solidity/libsolidity/ast/ASTVisitor.h

/*
	This file is part of solidity.

	solidity is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	solidity is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with solidity.  If not, see <http://www.gnu.org/licenses/>.
*/
/**
 * @author Christian <c@ethdev.com>
 * @date 2014
 * AST visitor base class.
 */

#pragma once

#include <libsolidity/ast/AST.h>
#include <functional>
#include <string>
#include <vector>

namespace solidity::frontend
{

/**
 * Visitor interface for the abstract syntax tree. This class is tightly bound to the
 * implementation of @ref ASTNode::accept and its overrides. After a call to
 * @ref ASTNode::accept, the function visit for the appropriate parameter is called and then
 * (if it returns true) this continues recursively for all child nodes in document order
 * (there is an exception for contracts). After all child nodes have been visited, endVisit is
 * called for the node.
 */
class ASTVisitor
{
public:
	virtual ~ASTVisitor() = default;
	virtual bool visit(SourceUnit& _node) { return visitNode(_node); }
	virtual bool visit(PragmaDirective& _node) { return visitNode(_node); }
	virtual bool visit(ImportDirective& _node) { return visitNode(_node); }
	virtual bool visit(ContractDefinition& _node) { return visitNode(_node); }
	virtual bool visit(InheritanceSpecifier& _node) { return visitNode(_node); }
	virtual bool visit(UsingForDirective& _node) { return visitNode(_node); }
	virtual bool visit(StructDefinition& _node) { return visitNode(_node); }
	virtual bool visit(EnumDefinition& _node) { return visitNode(_node); }
	virtual bool visit(EnumValue& _node) { return visitNode(_node); }
	virtual bool visit(ParameterList& _node) { return visitNode(_node); }
	virtual bool visit(OverrideSpecifier& _node) { return visitNode(_node); }
	virtual bool visit(FunctionDefinition& _node) { return visitNode(_node); }
	virtual bool visit(VariableDeclaration& _node) { return visitNode(_node); }
	virtual bool visit(ModifierDefinition& _node) { return visitNode(_node); }
	virtual bool visit(ModifierInvocation& _node) { return visitNode(_node); }
	virtual bool visit(EventDefinition& _node) { return visitNode(_node); }
	virtual bool visit(ElementaryTypeName& _node) { return visitNode(_node); }
	virtual bool visit(UserDefinedTypeName& _node) { return visitNode(_node); }
	virtual bool visit(FunctionTypeName& _node) { return visitNode(_node); }
	virtual bool visit(Mapping& _node) { return visitNode(_node); }
	virtual bool visit(ArrayTypeName& _node) { return visitNode(_node); }
	virtual bool visit(InlineAssembly& _node) { return visitNode(_node); }
	virtual bool visit(Block& _node) { return visitNode(_node); }
	virtual bool visit(PlaceholderStatement& _node) { return visitNode(_node); }
	virtual bool visit(IfStatement& _node) { return visitNode(_node); }
	virtual bool visit(TryCatchClause& _node) { return visitNode(_node); }
	virtual bool visit(TryStatement& _node) { return visitNode(_node); }
	virtual bool visit(WhileStatement& _node) { return visitNode(_node); }
	virtual bool visit(ForStatement& _node) { return visitNode(_node); }
	virtual bool visit(Continue& _node) { return visitNode(_node); }
	virtual bool visit(Break& _node) { return visitNode(_node); }
	virtual bool visit(Return& _node) { return visitNode(_node); }
	virtual bool visit(Throw& _node) { return visitNode(_node); }
	virtual bool visit(EmitStatement& _node) { return visitNode(_node); }
	virtual bool visit(VariableDeclarationStatement& _node) { return visitNode(_node); }
	virtual bool visit(ExpressionStatement& _node) { return visitNode(_node); }
	virtual bool visit(Conditional& _node) { return visitNode(_node); }
	virtual bool visit(Assignment& _node) { return visitNode(_node); }
	virtual bool visit(TupleExpression& _node) { return visitNode(_node); }
	virtual bool visit(UnaryOperation& _node) { return visitNode(_node); }
	virtual bool visit(BinaryOperation& _node) { return visitNode(_node); }
	virtual bool visit(FunctionCall& _node) { return visitNode(_node); }
	virtual bool visit(NewExpression& _node) { return visitNode(_node); }
	virtual bool visit(MemberAccess& _node) { return visitNode(_node); }
	virtual bool visit(IndexAccess& _node) { return visitNode(_node); }
	virtual bool visit(IndexRangeAccess& _node) { return visitNode(_node); }
	virtual bool visit(Identifier& _node) { return visitNode(_node); }
	virtual bool visit(ElementaryTypeNameExpression& _node) { return visitNode(_node); }
	virtual bool visit(Literal& _node) { return visitNode(_node); }

