mariadb-columnstore-engine/dbcon/execplan/expressionparser.h

/* Copyright (C) 2014 InfiniDB, Inc.

   This program 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; version 2 of
   the License.

   This program 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 this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   MA 02110-1301, USA. */

/***********************************************************************
 *   $Id: expressionparser.h 9633 2013-06-19 13:36:01Z rdempsey $
 *
 *
 ***********************************************************************/
/** @file */
#pragma once

#include <iostream>
#include <cassert>
#include <vector>
#include <stack>
#include <cmath>
#include <cctype>
#include <cstdlib>
#include <string>
#include "exp_templates.h"
#include "treenode.h"
#include "parsetree.h"
#include "operator.h"

namespace execplan
{
/**
 * type define
 */
typedef std::stack<ParseTree*> OperandStack;
typedef std::stack<TreeNode*> OperatorStack;

/**@brief a structure to respent a token accepted by the parser
 *
 * token structure
 */
struct Token
{
  TreeNode* value;
  bool is_operator() const
  {
    if (value == nullptr)
      return false;

    return (typeid(*value) == typeid(Operator));
  }
  Token() : value(nullptr)
  {
  }
  Token(TreeNode* v) : value(v)
  {
  }

 private:
  // technically, these should be defined since Token is used in a
  // std::vector, but it appears to work okay...ownership of the
  // value ptr is dubious
  // Token(const Token& rhs);
  // Token& operator=(const Token& rhs);
};

/**
 * @brief this class builds an expression tree
 *
 * This struct parse the incomming tokens from an expression and
 * build a expression tree according to the pre-defined precedence
 * rules. The operators handled are: +, -, *, /, ||, (, ), func (,
 * func ), and, or.
 */
class ExpressionParser : public expression::default_expression_parser_error_policy
{
 public:
  /**
   * Constructors/Destructors
   */
  ExpressionParser();
  virtual ~ExpressionParser();

  /**
   * Operations
   */

  /*
   * Error handling
   */
  static void invalid_operator_position(TreeNode* oper);
  static void invalid_operator_position(const Token& oper);
  static void invalid_operand_position(ParseTree* operand);
  static void unbalanced_confix(TreeNode* oper);
  static void missing_operand(const Token& oper);

  /**
   * Syntax and precedence rules
   */
  static int positions(Token t);
  static int position(TreeNode* op);
  inline static bool is_operator(const Token& t)
  {
    return t.is_operator();
  }
  static ParseTree* as_operand(Token t);
  static TreeNode* as_operator(Token t, int pos);
  static expression::precedence precedence(TreeNode* op1, TreeNode* op2);
  static expression::associativity associativity(TreeNode* op1, TreeNode* op2);

  /**
   * Build an expression tree with the tokens
   */
  static ParseTree* reduce(TreeNode* op, ParseTree* value);
  static ParseTree* reduce(TreeNode* op, ParseTree* lhs, ParseTree* rhs);

  // parenthesis
  static ParseTree* reduce(TreeNode* a, TreeNode* b, ParseTree* value);

  // function call
  static ParseTree* reduce(ParseTree* a, TreeNode* b, ParseTree* value, TreeNode* d);

  /**
   * to clean up operator and operand stack when exception throws.
   * this is to be used by Calpont execplan project, where the operator
   * and operand are pointers. added by Zhixuan Zhu 06/30/06
   */
  static void cleanup(std::stack<ParseTree*> operandStack, std::stack<TreeNode*> operatorStack);

 private:
  static int precnum(TreeNode* op);
  static expression::associativity assoc(TreeNode* op);
};

/** @brief Do a deep, strict (as opposed to semantic) equivalence test
 *
 * Do a deep, strict (as opposed to semantic) equivalence test.
 * @return true iff every member of t1 is a duplicate copy of every member of t2; false otherwise
 */
bool operator==(const ParseTree& t1, const ParseTree& t2);

/** @brief Do a deep, strict (as opposed to semantic) equivalence test
 *
 * Do a deep, strict (as opposed to semantic) equivalence test.
 * @return false iff every member of t1 is a duplicate copy of every member of t2; true otherwise
 */
bool operator!=(const ParseTree& t1, const ParseTree& t2);

}  // namespace execplan