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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef CONSTANT_EXPRESSION_H_
#define CONSTANT_EXPRESSION_H_
#include <android-base/macros.h>
#include <functional>
#include <memory>
#include <string>
#include <unordered_set>
#include <vector>
#include "Reference.h"
#include "ScalarType.h"
namespace android {
struct LocalIdentifier;
struct LiteralConstantExpression;
struct UnaryConstantExpression;
struct BinaryConstantExpression;
struct TernaryConstantExpression;
struct ReferenceConstantExpression;
/**
* A constant expression is represented by a tree.
*/
struct ConstantExpression {
static std::unique_ptr<ConstantExpression> Zero(ScalarType::Kind kind);
static std::unique_ptr<ConstantExpression> One(ScalarType::Kind kind);
static std::unique_ptr<ConstantExpression> ValueOf(ScalarType::Kind kind, uint64_t value);
ConstantExpression(const std::string& expr);
virtual ~ConstantExpression() {}
virtual bool isReferenceConstantExpression() const;
void surroundWithParens();
// Proceeds recursive pass
// Makes sure to visit each node only once
// Used to provide lookup and lazy evaluation
status_t recursivePass(const std::function<status_t(ConstantExpression*)>& func,
std::unordered_set<const ConstantExpression*>* visited,
bool processBeforeDependencies);
status_t recursivePass(const std::function<status_t(const ConstantExpression*)>& func,
std::unordered_set<const ConstantExpression*>* visited,
bool processBeforeDependencies) const;
// If this object is in an invalid state.
virtual status_t validate() const;
// Evaluates current constant expression
// Doesn't call recursive evaluation, so must be called after dependencies
virtual void evaluate() = 0;
std::vector<ConstantExpression*> getConstantExpressions();
virtual std::vector<const ConstantExpression*> getConstantExpressions() const = 0;
std::vector<Reference<LocalIdentifier>*> getReferences();
virtual std::vector<const Reference<LocalIdentifier>*> getReferences() const;
std::vector<Reference<Type>*> getTypeReferences();
virtual std::vector<const Reference<Type>*> getTypeReferences() const;
// Recursive tree pass checkAcyclic return type.
// Stores cycle end for nice error messages.
struct CheckAcyclicStatus {
CheckAcyclicStatus(status_t status, const ConstantExpression* cycleEnd = nullptr,
const ReferenceConstantExpression* lastReferenceExpression = nullptr);
status_t status;
// If a cycle is found, stores the end of cycle.
// While going back in recursion, this is used to stop printing the cycle.
const ConstantExpression* cycleEnd;
// The last ReferenceConstantExpression visited on the cycle.
const ReferenceConstantExpression* lastReference;
};
// Recursive tree pass that ensures that constant expressions definitions
// are acyclic.
CheckAcyclicStatus checkAcyclic(std::unordered_set<const ConstantExpression*>* visited,
std::unordered_set<const ConstantExpression*>* stack) const;
/* Returns true iff the value has already been evaluated. */
bool isEvaluated() const;
/* Evaluated result in a string form with comment if applicable. */
std::string value() const;
/* Evaluated result in a string form with comment if applicable. */
std::string cppValue() const;
/* Evaluated result in a string form with comment if applicable. */
std::string javaValue() const;
/* Evaluated result in a string form, with given contextual kind. */
std::string value(ScalarType::Kind castKind) const;
/* Evaluated result in a string form, with given contextual kind. */
std::string cppValue(ScalarType::Kind castKind) const;
/* Evaluated result in a string form, with given contextual kind. */
std::string javaValue(ScalarType::Kind castKind) const;
/* The expression representing this value for use in comments when the value is not needed */
const std::string& expression() const;
/* Return a ConstantExpression that is 1 plus the original. */
std::unique_ptr<ConstantExpression> addOne(ScalarType::Kind baseKind);
size_t castSizeT() const;
// Marks that package proceeding is completed
// Post parse passes must be proceeded during owner package parsin
void setPostParseCompleted();
/*
* Helper function for all cpp/javaValue methods.
* Returns a plain string (without any prefixes or suffixes, just the
* digits) converted from mValue.
*/
std::string rawValue() const;
std::string rawValue(ScalarType::Kind castKind) const;
private:
/* If the result value has been evaluated. */
bool mIsEvaluated = false;
/* The formatted expression. */
std::string mExpr;
/* The kind of the result value. */
ScalarType::Kind mValueKind;
/* The stored result value. */
uint64_t mValue;
/* true if description() does not offer more information than value(). */
bool mTrivialDescription = false;
bool mIsPostParseCompleted = false;
/*
* Helper function, gives suffix comment to add to value/cppValue/javaValue
*/
std::string descriptionSuffix() const;
/*
* Return the value casted to the given type.
* First cast it according to mValueKind, then cast it to T.
* Assumes !containsIdentifiers()
*/
template <typename T>
T cast() const;
friend struct LiteralConstantExpression;
friend struct UnaryConstantExpression;
friend struct BinaryConstantExpression;
friend struct TernaryConstantExpression;
friend struct ReferenceConstantExpression;
friend struct AttributeConstantExpression;
};
struct LiteralConstantExpression : public ConstantExpression {
LiteralConstantExpression(ScalarType::Kind kind, uint64_t value);
LiteralConstantExpression(ScalarType::Kind kind, uint64_t value, const std::string& expr);
void evaluate() override;
std::vector<const ConstantExpression*> getConstantExpressions() const override;
static LiteralConstantExpression* tryParse(const std::string& value);
};
struct UnaryConstantExpression : public ConstantExpression {
UnaryConstantExpression(const std::string& mOp, ConstantExpression* value);
void evaluate() override;
std::vector<const ConstantExpression*> getConstantExpressions() const override;
private:
ConstantExpression* const mUnary;
std::string mOp;
};
struct BinaryConstantExpression : public ConstantExpression {
BinaryConstantExpression(ConstantExpression* lval, const std::string& op,
ConstantExpression* rval);
void evaluate() override;
std::vector<const ConstantExpression*> getConstantExpressions() const override;
private:
ConstantExpression* const mLval;
ConstantExpression* const mRval;
const std::string mOp;
};
struct TernaryConstantExpression : public ConstantExpression {
TernaryConstantExpression(ConstantExpression* cond, ConstantExpression* trueVal,
ConstantExpression* falseVal);
void evaluate() override;
std::vector<const ConstantExpression*> getConstantExpressions() const override;
private:
ConstantExpression* const mCond;
ConstantExpression* const mTrueVal;
ConstantExpression* const mFalseVal;
};
struct ReferenceConstantExpression : public ConstantExpression {
ReferenceConstantExpression(const Reference<LocalIdentifier>& value, const std::string& expr);
bool isReferenceConstantExpression() const override;
void evaluate() override;
std::vector<const ConstantExpression*> getConstantExpressions() const override;
std::vector<const Reference<LocalIdentifier>*> getReferences() const override;
private:
Reference<LocalIdentifier> mReference;
};
// This constant expression is a compile-time calculatable expression based on another type
struct AttributeConstantExpression : public ConstantExpression {
AttributeConstantExpression(const Reference<Type>& value, const std::string& fqname,
const std::string& tag);
status_t validate() const override;
void evaluate() override;
std::vector<const ConstantExpression*> getConstantExpressions() const override;
std::vector<const Reference<Type>*> getTypeReferences() const override;
private:
Reference<Type> mReference;
const std::string mTag;
};
} // namespace android
#endif // CONSTANT_EXPRESSION_H_