	virtual void endVisit(SourceUnit& _node) { endVisitNode(_node); }
	virtual void endVisit(PragmaDirective& _node) { endVisitNode(_node); }
	virtual void endVisit(ImportDirective& _node) { endVisitNode(_node); }
	virtual void endVisit(ContractDefinition& _node) { endVisitNode(_node); }
	virtual void endVisit(InheritanceSpecifier& _node) { endVisitNode(_node); }
	virtual void endVisit(UsingForDirective& _node) { endVisitNode(_node); }
	virtual void endVisit(StructDefinition& _node) { endVisitNode(_node); }
	virtual void endVisit(EnumDefinition& _node) { endVisitNode(_node); }
	virtual void endVisit(EnumValue& _node) { endVisitNode(_node); }
	virtual void endVisit(ParameterList& _node) { endVisitNode(_node); }
	virtual void endVisit(OverrideSpecifier& _node) { endVisitNode(_node); }
	virtual void endVisit(FunctionDefinition& _node) { endVisitNode(_node); }
	virtual void endVisit(VariableDeclaration& _node) { endVisitNode(_node); }
	virtual void endVisit(ModifierDefinition& _node) { endVisitNode(_node); }
	virtual void endVisit(ModifierInvocation& _node) { endVisitNode(_node); }
	virtual void endVisit(EventDefinition& _node) { endVisitNode(_node); }
	virtual void endVisit(ElementaryTypeName& _node) { endVisitNode(_node); }
	virtual void endVisit(UserDefinedTypeName& _node) { endVisitNode(_node); }
	virtual void endVisit(FunctionTypeName& _node) { endVisitNode(_node); }
	virtual void endVisit(Mapping& _node) { endVisitNode(_node); }
	virtual void endVisit(ArrayTypeName& _node) { endVisitNode(_node); }
	virtual void endVisit(InlineAssembly& _node) { endVisitNode(_node); }
	virtual void endVisit(Block& _node) { endVisitNode(_node); }
	virtual void endVisit(PlaceholderStatement& _node) { endVisitNode(_node); }
	virtual void endVisit(IfStatement& _node) { endVisitNode(_node); }
	virtual void endVisit(TryCatchClause& _node) { endVisitNode(_node); }
	virtual void endVisit(TryStatement& _node) { endVisitNode(_node); }
	virtual void endVisit(WhileStatement& _node) { endVisitNode(_node); }
	virtual void endVisit(ForStatement& _node) { endVisitNode(_node); }
	virtual void endVisit(Continue& _node) { endVisitNode(_node); }
	virtual void endVisit(Break& _node) { endVisitNode(_node); }
	virtual void endVisit(Return& _node) { endVisitNode(_node); }
	virtual void endVisit(Throw& _node) { endVisitNode(_node); }
	virtual void endVisit(EmitStatement& _node) { endVisitNode(_node); }
	virtual void endVisit(VariableDeclarationStatement& _node) { endVisitNode(_node); }
	virtual void endVisit(ExpressionStatement& _node) { endVisitNode(_node); }
	virtual void endVisit(Conditional& _node) { endVisitNode(_node); }
	virtual void endVisit(Assignment& _node) { endVisitNode(_node); }
	virtual void endVisit(TupleExpression& _node) { endVisitNode(_node); }
	virtual void endVisit(UnaryOperation& _node) { endVisitNode(_node); }
	virtual void endVisit(BinaryOperation& _node) { endVisitNode(_node); }
	virtual void endVisit(FunctionCall& _node) { endVisitNode(_node); }
	virtual void endVisit(NewExpression& _node) { endVisitNode(_node); }
	virtual void endVisit(MemberAccess& _node) { endVisitNode(_node); }
	virtual void endVisit(IndexAccess& _node) { endVisitNode(_node); }
	virtual void endVisit(IndexRangeAccess& _node) { endVisitNode(_node); }
	virtual void endVisit(Identifier& _node) { endVisitNode(_node); }
	virtual void endVisit(ElementaryTypeNameExpression& _node) { endVisitNode(_node); }
	virtual void endVisit(Literal& _node) { endVisitNode(_node); }

