
+    pub fn encoding(&self) -> Option<Encoding> {
+        match self {
+            Self::LiteralString => Some(Encoding::LiteralString),
+            Self::BasicString => Some(Encoding::BasicString),
+            Self::MlLiteralString => Some(Encoding::MlLiteralString),
+            Self::MlBasicString => Some(Encoding::MlBasicString),
+            Self::Atom
+            | Self::LeftSquareBracket
+            | Self::RightSquareBracket
+            | Self::Dot
+            | Self::Equals
+            | Self::Comma
+            | Self::RightCurlyBracket
+            | Self::LeftCurlyBracket
+            | Self::Whitespace
+            | Self::Newline
+            | Self::Comment
+            | Self::Eof => None,
+        }
+    }
+}

vendor/toml_parser/src/lib.rs

@@ -0,0 +1,49 @@
+//! TOML lexer and parser
+//!
+//! Characteristics:
+//! - Error recovery
+//! - Lazy validation
+//! - `forbid(unsafe)` by default, requiring the `unsafe` feature otherwise
+//! - `no_std` support, including putting users in charge of allocation choices (including not
+//!   allocating)
+//!
+//! Full parsing is broken into three phases:
+//! 1. [Lexing tokens][lexer]
+//! 2. [Parsing tokens][parser] (push parser)
+//! 3. Organizing the physical layout into the logical layout,
+//!    including [decoding keys and values][decoder]
+
+#![cfg_attr(all(not(feature = "std"), not(test)), no_std)]
+#![cfg_attr(docsrs, feature(doc_cfg))]
+#![cfg_attr(not(feature = "unsafe"), forbid(unsafe_code))]
+#![warn(clippy::std_instead_of_core)]
+#![warn(clippy::std_instead_of_alloc)]
+#![warn(clippy::print_stderr)]
+#![warn(clippy::print_stdout)]
+
+#[cfg(feature = "alloc")]
+extern crate alloc;
+
+#[macro_use]
+mod macros;
+
+#[cfg(feature = "debug")]
+pub(crate) mod debug;
+mod error;
+mod source;
+
+pub mod decoder;
+pub mod lexer;
+pub mod parser;
+
+pub use error::ErrorSink;
+pub use error::Expected;
+pub use error::ParseError;
+pub use source::Raw;
+pub use source::Source;
+pub use source::SourceIndex;
+pub use source::Span;
+
+#[doc = include_str!("../README.md")]
+#[cfg(doctest)]
+pub struct ReadmeDoctests;

vendor/toml_parser/src/macros.rs

@@ -0,0 +1 @@
+

vendor/toml_parser/src/parser/event.rs

@@ -0,0 +1,543 @@
+use crate::ErrorSink;
+use crate::ParseError;
+use crate::Source;
+use crate::Span;
+use crate::decoder::Encoding;
+
+pub trait EventReceiver {
+    fn std_table_open(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    fn std_table_close(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    fn array_table_open(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    fn array_table_close(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    /// Returns if entering the inline table is allowed
+    #[must_use]
+    fn inline_table_open(&mut self, _span: Span, _error: &mut dyn ErrorSink) -> bool {
+        true
+    }
+    fn inline_table_close(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    /// Returns if entering the array is allowed
+    #[must_use]
+    fn array_open(&mut self, _span: Span, _error: &mut dyn ErrorSink) -> bool {
+        true
+    }
+    fn array_close(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    fn simple_key(&mut self, _span: Span, _kind: Option<Encoding>, _error: &mut dyn ErrorSink) {}
+    fn key_sep(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    fn key_val_sep(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    fn scalar(&mut self, _span: Span, _kind: Option<Encoding>, _error: &mut dyn ErrorSink) {}
+    fn value_sep(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    fn whitespace(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    fn comment(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    fn newline(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+    fn error(&mut self, _span: Span, _error: &mut dyn ErrorSink) {}
+}
+
+impl<F> EventReceiver for F
+where
+    F: FnMut(Event),
+{
+    fn std_table_open(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::StdTableOpen,
+            encoding: None,
+            span,
+        });
+    }
+    fn std_table_close(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::StdTableClose,
+            encoding: None,
+            span,
+        });
+    }
+    fn array_table_open(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::ArrayTableOpen,
+            encoding: None,
+            span,
+        });
+    }
+    fn array_table_close(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::ArrayTableClose,
+            encoding: None,
+            span,
+        });
+    }
+    fn inline_table_open(&mut self, span: Span, _error: &mut dyn ErrorSink) -> bool {
+        (self)(Event {
+            kind: EventKind::InlineTableOpen,
+            encoding: None,
+            span,
+        });
+        true
+    }
+    fn inline_table_close(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::InlineTableClose,
+            encoding: None,
+            span,
+        });
+    }
+    fn array_open(&mut self, span: Span, _error: &mut dyn ErrorSink) -> bool {
