Optimized away the expensive StringBuilder.Remove(0, 1) in CodeInlineParser

src/Markdig/Parsers/Inlines/CodeInlineParser.cs

@@ -1,47 +1,47 @@
-// Copyright (c) Alexandre Mutel. All rights reserved.
-// This file is licensed under the BSD-Clause 2 license. 
-// See the license.txt file in the project root for more information.
-using Markdig.Helpers;
-using Markdig.Syntax;
-using Markdig.Syntax.Inlines;
-
-namespace Markdig.Parsers.Inlines
-{
- /// <summary>
- /// An inline parser for a <see cref="CodeInline"/>.
- /// </summary>
- /// <seealso cref="Markdig.Parsers.InlineParser" />
- public class CodeInlineParser : InlineParser
- {
- /// <summary>
- /// Initializes a new instance of the <see cref="CodeInlineParser"/> class.
- /// </summary>
- public CodeInlineParser()
- {
- OpeningCharacters = new[] { '`' };
- }
-
- public override bool Match(InlineProcessor processor, ref StringSlice slice)
- {
- var match = slice.CurrentChar;
- if (slice.PeekCharExtra(-1) == match)
- {
- return false;
- }
-
- var startPosition = slice.Start;
-
- int openSticks = 0;
- int closeSticks = 0;
-
- // Match the opened sticks
- char c = slice.CurrentChar;
- while (c == match)
- {
- openSticks++;
- c = slice.NextChar();
- }
-
+// Copyright (c) Alexandre Mutel. All rights reserved.
+// This file is licensed under the BSD-Clause 2 license. 
+// See the license.txt file in the project root for more information.
+using Markdig.Helpers;
+using Markdig.Syntax;
+using Markdig.Syntax.Inlines;
+
+namespace Markdig.Parsers.Inlines
+{
+ /// <summary>
+ /// An inline parser for a <see cref="CodeInline"/>.
+ /// </summary>
+ /// <seealso cref="Markdig.Parsers.InlineParser" />
+ public class CodeInlineParser : InlineParser
+ {
+ /// <summary>
+ /// Initializes a new instance of the <see cref="CodeInlineParser"/> class.
+ /// </summary>
+ public CodeInlineParser()
+ {
+ OpeningCharacters = new[] { '`' };
+ }
+
+ public override bool Match(InlineProcessor processor, ref StringSlice slice)
+ {
+ var match = slice.CurrentChar;
+ if (slice.PeekCharExtra(-1) == match)
+ {
+ return false;
+ }
+
+ var startPosition = slice.Start;
+
+ int openSticks = 0;
+ int closeSticks = 0;
+
+ // Match the opened sticks
+ char c = slice.CurrentChar;
+ while (c == match)
+ {
+ openSticks++;
+ c = slice.NextChar();
+ }
+
  var builder = processor.StringBuilders.Get();
 
  // A backtick string is a string of one or more backtick characters (`) that is neither preceded nor followed by a backtick.
@@ -53,71 +53,76 @@ public override bool Match(InlineProcessor processor, ref StringSlice slice)
  // 2. If the resulting string both begins AND ends with a space character, but does not consist entirely
  // of space characters, a single space character is removed from the front and back.
  // This allows you to include code that begins or ends with backtick characters, which must be separated by
- // whitespace from the opening or closing backtick strings.
-
- bool allSpace = true;
-
- while (c != '\0')
- {
- // Transform '\n' into a single space
- if (c == '\n')
- {
- c = ' ';
- }
-
+ // whitespace from the opening or closing backtick strings.
+
+ bool allSpace = true;
+
+ while (c != '\0')
+ {
+ // Transform '\n' into a single space
+ if (c == '\n')
+ {
+ c = ' ';
+ }
+
  if (c == match)
  {
- do
- {
- closeSticks++;
- c = slice.NextChar();
+ do
+ {
+ closeSticks++;
+ c = slice.NextChar();
  }
  while (c == match);
 
- if (openSticks == closeSticks)
- {
- break;
- }
-
- allSpace = false;
- builder.Append(match, closeSticks);
+ if (openSticks == closeSticks)
+ {
+ break;
+ }
+
+ allSpace = false;
+ builder.Append(match, closeSticks);
  closeSticks = 0;
- }
+ }
  else
  {
  builder.Append(c);
  if (c != ' ')
  {
  allSpace = false;
- }
+ }
  c = slice.NextChar();
- }
- }
-
- bool isMatching = false;
- if (closeSticks == openSticks)
- {
- // Remove one space from front and back if the string is not all spaces
- if (!allSpace && builder.Length > 2 && builder[0] == ' ' && builder[builder.Length - 1] == ' ')
- {
- builder.Length--;
- builder.Remove(0, 1); // More expensive, alternative is to have a double-pass algorithm
- }
-
- processor.Inline = new CodeInline()
- {
- Delimiter = match,
- Content = builder.ToString(),
- Span = new SourceSpan(processor.GetSourcePosition(startPosition, out int line, out int column), processor.GetSourcePosition(slice.Start - 1)),
- Line = line,
- Column = column
- };
- isMatching = true;
- }
-
- // Release the builder if not used
- processor.StringBuilders.Release(builder);
- return isMatching;
- }
- }
+ }
+ }
+
+ bool isMatching = false;
+ if (closeSticks == openSticks)
+ {
+ string content;
+
+ // Remove one space from front and back if the string is not all spaces
+ if (!allSpace && builder.Length > 2 && builder[0] == ' ' && builder[builder.Length - 1] == ' ')
+ {
+ content = builder.ToString(1, builder.Length - 2);
+ }
+ else
+ {
+ content = builder.ToString();
+ }
+
+ processor.Inline = new CodeInline()
+ {
+ Delimiter = match,
+ Content = content,
+ Span = new SourceSpan(processor.GetSourcePosition(startPosition, out int line, out int column), processor.GetSourcePosition(slice.Start - 1)),
+ Line = line,
+ Column = column
+ };
+ isMatching = true;
+ }
+
+ // Release the builder if not used
+ processor.StringBuilders.Release(builder);
+ return isMatching;
+ }
+ }
 }