source: Remove unnecessary string length comparisons in the case of string comparisons (#116)

## Why https://github.com/ruby/rexml/blob/370666e314816b57ecd5878e757224c3b6bc93f5/lib/rexml/source.rb#L208-L234 Because `@line_break = encode(">")`, the end of `@scanner << readline` is one of the following. 1. ">" 2. "X>" 3. "X" (eof) This will not be matched by additional reads in the following cases. - `@source.match("<?")` - `@source.match("--")` - `@source.match("DOCTYPE")` In the following cases, additional reads may result in a match, but explicitly prohibiting such a specification with a comment makes the string length check unnecessary. - `@source.match(">>")` - `@source.match(">X")` ## Benchmark ``` RUBYLIB= BUNDLER_ORIG_RUBYLIB= /Users/naitoh/.rbenv/versions/3.3.0/bin/ruby -v -S benchmark-driver /Users/naitoh/ghq/github.com/naitoh/rexml/benchmark/parse.yaml ruby 3.3.0 (2023-12-25 revision 5124f9ac75) [arm64-darwin22] Calculating ------------------------------------- before after before(YJIT) after(YJIT) dom 10.689 10.736 18.484 18.108 i/s - 100.000 times in 9.355754s 9.314792s 5.409984s 5.522527s sax 30.793 31.583 52.965 52.641 i/s - 100.000 times in 3.247486s 3.166258s 1.888036s 1.899660s pull 36.308 37.182 63.773 64.669 i/s - 100.000 times in 2.754203s 2.689440s 1.568069s 1.546325s stream 34.936 35.991 56.830 57.729 i/s - 100.000 times in 2.862361s 2.778467s 1.759632s 1.732238s Comparison: dom before(YJIT): 18.5 i/s after(YJIT): 18.1 i/s - 1.02x slower after: 10.7 i/s - 1.72x slower before: 10.7 i/s - 1.73x slower sax before(YJIT): 53.0 i/s after(YJIT): 52.6 i/s - 1.01x slower after: 31.6 i/s - 1.68x slower before: 30.8 i/s - 1.72x slower pull after(YJIT): 64.7 i/s before(YJIT): 63.8 i/s - 1.01x slower after: 37.2 i/s - 1.74x slower before: 36.3 i/s - 1.78x slower stream after(YJIT): 57.7 i/s before(YJIT): 56.8 i/s - 1.02x slower after: 36.0 i/s - 1.60x slower before: 34.9 i/s - 1.65x slower ``` - YJIT=ON : 0.98x - 1.02x faster - YJIT=OFF : 1.00x - 1.03x faster

Author: naitoh

lib/rexml/source.rb

@@ -161,6 +161,9 @@ def read
  end
  end
 
+ # Note: When specifying a string for 'pattern', it must not include '>' except in the following formats:
+ # - ">"
+ # - "XXX>" (X is any string excluding '>')
  def match( pattern, cons=false )
  read if @scanner.eos? && @source
  while true
@@ -170,7 +173,7 @@ def match( pattern, cons=false )
  md = @scanner.check(pattern)
  end
  break if md
- return nil if pattern.is_a?(String) && pattern.bytesize <= @scanner.rest_size
+ return nil if pattern.is_a?(String)
  return nil if @source.nil?
  return nil unless read
  end