+        (self)(Event {
+            kind: EventKind::ArrayOpen,
+            encoding: None,
+            span,
+        });
+        true
+    }
+    fn array_close(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::ArrayClose,
+            encoding: None,
+            span,
+        });
+    }
+    fn simple_key(&mut self, span: Span, encoding: Option<Encoding>, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::SimpleKey,
+            encoding,
+            span,
+        });
+    }
+    fn key_sep(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::KeySep,
+            encoding: None,
+            span,
+        });
+    }
+    fn key_val_sep(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::KeyValSep,
+            encoding: None,
+            span,
+        });
+    }
+    fn scalar(&mut self, span: Span, encoding: Option<Encoding>, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::Scalar,
+            encoding,
+            span,
+        });
+    }
+    fn value_sep(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::ValueSep,
+            encoding: None,
+            span,
+        });
+    }
+    fn whitespace(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::Whitespace,
+            encoding: None,
+            span,
+        });
+    }
+    fn comment(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::Comment,
+            encoding: None,
+            span,
+        });
+    }
+    fn newline(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::Newline,
+            encoding: None,
+            span,
+        });
+    }
+    fn error(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        (self)(Event {
+            kind: EventKind::Error,
+            encoding: None,
+            span,
+        });
+    }
+}
+
+#[cfg(feature = "alloc")]
+#[allow(unused_qualifications)]
+impl EventReceiver for alloc::vec::Vec<Event> {
+    fn std_table_open(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::StdTableOpen,
+            encoding: None,
+            span,
+        });
+    }
+    fn std_table_close(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::StdTableClose,
+            encoding: None,
+            span,
+        });
+    }
+    fn array_table_open(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::ArrayTableOpen,
+            encoding: None,
+            span,
+        });
+    }
+    fn array_table_close(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::ArrayTableClose,
+            encoding: None,
+            span,
+        });
+    }
+    fn inline_table_open(&mut self, span: Span, _error: &mut dyn ErrorSink) -> bool {
+        self.push(Event {
+            kind: EventKind::InlineTableOpen,
+            encoding: None,
+            span,
+        });
+        true
+    }
+    fn inline_table_close(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::InlineTableClose,
+            encoding: None,
+            span,
+        });
+    }
+    fn array_open(&mut self, span: Span, _error: &mut dyn ErrorSink) -> bool {
+        self.push(Event {
+            kind: EventKind::ArrayOpen,
+            encoding: None,
+            span,
+        });
+        true
+    }
+    fn array_close(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::ArrayClose,
+            encoding: None,
+            span,
+        });
+    }
+    fn simple_key(&mut self, span: Span, encoding: Option<Encoding>, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::SimpleKey,
+            encoding,
+            span,
+        });
+    }
+    fn key_sep(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::KeySep,
+            encoding: None,
+            span,
+        });
+    }
+    fn key_val_sep(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::KeyValSep,
+            encoding: None,
+            span,
+        });
+    }
+    fn scalar(&mut self, span: Span, encoding: Option<Encoding>, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::Scalar,
+            encoding,
+            span,
+        });
+    }
+    fn value_sep(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::ValueSep,
+            encoding: None,
+            span,
+        });
+    }
+    fn whitespace(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::Whitespace,
+            encoding: None,
+            span,
+        });
+    }
+    fn comment(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::Comment,
+            encoding: None,
+            span,
+        });
+    }
+    fn newline(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::Newline,
+            encoding: None,
+            span,
+        });
+    }
+    fn error(&mut self, span: Span, _error: &mut dyn ErrorSink) {
+        self.push(Event {
+            kind: EventKind::Error,
+            encoding: None,
+            span,
+        });
+    }
+}
+
+impl EventReceiver for () {}
+
+/// Centralize validation for all whitespace-like content
+pub struct ValidateWhitespace<'r, 's> {
