1 // Copyright 2012 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_INTERFACE_H_ 29 #define V8_INTERFACE_H_ 30 31 #include "zone-inl.h" // For operator new. 32 33 namespace v8 { 34 namespace internal { 35 36 37 // This class implements the following abstract grammar of interfaces 38 // (i.e. module types): 39 // interface ::= UNDETERMINED | VALUE | MODULE(exports) 40 // exports ::= {name : interface, ...} 41 // A frozen module type is one that is fully determined. Unification does not 42 // allow adding additional exports to frozen interfaces. 43 // Otherwise, unifying modules merges their exports. 44 // Undetermined types are unification variables that can be unified freely. 45 46 class Interface : public ZoneObject { 47 public: 48 // --------------------------------------------------------------------------- 49 // Factory methods. 50 NewValue()51 static Interface* NewValue() { 52 static Interface value_interface(VALUE + FROZEN); // Cached. 53 return &value_interface; 54 } 55 NewUnknown()56 static Interface* NewUnknown() { 57 return new Interface(NONE); 58 } 59 NewModule()60 static Interface* NewModule() { 61 return new Interface(MODULE); 62 } 63 64 // --------------------------------------------------------------------------- 65 // Mutators. 66 67 // Add a name to the list of exports. If it already exists, unify with 68 // interface, otherwise insert unless this is closed. Add(Handle<String> name,Interface * interface,bool * ok)69 void Add(Handle<String> name, Interface* interface, bool* ok) { 70 DoAdd(name.location(), name->Hash(), interface, ok); 71 } 72 73 // Unify with another interface. If successful, both interface objects will 74 // represent the same type, and changes to one are reflected in the other. 75 void Unify(Interface* that, bool* ok); 76 77 // Determine this interface to be a value interface. MakeValue(bool * ok)78 void MakeValue(bool* ok) { 79 *ok = !IsModule(); 80 if (*ok) Chase()->flags_ |= VALUE; 81 } 82 83 // Determine this interface to be a module interface. MakeModule(bool * ok)84 void MakeModule(bool* ok) { 85 *ok = !IsValue(); 86 if (*ok) Chase()->flags_ |= MODULE; 87 } 88 89 // Do not allow any further refinements, directly or through unification. Freeze(bool * ok)90 void Freeze(bool* ok) { 91 *ok = IsValue() || IsModule(); 92 if (*ok) Chase()->flags_ |= FROZEN; 93 } 94 95 // --------------------------------------------------------------------------- 96 // Accessors. 97 98 // Look up an exported name. Returns NULL if not (yet) defined. 99 Interface* Lookup(Handle<String> name); 100 101 // Check whether this is still a fully undetermined type. IsUnknown()102 bool IsUnknown() { return Chase()->flags_ == NONE; } 103 104 // Check whether this is a value type. IsValue()105 bool IsValue() { return Chase()->flags_ & VALUE; } 106 107 // Check whether this is a module type. IsModule()108 bool IsModule() { return Chase()->flags_ & MODULE; } 109 110 // Check whether this is closed (i.e. fully determined). IsFrozen()111 bool IsFrozen() { return Chase()->flags_ & FROZEN; } 112 113 // --------------------------------------------------------------------------- 114 // Debugging. 115 #ifdef DEBUG 116 void Print(int n = 0); // n = indentation; n < 0 => don't print recursively 117 #endif 118 119 // --------------------------------------------------------------------------- 120 // Implementation. 121 private: 122 enum Flags { // All flags are monotonic 123 NONE = 0, 124 VALUE = 1, // This type describes a value 125 MODULE = 2, // This type describes a module 126 FROZEN = 4 // This type is fully determined 127 }; 128 129 int flags_; 130 Interface* forward_; // Unification link 131 ZoneHashMap* exports_; // Module exports and their types (allocated lazily) 132 Interface(int flags)133 explicit Interface(int flags) 134 : flags_(flags), 135 forward_(NULL), 136 exports_(NULL) { 137 #ifdef DEBUG 138 if (FLAG_print_interface_details) 139 PrintF("# Creating %p\n", static_cast<void*>(this)); 140 #endif 141 } 142 Chase()143 Interface* Chase() { 144 Interface* result = this; 145 while (result->forward_ != NULL) result = result->forward_; 146 if (result != this) forward_ = result; // On-the-fly path compression. 147 return result; 148 } 149 150 void DoAdd(void* name, uint32_t hash, Interface* interface, bool* ok); 151 void DoUnify(Interface* that, bool* ok); 152 }; 153 154 } } // namespace v8::internal 155 156 #endif // V8_INTERFACE_H_ 157