perf: write_to_string

Author: SyMind

src/cached_source.rs

@@ -128,6 +128,10 @@ impl Source for CachedSource {
     }
   }
 
+  fn write_to_string(&self, string: &mut String) {
+    self.inner.write_to_string(string);
+  }
+
   fn to_writer(&self, writer: &mut dyn std::io::Write) -> std::io::Result<()> {
     self.inner.to_writer(writer)
   }

src/concat_source.rs

@@ -167,7 +167,11 @@ impl Source for ConcatSource {
     if children.len() == 1 {
       children[0].source()
     } else {
-      SourceValue::String(Cow::Owned(self.rope().join("")))
+      // Use to_writer to avoid multiple heap allocations that would occur
+      // when concatenating nested ConcatSource instances directly
+      let mut string = String::with_capacity(self.size());
+      self.write_to_string(&mut string);
+      SourceValue::String(Cow::Owned(string))
     }
   }
 
@@ -214,6 +218,12 @@ impl Source for ConcatSource {
     result
   }
 
+  fn write_to_string(&self, string: &mut String) {
+    for child in self.optimized_children() {
+      child.write_to_string(string);
+    }
+  }
+
   fn to_writer(&self, writer: &mut dyn std::io::Write) -> std::io::Result<()> {
     for child in self.optimized_children() {
       child.to_writer(writer)?;

src/original_source.rs

@@ -77,6 +77,10 @@ impl Source for OriginalSource {
     get_map(object_pool, chunks.as_ref(), options)
   }
 
+  fn write_to_string(&self, string: &mut String) {
+    string.push_str(self.value.as_ref());
+  }
+
   fn to_writer(&self, writer: &mut dyn std::io::Write) -> std::io::Result<()> {
     writer.write_all(self.value.as_bytes())
   }

src/raw_source.rs

@@ -80,6 +80,10 @@ impl Source for RawStringSource {
     None
   }
 
+  fn write_to_string(&self, string: &mut String) {
+    string.push_str(self.0.as_ref());
+  }
+
   fn to_writer(&self, writer: &mut dyn std::io::Write) -> std::io::Result<()> {
     writer.write_all(self.0.as_bytes())
   }
@@ -226,6 +230,10 @@ impl Source for RawBufferSource {
     None
   }
 
+  fn write_to_string(&self, string: &mut String) {
+    string.push_str(self.get_or_init_value_as_string());
+  }
+
   fn to_writer(&self, writer: &mut dyn std::io::Write) -> std::io::Result<()> {
     writer.write_all(&self.value)
   }

src/replace_source.rs

@@ -181,7 +181,7 @@ impl Source for ReplaceSource {
       < self.replacements.len())
     .then(|| self.replacements[replacement_idx].start as usize);
 
-    'chunk_loop: for chunk in self.inner.rope() {
+    'chunk_loop: for chunk in inner_rope {
       let mut chunk_pos = 0;
       let end_pos = pos + chunk.len();
 
@@ -323,6 +323,12 @@ impl Source for ReplaceSource {
     get_map(&ObjectPool::default(), chunks.as_ref(), options)
   }
 
+  fn write_to_string(&self, string: &mut String) {
+    for chunk in self.rope() {
+      string.push_str(chunk);
+    }
+  }
+
   fn to_writer(&self, writer: &mut dyn std::io::Write) -> std::io::Result<()> {
     for text in self.rope() {
       writer.write_all(text.as_bytes())?;

src/source.rs

@@ -135,6 +135,14 @@ pub trait Source:
     self.dyn_hash(state);
   }
 
+  /// Appends the source content to the provided string buffer.
+  ///
+  /// This method efficiently writes the source content directly into an existing
+  /// string buffer, avoiding additional memory allocations when the buffer has
+  /// sufficient capacity. This is particularly useful for concatenating multiple
+  /// sources or building larger strings incrementally.
+  fn write_to_string(&self, string: &mut String);
+
   /// Writes the source into a writer, preferably a `std::io::BufWriter<std::io::Write>`.
   fn to_writer(&self, writer: &mut dyn std::io::Write) -> std::io::Result<()>;
 }
@@ -164,6 +172,10 @@ impl Source for BoxSource {
     self.as_ref().map(object_pool, options)
   }
 
+  fn write_to_string(&self, string: &mut String) {
+    self.as_ref().write_to_string(string)
+  }
+
   fn to_writer(&self, writer: &mut dyn std::io::Write) -> std::io::Result<()> {
     self.as_ref().to_writer(writer)
   }

src/source_map_source.rs

@@ -118,6 +118,10 @@ impl Source for SourceMapSource {
     get_map(object_pool, chunks.as_ref(), options)
   }
 
+  fn write_to_string(&self, string: &mut String) {
+    string.push_str(self.value.as_ref());
+  }
+
   fn to_writer(&self, writer: &mut dyn std::io::Write) -> std::io::Result<()> {
     writer.write_all(self.value.as_bytes())
   }

tests/compat_source.rs

@@ -39,6 +39,10 @@ impl Source for CompatSource {
     self.1.clone()
   }
 
+  fn write_to_string(&self, string: &mut String) {
+    string.push_str(self.0.as_ref())
+  }
+
   fn to_writer(&self, writer: &mut dyn std::io::Write) -> std::io::Result<()> {
     writer.write_all(self.0.as_bytes())
   }