protected:
	/// Generic function called by default for each node, to be overridden by derived classes
	/// if behaviour unspecific to a node type is desired.
	virtual bool visitNode(ASTNode&) { return true; }
	/// Generic function called by default for each node, to be overridden by derived classes
	/// if behaviour unspecific to a node type is desired.
	virtual void endVisitNode(ASTNode&) { }
};

class ASTConstVisitor
{
public:
	virtual ~ASTConstVisitor() = default;
	virtual bool visit(SourceUnit const& _node) { return visitNode(_node); }
	virtual bool visit(PragmaDirective const& _node) { return visitNode(_node); }
	virtual bool visit(ImportDirective const& _node) { return visitNode(_node); }
	virtual bool visit(ContractDefinition const& _node) { return visitNode(_node); }
	virtual bool visit(InheritanceSpecifier const& _node) { return visitNode(_node); }
	virtual bool visit(StructDefinition const& _node) { return visitNode(_node); }
	virtual bool visit(UsingForDirective const& _node) { return visitNode(_node); }
	virtual bool visit(EnumDefinition const& _node) { return visitNode(_node); }
	virtual bool visit(EnumValue const& _node) { return visitNode(_node); }
	virtual bool visit(ParameterList const& _node) { return visitNode(_node); }
	virtual bool visit(OverrideSpecifier const& _node) { return visitNode(_node); }
	virtual bool visit(FunctionDefinition const& _node) { return visitNode(_node); }
	virtual bool visit(VariableDeclaration const& _node) { return visitNode(_node); }
	virtual bool visit(ModifierDefinition const& _node) { return visitNode(_node); }
	virtual bool visit(ModifierInvocation const& _node) { return visitNode(_node); }
	virtual bool visit(EventDefinition const& _node) { return visitNode(_node); }
	virtual bool visit(ElementaryTypeName const& _node) { return visitNode(_node); }
	virtual bool visit(UserDefinedTypeName const& _node) { return visitNode(_node); }
	virtual bool visit(FunctionTypeName const& _node) { return visitNode(_node); }
	virtual bool visit(Mapping const& _node) { return visitNode(_node); }
	virtual bool visit(ArrayTypeName const& _node) { return visitNode(_node); }
	virtual bool visit(Block const& _node) { return visitNode(_node); }
	virtual bool visit(PlaceholderStatement const& _node) { return visitNode(_node); }
	virtual bool visit(IfStatement const& _node) { return visitNode(_node); }
	virtual bool visit(TryCatchClause const& _node) { return visitNode(_node); }
	virtual bool visit(TryStatement const& _node) { return visitNode(_node); }
	virtual bool visit(WhileStatement const& _node) { return visitNode(_node); }
	virtual bool visit(ForStatement const& _node) { return visitNode(_node); }
	virtual bool visit(Continue const& _node) { return visitNode(_node); }
	virtual bool visit(InlineAssembly const& _node) { return visitNode(_node); }
	virtual bool visit(Break const& _node) { return visitNode(_node); }
	virtual bool visit(Return const& _node) { return visitNode(_node); }
	virtual bool visit(Throw const& _node) { return visitNode(_node); }
	virtual bool visit(EmitStatement const& _node) { return visitNode(_node); }
	virtual bool visit(VariableDeclarationStatement const& _node) { return visitNode(_node); }
	virtual bool visit(ExpressionStatement const& _node) { return visitNode(_node); }
	virtual bool visit(Conditional const& _node) { return visitNode(_node); }
	virtual bool visit(Assignment const& _node) { return visitNode(_node); }
	virtual bool visit(TupleExpression const& _node) { return visitNode(_node); }
	virtual bool visit(UnaryOperation const& _node) { return visitNode(_node); }
	virtual bool visit(BinaryOperation const& _node) { return visitNode(_node); }
	virtual bool visit(FunctionCall const& _node) { return visitNode(_node); }
	virtual bool visit(NewExpression const& _node) { return visitNode(_node); }
	virtual bool visit(MemberAccess const& _node) { return visitNode(_node); }
	virtual bool visit(IndexAccess const& _node) { return visitNode(_node); }
	virtual bool visit(IndexRangeAccess const& _node) { return visitNode(_node); }
	virtual bool visit(Identifier const& _node) { return visitNode(_node); }
	virtual bool visit(ElementaryTypeNameExpression const& _node) { return visitNode(_node); }
	virtual bool visit(Literal const& _node) { return visitNode(_node); }

