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Side by Side Diff: third_party/WebKit/Source/bindings/core/v8/StringResource.cpp

Issue 2843603002: Move ScriptWrappable and dependencies to platform/bindings (Closed)
Patch Set: Rebase and try again Created 3 years, 7 months ago
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1 // Copyright 2017 The Chromium 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 "bindings/core/v8/StringResource.h"
6
7 #include "bindings/core/v8/V8Binding.h"
8
9 namespace blink {
10
11 template <class StringClass>
12 struct StringTraits {
13 static const StringClass& FromStringResource(StringResourceBase*);
14 template <typename V8StringTrait>
15 static StringClass FromV8String(v8::Local<v8::String>, int);
16 };
17
18 template <>
19 struct StringTraits<String> {
20 static const String& FromStringResource(StringResourceBase* resource) {
21 return resource->WebcoreString();
22 }
23 template <typename V8StringTrait>
24 static String FromV8String(v8::Local<v8::String>, int);
25 };
26
27 template <>
28 struct StringTraits<AtomicString> {
29 static const AtomicString& FromStringResource(StringResourceBase* resource) {
30 return resource->GetAtomicString();
31 }
32 template <typename V8StringTrait>
33 static AtomicString FromV8String(v8::Local<v8::String>, int);
34 };
35
36 struct V8StringTwoBytesTrait {
37 typedef UChar CharType;
38 ALWAYS_INLINE static void Write(v8::Local<v8::String> v8_string,
39 CharType* buffer,
40 int length) {
41 v8_string->Write(reinterpret_cast<uint16_t*>(buffer), 0, length);
42 }
43 };
44
45 struct V8StringOneByteTrait {
46 typedef LChar CharType;
47 ALWAYS_INLINE static void Write(v8::Local<v8::String> v8_string,
48 CharType* buffer,
49 int length) {
50 v8_string->WriteOneByte(buffer, 0, length);
51 }
52 };
53
54 template <typename V8StringTrait>
55 String StringTraits<String>::FromV8String(v8::Local<v8::String> v8_string,
56 int length) {
57 DCHECK(v8_string->Length() == length);
58 typename V8StringTrait::CharType* buffer;
59 String result = String::CreateUninitialized(length, buffer);
60 V8StringTrait::Write(v8_string, buffer, length);
61 return result;
62 }
63
64 template <typename V8StringTrait>
65 AtomicString StringTraits<AtomicString>::FromV8String(
66 v8::Local<v8::String> v8_string,
67 int length) {
68 DCHECK(v8_string->Length() == length);
69 static const int kInlineBufferSize =
70 32 / sizeof(typename V8StringTrait::CharType);
71 if (length <= kInlineBufferSize) {
72 typename V8StringTrait::CharType inline_buffer[kInlineBufferSize];
73 V8StringTrait::Write(v8_string, inline_buffer, length);
74 return AtomicString(inline_buffer, length);
75 }
76 typename V8StringTrait::CharType* buffer;
77 String string = String::CreateUninitialized(length, buffer);
78 V8StringTrait::Write(v8_string, buffer, length);
79 return AtomicString(string);
80 }
81
82 template <typename StringType>
83 StringType V8StringToWebCoreString(v8::Local<v8::String> v8_string,
84 ExternalMode external) {
85 {
86 // This portion of this function is very hot in certain Dromeao benchmarks.
87 v8::String::Encoding encoding;
88 v8::String::ExternalStringResourceBase* resource =
89 v8_string->GetExternalStringResourceBase(&encoding);
90 if (LIKELY(!!resource)) {
91 StringResourceBase* base;
92 if (encoding == v8::String::ONE_BYTE_ENCODING)
93 base = static_cast<StringResource8*>(resource);
94 else
95 base = static_cast<StringResource16*>(resource);
96 return StringTraits<StringType>::FromStringResource(base);
97 }
98 }
99
100 int length = v8_string->Length();
101 if (UNLIKELY(!length))
102 return StringType("");
103
104 bool one_byte = v8_string->ContainsOnlyOneByte();
105 StringType result(one_byte ? StringTraits<StringType>::template FromV8String<
106 V8StringOneByteTrait>(v8_string, length)
107 : StringTraits<StringType>::template FromV8String<
108 V8StringTwoBytesTrait>(v8_string, length));
109
110 if (external != kExternalize || !v8_string->CanMakeExternal())
111 return result;
112
113 if (result.Is8Bit()) {
114 StringResource8* string_resource = new StringResource8(result);
115 if (UNLIKELY(!v8_string->MakeExternal(string_resource)))
116 delete string_resource;
117 } else {
118 StringResource16* string_resource = new StringResource16(result);
119 if (UNLIKELY(!v8_string->MakeExternal(string_resource)))
120 delete string_resource;
121 }
122 return result;
123 }
124
125 // Explicitly instantiate the above template with the expected
126 // parameterizations, to ensure the compiler generates the code; otherwise link
127 // errors can result in GCC 4.4.
128 template String V8StringToWebCoreString<String>(v8::Local<v8::String>,
129 ExternalMode);
130 template AtomicString V8StringToWebCoreString<AtomicString>(
131 v8::Local<v8::String>,
132 ExternalMode);
133
134 // Fast but non thread-safe version.
135 String Int32ToWebCoreStringFast(int value) {
136 // Caching of small strings below is not thread safe: newly constructed
137 // AtomicString are not safely published.
138 DCHECK(IsMainThread());
139
140 // Most numbers used are <= 100. Even if they aren't used there's very little
141 // cost in using the space.
142 const int kLowNumbers = 100;
143 DEFINE_STATIC_LOCAL(Vector<AtomicString>, low_numbers, (kLowNumbers + 1));
144 String web_core_string;
145 if (0 <= value && value <= kLowNumbers) {
146 web_core_string = low_numbers[value];
147 if (!web_core_string) {
148 AtomicString value_string = AtomicString::Number(value);
149 low_numbers[value] = value_string;
150 web_core_string = value_string;
151 }
152 } else {
153 web_core_string = String::Number(value);
154 }
155 return web_core_string;
156 }
157
158 String Int32ToWebCoreString(int value) {
159 // If we are on the main thread (this should always true for non-workers),
160 // call the faster one.
161 if (IsMainThread())
162 return Int32ToWebCoreStringFast(value);
163 return String::Number(value);
164 }
165
166 } // namespace blink
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