ASTVisitor.h

#pragma once

#include "AST.h"

/*! \brief Base class for AST visitors.
 *
 * The AST visitor class abstracts the traversal of an AST.  It works
 * in concert with the accept methods of ASTNode subtypes.  Each of those
 * nodes performs a traversal of its children in an order corresponding to
 * their appearance in the source program.  This class defines default behavior
 * for the processing performed when the traversal reaches a node of a given
 * type. By default the visit method returns true, indicating that the children
 * of the node should also be visited, and the endVisit method does nothing.
 *
 * Subtypes of ASTVisitor will selectively override these default methods.
 * Overriding a visit permits a pre-order processing during traversal and
 * overriding endVisit permits a post-order processing.
 *
 * Subtype of ASTVisitor will also define member data that can be referenced
 * by overridden methods to communicate information along the traversal to
 * future method invocations.
 */
class ASTVisitor {
public:
  virtual bool visit(ASTProgram *element) { return true; }
  virtual void endVisit(ASTProgram *element) {}
  virtual bool visit(ASTFunction *element) { return true; }
  virtual void endVisit(ASTFunction *element) {}
  virtual bool visit(ASTNumberExpr *element) { return true; }
  virtual void endVisit(ASTNumberExpr *element) {}
  virtual bool visit(ASTVariableExpr *element) { return true; }
  virtual void endVisit(ASTVariableExpr *element) {}
  virtual bool visit(ASTBinaryExpr *element) { return true; }
  virtual void endVisit(ASTBinaryExpr *element) {}
  virtual bool visit(ASTInputExpr *element) { return true; }
  virtual void endVisit(ASTInputExpr *element) {}
  virtual bool visit(ASTFunAppExpr *element) { return true; }
  virtual void endVisit(ASTFunAppExpr *element) {}
  virtual bool visit(ASTAllocExpr *element) { return true; }
  virtual void endVisit(ASTAllocExpr *element) {}
  virtual bool visit(ASTRefExpr *element) { return true; }
  virtual void endVisit(ASTRefExpr *element) {}
  virtual bool visit(ASTDeRefExpr *element) { return true; }
  virtual void endVisit(ASTDeRefExpr *element) {}
  virtual bool visit(ASTNullExpr *element) { return true; }
  virtual void endVisit(ASTNullExpr *element) {}
  virtual bool visit(ASTFieldExpr *element) { return true; }
  virtual void endVisit(ASTFieldExpr *element) {}
  virtual bool visit(ASTRecordExpr *element) { return true; }
  virtual void endVisit(ASTRecordExpr *element) {}
  virtual bool visit(ASTAccessExpr *element) { return true; }
  virtual void endVisit(ASTAccessExpr *element) {}
  virtual bool visit(ASTDeclNode *element) { return true; }
  virtual void endVisit(ASTDeclNode *element) {}
  virtual bool visit(ASTDeclStmt *element) { return true; }
  virtual void endVisit(ASTDeclStmt *element) {}
  virtual bool visit(ASTAssignStmt *element) { return true; }
  virtual void endVisit(ASTAssignStmt *element) {}
  virtual bool visit(ASTWhileStmt *element) { return true; }
  virtual void endVisit(ASTWhileStmt *element) {}
  virtual bool visit(ASTIfStmt *element) { return true; }
  virtual void endVisit(ASTIfStmt *element) {}
  virtual bool visit(ASTOutputStmt *element) { return true; }
  virtual void endVisit(ASTOutputStmt *element) {}
  virtual bool visit(ASTReturnStmt *element) { return true; }
  virtual void endVisit(ASTReturnStmt *element) {}
  virtual bool visit(ASTErrorStmt *element) { return true; }
  virtual void endVisit(ASTErrorStmt *element) {}
  virtual bool visit(ASTBlockStmt *element) { return true; }
  virtual void endVisit(ASTBlockStmt *element) {}
};