	virtual void endVisit(SourceUnit const& _node) { endVisitNode(_node); }
	virtual void endVisit(PragmaDirective const& _node) { endVisitNode(_node); }
	virtual void endVisit(ImportDirective const& _node) { endVisitNode(_node); }
	virtual void endVisit(ContractDefinition const& _node) { endVisitNode(_node); }
	virtual void endVisit(InheritanceSpecifier const& _node) { endVisitNode(_node); }
	virtual void endVisit(UsingForDirective const& _node) { endVisitNode(_node); }
	virtual void endVisit(StructDefinition const& _node) { endVisitNode(_node); }
	virtual void endVisit(EnumDefinition const& _node) { endVisitNode(_node); }
	virtual void endVisit(EnumValue const& _node) { endVisitNode(_node); }
	virtual void endVisit(ParameterList const& _node) { endVisitNode(_node); }
	virtual void endVisit(OverrideSpecifier const& _node) { endVisitNode(_node); }
	virtual void endVisit(FunctionDefinition const& _node) { endVisitNode(_node); }
	virtual void endVisit(VariableDeclaration const& _node) { endVisitNode(_node); }
	virtual void endVisit(ModifierDefinition const& _node) { endVisitNode(_node); }
	virtual void endVisit(ModifierInvocation const& _node) { endVisitNode(_node); }
	virtual void endVisit(EventDefinition const& _node) { endVisitNode(_node); }
	virtual void endVisit(ElementaryTypeName const& _node) { endVisitNode(_node); }
	virtual void endVisit(UserDefinedTypeName const& _node) { endVisitNode(_node); }
	virtual void endVisit(FunctionTypeName const& _node) { endVisitNode(_node); }
	virtual void endVisit(Mapping const& _node) { endVisitNode(_node); }
	virtual void endVisit(ArrayTypeName const& _node) { endVisitNode(_node); }
	virtual void endVisit(Block const& _node) { endVisitNode(_node); }
	virtual void endVisit(PlaceholderStatement const& _node) { endVisitNode(_node); }
	virtual void endVisit(IfStatement const& _node) { endVisitNode(_node); }
	virtual void endVisit(TryCatchClause const& _node) { endVisitNode(_node); }
	virtual void endVisit(TryStatement const& _node) { endVisitNode(_node); }
	virtual void endVisit(WhileStatement const& _node) { endVisitNode(_node); }
	virtual void endVisit(ForStatement const& _node) { endVisitNode(_node); }
	virtual void endVisit(Continue const& _node) { endVisitNode(_node); }
	virtual void endVisit(InlineAssembly const& _node) { endVisitNode(_node); }
	virtual void endVisit(Break const& _node) { endVisitNode(_node); }
	virtual void endVisit(Return const& _node) { endVisitNode(_node); }
	virtual void endVisit(Throw const& _node) { endVisitNode(_node); }
	virtual void endVisit(EmitStatement const& _node) { endVisitNode(_node); }
	virtual void endVisit(VariableDeclarationStatement const& _node) { endVisitNode(_node); }
	virtual void endVisit(ExpressionStatement const& _node) { endVisitNode(_node); }
	virtual void endVisit(Conditional const& _node) { endVisitNode(_node); }
	virtual void endVisit(Assignment const& _node) { endVisitNode(_node); }
	virtual void endVisit(TupleExpression const& _node) { endVisitNode(_node); }
	virtual void endVisit(UnaryOperation const& _node) { endVisitNode(_node); }
	virtual void endVisit(BinaryOperation const& _node) { endVisitNode(_node); }
	virtual void endVisit(FunctionCall const& _node) { endVisitNode(_node); }
	virtual void endVisit(NewExpression const& _node) { endVisitNode(_node); }
	virtual void endVisit(MemberAccess const& _node) { endVisitNode(_node); }
	virtual void endVisit(IndexAccess const& _node) { endVisitNode(_node); }
	virtual void endVisit(IndexRangeAccess const& _node) { endVisitNode(_node); }
	virtual void endVisit(Identifier const& _node) { endVisitNode(_node); }
	virtual void endVisit(ElementaryTypeNameExpression const& _node) { endVisitNode(_node); }
	virtual void endVisit(Literal const& _node) { endVisitNode(_node); }

