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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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