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 // If this object is in an invalid state. 64 virtual status_t validate() const; 65 66 // Evaluates current constant expression 67 // Doesn't call recursive evaluation, so must be called after dependencies 68 virtual void evaluate() = 0; 69 70 std::vector<ConstantExpression*> getConstantExpressions(); 71 virtual std::vector<const ConstantExpression*> getConstantExpressions() const = 0; 72 73 std::vector<Reference<LocalIdentifier>*> getReferences(); 74 virtual std::vector<const Reference<LocalIdentifier>*> getReferences() const; 75 76 std::vector<Reference<Type>*> getTypeReferences(); 77 virtual std::vector<const Reference<Type>*> getTypeReferences() const; 78 79 // Recursive tree pass checkAcyclic return type. 80 // Stores cycle end for nice error messages. 81 struct CheckAcyclicStatus { 82 CheckAcyclicStatus(status_t status, const ConstantExpression* cycleEnd = nullptr, 83 const ReferenceConstantExpression* lastReferenceExpression = nullptr); 84 85 status_t status; 86 87 // If a cycle is found, stores the end of cycle. 88 // While going back in recursion, this is used to stop printing the cycle. 89 const ConstantExpression* cycleEnd; 90 91 // The last ReferenceConstantExpression visited on the cycle. 92 const ReferenceConstantExpression* lastReference; 93 }; 94 95 // Recursive tree pass that ensures that constant expressions definitions 96 // are acyclic. 97 CheckAcyclicStatus checkAcyclic(std::unordered_set<const ConstantExpression*>* visited, 98 std::unordered_set<const ConstantExpression*>* stack) const; 99 100 /* Returns true iff the value has already been evaluated. */ 101 bool isEvaluated() const; 102 /* Evaluated result in a string form with comment if applicable. */ 103 std::string value() const; 104 /* Evaluated result in a string form with comment if applicable. */ 105 std::string cppValue() const; 106 /* Evaluated result in a string form with comment if applicable. */ 107 std::string javaValue() const; 108 /* Evaluated result in a string form, with given contextual kind. */ 109 std::string value(ScalarType::Kind castKind) const; 110 /* Evaluated result in a string form, with given contextual kind. */ 111 std::string cppValue(ScalarType::Kind castKind) const; 112 /* Evaluated result in a string form, with given contextual kind. */ 113 std::string javaValue(ScalarType::Kind castKind) const; 114 115 /* The expression representing this value for use in comments when the value is not needed */ 116 const std::string& expression() const; 117 118 /* Return a ConstantExpression that is 1 plus the original. */ 119 std::unique_ptr<ConstantExpression> addOne(ScalarType::Kind baseKind); 120 121 size_t castSizeT() const; 122 123 // Marks that package proceeding is completed 124 // Post parse passes must be proceeded during owner package parsin 125 void setPostParseCompleted(); 126 127 /* 128 * Helper function for all cpp/javaValue methods. 129 * Returns a plain string (without any prefixes or suffixes, just the 130 * digits) converted from mValue. 131 */ 132 std::string rawValue() const; 133 std::string rawValue(ScalarType::Kind castKind) const; 134 135 private: 136 /* If the result value has been evaluated. */ 137 bool mIsEvaluated = false; 138 /* The formatted expression. */ 139 std::string mExpr; 140 /* The kind of the result value. */ 141 ScalarType::Kind mValueKind; 142 /* The stored result value. */ 143 uint64_t mValue; 144 /* true if description() does not offer more information than value(). */ 145 bool mTrivialDescription = false; 146 147 bool mIsPostParseCompleted = false; 148 149 /* 150 * Helper function, gives suffix comment to add to value/cppValue/javaValue 151 */ 152 std::string descriptionSuffix() const; 153 154 /* 155 * Return the value casted to the given type. 156 * First cast it according to mValueKind, then cast it to T. 157 * Assumes !containsIdentifiers() 158 */ 159 template <typename T> 160 T cast() const; 161 162 friend struct LiteralConstantExpression; 163 friend struct UnaryConstantExpression; 164 friend struct BinaryConstantExpression; 165 friend struct TernaryConstantExpression; 166 friend struct ReferenceConstantExpression; 167 friend struct AttributeConstantExpression; 168 }; 169 170 struct LiteralConstantExpression : public ConstantExpression { 171 LiteralConstantExpression(ScalarType::Kind kind, uint64_t value); 172 LiteralConstantExpression(ScalarType::Kind kind, uint64_t value, const std::string& expr); 173 void evaluate() override; 174 std::vector<const ConstantExpression*> getConstantExpressions() const override; 175 176 static LiteralConstantExpression* tryParse(const std::string& value); 177 }; 178 179 struct UnaryConstantExpression : public ConstantExpression { 180 UnaryConstantExpression(const std::string& mOp, ConstantExpression* value); 181 void evaluate() override; 182 std::vector<const ConstantExpression*> getConstantExpressions() const override; 183 184 private: 185 ConstantExpression* const mUnary; 186 std::string mOp; 187 }; 188 189 struct BinaryConstantExpression : public ConstantExpression { 190 BinaryConstantExpression(ConstantExpression* lval, const std::string& op, 191 ConstantExpression* rval); 192 void evaluate() override; 193 std::vector<const ConstantExpression*> getConstantExpressions() const override; 194 195 private: 196 ConstantExpression* const mLval; 197 ConstantExpression* const mRval; 198 const std::string mOp; 199 }; 200 201 struct TernaryConstantExpression : public ConstantExpression { 202 TernaryConstantExpression(ConstantExpression* cond, ConstantExpression* trueVal, 203 ConstantExpression* falseVal); 204 void evaluate() override; 205 std::vector<const ConstantExpression*> getConstantExpressions() const override; 206 207 private: 208 ConstantExpression* const mCond; 209 ConstantExpression* const mTrueVal; 210 ConstantExpression* const mFalseVal; 211 }; 212 213 struct ReferenceConstantExpression : public ConstantExpression { 214 ReferenceConstantExpression(const Reference<LocalIdentifier>& value, const std::string& expr); 215 216 bool isReferenceConstantExpression() const override; 217 void evaluate() override; 218 std::vector<const ConstantExpression*> getConstantExpressions() const override; 219 std::vector<const Reference<LocalIdentifier>*> getReferences() const override; 220 221 private: 222 Reference<LocalIdentifier> mReference; 223 }; 224 225 // This constant expression is a compile-time calculatable expression based on another type 226 struct AttributeConstantExpression : public ConstantExpression { 227 AttributeConstantExpression(const Reference<Type>& value, const std::string& fqname, 228 const std::string& tag); 229 230 status_t validate() const override; 231 void evaluate() override; 232 233 std::vector<const ConstantExpression*> getConstantExpressions() const override; 234 std::vector<const Reference<Type>*> getTypeReferences() const override; 235 236 private: 237 Reference<Type> mReference; 238 const std::string mTag; 239 }; 240 241 } // namespace android 242 243 #endif // CONSTANT_EXPRESSION_H_ 244