+    receiver: &'r mut dyn EventReceiver,
+    source: Source<'s>,
+}
+
+impl<'r, 's> ValidateWhitespace<'r, 's> {
+    pub fn new(receiver: &'r mut dyn EventReceiver, source: Source<'s>) -> Self {
+        Self { receiver, source }
+    }
+}
+
+impl EventReceiver for ValidateWhitespace<'_, '_> {
+    fn std_table_open(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.std_table_open(span, error);
+    }
+    fn std_table_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.std_table_close(span, error);
+    }
+    fn array_table_open(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.array_table_open(span, error);
+    }
+    fn array_table_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.array_table_close(span, error);
+    }
+    fn inline_table_open(&mut self, span: Span, error: &mut dyn ErrorSink) -> bool {
+        self.receiver.inline_table_open(span, error)
+    }
+    fn inline_table_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.inline_table_close(span, error);
+    }
+    fn array_open(&mut self, span: Span, error: &mut dyn ErrorSink) -> bool {
+        self.receiver.array_open(span, error)
+    }
+    fn array_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.array_close(span, error);
+    }
+    fn simple_key(&mut self, span: Span, encoding: Option<Encoding>, error: &mut dyn ErrorSink) {
+        self.receiver.simple_key(span, encoding, error);
+    }
+    fn key_sep(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.key_sep(span, error);
+    }
+    fn key_val_sep(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.key_val_sep(span, error);
+    }
+    fn scalar(&mut self, span: Span, encoding: Option<Encoding>, error: &mut dyn ErrorSink) {
+        self.receiver.scalar(span, encoding, error);
+    }
+    fn value_sep(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.value_sep(span, error);
+    }
+    fn whitespace(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        #[cfg(feature = "unsafe")] // SAFETY: callers must use valid span
+        let raw = unsafe { self.source.get_unchecked(span) };
+        #[cfg(not(feature = "unsafe"))]
+        let raw = self.source.get(span).expect("token spans are valid");
+        raw.decode_whitespace(error);
+
+        self.receiver.whitespace(span, error);
+    }
+    fn comment(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        #[cfg(feature = "unsafe")] // SAFETY: callers must use valid span
+        let raw = unsafe { self.source.get_unchecked(span) };
+        #[cfg(not(feature = "unsafe"))]
+        let raw = self.source.get(span).expect("token spans are valid");
+        raw.decode_comment(error);
+
+        self.receiver.comment(span, error);
+    }
+    fn newline(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        #[cfg(feature = "unsafe")] // SAFETY: callers must use valid span
+        let raw = unsafe { self.source.get_unchecked(span) };
+        #[cfg(not(feature = "unsafe"))]
+        let raw = self.source.get(span).expect("token spans are valid");
+        raw.decode_newline(error);
+
+        self.receiver.newline(span, error);
+    }
+    fn error(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.error(span, error);
+    }
+}
+
+pub struct RecursionGuard<'r> {
+    receiver: &'r mut dyn EventReceiver,
+    max_depth: u32,
+    depth: i64,
+}
+
+impl<'r> RecursionGuard<'r> {
+    pub fn new(receiver: &'r mut dyn EventReceiver, max_depth: u32) -> Self {
+        Self {
+            receiver,
+            max_depth,
+            depth: 0,
+        }
+    }
+
+    fn within_depth(&self) -> bool {
+        self.depth <= self.max_depth as i64
+    }
+}
+
+impl EventReceiver for RecursionGuard<'_> {
+    fn std_table_open(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.std_table_open(span, error);
+    }
+    fn std_table_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.std_table_close(span, error);
+    }
+    fn array_table_open(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.array_table_open(span, error);
+    }
+    fn array_table_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.array_table_close(span, error);
+    }
+    fn inline_table_open(&mut self, span: Span, error: &mut dyn ErrorSink) -> bool {
+        let allowed = self.receiver.inline_table_open(span, error);
+        self.depth += 1;
+        let within_depth = self.within_depth();
+        if allowed && !within_depth {
+            error.report_error(
+                ParseError::new("cannot recurse further; max recursion depth met")
+                    .with_unexpected(span),
+            );
+        }
+        allowed && within_depth
+    }
+    fn inline_table_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.depth -= 1;
+        self.receiver.inline_table_close(span, error);
+    }
+    fn array_open(&mut self, span: Span, error: &mut dyn ErrorSink) -> bool {
+        let allowed = self.receiver.array_open(span, error);
+        self.depth += 1;
+        let within_depth = self.within_depth();
+        if allowed && !within_depth {
