parse segments before to_tokens

packages/rsx/src/ifmt.rs

@@ -8,11 +8,42 @@ use ::syn::{
 use proc_macro2::TokenStream;
 
 pub fn format_args_f_impl(input: IfmtInput) -> Result<TokenStream> {
+    let IfmtInput {
+        format_literal,
+        positional_args,
+        named_args,
+    } = input;
+
+    let named_args = named_args.into_iter().map(|(ident, expr)| {
+        quote! {
+            #ident = #expr
+        }
+    });
+
+    Ok(quote! {
+        format_args!(
+            #format_literal
+            #(, #positional_args)*
+            #(, #named_args)*
+        )
+    })
+}
+
+#[allow(dead_code)] // dumb compiler does not see the struct being used...
+#[derive(Debug)]
+pub struct IfmtInput {
+    pub format_literal: LitStr,
+    pub positional_args: Vec<Expr>,
+    pub named_args: Vec<(Ident, Expr)>,
+}
+
+impl IfmtInput {
+    fn parse_segments(self) -> Result<Self> {
         let IfmtInput {
             mut format_literal,
             mut positional_args,
             mut named_args,
-    } = input;
+        } = self;
 
         let s = format_literal.value();
         let out_format_literal = &mut String::with_capacity(s.len());
@@ -29,8 +60,7 @@ pub fn format_args_f_impl(input: IfmtInput) -> Result<TokenStream> {
                 out_format_literal.push('{');
                 continue;
             }
-        let (end, colon_or_closing_brace) =
-            iterator
+            let (end, colon_or_closing_brace) = iterator
                 .find(|&(_, c)| c == '}' || c == ':')
                 .expect(concat!(
                     "Invalid format string literal\n",
@@ -56,6 +86,7 @@ pub fn format_args_f_impl(input: IfmtInput) -> Result<TokenStream> {
                 continue;
             }
 
+            #[derive(Debug)]
             enum Segment {
                 Ident(Ident),
                 LitInt(LitInt),
@@ -121,32 +152,16 @@ pub fn format_args_f_impl(input: IfmtInput) -> Result<TokenStream> {
                 }
             }
         }
-
-    let named_args = named_args.into_iter().map(|(ident, expr)| {
-        quote! {
-            #ident = #expr
-        }
-    });
         format_literal = LitStr::new(out_format_literal, format_literal.span());
 
-    Ok(quote! {
-        format_args!(
-            #format_literal
-            #(, #positional_args)*
-            #(, #named_args)*
-        )
+        Ok(Self {
+            format_literal,
+            positional_args,
+            named_args,
         })
     }
 
-#[allow(dead_code)] // dumb compiler does not see the struct being used...
-pub struct IfmtInput {
-    pub format_literal: LitStr,
-    pub positional_args: Vec<Expr>,
-    pub named_args: Vec<(Ident, Expr)>,
-}
-
-impl Parse for IfmtInput {
-    fn parse(input: ParseStream) -> Result<Self> {
+    fn parse_positional_args(input: ParseStream) -> Result<Self> {
         let format_literal = input.parse()?;
         let mut positional_args = vec![];
         loop {
@@ -173,6 +188,7 @@ impl Parse for IfmtInput {
         })?
         .into_iter()
         .collect();
+
         Ok(Self {
             format_literal,
             positional_args,
@@ -181,6 +197,12 @@ impl Parse for IfmtInput {
     }
 }
 
+impl Parse for IfmtInput {
+    fn parse(input: ParseStream) -> Result<Self> {
+        Self::parse_positional_args(input).and_then(|new| new.parse_segments())
+    }
+}
+
 pub fn defer<'a, T: 'a, Drop: 'a>(x: T, drop: Drop) -> impl ::core::ops::DerefMut<Target = T> + 'a
 where
     Drop: FnOnce(T),