parse segments before to_tokens
This commit is contained in:
Evan Almloff committed
1 parent
71eaafaa00
commit
f8143a5fc1
1 file changed
+136
-114
+136
-114
@@ -9,125 +9,16 @@ use proc_macro2::TokenStream;
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pub fn format_args_f_impl(input: IfmtInput) -> Result<TokenStream> {
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let IfmtInput {
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mut format_literal,
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mut positional_args,
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mut named_args,
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format_literal,
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positional_args,
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named_args,
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} = input;
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let s = format_literal.value();
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let out_format_literal = &mut String::with_capacity(s.len());
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let mut iterator = s.char_indices().peekable();
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while let Some((i, c)) = iterator.next() {
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out_format_literal.push(c);
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if c != '{' {
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continue;
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}
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// encountered `{`, let's see if it was `{{`
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if let Some(&(_, '{')) = iterator.peek() {
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let _ = iterator.next();
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out_format_literal.push('{');
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continue;
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}
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let (end, colon_or_closing_brace) =
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iterator
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.find(|&(_, c)| c == '}' || c == ':')
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.expect(concat!(
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"Invalid format string literal\n",
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"note: if you intended to print `{`, ",
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"you can escape it using `{{`",
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));
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// We use defer to ensure all the `continue`s append the closing char.
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let mut out_format_literal = defer(&mut *out_format_literal, |it| {
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it.push(colon_or_closing_brace)
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});
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let out_format_literal: &mut String = *out_format_literal;
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let mut arg = s[i + 1..end].trim();
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if let Some("=") = arg.get(arg.len().saturating_sub(1)..) {
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assert_eq!(
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out_format_literal.pop(), // Remove the opening brace
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Some('{'),
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);
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arg = &arg[..arg.len() - 1];
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out_format_literal.push_str(arg);
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out_format_literal.push_str(" = {");
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}
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if arg.is_empty() {
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continue;
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}
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enum Segment {
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Ident(Ident),
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LitInt(LitInt),
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}
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let segments: Vec<Segment> = {
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impl Parse for Segment {
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fn parse(input: ParseStream<'_>) -> Result<Self> {
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let lookahead = input.lookahead1();
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if lookahead.peek(Ident) {
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input.parse().map(Segment::Ident)
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} else if lookahead.peek(LitInt) {
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input.parse().map(Segment::LitInt)
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} else {
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Err(lookahead.error())
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}
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}
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}
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match ::syn::parse::Parser::parse_str(
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Punctuated::<Segment, Token![.]>::parse_separated_nonempty,
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arg,
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) {
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Ok(segments) => segments.into_iter().collect(),
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Err(err) => return Err(err),
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}
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};
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match segments.len() {
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0 => unreachable!("`parse_separated_nonempty` returned empty"),
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1 => {
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out_format_literal.push_str(arg);
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match { segments }.pop().unwrap() {
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Segment::LitInt(_) => {
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// found something like `{0}`, let `format_args!`
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// handle it.
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continue;
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}
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Segment::Ident(ident) => {
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// if `ident = ...` is not yet among the extra args
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if named_args.iter().all(|(it, _)| *it != ident) {
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named_args.push((
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ident.clone(),
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parse_quote!(#ident), // Expr
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));
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}
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}
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}
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}
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_ => {
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::std::fmt::Write::write_fmt(
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out_format_literal,
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format_args!("{}", positional_args.len()),
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)
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.expect("`usize` or `char` Display impl cannot panic");
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let segments: Punctuated<TokenStream, Token![.]> = segments
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.into_iter()
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.map(|it| match it {
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Segment::Ident(ident) => ident.into_token_stream(),
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Segment::LitInt(literal) => literal.into_token_stream(),
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})
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.collect();
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positional_args.push(parse_quote! {
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#segments
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})
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}
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}
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}
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let named_args = named_args.into_iter().map(|(ident, expr)| {
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quote! {
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#ident = #expr
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}
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});
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format_literal = LitStr::new(out_format_literal, format_literal.span());
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Ok(quote! {
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format_args!(
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@@ -139,14 +30,138 @@ pub fn format_args_f_impl(input: IfmtInput) -> Result<TokenStream> {
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}
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#[allow(dead_code)] // dumb compiler does not see the struct being used...
