Switch RegularExpression from YARR to V8

Source/core/platform/text/RegularExpression.cpp

Index: Source/core/platform/text/RegularExpression.cpp
diff --git a/Source/core/platform/text/RegularExpression.cpp b/Source/core/platform/text/RegularExpression.cpp
index 2b225ade22404e6a9f0898590695203021b4a10e..ad1a5beccb9c7d79d556c073c9f5db2c3da6e2d9 100644
--- a/Source/core/platform/text/RegularExpression.cpp
+++ b/Source/core/platform/text/RegularExpression.cpp
@@ -2,6 +2,7 @@
  * Copyright (C) 2004, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Collabora Ltd.
  * Copyright (C) 2011 Peter Varga (pvarga@webkit.org), University of Szeged
+ * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -28,67 +29,79 @@
 #include "config.h"
 #include "RegularExpression.h"
 
-#include <wtf/BumpPointerAllocator.h>
-#include <yarr/Yarr.h>
-#include "Logging.h"
+// FIXME: These seem like a layering violation, but converting the strings manually
+// without v8String is difficult, and calling into v8 without V8RecursionScope will
+// assert. Perhaps v8 basic utilities shouldn't be in bindings, or we should put
+// RegularExpression as some kind of abstract interface that's implemented in bindings.
+#include "V8Binding.h"
+#include "V8RecursionScope.h"
+#include <wtf/MainThread.h>
 
 namespace WebCore {
 
-RegularExpression::RegularExpression(const String& pattern, TextCaseSensitivity caseSensitivity, MultilineMode multilineMode)
-    : m_numSubpatterns(0)
-    , m_regExpByteCode(compile(pattern, caseSensitivity, multilineMode))
+static v8::Local<v8::Context> regexContext()
 {
+    ASSERT(isMainThread());
+    static ScopedPersistent<v8::Context>* staticRegexContext = new ScopedPersistent<v8::Context>(v8::Context::New());
+    return v8::Local<v8::Context>::New(staticRegexContext->get());
 }
 
-PassOwnPtr<JSC::Yarr::BytecodePattern> RegularExpression::compile(const String& patternString, TextCaseSensitivity caseSensitivity, MultilineMode multilineMode)
+RegularExpression::RegularExpression(const String& pattern, TextCaseSensitivity caseSensitivity, MultilineMode multilineMode)
 {
-    const char* constructionError = 0;
-    JSC::Yarr::YarrPattern pattern(patternString, (caseSensitivity == TextCaseInsensitive), (multilineMode == MultilineEnabled), &constructionError);
-    if (constructionError) {
-        LOG_ERROR("RegularExpression: YARR compile failed with '%s'", constructionError);
-        return nullptr;
-    }
-
-    m_numSubpatterns = pattern.m_numSubpatterns;
-
-    return JSC::Yarr::byteCompile(pattern, &m_regexAllocator);
+    v8::HandleScope handleScope;
+    v8::Local<v8::Context> context(regexContext());
+    v8::Context::Scope scope(context);
+
+    unsigned flags = v8::RegExp::kNone;
+    if (caseSensitivity == TextCaseInsensitive)
+        flags |= v8::RegExp::kIgnoreCase;
+    if (multilineMode == MultilineEnabled)
+        flags |= v8::RegExp::kMultiline;
+
+    v8::TryCatch tryCatch;
+    m_regex.set(v8::RegExp::New(v8String(pattern, context->GetIsolate()), static_cast<v8::RegExp::Flags>(flags)));

[adamk, 2013/04/22 17:48:03]

I think it would be clearer if you split this into two lines with an "if
(!regex.IsEmpty())" so it's more obvious that m_regex will sometimes not be set,
rather than relying on the API to return an empty handle in case of an
exception.

 }
 
-int RegularExpression::match(const String& str, int startFrom, int* matchLength) const
+int RegularExpression::match(const String& string, int startFrom, int* matchLength) const
 {
-    if (!m_regExpByteCode)
+    if (m_regex.isEmpty() || string.isNull())
         return -1;
 
-    if (str.isNull())
+    // v8 strings are limited to int.
+    if (string.length() > INT_MAX)
         return -1;
 
-    int offsetVectorSize = (m_numSubpatterns + 1) * 2;
-    unsigned* offsetVector;
-    Vector<unsigned, 32> nonReturnedOvector;
+    v8::HandleScope handleScope;
+    v8::Local<v8::Context> context(regexContext());
+    v8::Context::Scope scope(context);
+    v8::TryCatch tryCatch;
 
-    nonReturnedOvector.resize(offsetVectorSize);
-    offsetVector = nonReturnedOvector.data();
+    V8RecursionScope::MicrotaskSuppression microtaskScope;
 
-    ASSERT(offsetVector);
-    for (unsigned j = 0, i = 0; i < m_numSubpatterns + 1; j += 2, i++)
-        offsetVector[j] = JSC::Yarr::offsetNoMatch;
+    v8::Local<v8::Function> exec = m_regex->Get(v8::String::NewSymbol("exec")).As<v8::Function>();
 
-    unsigned result;
-    if (str.length() <= INT_MAX)
-        result = JSC::Yarr::interpret(m_regExpByteCode.get(), str, startFrom, offsetVector);
-    else {
-        // This code can't handle unsigned offsets. Limit our processing to strings with offsets that 
-        // can be represented as ints.
-        result = JSC::Yarr::offsetNoMatch;
-    }
+    v8::Handle<v8::Value> argv[] = { v8String(string, context->GetIsolate()) };
+    v8::Local<v8::Value> returnValue = exec->Call(m_regex.get(), 1, argv);
+
+    // RegExp#exec returns null if there's no match, otherwise it returns an
+    // Array of strings with the first being the whole match string and others
+    // being subgroups. The Array also has some random properties tacked on like
+    // "index" which is the offset of the match.
+    //
+    // https://developer.mozilla.org/en-US/docs/JavaScript/Reference/Global_Objects/RegExp/exec
 
-    if (result == JSC::Yarr::offsetNoMatch)
+    if (!returnValue->IsArray())
         return -1;
 
-    // 1 means 1 match; 0 means more than one match. First match is recorded in offsetVector.
-    if (matchLength)
-        *matchLength = offsetVector[1] - offsetVector[0];
-    return offsetVector[0];
+    v8::Local<v8::Array> result = returnValue.As<v8::Array>();
+    int matchOffset = result->Get(v8::String::NewSymbol("index"))->ToInt32()->Value();
+
+    if (matchLength) {
+        v8::Local<v8::String> match = result->Get(0).As<v8::String>();
+        *matchLength = match->Length();
+    }
+
+    return matchOffset;
 }
 
 void replace(String& string, const RegularExpression& target, const String& replacement)