+            error.report_error(
+                ParseError::new("cannot recurse further; max recursion depth met")
+                    .with_unexpected(span),
+            );
+        }
+        allowed && within_depth
+    }
+    fn array_close(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.depth -= 1;
+        self.receiver.array_close(span, error);
+    }
+    fn simple_key(&mut self, span: Span, encoding: Option<Encoding>, error: &mut dyn ErrorSink) {
+        self.receiver.simple_key(span, encoding, error);
+    }
+    fn key_sep(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.key_sep(span, error);
+    }
+    fn key_val_sep(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.key_val_sep(span, error);
+    }
+    fn scalar(&mut self, span: Span, encoding: Option<Encoding>, error: &mut dyn ErrorSink) {
+        self.receiver.scalar(span, encoding, error);
+    }
+    fn value_sep(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.value_sep(span, error);
+    }
+    fn whitespace(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.whitespace(span, error);
+    }
+    fn comment(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.comment(span, error);
+    }
+    fn newline(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.newline(span, error);
+    }
+    fn error(&mut self, span: Span, error: &mut dyn ErrorSink) {
+        self.receiver.error(span, error);
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub struct Event {
+    kind: EventKind,
+    encoding: Option<Encoding>,
+    span: Span,
+}
+
+impl Event {
+    pub fn new_unchecked(kind: EventKind, encoding: Option<Encoding>, span: Span) -> Self {
+        Self {
+            kind,
+            encoding,
+            span,
+        }
+    }
+
+    #[inline(always)]
+    pub fn kind(&self) -> EventKind {
+        self.kind
+    }
+
+    #[inline(always)]
+    pub fn encoding(&self) -> Option<Encoding> {
+        self.encoding
+    }
+
+    #[inline(always)]
+    pub fn span(&self) -> Span {
+        self.span
+    }
+}
+
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub enum EventKind {
+    StdTableOpen,
+    StdTableClose,
+    ArrayTableOpen,
+    ArrayTableClose,
+    InlineTableOpen,
+    InlineTableClose,
+    ArrayOpen,
+    ArrayClose,
+    SimpleKey,
+    KeySep,
+    KeyValSep,
+    Scalar,
+    ValueSep,
+    Whitespace,
+    Comment,
+    Newline,
+    Error,
+}
+
+impl EventKind {
+    pub const fn description(&self) -> &'static str {
+        match self {
+            Self::StdTableOpen => "std-table open",
+            Self::StdTableClose => "std-table close",
+            Self::ArrayTableOpen => "array-table open",
+            Self::ArrayTableClose => "array-table close",
+            Self::InlineTableOpen => "inline-table open",
+            Self::InlineTableClose => "inline-table close",
+            Self::ArrayOpen => "array open",
+            Self::ArrayClose => "array close",
+            Self::SimpleKey => "key",
+            Self::KeySep => "key separator",
+            Self::KeyValSep => "key-value separator",
+            Self::Scalar => "value",
+            Self::ValueSep => "value separator",
+            Self::Whitespace => "whitespace",
+            Self::Comment => "comment",
+            Self::Newline => "newline",
+            Self::Error => "error",
+        }
+    }
+}

vendor/toml_parser/src/parser/mod.rs

@@ -0,0 +1,16 @@
+//! A TOML push [parser][parse_document]
+//!
+//! This takes TOML [tokens][crate::lexer::Token] and [emits][EventReceiver] [events][Event].
+
+mod document;
+mod event;
+
+pub use document::parse_document;
+pub use document::parse_key;
+pub use document::parse_simple_key;
+pub use document::parse_value;
+pub use event::Event;
+pub use event::EventKind;
+pub use event::EventReceiver;
+pub use event::RecursionGuard;
+pub use event::ValidateWhitespace;

vendor/toml_parser/src/source.rs

@@ -0,0 +1,394 @@
+use crate::ErrorSink;
+use crate::Expected;
+use crate::decoder::Encoding;
+use crate::decoder::StringBuilder;
+use crate::lexer::Lexer;
+
+/// Data encoded as TOML
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub struct Source<'i> {
+    input: &'i str,
+}
+
+impl<'i> Source<'i> {
+    pub fn new(input: &'i str) -> Self {
+        Self { input }
+    }
+
+    /// Start lexing the TOML encoded data
+    pub fn lex(&self) -> Lexer<'i> {
+        Lexer::new(self.input)
+    }
+
+    /// Access the TOML encoded `&str`
+    pub fn input(&self) -> &'i str {
+        self.input
+    }
+
+    /// Return a subslice of the input
+    pub fn get(&self, span: impl SourceIndex) -> Option<Raw<'i>> {
+        span.get(self)
+    }
+
+    /// Return an unchecked subslice of the input
+    ///
+    /// ## Safety
+    ///
+    /// Callers of this function are responsible that these preconditions are satisfied:
+    /// - The starting index must not exceed the ending index;
+    /// - Indexes must be within bounds of the original slice;
+    /// - Indexes must lie on UTF-8 sequence boundaries.
