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| 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 |
| 51 static Interface* NewValue() { |
| 52 static Interface value_interface(VALUE + FROZEN); // Cached. |
| 53 return &value_interface; |
| 54 } |
| 55 |
| 56 static Interface* NewUnknown() { |
| 57 return new Interface(NONE); |
| 58 } |
| 59 |
| 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. |
| 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. |
| 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. |
| 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. |
| 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. |
| 102 bool IsUnknown() { return Chase()->flags_ == NONE; } |
| 103 |
| 104 // Check whether this is a value type. |
| 105 bool IsValue() { return Chase()->flags_ & VALUE; } |
| 106 |
| 107 // Check whether this is a module type. |
| 108 bool IsModule() { return Chase()->flags_ & MODULE; } |
| 109 |
| 110 // Check whether this is closed (i.e. fully determined). |
| 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 |
| 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 |
| 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_ |
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