perf: ConcatSource source (#199)

Author: SyMind

src/concat_source.rs

@@ -163,8 +163,16 @@ impl ConcatSource {
 
 impl Source for ConcatSource {
  fn source(&self) -> SourceValue {
- let rope = self.rope();
- SourceValue::String(Cow::Owned(rope.to_string()))
+ let children = self.optimized_children();
+ if children.len() == 1 {
+ children[0].source()
+ } else {
+ let mut buf = String::with_capacity(self.size());
+ for child in children {
+ buf.push_str(&child.source().into_string_lossy());
+ }
+ SourceValue::String(Cow::Owned(buf))
+ }
  }
 
  fn rope(&self) -> Rope<'_> {
@@ -186,7 +194,7 @@ impl Source for ConcatSource {
  if children.len() == 1 {
  children[0].buffer()
  } else {
- let mut buffer = vec![];
+ let mut buffer = Vec::with_capacity(self.size());
  self.to_writer(&mut buffer).unwrap();
  Cow::Owned(buffer)
  }