+    ///
+    /// Or one of:
+    /// - `span` came from [`Source::lex`]
+    ///
+    /// Failing any of those, the returned string slice may reference invalid memory or violate the invariants communicated by `str` type.
+    #[cfg(feature = "unsafe")]
+    pub unsafe fn get_unchecked(&self, span: impl SourceIndex) -> Raw<'i> {
+        // SAFETY: Same safety guarantees are required
+        unsafe { span.get_unchecked(self) }
+    }
+
+    /// Return a subslice of the input
+    fn get_raw_str(&self, span: Span) -> Option<&'i str> {
+        let index = span.start()..span.end();
+        self.input.get(index)
+    }
+
+    /// Return an unchecked subslice of the input
+    ///
+    /// ## Safety
+    ///
+    /// Callers of this function are responsible that these preconditions are satisfied:
+    /// - The starting index must not exceed the ending index;
+    /// - Indexes must be within bounds of the original slice;
+    /// - Indexes must lie on UTF-8 sequence boundaries.
+    ///
+    /// Or one of:
+    /// - `span` came from [`Source::lex`]
+    ///
+    /// Failing any of those, the returned string slice may reference invalid memory or violate the invariants communicated by `str` type.
+    #[cfg(feature = "unsafe")]
+    unsafe fn get_raw_str_unchecked(&self, span: Span) -> &'i str {
+        let index = span.start()..span.end();
+        // SAFETY: Same safety guarantees are required
+        unsafe { self.input.get_unchecked(index) }
+    }
+}
+
+/// A slice of [`Source`]
+#[derive(Copy, Clone, Debug)]
+pub struct Raw<'i> {
+    raw: &'i str,
+    encoding: Option<Encoding>,
+    span: Span,
+}
+
+impl<'i> Raw<'i> {
+    pub fn new_unchecked(raw: &'i str, encoding: Option<Encoding>, span: Span) -> Self {
+        Self {
+            raw,
+            encoding,
+            span,
+        }
+    }
+
+    pub fn decode_key(&self, output: &mut dyn StringBuilder<'i>, error: &mut dyn ErrorSink) {
+        let mut error = |err: crate::ParseError| {
+            error.report_error(err.rebase_spans(self.span.start));
+        };
+        match self.encoding {
+            Some(Encoding::LiteralString) => {
+                crate::decoder::string::decode_literal_string(*self, output, &mut error);
+            }
+            Some(Encoding::BasicString) => {
+                crate::decoder::string::decode_basic_string(*self, output, &mut error);
+            }
+            Some(Encoding::MlLiteralString) => {
+                error.report_error(
+                    crate::ParseError::new("keys cannot be multi-line literal strings")
+                        .with_expected(&[
+                            Expected::Description("basic string"),
+                            Expected::Description("literal string"),
+                        ])
+                        .with_unexpected(Span::new_unchecked(0, self.len())),
+                );
+                crate::decoder::string::decode_ml_literal_string(*self, output, &mut error);
+            }
+            Some(Encoding::MlBasicString) => {
+                error.report_error(
+                    crate::ParseError::new("keys cannot be multi-line basic strings")
+                        .with_expected(&[
+                            Expected::Description("basic string"),
+                            Expected::Description("literal string"),
+                        ])
+                        .with_unexpected(Span::new_unchecked(0, self.len())),
+                );
+                crate::decoder::string::decode_ml_basic_string(*self, output, &mut error);
+            }
+            None => crate::decoder::string::decode_unquoted_key(*self, output, &mut error),
+        }
+    }
+
+    #[must_use]
+    pub fn decode_scalar(
+        &self,
+        output: &mut dyn StringBuilder<'i>,
+        error: &mut dyn ErrorSink,
+    ) -> crate::decoder::scalar::ScalarKind {
+        let mut error = |err: crate::ParseError| {
+            error.report_error(err.rebase_spans(self.span.start));
+        };
+        match self.encoding {
+            Some(Encoding::LiteralString) => {
