pgtokenizer.java

来自「PostgreSQL7.4.6 for Linux」· Java 代码 · 共 215 行

/*-------------------------------------------------------------------------
 *
 * PGtokenizer.java
 *     This class is used to tokenize the text output of org.postgres.
 *
 * Copyright (c) 2003, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/interfaces/jdbc/org/postgresql/util/Attic/PGtokenizer.java,v 1.7 2003/05/29 04:39:51 barry Exp $
 *
 *-------------------------------------------------------------------------
 */
package org.postgresql.util;

import java.util.Vector;

/*
 * It's mainly used by the geometric classes, but is useful in parsing any
 * output from custom data types output from org.postgresql.
 *
 * @see org.postgresql.geometric.PGbox
 * @see org.postgresql.geometric.PGcircle
 * @see org.postgresql.geometric.PGlseg
 * @see org.postgresql.geometric.PGpath
 * @see org.postgresql.geometric.PGpoint
 * @see org.postgresql.geometric.PGpolygon
 */
public class PGtokenizer
{
	// Our tokens
	protected Vector	tokens;

	/*
	 * Create a tokeniser.
	 *
	 * <p>We could have used StringTokenizer to do this, however, we needed to
	 * handle nesting of '(' ')' '[' ']' '&lt;' and '&gt;' as these are used
	 * by the geometric data types.
	 *
	 * @param string containing tokens
	 * @param delim single character to split the tokens
	 */
	public PGtokenizer(String string, char delim)
	{
		tokenize(string, delim);
	}

	/*
	 * This resets this tokenizer with a new string and/or delimiter.
	 *
	 * @param string containing tokens
	 * @param delim single character to split the tokens
	 */
	public int tokenize(String string, char delim)
	{
		tokens = new Vector();

		// nest holds how many levels we are in the current token.
		// if this is > 0 then we don't split a token when delim is matched.
		//
		// The Geometric datatypes use this, because often a type may have others
		// (usualls PGpoint) imbedded within a token.
		//
		// Peter 1998 Jan 6 - Added < and > to the nesting rules
		int nest = 0, p, s;

		for (p = 0, s = 0;p < string.length();p++)
		{
			char c = string.charAt(p);

			// increase nesting if an open character is found
			if (c == '(' || c == '[' || c == '<')
				nest++;

			// decrease nesting if a close character is found
			if (c == ')' || c == ']' || c == '>')
				nest--;

			if (nest == 0 && c == delim)
			{
				tokens.addElement(string.substring(s, p));
				s = p + 1; // +1 to skip the delimiter
			}

		}

		// Don't forget the last token ;-)



		if (s < string.length())
			tokens.addElement(string.substring(s));

		return tokens.size();
	}

	/*
	 * @return the number of tokens available
	 */
	public int getSize()
	{
		return tokens.size();
	}

	/*
	 * @param n Token number ( 0 ... getSize()-1 )
	 * @return The token value
	 */
	public String getToken(int n)
	{
		return (String)tokens.elementAt(n);
	}

	/*
	 * This returns a new tokenizer based on one of our tokens.
	 *
	 * The geometric datatypes use this to process nested tokens (usually
	 * PGpoint).
	 *
	 * @param n Token number ( 0 ... getSize()-1 )
	 * @param delim The delimiter to use
	 * @return A new instance of PGtokenizer based on the token
	 */
	public PGtokenizer tokenizeToken(int n, char delim)
	{
		return new PGtokenizer(getToken(n), delim);
	}

	/*
	 * This removes the lead/trailing strings from a string
	 * @param s Source string
	 * @param l Leading string to remove
	 * @param t Trailing string to remove
	 * @return String without the lead/trailing strings
	 */
	public static String remove(String s, String l, String t)
	{
		if (s.startsWith(l))
			s = s.substring(l.length());
		if (s.endsWith(t))
			s = s.substring(0, s.length() - t.length());
		return s;
	}

	/*
	 * This removes the lead/trailing strings from all tokens
	 * @param l Leading string to remove
	 * @param t Trailing string to remove
	 */
	public void remove(String l, String t)
	{
		for (int i = 0;i < tokens.size();i++)
		{
			tokens.setElementAt(remove((String)tokens.elementAt(i), l, t), i);
		}
	}

	/*
	 * Removes ( and ) from the beginning and end of a string
	 * @param s String to remove from
	 * @return String without the ( or )
	 */
	public static String removePara(String s)
	{
		return remove(s, "(", ")");
	}

	/*
	 * Removes ( and ) from the beginning and end of all tokens
	 * @return String without the ( or )
	 */
	public void removePara()
	{
		remove("(", ")");
	}

	/*
	 * Removes [ and ] from the beginning and end of a string
	 * @param s String to remove from
	 * @return String without the [ or ]
	 */
	public static String removeBox(String s)
	{
		return remove(s, "[", "]");
	}

	/*
	 * Removes [ and ] from the beginning and end of all tokens
	 * @return String without the [ or ]
	 */
	public void removeBox()
	{
		remove("[", "]");
	}

	/*
	 * Removes &lt; and &gt; from the beginning and end of a string
	 * @param s String to remove from
	 * @return String without the &lt; or &gt;
	 */
	public static String removeAngle(String s)
	{
		return remove(s, "<", ">");
	}

	/*
	 * Removes &lt; and &gt; from the beginning and end of all tokens
	 * @return String without the &lt; or &gt;
	 */
	public void removeAngle()
	{
		remove("<", ">");
	}
}