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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_VARIABLEREFERENCE
#define SKSL_VARIABLEREFERENCE
#include "SkSLExpression.h"
#include "SkSLFloatLiteral.h"
#include "SkSLIRGenerator.h"
#include "SkSLIntLiteral.h"
namespace SkSL {
/**
* A reference to a variable, through which it can be read or written. In the statement:
*
* x = x + 1;
*
* there is only one Variable 'x', but two VariableReferences to it.
*/
struct VariableReference : public Expression {
enum RefKind {
kRead_RefKind,
kWrite_RefKind,
kReadWrite_RefKind
};
VariableReference(Position position, const Variable& variable, RefKind refKind = kRead_RefKind)
: INHERITED(position, kVariableReference_Kind, variable.fType)
, fVariable(variable)
, fRefKind(refKind) {
if (refKind != kRead_RefKind) {
fVariable.fWriteCount++;
}
if (refKind != kWrite_RefKind) {
fVariable.fReadCount++;
}
}
virtual ~VariableReference() override {
if (fRefKind != kWrite_RefKind) {
fVariable.fReadCount--;
}
}
RefKind refKind() {
return fRefKind;
}
void setRefKind(RefKind refKind) {
if (fRefKind != kRead_RefKind) {
fVariable.fWriteCount--;
}
if (fRefKind != kWrite_RefKind) {
fVariable.fReadCount--;
}
if (refKind != kRead_RefKind) {
fVariable.fWriteCount++;
}
if (refKind != kWrite_RefKind) {
fVariable.fReadCount++;
}
fRefKind = refKind;
}
SkString description() const override {
return fVariable.fName;
}
virtual std::unique_ptr<Expression> constantPropagate(
const IRGenerator& irGenerator,
const DefinitionMap& definitions) override {
auto exprIter = definitions.find(&fVariable);
if (exprIter != definitions.end() && exprIter->second) {
const Expression* expr = exprIter->second->get();
switch (expr->fKind) {
case Expression::kIntLiteral_Kind:
return std::unique_ptr<Expression>(new IntLiteral(
irGenerator.fContext,
Position(),
((IntLiteral*) expr)->fValue));
case Expression::kFloatLiteral_Kind:
return std::unique_ptr<Expression>(new FloatLiteral(
irGenerator.fContext,
Position(),
((FloatLiteral*) expr)->fValue));
default:
break;
}
}
return nullptr;
}
const Variable& fVariable;
private:
RefKind fRefKind;
typedef Expression INHERITED;
};
} // namespace
#endif
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