Reduce allocations in CommandLineParser.CondenseDoubledBackslashes

Remove unused CommandLineSplitter class and update unit tests. (changeset 1407192)

src/Compilers/Core/CodeAnalysisTest/CommonCommandLineParserTests.cs

@@ -12,9 +12,9 @@ public class CommonCommandLineParserTests : TestBase
     {
         private const int EN_US = 1033;
 
-        private void VerifyCommandLineSplitter(string commandLine, string[] expected)
+        private void VerifyCommandLineSplitter(string commandLine, string[] expected, bool removeHashComments = false)
         {
-            string[] actual = CommandLineSplitter.SplitCommandLine(commandLine);
+            var actual = CommandLineParser.SplitCommandLineIntoArguments(commandLine, removeHashComments).ToArray();
 
             Assert.Equal(expected.Length, actual.Length);
             for (int i = 0; i < actual.Length; ++i)
@@ -94,6 +94,8 @@ public void TestCommandLineSplitter()
                                         new string[] { @"\""abc def""", @"\""abc", @"def""" });
             VerifyCommandLineSplitter(@"  \\\\""abc def""  \\\\\""abc def"" ",
                                         new string[] { @"\\""abc def""", @"\\""abc", @"def""" });
+            VerifyCommandLineSplitter(@"abc #Comment ignored",
+                                        new string[] { @"abc" }, removeHashComments: true);
         }
 
         [Fact]

src/Compilers/Core/Desktop/CommandLine/CommonCommandLineParser.cs

@@ -7,7 +7,7 @@
 using System.IO;
 using System.Linq;
 using System.Text;
-using Microsoft.CodeAnalysis.Diagnostics;
+using Microsoft.CodeAnalysis.Collections;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
 
@@ -509,15 +509,20 @@ private static IEnumerable<string> Split(string str, Func<char, bool> splitHere)
         /// </summary>
         private static string CondenseDoubledBackslashes(string input)
         {
+            int i = input.IndexOf('\\');
+
             // Simple case -- no backslashes.
-            if (!input.Contains('\\'))
+            if (i < 0)
                 return input;
 
-            StringBuilder builder = new StringBuilder();
-            int backslashCount = 0;
+            var pooledBuilder = PooledStringBuilder.GetInstance();
+            var builder = pooledBuilder.Builder;
+            builder.Append(input, 0, i);
 
-            foreach (char c in input)
+            int backslashCount = 0;
+            do
             {
+                char c = input[i];
                 if (c == '\\')
                 {
                     ++backslashCount;
@@ -537,10 +542,10 @@ private static string CondenseDoubledBackslashes(string input)
                     builder.Append(c);
                     backslashCount = 0;
                 }
-            }
+            } while (++i < input.Length);
 
             AddBackslashes(builder, backslashCount);
-            return builder.ToString();
+            return pooledBuilder.ToStringAndFree();
         }
 
         /// <summary>
@@ -865,153 +870,4 @@ internal static bool TryParseUInt16(string value, out ushort result)
             return true;
         }
     }
-
-    /// <remarks>
-    /// Rules for command line parsing, according to MSDN:
-    /// 
-    /// Arguments are delimited by white space, which is either a space or a tab.
-    ///  
-    /// A string surrounded by double quotation marks ("string") is interpreted 
-    /// as a single argument, regardless of white space contained within. 
-    /// A quoted string can be embedded in an argument.
-    ///  
-    /// A double quotation mark preceded by a backslash (\") is interpreted as a 
-    /// literal double quotation mark character (").
-    ///  
-    /// Backslashes are interpreted literally, unless they immediately precede a 
-    /// double quotation mark.
-    ///  
-    /// If an even number of backslashes is followed by a double quotation mark, 
-    /// one backslash is placed in the argv array for every pair of backslashes, 
-    /// and the double quotation mark is interpreted as a string delimiter.
-    ///  
-    /// If an odd number of backslashes is followed by a double quotation mark, 
-    /// one backslash is placed in the argv array for every pair of backslashes, 
-    /// and the double quotation mark is "escaped" by the remaining backslash, 
-    /// causing a literal double quotation mark (") to be placed in argv.
-    /// </remarks>
-    internal static class CommandLineSplitter
-    {
-        public static bool IsDelimiter(char c)
-        {
-            return c == ' ' || c == '\t';
-        }
-
-        public static bool IsQuote(char c)
-        {
-            // Only double quotes are respected, according to MSDN.
-            return c == '\"';
-        }
-
-        private const char Backslash = '\\';
-
-        // Split a command line by the same rules as Main would get the commands.
-        public static string[] SplitCommandLine(string commandLine)
-        {
-            bool inQuotes = false;
-            int backslashCount = 0;
-
-            return commandLine.Split(c =>
-            {
-                if (c == Backslash)
-                {
-                    backslashCount += 1;
-                }
-                else if (IsQuote(c))
-                {
-                    if ((backslashCount & 1) != 1)
-                    {
-                        inQuotes = !inQuotes;
-                    }
-                    backslashCount = 0;
-                }
-                else
-                {
-                    backslashCount = 0;
-                }
-
-                return !inQuotes && IsDelimiter(c);
-            })
-            .Select(arg => arg.Trim().CondenseDoubledBackslashes().TrimMatchingQuotes())
-            .Where(arg => !string.IsNullOrEmpty(arg))
-            .ToArray();
-        }
-
-        // Split a string, based on whether "splitHere" returned true on each character.
-        private static IEnumerable<string> Split(this string str,
-                                                 Func<char, bool> splitHere)
-        {
-            int nextPiece = 0;
-
-            for (int c = 0; c < str.Length; c++)
-            {
-                if (splitHere(str[c]))
-                {
-                    yield return str.Substring(nextPiece, c - nextPiece);
-                    nextPiece = c + 1;
-                }
-            }
-
-            yield return str.Substring(nextPiece);
-        }
-
-        // Trim leading and trailing quotes from a string, if they are there. Only trims
-        // one pair.
-        private static string TrimMatchingQuotes(this string input)
-        {
-            if ((input.Length >= 2) &&
-                (IsQuote(input[0])) &&
-                (IsQuote(input[input.Length - 1])))
-            {
-                return input.Substring(1, input.Length - 2);
-            }
-            else
-            {
-                return input;
-            }
-        }
-
-        // Condense double backslashes that precede a quotation mark to single backslashes.
-        private static string CondenseDoubledBackslashes(this string input)
-        {
-            // Simple case -- no backslashes.
-            if (!input.Contains(Backslash))
-                return input;
-
-            StringBuilder builder = new StringBuilder();
-            int doubleQuoteCount = 0;
-
-            foreach (char c in input)
-            {
-                if (c == Backslash)
-                {
-                    ++doubleQuoteCount;
-                }
-                else
-                {
-                    // Add right amount of pending backslashes.
-                    if (IsQuote(c))
-                    {
-                        AddBackslashes(builder, doubleQuoteCount / 2);
-                    }
-                    else
-                    {
-                        AddBackslashes(builder, doubleQuoteCount);
-                    }
-
-                    builder.Append(c);
-                    doubleQuoteCount = 0;
-                }
-            }
-
-            AddBackslashes(builder, doubleQuoteCount);
-            return builder.ToString();
-        }
-
-        private static void AddBackslashes(StringBuilder builder, int count)
-        {
-            for (int i = 0; i < count; ++i)
-                builder.Append(Backslash);
-        }
-    }
 }