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/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SKSL_EXPRESSION
#define SKSL_EXPRESSION
#include "SkSLType.h"
#include "SkSLVariable.h"
#include <unordered_map>
namespace SkSL {
struct Expression;
class IRGenerator;
typedef std::unordered_map<const Variable*, std::unique_ptr<Expression>*> DefinitionMap;
/**
* Abstract supertype of all expressions.
*/
struct Expression : public IRNode {
enum Kind {
kAppendStage_Kind,
kBinary_Kind,
kBoolLiteral_Kind,
kConstructor_Kind,
kIntLiteral_Kind,
kFieldAccess_Kind,
kFloatLiteral_Kind,
kFunctionReference_Kind,
kFunctionCall_Kind,
kIndex_Kind,
kPrefix_Kind,
kPostfix_Kind,
kSetting_Kind,
kSwizzle_Kind,
kVariableReference_Kind,
kTernary_Kind,
kTypeReference_Kind,
kDefined_Kind
};
Expression(int offset, Kind kind, const Type& type)
: INHERITED(offset)
, fKind(kind)
, fType(std::move(type)) {}
/**
* Returns true if this expression is constant. compareConstant must be implemented for all
* constants!
*/
virtual bool isConstant() const {
return false;
}
/**
* Compares this constant expression against another constant expression of the same type. It is
* an error to call this on non-constant expressions, or if the types of the expressions do not
* match.
*/
virtual bool compareConstant(const Context& context, const Expression& other) const {
ABORT("cannot call compareConstant on this type");
}
/**
* For an expression which evaluates to a constant int, returns the value. Otherwise calls
* ABORT.
*/
virtual int64_t getConstantInt() const {
ABORT("not a constant int");
}
/**
* For an expression which evaluates to a constant float, returns the value. Otherwise calls
* ABORT.
*/
virtual double getConstantFloat() const {
ABORT("not a constant float");
}
/**
* Returns true if evaluating the expression potentially has side effects. Expressions may never
* return false if they actually have side effects, but it is legal (though suboptimal) to
* return true if there are not actually any side effects.
*/
virtual bool hasSideEffects() const = 0;
/**
* Given a map of known constant variable values, substitute them in for references to those
* variables occurring in this expression and its subexpressions. Similar simplifications, such
* as folding a constant binary expression down to a single value, may also be performed.
* Returns a new expression which replaces this expression, or null if no replacements were
* made. If a new expression is returned, this expression is no longer valid.
*/
virtual std::unique_ptr<Expression> constantPropagate(const IRGenerator& irGenerator,
const DefinitionMap& definitions) {
return nullptr;
}
virtual int coercionCost(const Type& target) const {
return fType.coercionCost(target);
}
const Kind fKind;
const Type& fType;
typedef IRNode INHERITED;
};
} // namespace
#endif
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