Ensure template is recompiled when template file changes (#65)

Author: casey

crates/boilerplate-macros/src/implementation.rs

@@ -3,7 +3,6 @@ use super::*;
 pub(crate) struct Implementation<'src> {
   pub(crate) body: TokenStream,
   pub(crate) text: Vec<&'src str>,
-  pub(crate) tokens: Vec<Token<'src>>,
 }
 
 impl<'src> Implementation<'src> {
@@ -48,6 +47,6 @@ impl<'src> Implementation<'src> {
       .parse()
       .unwrap();
 
-    Self { body, text, tokens }
+    Self { body, text }
   }
 }

crates/boilerplate-macros/src/lib.rs

@@ -6,7 +6,7 @@ use {
   darling::FromDeriveInput,
   new_mime_guess::Mime,
   proc_macro2::{Span, TokenStream},
-  quote::quote,
+  quote::{quote, ToTokens, TokenStreamExt},
   std::path::Path,
   syn::{parse_macro_input, DeriveInput, Generics, Ident, LitStr},
 };
@@ -21,7 +21,7 @@ pub fn boilerplate(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
   let template = parse_macro_input!(input as LitStr);
   let src = template.value();
 
-  let Implementation { body, text, .. } = Implementation::parse(&src, false, true);
+  let Implementation { body, text } = Implementation::parse(&src, false, true);
 
   quote! {
     {

crates/boilerplate-macros/src/source.rs

@@ -14,3 +14,15 @@ impl Source {
     }
   }
 }
+
+impl ToTokens for Source {
+  fn to_tokens(&self, tokens: &mut TokenStream) {
+    match self {
+      Self::Literal(literal) => tokens.append(literal.token()),
+      Self::Path(path) => {
+        let path = LitStr::new(path, Span::call_site());
+        tokens.append_all(quote!(include_str!(#path)));
+      }
+    }
+  }
+}

crates/boilerplate-macros/src/template.rs

@@ -30,38 +30,10 @@ impl Template {
     let source = &self.source;
     let src = source.src();
 
-    let Implementation { body, text, tokens } = Implementation::parse(&src, self.escape, false);
+    let Implementation { body, text } = Implementation::parse(&src, self.escape, false);
 
     let (impl_generics, ty_generics, where_clause) = self.generics.split_for_impl();
 
-    let tokens = if cfg!(feature = "reload") {
-      let tokens = tokens
-        .into_iter()
-        .map(|token| match token {
-          Token::Code { contents } => quote!(::boilerplate::Token::Code { contents: #contents }),
-          Token::CodeLine { closed, contents } => {
-            quote!(::boilerplate::Token::CodeLine { closed: #closed, contents: #contents })
-          }
-          Token::Interpolation { contents } => {
-            quote!(::boilerplate::Token::Interpolation { contents: #contents })
-          }
-          Token::InterpolationLine { contents, closed } => {
-            quote!(::boilerplate::Token::InterpolationLine { closed: #closed, contents: #contents })
-          }
-          Token::Text { contents, index } => quote!(::boilerplate::Token::Text {
-            contents: #contents,
-            index: #index
-          }),
-        })
-        .collect::<Vec<TokenStream>>();
-
-      Some(quote! {
-        const TOKENS: &'static [::boilerplate::Token<'static>] = &[ #(#tokens),* ];
-      })
-    } else {
-      None
-    };
-
     let path = if cfg!(feature = "reload") {
       if let Source::Path(path) = &self.source {
         Some(quote!(const PATH: Option<&'static str> = Some(#path);))
@@ -76,9 +48,9 @@ impl Template {
 
     quote! {
       impl #impl_generics ::boilerplate::Boilerplate for #ident #ty_generics #where_clause {
-        const TEXT: &'static [&'static str] = &[ #(#text),* ];
+        const TEMPLATE: &'static str = #source;
 
-        #tokens
+        const TEXT: &'static [&'static str] = &[ #(#text),* ];
 
         #path
 
@@ -132,16 +104,6 @@ mod tests {
 
   #[test]
   fn display_impl() {
-    let tokens = if cfg!(feature = "reload") {
-      Some(quote! {
-        const TOKENS: &'static [::boilerplate::Token<'static>] = &[
-          ::boilerplate::Token::Text { contents: "", index: 0usize }
-        ];
-      })
-    } else {
-      None
-    };
-
     let path = if cfg!(feature = "reload") {
       Some(quote!(
         const PATH: Option<&'static str> = None;
@@ -175,9 +137,9 @@ mod tests {
       .to_string(),
       quote!(
         impl ::boilerplate::Boilerplate for Foo {
-            const TEXT: &'static [&'static str] = &[#text];
+            const TEMPLATE: &'static str = "";
 
-            #tokens
+            const TEXT: &'static [&'static str] = &[#text];
 
             #path
 

src/lib.rs

@@ -703,13 +703,12 @@ mod reload;
 /// The boilerplate trait, automatically implemented by the `Boilerplate`
 /// derive macro.
 pub trait Boilerplate {
+  /// The original template.
+  const TEMPLATE: &'static str;
+
   /// The parsed template's text blocks.
   const TEXT: &'static [&'static str];
 
-  #[cfg(feature = "reload")]
-  /// The parsed template's tokens.
-  const TOKENS: &'static [Token<'static>];
-
   #[cfg(feature = "reload")]
   /// Path to the original template file.
   const PATH: Option<&'static str>;
@@ -734,16 +733,17 @@ pub trait Boilerplate {
   ///
   /// - `src` - The new template source text.
   fn reload(&self, src: &str) -> Result<Reload<&Self>, Error> {
-    let tokens = Token::parse(src).map_err(Error::Parse)?;
+    let new = Token::parse(src).map_err(Error::ParseNew)?;
+    let old = Token::parse(Self::TEMPLATE).map_err(Error::ParseOld)?;
 
-    if tokens.len() != Self::TOKENS.len() {
+    if new.len() != old.len() {
       return Err(Error::Length {
-        new: tokens.len(),
-        old: Self::TOKENS.len(),
+        new: new.len(),
+        old: old.len(),
       });
     }
 
-    for (new, old) in tokens.iter().copied().zip(Self::TOKENS.iter().copied()) {
+    for (new, old) in new.iter().zip(old) {
       if !new.is_compatible_with(old) {
         return Err(Error::Incompatible {
           new: new.to_string(),
@@ -754,7 +754,7 @@ pub trait Boilerplate {
 
     Ok(Reload {
       inner: self,
-      text: tokens
+      text: new
         .into_iter()
         .filter_map(Token::text)
         .map(ToOwned::to_owned)

src/reload.rs

@@ -28,7 +28,9 @@ pub enum Error {
   /// New template does not have the same number of blocks.
   Length { new: usize, old: usize },
   /// Failed to parse new template.
-  Parse(boilerplate_parser::Error),
+  ParseNew(boilerplate_parser::Error),
+  /// Failed to parse old template.
+  ParseOld(boilerplate_parser::Error),
   /// Template has no path
   Path,
 }
@@ -44,7 +46,8 @@ impl Display for Error {
         f,
         "new template has {new} blocks but old template has {old} blocks",
       ),
-      Self::Parse(err) => write!(f, "failed to parse new template: {err}"),
+      Self::ParseNew(err) => write!(f, "failed to parse new template: {err}"),
+      Self::ParseOld(err) => write!(f, "failed to parse old template: {err}"),
       Self::Path => write!(f, "template has no path"),
     }
   }