1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef CONSTANT_EXPRESSION_H_ 18 19 #define CONSTANT_EXPRESSION_H_ 20 21 #include <android-base/macros.h> 22 #include <functional> 23 #include <memory> 24 #include <string> 25 #include <unordered_set> 26 #include <vector> 27 28 #include "Reference.h" 29 #include "ScalarType.h" 30 31 namespace android { 32 33 struct LocalIdentifier; 34 35 struct LiteralConstantExpression; 36 struct UnaryConstantExpression; 37 struct BinaryConstantExpression; 38 struct TernaryConstantExpression; 39 struct ReferenceConstantExpression; 40 41 /** 42 * A constant expression is represented by a tree. 43 */ 44 struct ConstantExpression { 45 static std::unique_ptr<ConstantExpression> Zero(ScalarType::Kind kind); 46 static std::unique_ptr<ConstantExpression> One(ScalarType::Kind kind); 47 static std::unique_ptr<ConstantExpression> ValueOf(ScalarType::Kind kind, uint64_t value); 48 ~ConstantExpressionConstantExpression49 virtual ~ConstantExpression() {} 50 51 virtual bool isReferenceConstantExpression() const; 52 53 // Proceeds recursive pass 54 // Makes sure to visit each node only once 55 // Used to provide lookup and lazy evaluation 56 status_t recursivePass(const std::function<status_t(ConstantExpression*)>& func, 57 std::unordered_set<const ConstantExpression*>* visited, 58 bool processBeforeDependencies); 59 status_t recursivePass(const std::function<status_t(const ConstantExpression*)>& func, 60 std::unordered_set<const ConstantExpression*>* visited, 61 bool processBeforeDependencies) const; 62 63 // Evaluates current constant expression 64 // Doesn't call recursive evaluation, so must be called after dependencies 65 virtual void evaluate() = 0; 66 67 std::vector<ConstantExpression*> getConstantExpressions(); 68 virtual std::vector<const ConstantExpression*> getConstantExpressions() const = 0; 69 70 std::vector<Reference<LocalIdentifier>*> getReferences(); 71 virtual std::vector<const Reference<LocalIdentifier>*> getReferences() const; 72 73 // Recursive tree pass checkAcyclic return type. 74 // Stores cycle end for nice error messages. 75 struct CheckAcyclicStatus { 76 CheckAcyclicStatus(status_t status, const ConstantExpression* cycleEnd = nullptr, 77 const ReferenceConstantExpression* lastReferenceExpression = nullptr); 78 79 status_t status; 80 81 // If a cycle is found, stores the end of cycle. 82 // While going back in recursion, this is used to stop printing the cycle. 83 const ConstantExpression* cycleEnd; 84 85 // The last ReferenceConstantExpression visited on the cycle. 86 const ReferenceConstantExpression* lastReference; 87 }; 88 89 // Recursive tree pass that ensures that constant expressions definitions 90 // are acyclic. 91 CheckAcyclicStatus checkAcyclic(std::unordered_set<const ConstantExpression*>* visited, 92 std::unordered_set<const ConstantExpression*>* stack) const; 93 94 /* Returns true iff the value has already been evaluated. */ 95 bool isEvaluated() const; 96 /* Evaluated result in a string form. */ 97 std::string value() const; 98 /* Evaluated result in a string form. */ 99 std::string cppValue() const; 100 /* Evaluated result in a string form. */ 101 std::string javaValue() const; 102 /* Evaluated result in a string form, with given contextual kind. */ 103 std::string value(ScalarType::Kind castKind) const; 104 /* Evaluated result in a string form, with given contextual kind. */ 105 std::string cppValue(ScalarType::Kind castKind) const; 106 /* Evaluated result in a string form, with given contextual kind. */ 107 std::string javaValue(ScalarType::Kind castKind) const; 108 /* Formatted expression with type. */ 109 const std::string& description() const; 110 /* See mTrivialDescription */ 111 bool