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/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* This file incorporates work covered by the following license notice:
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright
* ownership. The ASF licenses this file to you under the Apache
* License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.apache.org/licenses/LICENSE-2.0 .
*/
package org.openoffice.xmerge.converter.xml.sxc.pexcel.records.formula;
import java.util.*;
import org.openoffice.xmerge.util.Debug;
/**
* FormulaCompiler converts Calc formula string into PocketXL bytes
* and PocketXL formula bytes into Calc Formula strings
*
* For converting from infix to Reverse Polish (or Postfix) notation the string is
* converted into a vector of Tokens and then re-ordered based on a modified version
* of the standard Infix to RPN conversion algorithms.
* <pre>
* Infix2Rpn(tokens)
* while have more tokens
* if token is operand
* push to stack
* else if token is function, argument separater, or open bracket
* push token
* extract tokens to matching close bracket into param
* Infix2Rpn(param)
* else if token is close bracket
* pop from stack into result until close bracket or function
* else
* while stack.top.priority >= token.priority
* add stack.pop to result
* push token onto stack
* </pre>
* For converting from RPN to Infix the following algorithm is applied:
* <pre>
* while have more tokens
* if token is operand
* push token to stack
* else if token is function or operator
* pop from stack number of args required by token
* apply token to params to make expr
* push expr to stack
* return stack.pop
* </pre>
*/
public class FormulaCompiler {
/**
* Constructs a FormulaCompiler object
*/
public FormulaCompiler() {
}
private boolean isPercent(Token pt) {
return pt.getTokenID() == TokenConstants.TPERCENT;
}
private boolean isOpenBrace(Token pt) {
return pt.getTokenID() == TokenConstants.TPAREN;
}
private boolean isCloseBrace(Token pt) {
return pt.getValue().compareTo(")") == 0;
}
private boolean isParamDelimiter(Token pt) {
return pt.getTokenID() == TokenConstants.TARGSEP;
}
private boolean isBinaryOperator(Token pt) {
return false;
}
/**
* Re-order into Infix format
* @param tokens The tokens in RPN form
* @return The vector of tokens re-ordered in Infix notation
*/
public Vector RPN2Infix(Vector tokens) {
Vector infixExpr = new Vector(15);
ListIterator iter = tokens.listIterator();
Stack evalStack = new Stack();
Stack args = new Stack();
while (iter.hasNext()) {
Token pt = (Token)iter.next();
if (pt.isOperand()) {
Vector expr = new Vector(5);
expr.add(pt);
evalStack.push(expr);
} else if (pt.isOperator() || pt.isFunction()) {
args.clear();
for (int i=0; i< pt.getNumArgs(); i++) {
args.push(evalStack.pop());
}
evalStack.push(makeExpression(pt, args));
}
}
return (Vector)evalStack.elementAt(0);
}
/**
* Convert the infix expression to RPN. Note that open brackets are saved onto the stack to preserve the users bracketing.
* <p>Also note that the open bracket following functions is not pushed onto the stack - it is always implied when
* writing out results
*
* @param tokens The vector of tokens in Infix form
*
* @return A vector of tokens for the expression in Reverse Polish Notation order
*/
public Vector infix2RPN(Vector tokens) {
Vector rpnExpr = new Vector(15);
Stack evalStack = new Stack();
ListIterator iter = tokens.listIterator();
while (iter.hasNext()) {
Token pt = (Token)iter.next();
if (pt.isOperand()) { //Operands are output immediately
rpnExpr.add(pt);
} else if (pt.isFunction() || isParamDelimiter(pt) || isOpenBrace(pt)) { //Extract parameters after afunction or comma
evalStack.push(pt);
if (pt.isFunction()) {
iter.next();
}
Vector param = extractParameter(iter);
Debug.log(Debug.TRACE, "Extracted parameter " + param);
rpnExpr.addAll(infix2RPN(param));
} else if (isCloseBrace(pt)) { //Pop off stack till you meet a function or an open bracket
Token tmpTok = null;
boolean bPop = true;
while (bPop) {
if (evalStack.isEmpty()) {
bPop = false;
} else {
tmpTok = (Token)evalStack.pop();
if (!isParamDelimiter(tmpTok)) { //Don't output commas
rpnExpr.add(tmpTok);
}
if (tmpTok.isFunction() || isOpenBrace(tmpTok)) {
bPop = false;
}
}
}
} else {
if (!evalStack.isEmpty()) {
while (!evalStack.isEmpty() &&
(((Token)evalStack.peek()).getTokenPriority() >=pt.getTokenPriority())) {
Token topTok = (Token)evalStack.peek();
if (topTok.isFunction() || isOpenBrace(topTok)) {
break;
}
rpnExpr.add(evalStack.pop());
}
}
evalStack.push(pt);
}
}
while (!evalStack.isEmpty()) {
Token topTok = (Token)evalStack.peek();
if (!(isOpenBrace(topTok) || isParamDelimiter(topTok))) { //Don't output brackets and commas
rpnExpr.add(evalStack.pop());
}
else
{
evalStack.pop();
}
}
return rpnExpr;
}
/**
* Extract a parameter or bracketed sub-expression
* @param iter an iterator into the list
* @return A complete sub-expression
*/
protected Vector extractParameter(ListIterator iter) {
Vector param = new Vector(5);
int subExprCount = 0;
while (iter.hasNext()) {
Token pt = (Token)iter.next();
Debug.log(Debug.TRACE, "Token is " + pt + " and subExprCount is " + subExprCount);
if (isOpenBrace(pt)) {
subExprCount++;
param.add(pt);
} else if (isCloseBrace(pt)) {
if (subExprCount == 0) {
iter.previous();
return param;
} else {
subExprCount--;
param.add(pt);
}
} else if (isParamDelimiter(pt) && (subExprCount == 0)) {
iter.previous();
return param;
} else {
param.add(pt);
}
}
return param;
}
/**
* Given the operator and it's operators
* @param pt The operator token
* @param args The arguments for this operator
* @return A correctly ordered expression
*/
protected Vector makeExpression(Token pt, Stack args) {
Vector tmp = new Vector(5);
TokenFactory tf = new TokenFactory();
if (pt.isOperator()) {
if (pt.getNumArgs()==2) { //Binary operator
tmp.addAll((Vector)args.pop());
tmp.add(pt);
tmp.addAll((Vector)args.pop());
} else if (pt.getNumArgs() == 1) {
if(isPercent(pt)) {
tmp.addAll((Vector)args.elementAt(0));
tmp.add(pt);
} else {
tmp.add(pt);
tmp.addAll((Vector)args.elementAt(0));
}
if (isOpenBrace(pt)) {
tmp.add(tf.getOperatorToken(")",1));
}
}
} else if (pt.isFunction()) {
tmp.add(pt);
tmp.add(tf.getOperatorToken("(",1));
if (!args.isEmpty()) {
Vector v = (Vector)args.pop();
tmp.addAll(v);
}
while (!args.isEmpty()) {
tmp.add(tf.getOperatorToken(",",1));
Vector v = (Vector)args.pop();
tmp.addAll(v);
}
tmp.add(tf.getOperatorToken(")",1));
}
return tmp;
}
}
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