Reduce allocations and make things go faster (#13)

.gitignore

@@ -27,4 +27,6 @@ nuget.exe
 project.lock.json
 .vs
 .build/
-.testPublish/
+.testPublish/
+.idea
+BenchmarkDotNet.Artifacts*

samples/Esprima.Benchmark/Esprima.Benchmark.csproj

@@ -1,14 +1,15 @@
-<Project Sdk="Microsoft.NET.Sdk">
-
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <AssemblyName>Esprima.Benchmark</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>Esprima.Benchmark</PackageId>
-    <TargetFramework>netstandard2.0</TargetFramework>
+    <TargetFramework>netcoreapp2.0</TargetFramework>
   </PropertyGroup>
-
+  <ItemGroup>
+    <None Include="..\..\test\Esprima.Tests\Fixtures\3rdparty\**" CopyToOutputDirectory="PreserveNewest" LinkBase="3rdparty" />
+  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\..\src\Esprima\Esprima.csproj" />
+    <PackageReference Include="BenchmarkDotNet" Version="0.10.11" />
   </ItemGroup>
-
-</Project>
+</Project>

samples/Esprima.Benchmark/FileParsingBenchmark.cs

@@ -0,0 +1,49 @@
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using BenchmarkDotNet.Attributes;
+
+namespace Esprima.Benchmark
+{
+    [MemoryDiagnoser]
+    public class FileParsingBenchmark
+    {
+        private static readonly Dictionary<string, string> files = new Dictionary<string, string>
+        {
+            {"underscore-1.5.2", null},
+            {"backbone-1.1.0", null},
+            {"mootools-1.4.5", null},
+            {"jquery-1.9.1", null},
+            {"yui-3.12.0", null},
+            {"jquery.mobile-1.4.2", null},
+            {"angular-1.2.5", null}
+        };
+
+        [GlobalSetup]
+        public void Setup()
+        {
+            foreach (var fileName in files.Keys.ToList())
+            {
+                files[fileName] = File.ReadAllText($"3rdparty/{fileName}.js");
+            }
+        }
+
+        [ParamsSource(nameof(FileNames))]
+        public string FileName { get; set; }
+
+        public IEnumerable<string> FileNames()
+        {
+            foreach (var entry in files)
+            {
+                yield return entry.Key;
+            }
+        }
+
+        [Benchmark]
+        public void ParseProgram()
+        {
+            var parser = new JavaScriptParser(files[FileName]);
+            parser.ParseProgram();
+        }
+    }
+}

samples/Esprima.Benchmark/Program.cs

@@ -1,59 +1,14 @@
-using System;
-using System.Collections.Generic;
-using System.Diagnostics;
-using System.IO;
-using System.Linq;
+using System.Reflection;
+
+using BenchmarkDotNet.Running;
 
 namespace Esprima.Benchmark
 {
     public class Program
     {
         public static void Main(string[] args)
         {
-            var scripts =new [] {
-                "underscore-1.5.2",
-                "backbone-1.1.0",
-                "mootools-1.4.5",
-                "jquery-1.9.1",
-                "yui-3.12.0",
-                "jquery.mobile-1.4.2",
-                "angular-1.2.5"
-            };
-
-            foreach(var script in scripts)
-            {
-                Bench(script);
-            }
-        }
-
-        public static void Bench(string script)
-        {
-            var repeat = 120;
-            var exclude = 10;
-
-            var filename = $"../../test/Esprima.Tests/Fixtures/3rdparty/{script}.js";
-            var content = File.ReadAllText(filename);
-
-            var sw = new Stopwatch();
-            var results = new List<long>();
-
-            for(var i=0; i<repeat; i++)
-            {
-                var parser = new JavaScriptParser(content);
-                sw.Restart();
-
-                parser.ParseProgram();
-                results.Add(sw.ElapsedMilliseconds);
-            }
-
-            var average = results
-                .OrderBy(x => x)
-                .Skip(exclude)
-                .Take(repeat - exclude * 2)
-                .Average();
-
-            Console.WriteLine("{0} ({2}KB): {1} ms", script, Math.Round(average, 1), content.Length / 1024);
+            BenchmarkSwitcher.FromAssembly(typeof(Program).GetTypeInfo().Assembly).Run(args);
         }
-
     }
 }

src/Esprima/Ast/Literal.cs

@@ -75,7 +75,8 @@ public Literal(string pattern, string flags, object value, string raw)
 
         string PropertyKey.GetKey()
         {
-            return Convert.ToString(Value);
+            var s = Value as string;
+            return s ?? Convert.ToString(Value);
         }
     }
 }

src/Esprima/Ast/Node.cs

@@ -5,13 +5,19 @@ namespace Esprima.Ast
 {
     public class Node : INode
     {
+        private Location _location;
+
         [JsonProperty(Order = -100)]
         [JsonConverter(typeof(StringEnumConverter))]
         public Nodes Type { get; set; }
 
         public int[] Range { get; set; }
 
         [JsonProperty(PropertyName = "Loc")]
-        public Location Location { get; set; } = new Location();
+        public Location Location
+        {
+            get => _location  = _location ?? new Location();
+            set => _location = value;
+        }
     }
 }

src/Esprima/Character.cs

@@ -51,7 +51,7 @@ public static bool IsIdentifierStart(char ch)
                    (ch >= 'A' && ch <= 'Z') ||
                    (ch >= 'a' && ch <= 'z') ||
                    (ch == '\\') ||
-                   ((ch >= 0x80) && NonAsciiIdentifierStart.IsMatch(ch.ToString()));
+                   ((ch >= 0x80) && NonAsciiIdentifierStart.IsMatch(ParserExtensions.CharToString(ch)));
         }
 
         public static bool IsIdentifierPart(char ch)
@@ -61,7 +61,7 @@ public static bool IsIdentifierPart(char ch)
                    (ch >= 'a' && ch <= 'z') ||
                    (ch >= '0' && ch <= '9') ||
                    (ch == '\\') ||
-                   ((ch >= 0x80) && NonAsciiIdentifierPart.IsMatch(ch.ToString()));
+                   ((ch >= 0x80) && NonAsciiIdentifierPart.IsMatch(ParserExtensions.CharToString(ch)));
         }
 
         public static bool IsIdentifierStart(string ch)