+                crate::decoder::string::decode_literal_string(*self, output, &mut error);
+                crate::decoder::scalar::ScalarKind::String
+            }
+            Some(Encoding::BasicString) => {
+                crate::decoder::string::decode_basic_string(*self, output, &mut error);
+                crate::decoder::scalar::ScalarKind::String
+            }
+            Some(Encoding::MlLiteralString) => {
+                crate::decoder::string::decode_ml_literal_string(*self, output, &mut error);
+                crate::decoder::scalar::ScalarKind::String
+            }
+            Some(Encoding::MlBasicString) => {
+                crate::decoder::string::decode_ml_basic_string(*self, output, &mut error);
+                crate::decoder::scalar::ScalarKind::String
+            }
+            None => crate::decoder::scalar::decode_unquoted_scalar(*self, output, &mut error),
+        }
+    }
+
+    pub fn decode_whitespace(&self, _error: &mut dyn ErrorSink) {
+        // whitespace is always valid
+    }
+
+    pub fn decode_comment(&self, error: &mut dyn ErrorSink) {
+        let mut error = |err: crate::ParseError| {
+            error.report_error(err.rebase_spans(self.span.start));
+        };
+        crate::decoder::ws::decode_comment(*self, &mut error);
+    }
+
+    pub fn decode_newline(&self, error: &mut dyn ErrorSink) {
+        let mut error = |err: crate::ParseError| {
+            error.report_error(err.rebase_spans(self.span.start));
+        };
+        crate::decoder::ws::decode_newline(*self, &mut error);
+    }
+
+    pub fn as_str(&self) -> &'i str {
+        self.raw
+    }
+
+    pub fn as_bytes(&self) -> &'i [u8] {
+        self.raw.as_bytes()
+    }
+
+    pub fn len(&self) -> usize {
+        self.raw.len()
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.raw.is_empty()
+    }
+}
+
+/// Location within the [`Source`]
+#[derive(Copy, Clone, Default, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct Span {
+    start: usize,
+    end: usize,
+}
+
+impl Span {
+    pub fn new_unchecked(start: usize, end: usize) -> Self {
+        Self { start, end }
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.end <= self.start
+    }
+
+    pub fn len(&self) -> usize {
+        self.end - self.start
+    }
+
+    pub fn start(&self) -> usize {
+        self.start
+    }
+
+    pub fn end(&self) -> usize {
+        self.end
+    }
+
+    pub fn before(&self) -> Self {
+        Self::new_unchecked(self.start, self.start)
+    }
+
+    pub fn after(&self) -> Self {
+        Self::new_unchecked(self.end, self.end)
+    }
+
+    /// Extend this `Raw` to the end of `after`
+    #[must_use]
+    pub fn append(&self, after: Self) -> Self {
+        Self::new_unchecked(self.start, after.end)
+    }
+}
+
+impl core::fmt::Debug for Span {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        (self.start..self.end).fmt(f)
+    }
+}
+
+impl core::ops::Add<usize> for Span {
+    type Output = Self;
+
+    fn add(self, offset: usize) -> Self::Output {
+        Self::Output {
+            start: self.start + offset,
+            end: self.end + offset,
+        }
+    }
+}
+
+impl core::ops::Add<Span> for usize {
+    type Output = Span;
+
+    fn add(self, span: Span) -> Self::Output {
+        Self::Output {
+            start: span.start + self,
+            end: span.end + self,
+        }
+    }
+}
+
+impl core::ops::AddAssign<usize> for Span {
+    fn add_assign(&mut self, rhs: usize) {
+        self.start += rhs;
+        self.end += rhs;
+    }
+}
+
+/// A helper trait used for indexing operations on [`Source`]
+pub trait SourceIndex: sealed::Sealed {
+    /// Return a subslice of the input
+    fn get<'i>(self, source: &Source<'i>) -> Option<Raw<'i>>;
+
+    /// Return an unchecked subslice of the input
+    ///
+    /// ## Safety
+    ///
+    /// Callers of this function are responsible that these preconditions are satisfied:
+    /// - The starting index must not exceed the ending index;
+    /// - Indexes must be within bounds of the original slice;
+    /// - Indexes must lie on UTF-8 sequence boundaries.
