/*
 * Copyright (c) 2003, PostgreSQL Global Development Group
 * See the LICENSE file in the project root for more information.
 */

package org.postgresql.util;

import java.util.ArrayList;
import java.util.List;

This class is used to tokenize the text output of org.postgres. It's mainly used by the geometric
classes, but is useful in parsing any output from custom data types output from org.postgresql.
See Also:
PGbox
PGcircle
PGlseg
PGpath
PGpoint
PGpolygon/**
 * This class is used to tokenize the text output of org.postgres. 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 List<String> tokens;

  
Create a tokeniser.
We could have used StringTokenizer to do this, however, we needed to handle nesting of '(' ')'
'[' ']' '<' and '>' as these are used by the geometric data types.
Params:
string – containing tokens
delim – single character to split the tokens/**
   * <p>Create a tokeniser.</p>
   *
   * <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.</p>
   *
   * @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.
Params:
string – containing tokens
delim – single character to split the tokens
Returns:
number of tokens/**
   * This resets this tokenizer with a new string and/or delimiter.
   *
   * @param string containing tokens
   * @param delim single character to split the tokens
   * @return number of tokens
   */
  public int tokenize(String string, char delim) {
    tokens = new ArrayList<String>();

    // 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;
    int p;
    int s;
    boolean skipChar = false;
    boolean nestedDoubleQuote = false;

    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 == '<' || (!nestedDoubleQuote && !skipChar && c == '"')) {
        nest++;
        if (c == '"') {
          nestedDoubleQuote = true;
          skipChar = true;
        }
      }

      // decrease nesting if a close character is found
      if (c == ')' || c == ']' || c == '>' || (nestedDoubleQuote && !skipChar && c == '"')) {
        nest--;
        if (c == '"') {
          nestedDoubleQuote = false;
        }
      }

      skipChar = c == '\\';

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

    }

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


    if (s < string.length()) {
      tokens.add(string.substring(s));
    }

    return tokens.size();
  }

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

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

  
This returns a new tokenizer based on one of our tokens.
The geometric datatypes use this to process nested tokens (usually PGpoint).
Params:
n – Token number ( 0 ... getSize()-1 )
delim – The delimiter to use
Returns:
A new instance of PGtokenizer based on the token/**
   * <p>This returns a new tokenizer based on one of our tokens.</p>
   *
   * <p>The geometric datatypes use this to process nested tokens (usually PGpoint).</p>
   *
   * @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.
Params:
s – Source string
l – Leading string to remove
t – Trailing string to remove
Returns:
String without the lead/trailing strings/**
   * 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.
Params:
l – Leading string to remove
t – Trailing string to remove/**
   * 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.set(i, remove(tokens.get(i), l, t));
    }
  }

  
Removes ( and ) from the beginning and end of a string.
Params:
s – String to remove from
Returns:
String without the ( or )/**
   * 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.
/**
   * Removes ( and ) from the beginning and end of all tokens.
   */
  public void removePara() {
    remove("(", ")");
  }

  
Removes [ and ] from the beginning and end of a string.
Params:
s – String to remove from
Returns:
String without the [ or ]/**
   * 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.
/**
   * Removes [ and ] from the beginning and end of all tokens.
   */
  public void removeBox() {
    remove("[", "]");
  }

  
Removes < and > from the beginning and end of a string.
Params:
s – String to remove from
Returns:
String without the < or >/**
   * 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 < and > from the beginning and end of all tokens.
/**
   * Removes &lt; and &gt; from the beginning and end of all tokens.
   */
  public void removeAngle() {
    remove("<", ">");
  }

  
Removes curly braces { and } from the beginning and end of a string.
Params:
s – String to remove from
Returns:
String without the { or }/**
   * Removes curly braces { and } from the beginning and end of a string.
   *
   * @param s String to remove from
   * @return String without the { or }
   */
  public static String removeCurlyBrace(String s) {
    return remove(s, "{", "}");
  }

  
Removes < and > from the beginning and end of all tokens.
/**
   * Removes &lt; and &gt; from the beginning and end of all tokens.
   */
  public void removeCurlyBrace() {
    remove("{", "}");
  }

}