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#[derive(Debug)]
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pub struct IfmtInput {
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pub format_literal: LitStr,
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pub positional_args: Vec<Expr>,
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pub named_args: Vec<(Ident, Expr)>,
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}
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impl Parse for IfmtInput {
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fn parse(input: ParseStream) -> Result<Self> {
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impl IfmtInput {
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fn parse_segments(self) -> Result<Self> {
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let IfmtInput {
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mut format_literal,
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mut positional_args,
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mut named_args,
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} = self;
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let s = format_literal.value();
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let out_format_literal = &mut String::with_capacity(s.len());
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let mut iterator = s.char_indices().peekable();
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while let Some((i, c)) = iterator.next() {
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out_format_literal.push(c);
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if c != '{' {
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continue;
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}
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// encountered `{`, let's see if it was `{{`
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if let Some(&(_, '{')) = iterator.peek() {
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let _ = iterator.next();
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out_format_literal.push('{');
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continue;
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}
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let (end, colon_or_closing_brace) = iterator
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.find(|&(_, c)| c == '}' || c == ':')
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.expect(concat!(
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"Invalid format string literal\n",
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"note: if you intended to print `{`, ",
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"you can escape it using `{{`",
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));
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// We use defer to ensure all the `continue`s append the closing char.
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let mut out_format_literal = defer(&mut *out_format_literal, |it| {
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it.push(colon_or_closing_brace)
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});
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let out_format_literal: &mut String = *out_format_literal;
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let mut arg = s[i + 1..end].trim();
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if let Some("=") = arg.get(arg.len().saturating_sub(1)..) {
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assert_eq!(
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out_format_literal.pop(), // Remove the opening brace
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Some('{'),
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);
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arg = &arg[..arg.len() - 1];
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out_format_literal.push_str(arg);
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out_format_literal.push_str(" = {");
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}
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if arg.is_empty() {
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continue;
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}
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#[derive(Debug)]
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enum Segment {
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Ident(Ident),
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LitInt(LitInt),
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}
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let segments: Vec<Segment> = {
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impl Parse for Segment {
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fn parse(input: ParseStream<'_>) -> Result<Self> {
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let lookahead = input.lookahead1();
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if lookahead.peek(Ident) {
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input.parse().map(Segment::Ident)
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} else if lookahead.peek(LitInt) {
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input.parse().map(Segment::LitInt)
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} else {
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Err(lookahead.error())
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}
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}
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}
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match ::syn::parse::Parser::parse_str(
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Punctuated::<Segment, Token![.]>::parse_separated_nonempty,
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arg,
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) {
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Ok(segments) => segments.into_iter().collect(),
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Err(err) => return Err(err),
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}
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};
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match segments.len() {
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0 => unreachable!("`parse_separated_nonempty` returned empty"),
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1 => {
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out_format_literal.push_str(arg);
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match { segments }.pop().unwrap() {
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Segment::LitInt(_) => {
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// found something like `{0}`, let `format_args!`
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// handle it.
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continue;
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}
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Segment::Ident(ident) => {
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// if `ident = ...` is not yet among the extra args
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if named_args.iter().all(|(it, _)| *it != ident) {
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named_args.push((
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ident.clone(),
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parse_quote!(#ident), // Expr
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));
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}
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}
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}
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}
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_ => {
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::std::fmt::Write::write_fmt(
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out_format_literal,
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format_args!("{}", positional_args.len()),
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)
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.expect("`usize` or `char` Display impl cannot panic");
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let segments: Punctuated<TokenStream, Token![.]> = segments
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.into_iter()
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.map(|it| match it {
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Segment::Ident(ident) => ident.into_token_stream(),
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Segment::LitInt(literal) => literal.into_token_stream(),
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})
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.collect();
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positional_args.push(parse_quote! {
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#segments
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})
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}
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}
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}
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format_literal = LitStr::new(out_format_literal, format_literal.span());
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Ok(Self {
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format_literal,
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positional_args,
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named_args,
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})
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}
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fn parse_positional_args(input: ParseStream) -> Result<Self> {
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let format_literal = input.parse()?;
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let mut positional_args = vec![];
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loop {
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@@ -173,6 +188,7 @@ impl Parse for IfmtInput {
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})?
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.into_iter()
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.collect();
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Ok(Self {
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format_literal,
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positional_args,
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@@ -181,6 +197,12 @@ impl Parse for IfmtInput {
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}
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}
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impl Parse for IfmtInput {
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fn parse(input: ParseStream) -> Result<Self> {
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Self::parse_positional_args(input).and_then(|new| new.parse_segments())
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}
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}
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pub fn defer<'a, T: 'a, Drop: 'a>(x: T, drop: Drop) -> impl ::core::ops::DerefMut<Target = T> + 'a
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where
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Drop: FnOnce(T),
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