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 49 ConstantExpression(const std::string& expr); ~ConstantExpressionConstantExpression50 virtual ~ConstantExpression() {} 51 52 virtual bool isReferenceConstantExpression() const; 53 54 void surroundWithParens(); 55 56 // Proceeds recursive pass 57 // Makes sure to visit each node only once 58 // Used to provide lookup and lazy evaluation 59 status_t recursivePass(const std::function<status_t(ConstantExpression*)>& func, 60 std::unordered_set<const ConstantExpression*>* visited, 61 bool processBeforeDependencies); 62 status_t recursivePass(const std::function<status_t(const ConstantExpression*)>& func, 63 std::unordered_set<const ConstantExpression*>* visited, 64 bool processBeforeDependencies) const; 65 66 // If this object is in an invalid state. 67 virtual status_t validate() const; 68 69 // Evaluates current constant expression 70 // Doesn't call recursive evaluation, so must be called after dependencies 71 virtual void evaluate() = 0; 72 73 std::vector<ConstantExpression*> getConstantExpressions(); 74 virtual std::vector<const ConstantExpression*> getConstantExpressions() const = 0; 75 76 std::vector<Reference<LocalIdentifier>*> getReferences(); 77 virtual std::vector<const Reference<LocalIdentifier>*> getReferences() const; 78 79 std::vector<Reference<Type>*> getTypeReferences(); 80 virtual std::vector<const Reference<Type>*> getTypeReferences() const; 81 82 // Recursive tree pass checkAcyclic return type. 83 // Stores cycle end for nice error messages. 84 struct CheckAcyclicStatus { 85 CheckAcyclicStatus(status_t status, const ConstantExpression* cycleEnd = nullptr, 86 const ReferenceConstantExpression* lastReferenceExpression = nullptr); 87 88 status_t status; 89 90 // If a cycle is found, stores the end of cycle. 91 // While going back in recursion, this is used to stop printing the cycle. 92 const ConstantExpression* cycleEnd; 93 94 // The last ReferenceConstantExpression visited on the cycle. 95 const ReferenceConstantExpression* lastReference; 96 }; 97 98 // Recursive tree pass that ensures that constant expressions definitions 99 // are acyclic. 100 CheckAcyclicStatus checkAcyclic(std::unordered_set<const ConstantExpression*>* visited, 101 std::unordered_set<const ConstantExpression*>* stack) const; 102 103 /* Returns true iff the value has already been evaluated. */ 104 bool isEvaluated() const; 105 /* Evaluated result in a string form with comment if applicable. */ 106 std::string value() const; 107 /* Evaluated result in a string form with comment if applicable. */ 108 std::string cppValue() const; 109 /* Evaluated result in a string form with comment if applicable. */ 110 std::string javaValue() const; 111 /* Evaluated result in a string form, with given contextual kind. */ 112 std::string value(ScalarType::Kind castKind) const; 113 /* Evaluated result in a string form, with given contextual kind. */ 114 std::string cppValue(ScalarType::Kind castKind) const; 115 /* Evaluated result in a string form, with given contextual kind. */ 116 std::string javaValue(ScalarType::Kind castKind) const; 117 118 /* The expression representing this value for use in comments when the value is not needed */ 119 const std::string& expression() const; 120 121 /* Return a ConstantExpression that is 1 plus the original. */ 122 std::unique_ptr<ConstantExpression> addOne(ScalarType::Kind baseKind); 123 124 size_t castSizeT() const; 125 126 // Marks that package proceeding is completed 127 // Post parse passes must be proceeded during owner package parsin 128 void setPostParseCompleted(); 129 130 /* 131 * Helper function for all cpp/javaValue methods. 132 * Returns a plain string (without any prefixes or suffixes, just the 133 * digits) converted from mValue. 