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      1 // Copyright 2010 the V8 project authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "src/extensions/externalize-string-extension.h"
      6 
      7 #include "src/api.h"
      8 #include "src/handles.h"
      9 #include "src/isolate.h"
     10 
     11 namespace v8 {
     12 namespace internal {
     13 
     14 template <typename Char, typename Base>
     15 class SimpleStringResource : public Base {
     16  public:
     17   // Takes ownership of |data|.
     18   SimpleStringResource(Char* data, size_t length)
     19       : data_(data),
     20         length_(length) {}
     21 
     22   virtual ~SimpleStringResource() { delete[] data_; }
     23 
     24   virtual const Char* data() const { return data_; }
     25 
     26   virtual size_t length() const { return length_; }
     27 
     28  private:
     29   Char* const data_;
     30   const size_t length_;
     31 };
     32 
     33 
     34 typedef SimpleStringResource<char, v8::String::ExternalOneByteStringResource>
     35     SimpleOneByteStringResource;
     36 typedef SimpleStringResource<uc16, v8::String::ExternalStringResource>
     37     SimpleTwoByteStringResource;
     38 
     39 
     40 const char* const ExternalizeStringExtension::kSource =
     41     "native function externalizeString();"
     42     "native function isOneByteString();";
     43 
     44 v8::Local<v8::FunctionTemplate>
     45 ExternalizeStringExtension::GetNativeFunctionTemplate(
     46     v8::Isolate* isolate, v8::Local<v8::String> str) {
     47   if (strcmp(*v8::String::Utf8Value(str), "externalizeString") == 0) {
     48     return v8::FunctionTemplate::New(isolate,
     49                                      ExternalizeStringExtension::Externalize);
     50   } else {
     51     DCHECK(strcmp(*v8::String::Utf8Value(str), "isOneByteString") == 0);
     52     return v8::FunctionTemplate::New(isolate,
     53                                      ExternalizeStringExtension::IsOneByte);
     54   }
     55 }
     56 
     57 
     58 void ExternalizeStringExtension::Externalize(
     59     const v8::FunctionCallbackInfo<v8::Value>& args) {
     60   if (args.Length() < 1 || !args[0]->IsString()) {
     61     args.GetIsolate()->ThrowException(
     62         v8::String::NewFromUtf8(
     63             args.GetIsolate(),
     64             "First parameter to externalizeString() must be a string.",
     65             NewStringType::kNormal).ToLocalChecked());
     66     return;
     67   }
     68   bool force_two_byte = false;
     69   if (args.Length() >= 2) {
     70     if (args[1]->IsBoolean()) {
     71       force_two_byte =
     72           args[1]
     73               ->BooleanValue(args.GetIsolate()->GetCurrentContext())
     74               .FromJust();
     75     } else {
     76       args.GetIsolate()->ThrowException(
     77           v8::String::NewFromUtf8(
     78               args.GetIsolate(),
     79               "Second parameter to externalizeString() must be a boolean.",
     80               NewStringType::kNormal).ToLocalChecked());
     81       return;
     82     }
     83   }
     84   bool result = false;
     85   Handle<String> string = Utils::OpenHandle(*args[0].As<v8::String>());
     86   if (string->IsExternalString()) {
     87     args.GetIsolate()->ThrowException(
     88         v8::String::NewFromUtf8(args.GetIsolate(),
     89                                 "externalizeString() can't externalize twice.",
     90                                 NewStringType::kNormal).ToLocalChecked());
     91     return;
     92   }
     93   if (string->IsOneByteRepresentation() && !force_two_byte) {
     94     uint8_t* data = new uint8_t[string->length()];
     95     String::WriteToFlat(*string, data, 0, string->length());
     96     SimpleOneByteStringResource* resource = new SimpleOneByteStringResource(
     97         reinterpret_cast<char*>(data), string->length());
     98     result = string->MakeExternal(resource);
     99     if (result) {
    100       i::Isolate* isolate = reinterpret_cast<i::Isolate*>(args.GetIsolate());
    101       isolate->heap()->RegisterExternalString(*string);
    102     }
    103     if (!result) delete resource;
    104   } else {
    105     uc16* data = new uc16[string->length()];
    106     String::WriteToFlat(*string, data, 0, string->length());
    107     SimpleTwoByteStringResource* resource = new SimpleTwoByteStringResource(
    108         data, string->length());
    109     result = string->MakeExternal(resource);
    110     if (result) {
    111       i::Isolate* isolate = reinterpret_cast<i::Isolate*>(args.GetIsolate());
    112       isolate->heap()->RegisterExternalString(*string);
    113     }
    114     if (!result) delete resource;
    115   }
    116   if (!result) {
    117     args.GetIsolate()->ThrowException(
    118         v8::String::NewFromUtf8(args.GetIsolate(),
    119                                 "externalizeString() failed.",
    120                                 NewStringType::kNormal).ToLocalChecked());
    121     return;
    122   }
    123 }
    124 
    125 
    126 void ExternalizeStringExtension::IsOneByte(
    127     const v8::FunctionCallbackInfo<v8::Value>& args) {
    128   if (args.Length() != 1 || !args[0]->IsString()) {
    129     args.GetIsolate()->ThrowException(
    130         v8::String::NewFromUtf8(
    131             args.GetIsolate(),
    132             "isOneByteString() requires a single string argument.",
    133             NewStringType::kNormal).ToLocalChecked());
    134     return;
    135   }
    136   bool is_one_byte =
    137       Utils::OpenHandle(*args[0].As<v8::String>())->IsOneByteRepresentation();
    138   args.GetReturnValue().Set(is_one_byte);
    139 }
    140 
    141 }  // namespace internal
    142 }  // namespace v8
    143