1 // Copyright 2006-2008 the V8 project authors. All rights reserved. 2 // Redistribution and use in source and binary forms, with or without 3 // modification, are permitted provided that the following conditions are 4 // met: 5 // 6 // * Redistributions of source code must retain the above copyright 7 // notice, this list of conditions and the following disclaimer. 8 // * Redistributions in binary form must reproduce the above 9 // copyright notice, this list of conditions and the following 10 // disclaimer in the documentation and/or other materials provided 11 // with the distribution. 12 // * Neither the name of Google Inc. nor the names of its 13 // contributors may be used to endorse or promote products derived 14 // from this software without specific prior written permission. 15 // 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 28 #ifndef V8_ARGUMENTS_H_ 29 #define V8_ARGUMENTS_H_ 30 31 namespace v8 { 32 namespace internal { 33 34 // Arguments provides access to runtime call parameters. 35 // 36 // It uses the fact that the instance fields of Arguments 37 // (length_, arguments_) are "overlayed" with the parameters 38 // (no. of parameters, and the parameter pointer) passed so 39 // that inside the C++ function, the parameters passed can 40 // be accessed conveniently: 41 // 42 // Object* Runtime_function(Arguments args) { 43 // ... use args[i] here ... 44 // } 45 46 class Arguments BASE_EMBEDDED { 47 public: 48 Arguments(int length, Object** arguments) 49 : length_(length), arguments_(arguments) { } 50 51 Object*& operator[] (int index) { 52 ASSERT(0 <= index && index < length_); 53 return arguments_[-index]; 54 } 55 56 template <class S> Handle<S> at(int index) { 57 Object** value = &((*this)[index]); 58 // This cast checks that the object we're accessing does indeed have the 59 // expected type. 60 S::cast(*value); 61 return Handle<S>(reinterpret_cast<S**>(value)); 62 } 63 64 // Get the total number of arguments including the receiver. 65 int length() const { return length_; } 66 67 Object** arguments() { return arguments_; } 68 69 private: 70 int length_; 71 Object** arguments_; 72 }; 73 74 75 // Cursom arguments replicate a small segment of stack that can be 76 // accessed through an Arguments object the same way the actual stack 77 // can. 78 class CustomArguments : public Relocatable { 79 public: 80 inline CustomArguments(Object* data, 81 JSObject* self, 82 JSObject* holder) { 83 values_[3] = self; 84 values_[2] = holder; 85 values_[1] = Smi::FromInt(0); 86 values_[0] = data; 87 } 88 void IterateInstance(ObjectVisitor* v); 89 Object** end() { return values_ + 3; } 90 private: 91 Object* values_[4]; 92 }; 93 94 95 } } // namespace v8::internal 96 97 #endif // V8_ARGUMENTS_H_ 98
