AOO410/main/xmerge/source/pexcel/java/org/openoffice/xmerge/converter/xml/sxc/pexcel/records/formula/Token.java

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 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
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 * 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
 * 
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 * Unless required by applicable law or agreed to in writing,
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package org.openoffice.xmerge.converter.xml.sxc.pexcel.records.formula;


/**
 * A Token is the basic building block of any formula. 
 * A Token can be of four types (Operator, Operand, Function with fixed
 * arguments and function with a variable number of arguments. Each type can
 * have numerous id's. Thetypes are define in <code>ParseToken</code> and the 
 * id's are defined in <code>TokenConstants</code>. The other member variables 
 * are priority which is returned from the <code>PrecedenceTable</code>, the 
 * value which is the String equivalent of the token (eg. "+", "$A$12", "SUM")
 * and the number of arguments which is only valid for operators and functions.
 * Tokens should never be created directly and instead are created by the
 * <code>TokenFactory</code> 
 */
public class Token implements ParseToken {
    
	private String value;
	private int type;           // operator, operand, function fixed, function variable
	private int id;             // cell reference, SUM, integer
	private int priority;
	private int numArgs=-1;
        
	public Token(String op, int type, int id, int args) {
		this.value = op;
		this.type = type;
		this.id = id;
		this.numArgs = args;
		if(type==ParseToken.TOKEN_FUNCTION_VARIABLE) {
			priority = PrecedenceTable.getPrecedence("FUNCTION");
		} else if(type==ParseToken.TOKEN_OPERATOR) {
			priority = PrecedenceTable.getPrecedence(op);
		} else {
			priority = PrecedenceTable.getPrecedence("DEFAULT");
		}
	}        
       
	/**
	 * Checks if the current token is an operator
	 * 
	 * @return A <code>boolean</code> result of the comaparison
	 */
	public boolean isOperator() {
		return type == ParseToken.TOKEN_OPERATOR;
	}
        
	/**
	 * Checks if the current token is an operand
	 * 
	 * @return A <code>boolean</code> result of the comaparison
	 */
	public boolean isOperand() {
		return type == ParseToken.TOKEN_OPERAND;
	}
        
	/**
	 * Checks if the current token is a function
	 * 
	 * @return A <code>boolean</code> result of the comaparison
	 */
	public boolean isFunction() {
		return (type==ParseToken.TOKEN_FUNCTION_FIXED) || (type==ParseToken.TOKEN_FUNCTION_VARIABLE);
	}
        
	/**
	 * Returns the token type. This can be one of four values (TOKEN_OPERATOR,
	 * TOKEN_OPERAND, TOKEN_FUNCTION_FIXED, TOKEN_FUNCTION_VARIABLE) defined in
	 * <code>ParseToken</code> 
	 * 
	 * @return A <code>boolean</code> result of the comparison
	 */
	public int getTokenType() {
            
		return type;
	}    
        
	/**
	 * Returns the ID of this token. This ID is equivalent to the pexcel hex
	 * value and is defined in <code>ParseToken</code> 
	 * 
	 * @return Returns the id of this token
	 */
	public int getTokenID() {
            
		return id;
	}    
        
	/**
	 * Returns the <code>String</code> equivalent of this token 
	 * 
	 * @return The <code>String</code> representing this Token 
	 */
	public String getValue() {
		return value;
	}        

	/**
	 * Returns the number of arguments if this token represents an operator or
	 * function. Otherwise returns -1.
	 * 
	 * @return The number of arguments
	 */
	public int getNumArgs() {
		return numArgs;
	}
        
	/**
	 * Checks if the current token is an operator
	 * 
	 * @return A <code>boolean</code> result of the comparison
	 */
	public int getTokenPriority() {
		return priority;
	}
        
	/**
	 * Returns the <code>String</code> equivalent of this token 
	 * 
	 * @return The <code>String</code> representing this Token 
	 */
	public String toString() {
		return getValue();
	}
}