faster spans

rust-lang · Feb 4, 2021 · 60cca83 · 60cca83
1 parent 6ad11e2
commit 60cca83
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Showing 2 changed files with 10 additions and 8 deletions.
diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
@@ -22,6 +22,7 @@
 #![feature(nll)]
 #![feature(min_specialization)]
 #![feature(option_expect_none)]
+#![feature(str_split_once)]
 
 #[macro_use]
 extern crate rustc_macros;

diff --git a/compiler/rustc_span/src/source_map.rs b/compiler/rustc_span/src/source_map.rs
@@ -539,7 +539,7 @@ impl SourceMap {
 
  pub fn is_line_before_span_empty(&self, sp: Span) -> bool {
  match self.span_to_prev_source(sp) {
- Ok(s) => s.split('\n').last().map_or(false, |l| l.trim_start().is_empty()),
+ Ok(s) => s.rsplit_once('\n').unwrap_or(("", &s)).1.trim_start().is_empty(),
  Err(_) => false,
  }
  }
@@ -632,10 +632,11 @@ impl SourceMap {
  pub fn span_to_margin(&self, sp: Span) -> Option<usize> {
  match self.span_to_prev_source(sp) {
  Err(_) => None,
- Ok(source) => source
- .split('\n')
- .last()
- .map(|last_line| last_line.len() - last_line.trim_start().len()),
+ Ok(source) => {
+ let last_line = source.rsplit_once('\n').unwrap_or(("", &source)).1;
+
+ Some(last_line.len() - last_line.trim_start().len())
+ }
  }
  }
 
@@ -651,7 +652,7 @@ impl SourceMap {
  pub fn span_extend_to_prev_char(&self, sp: Span, c: char, accept_newlines: bool) -> Span {
  if let Ok(prev_source) = self.span_to_prev_source(sp) {
  let prev_source = prev_source.rsplit(c).next().unwrap_or("");
- if !prev_source.is_empty() && (!prev_source.contains('\n') || accept_newlines) {
+ if !prev_source.is_empty() && (accept_newlines || !prev_source.contains('\n')) {
  return sp.with_lo(BytePos(sp.lo().0 - prev_source.len() as u32));
  }
  }
@@ -673,7 +674,7 @@ impl SourceMap {
  let prev_source = prev_source.rsplit(&pat).next().unwrap_or("").trim_start();
  if prev_source.is_empty() && sp.lo().0 != 0 {
  return sp.with_lo(BytePos(sp.lo().0 - 1));
- } else if !prev_source.contains('\n') || accept_newlines {
+ } else if accept_newlines || !prev_source.contains('\n') {
  return sp.with_lo(BytePos(sp.lo().0 - prev_source.len() as u32));
  }
  }
@@ -693,7 +694,7 @@ impl SourceMap {
  pub fn span_extend_to_next_char(&self, sp: Span, c: char, accept_newlines: bool) -> Span {
  if let Ok(next_source) = self.span_to_next_source(sp) {
  let next_source = next_source.split(c).next().unwrap_or("");
- if !next_source.is_empty() && (!next_source.contains('\n') || accept_newlines) {
+ if !next_source.is_empty() && (accept_newlines || !next_source.contains('\n')) {
  return sp.with_hi(BytePos(sp.hi().0 + next_source.len() as u32));
  }
  }