134 */ 135 std::string rawValue() const; 136 std::string rawValue(ScalarType::Kind castKind) const; 137 138 private: 139 /* If the result value has been evaluated. */ 140 bool mIsEvaluated = false; 141 /* The formatted expression. */ 142 std::string mExpr; 143 /* The kind of the result value. */ 144 ScalarType::Kind mValueKind; 145 /* The stored result value. */ 146 uint64_t mValue; 147 /* true if description() does not offer more information than value(). */ 148 bool mTrivialDescription = false; 149 150 bool mIsPostParseCompleted = false; 151 152 /* 153 * Helper function, gives suffix comment to add to value/cppValue/javaValue 154 */ 155 std::string descriptionSuffix() const; 156 157 /* 158 * Return the value casted to the given type. 159 * First cast it according to mValueKind, then cast it to T. 160 * Assumes !containsIdentifiers() 161 */ 162 template <typename T> 163 T cast() const; 164 165 friend struct LiteralConstantExpression; 166 friend struct UnaryConstantExpression; 167 friend struct BinaryConstantExpression; 168 friend struct TernaryConstantExpression; 169 friend struct ReferenceConstantExpression; 170 friend struct AttributeConstantExpression; 171 }; 172 173 struct LiteralConstantExpression : public ConstantExpression { 174 LiteralConstantExpression(ScalarType::Kind kind, uint64_t value); 175 LiteralConstantExpression(ScalarType::Kind kind, uint64_t value, const std::string& expr); 176 void evaluate() override; 177 std::vector<const ConstantExpression*> getConstantExpressions() const override; 178 179 static LiteralConstantExpression* tryParse(const std::string& value); 180 }; 181 182 struct UnaryConstantExpression : public ConstantExpression { 183 UnaryConstantExpression(const std::string& mOp, ConstantExpression* value); 184 void evaluate() override; 185 std::vector<const ConstantExpression*> getConstantExpressions() const override; 186 187 private: 188 ConstantExpression* const mUnary; 189 std::string mOp; 190 }; 191 192 struct BinaryConstantExpression : public ConstantExpression { 193 BinaryConstantExpression(ConstantExpression* lval, const std::string& op, 194 ConstantExpression* rval); 195 void evaluate() override; 196 std::vector<const ConstantExpression*> getConstantExpressions() const override; 197 198 private: 199 ConstantExpression* const mLval; 200 ConstantExpression* const mRval; 201 const std::string mOp; 202 }; 203 204 struct TernaryConstantExpression : public ConstantExpression { 205 TernaryConstantExpression(ConstantExpression* cond, ConstantExpression* trueVal, 206 ConstantExpression* falseVal); 207 void evaluate() override; 208 std::vector<const ConstantExpression*> getConstantExpressions() const override; 209 210 private: 211 ConstantExpression* const mCond; 212 ConstantExpression* const mTrueVal; 213 ConstantExpression* const mFalseVal; 214 }; 215 216 struct ReferenceConstantExpression : public ConstantExpression { 217 ReferenceConstantExpression(const Reference<LocalIdentifier>& value, const std::string& expr); 218 219 bool isReferenceConstantExpression() const override; 220 void evaluate() override; 221 std::vector<const ConstantExpression*> getConstantExpressions() const override; 222 std::vector<const Reference<LocalIdentifier>*> getReferences() const override; 223 224 private: 225 Reference<LocalIdentifier> mReference; 226 }; 227 228 // This constant expression is a compile-time calculatable expression based on another type 229 struct AttributeConstantExpression : public ConstantExpression { 230 AttributeConstantExpression(const Reference<Type>& value, const std::string& fqname, 231 const std::string& tag); 232 233 status_t validate() const override; 234 void evaluate() override; 235 236 std::vector<const ConstantExpression*> getConstantExpressions() const override; 237 std::vector<const Reference<Type>*> getTypeReferences() const override; 238 239 private: 240 Reference<Type> mReference; 241 const std::string mTag; 242 }; 243 244 } // namespace android 245 246 #endif // CONSTANT_EXPRESSION_H_ 247