/*
* Copyright 2021 Google LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#ifndef SkSLProgramVisitor_DEFINED
#define SkSLProgramVisitor_DEFINED
#include <memory>
namespace SkSL {
struct Program;
class Expression;
class Statement;
class ProgramElement;
/**
* Utility class to visit every element, statement, and expression in an SkSL program IR.
* This is intended for simple analysis and accumulation, where custom visitation behavior is only
* needed for a limited set of expression kinds.
*
* Subclasses should override visitExpression/visitStatement/visitProgramElement as needed and
* intercept elements of interest. They can then invoke the base class's function to visit all
* sub expressions. They can also choose not to call the base function to arrest recursion, or
* implement custom recursion.
*
* The visit functions return a bool that determines how the default implementation recurses. Once
* any visit call returns true, the default behavior stops recursing and propagates true up the
* stack.
*/
template <
typename T>
class TProgramVisitor {
public:
virtual ~TProgramVisitor() =
default;
protected:
virtual bool visitExpression(
typename T::Expression& expression);
virtual bool visitStatement(
typename T::Statement& statement);
virtual bool visitProgramElement(
typename T::ProgramElement& programElement);
virtual bool visitExpressionPtr(
typename T::UniquePtrExpression& expr) = 0;
virtual bool visitStatementPtr(
typename T::UniquePtrStatement& stmt) = 0;
};
// ProgramVisitors take const types; ProgramWriters do not.
struct ProgramVisitorTypes {
using Program =
const SkSL::Program;
using Expression =
const SkSL::Expression;
using Statement =
const SkSL::Statement;
using ProgramElement =
const SkSL::ProgramElement;
using UniquePtrExpression =
const std::unique_ptr<SkSL::Expression>;
using UniquePtrStatement =
const std::unique_ptr<SkSL::Statement>;
};
extern template class TProgramVisitor<ProgramVisitorTypes>;
class ProgramVisitor :
public TProgramVisitor<ProgramVisitorTypes> {
public:
bool visit(
const Program& program);
private:
// ProgramVisitors shouldn't need access to unique_ptrs, and marking these as final should help
// these accessors inline away. Use ProgramWriter if you need the unique_ptrs.
bool visitExpressionPtr(
const std::unique_ptr<Expression>& e) final {
return this->visitExpression(*e);
}
bool visitStatementPtr(
const std::unique_ptr<Statement>& s) final {
return this->visitStatement(*s);
}
};
}
// namespace SkSL
#endif