protected:
	/// Generic function called by default for each node, to be overridden by derived classes
	/// if behaviour unspecific to a node type is desired.
	virtual bool visitNode(ASTNode const&) { return true; }
	/// Generic function called by default for each node, to be overridden by derived classes
	/// if behaviour unspecific to a node type is desired.
	virtual void endVisitNode(ASTNode const&) { }
};

/**
 * Utility class that accepts std::functions and calls them for visitNode and endVisitNode.
 */
class SimpleASTVisitor: public ASTConstVisitor
{
public:
	SimpleASTVisitor(
		std::function<bool(ASTNode const&)> _onVisit,
		std::function<void(ASTNode const&)> _onEndVisit
	): m_onVisit(_onVisit), m_onEndVisit(_onEndVisit) {}

protected:
	bool visitNode(ASTNode const& _n) override { return m_onVisit ? m_onVisit(_n) : true; }
	void endVisitNode(ASTNode const& _n) override { m_onEndVisit(_n); }

private:
	std::function<bool(ASTNode const&)> m_onVisit;
	std::function<void(ASTNode const&)> m_onEndVisit;
};

/**
 * Utility class that visits the AST in depth-first order and calls a function on each node and each edge.
 * Child nodes are only visited if the node callback of the parent returns true.
 * The node callback of a parent is called before any edge or node callback involving the children.
 * The edge callbacks of all children are called before the edge callback of the parent.
 * This way, the node callback can be used as an initializing callback and the edge callbacks can be
 * used to compute a "reduce" function.
 */
class ASTReduce: public ASTConstVisitor
{
public:
	/**
	 * Constructs a new ASTReduce object with the given callback functions.
	 * @param _onNode called for each node, before its child edges and nodes, should return true to descend deeper
	 * @param _onEdge called for each edge with (parent, child)
	 */
	ASTReduce(
		std::function<bool(ASTNode const&)> _onNode,
		std::function<void(ASTNode const&, ASTNode const&)> _onEdge
	): m_onNode(_onNode), m_onEdge(_onEdge)
	{
	}

protected:
	bool visitNode(ASTNode const& _node) override
	{
		m_parents.push_back(&_node);
		return m_onNode(_node);
	}
	void endVisitNode(ASTNode const& _node) override
	{
		m_parents.pop_back();
		if (!m_parents.empty())
			m_onEdge(*m_parents.back(), _node);
	}

private:
	std::vector<ASTNode const*> m_parents;
	std::function<bool(ASTNode const&)> m_onNode;
	std::function<void(ASTNode const&, ASTNode const&)> m_onEdge;
};

}