descriptionIsTrivial() const; 112 /* Return a ConstantExpression that is 1 plus the original. */ 113 std::unique_ptr<ConstantExpression> addOne(ScalarType::Kind baseKind); 114 115 size_t castSizeT() const; 116 117 // Marks that package proceeding is completed 118 // Post parse passes must be proceeded during owner package parsin 119 void setPostParseCompleted(); 120 121 private: 122 /* If the result value has been evaluated. */ 123 bool mIsEvaluated = false; 124 /* The formatted expression. */ 125 std::string mExpr; 126 /* The kind of the result value. */ 127 ScalarType::Kind mValueKind; 128 /* The stored result value. */ 129 uint64_t mValue; 130 /* true if description() does not offer more information than value(). */ 131 bool mTrivialDescription = false; 132 133 bool mIsPostParseCompleted = false; 134 135 /* 136 * Helper function for all cpp/javaValue methods. 137 * Returns a plain string (without any prefixes or suffixes, just the 138 * digits) converted from mValue. 139 */ 140 std::string rawValue(ScalarType::Kind castKind) const; 141 142 /* 143 * Return the value casted to the given type. 144 * First cast it according to mValueKind, then cast it to T. 145 * Assumes !containsIdentifiers() 146 */ 147 template <typename T> 148 T cast() const; 149 150 friend struct LiteralConstantExpression; 151 friend struct UnaryConstantExpression; 152 friend struct BinaryConstantExpression; 153 friend struct TernaryConstantExpression; 154 friend struct ReferenceConstantExpression; 155 }; 156 157 struct LiteralConstantExpression : public ConstantExpression { 158 LiteralConstantExpression(ScalarType::Kind kind, uint64_t value); 159 void evaluate() override; 160 std::vector<const ConstantExpression*> getConstantExpressions() const override; 161 162 static LiteralConstantExpression* tryParse(const std::string& value); 163 164 private: 165 LiteralConstantExpression(ScalarType::Kind kind, uint64_t value, const std::string& expr); 166 }; 167 168 struct UnaryConstantExpression : public ConstantExpression { 169 UnaryConstantExpression(const std::string& mOp, ConstantExpression* value); 170 void evaluate() override; 171 std::vector<const ConstantExpression*> getConstantExpressions() const override; 172 173 private: 174 ConstantExpression* const mUnary; 175 std::string mOp; 176 }; 177 178 struct BinaryConstantExpression : public ConstantExpression { 179 BinaryConstantExpression(ConstantExpression* lval, const std::string& op, 180 ConstantExpression* rval); 181 void evaluate() override; 182 std::vector<const ConstantExpression*> getConstantExpressions() const override; 183 184 private: 185 ConstantExpression* const mLval; 186 ConstantExpression* const mRval; 187 const std::string mOp; 188 }; 189 190 struct TernaryConstantExpression : public ConstantExpression { 191 TernaryConstantExpression(ConstantExpression* cond, ConstantExpression* trueVal, 192 ConstantExpression* falseVal); 193 void evaluate() override; 194 std::vector<const ConstantExpression*> getConstantExpressions() const override; 195 196 private: 197 ConstantExpression* const mCond; 198 ConstantExpression* const mTrueVal; 199 ConstantExpression* const mFalseVal; 200 }; 201 202 struct ReferenceConstantExpression : public ConstantExpression { 203 ReferenceConstantExpression(const Reference<LocalIdentifier>& value, const std::string& expr); 204 205 bool isReferenceConstantExpression() const override; 206 void evaluate() override; 207 std::vector<const ConstantExpression*> getConstantExpressions() const override; 208 std::vector<const Reference<LocalIdentifier>*> getReferences() const override; 209 210 private: 211 Reference<LocalIdentifier> mReference; 212 }; 213 214 } // namespace android 215 216 #endif // CONSTANT_EXPRESSION_H_ 217