+    ///
+    /// Or one of:
+    /// - `span` came from [`Source::lex`]
+    ///
+    /// Failing any of those, the returned string slice may reference invalid memory or violate the invariants communicated by `str` type.
+    #[cfg(feature = "unsafe")]
+    unsafe fn get_unchecked<'i>(self, source: &Source<'i>) -> Raw<'i>;
+}
+
+impl SourceIndex for Span {
+    fn get<'i>(self, source: &Source<'i>) -> Option<Raw<'i>> {
+        (&self).get(source)
+    }
+
+    #[cfg(feature = "unsafe")]
+    unsafe fn get_unchecked<'i>(self, source: &Source<'i>) -> Raw<'i> {
+        // SAFETY: Same safety guarantees are required
+        unsafe { (&self).get_unchecked(source) }
+    }
+}
+
+impl SourceIndex for &Span {
+    fn get<'i>(self, source: &Source<'i>) -> Option<Raw<'i>> {
+        let encoding = None;
+        source
+            .get_raw_str(*self)
+            .map(|s| Raw::new_unchecked(s, encoding, *self))
+    }
+
+    #[cfg(feature = "unsafe")]
+    unsafe fn get_unchecked<'i>(self, source: &Source<'i>) -> Raw<'i> {
+        let encoding = None;
+        // SAFETY: Same safety guarantees are required
+        let raw = unsafe { source.get_raw_str_unchecked(*self) };
+        Raw::new_unchecked(raw, encoding, *self)
+    }
+}
+
+impl SourceIndex for crate::lexer::Token {
+    fn get<'i>(self, source: &Source<'i>) -> Option<Raw<'i>> {
+        (&self).get(source)
+    }
+
+    #[cfg(feature = "unsafe")]
+    unsafe fn get_unchecked<'i>(self, source: &Source<'i>) -> Raw<'i> {
+        // SAFETY: Same safety guarantees are required
+        unsafe { (&self).get_unchecked(source) }
+    }
+}
+
+impl SourceIndex for &crate::lexer::Token {
+    fn get<'i>(self, source: &Source<'i>) -> Option<Raw<'i>> {
+        let encoding = self.kind().encoding();
+        source
+            .get_raw_str(self.span())
+            .map(|s| Raw::new_unchecked(s, encoding, self.span()))
+    }
+
+    #[cfg(feature = "unsafe")]
+    unsafe fn get_unchecked<'i>(self, source: &Source<'i>) -> Raw<'i> {
+        let encoding = self.kind().encoding();
+        // SAFETY: Same safety guarantees are required
+        let raw = unsafe { source.get_raw_str_unchecked(self.span()) };
+        Raw::new_unchecked(raw, encoding, self.span())
+    }
+}
+
+impl SourceIndex for crate::parser::Event {
+    fn get<'i>(self, source: &Source<'i>) -> Option<Raw<'i>> {
+        (&self).get(source)
+    }
+
+    #[cfg(feature = "unsafe")]
+    unsafe fn get_unchecked<'i>(self, source: &Source<'i>) -> Raw<'i> {
+        // SAFETY: Same safety guarantees are required
+        unsafe { (&self).get_unchecked(source) }
+    }
+}
+
+impl SourceIndex for &crate::parser::Event {
+    fn get<'i>(self, source: &Source<'i>) -> Option<Raw<'i>> {
+        let encoding = self.encoding();
+        source
+            .get_raw_str(self.span())
+            .map(|s| Raw::new_unchecked(s, encoding, self.span()))
+    }
+
+    #[cfg(feature = "unsafe")]
+    unsafe fn get_unchecked<'i>(self, source: &Source<'i>) -> Raw<'i> {
+        let encoding = self.encoding();
+        // SAFETY: Same safety guarantees are required
+        let raw = unsafe { source.get_raw_str_unchecked(self.span()) };
+        Raw::new_unchecked(raw, encoding, self.span())
+    }
+}
+
+mod sealed {
+    pub trait Sealed {}
+
+    impl Sealed for crate::Span {}
+    impl Sealed for &crate::Span {}
+    impl Sealed for crate::lexer::Token {}
+    impl Sealed for &crate::lexer::Token {}
+    impl Sealed for crate::parser::Event {}
+    impl Sealed for &crate::parser::Event {}
+}