Copyright (c) 2000, 2011 IBM Corporation and others.
This program and the accompanying materials
are made available under the terms of the Eclipse Public License 2.0
which accompanies this distribution, and is available at
https://www.eclipse.org/legal/epl-2.0/
SPDX-License-Identifier: EPL-2.0
Contributors:
    IBM Corporation - initial API and implementation
/*******************************************************************************
 * Copyright (c) 2000, 2011 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.ui.util;

import java.util.Vector;

A string pattern matcher. Supports '*' and '?' wildcards.
/**
 * A string pattern matcher. Supports '*' and '?' wildcards.
 */
public class StringMatcher {
	protected String fPattern;
	protected int fLength; // pattern length
	protected boolean fIgnoreWildCards;
	protected boolean fIgnoreCase;
	protected boolean fHasLeadingStar;
	protected boolean fHasTrailingStar;
	protected String fSegments[]; //the given pattern is split into * separated segments

	/* boundary value beyond which we don't need to search in the text */
	protected int fBound= 0;


	protected static final char fSingleWildCard= '\u0000';

	public static class Position {
		int start; //inclusive
		int end; //exclusive
		public Position(int start, int end) {
			this.start= start;
			this.end= end;
		}
		public int getStart() {
			return start;
		}
		public int getEnd() {
			return end;
		}
	}
	
StringMatcher constructor takes in a String object that is a simple
pattern. The pattern may contain '*' for 0 and many characters and
'?' for exactly one character.
Literal '*' and '?' characters must be escaped in the pattern
e.g., "\*" means literal "*", etc.
Escaping any other character (including the escape character itself),
just results in that character in the pattern.
e.g., "\a" means "a" and "\\" means "\"
If invoking the StringMatcher with string literals in Java, don't forget
escape characters are represented by "\\".
Params:
pattern – the pattern to match text against
ignoreCase – if true, case is ignored
ignoreWildCards – if true, wild cards and their escape sequences are ignored
		  (everything is taken literally)./**
	 * StringMatcher constructor takes in a String object that is a simple
	 * pattern. The pattern may contain '*' for 0 and many characters and
	 * '?' for exactly one character.
	 *
	 * Literal '*' and '?' characters must be escaped in the pattern
	 * e.g., "\*" means literal "*", etc.
	 *
	 * Escaping any other character (including the escape character itself),
	 * just results in that character in the pattern.
	 * e.g., "\a" means "a" and "\\" means "\"
	 *
	 * If invoking the StringMatcher with string literals in Java, don't forget
	 * escape characters are represented by "\\".
	 *
	 * @param pattern the pattern to match text against
	 * @param ignoreCase if true, case is ignored
	 * @param ignoreWildCards if true, wild cards and their escape sequences are ignored
	 * 		  (everything is taken literally).
	 */
	public StringMatcher(String pattern, boolean ignoreCase, boolean ignoreWildCards) {
		if (pattern == null)
			throw new IllegalArgumentException();
		fIgnoreCase= ignoreCase;
		fIgnoreWildCards= ignoreWildCards;
		fPattern= pattern;
		fLength= pattern.length();

		if (fIgnoreWildCards) {
			parseNoWildCards();
		} else {
			parseWildCards();
		}
	}
	
Find the first occurrence of the pattern between startend(exclusive).
Params:
text – the String object to search in
start – the starting index of the search range, inclusive
end – the ending index of the search range, exclusive
Returns:
an StringMatcher.Position object that keeps the starting
(inclusive) and ending positions (exclusive) of the first occurrence of the
pattern in the specified range of the text; return null if not found or subtext
is empty (start==end). A pair of zeros is returned if pattern is empty string
Note that for pattern like "*abc*" with leading and trailing stars, position of "abc"
is returned. For a pattern like"*??*" in text "abcdf", (1,3) is returned/**
	 * Find the first occurrence of the pattern between <code>start</code)(inclusive)
	 * and <code>end</code>(exclusive).
	 * @param text the String object to search in
	 * @param start the starting index of the search range, inclusive
	 * @param end the ending index of the search range, exclusive
	 * @return an <code>StringMatcher.Position</code> object that keeps the starting
	 * (inclusive) and ending positions (exclusive) of the first occurrence of the
	 * pattern in the specified range of the text; return null if not found or subtext
	 * is empty (start==end). A pair of zeros is returned if pattern is empty string
	 * Note that for pattern like "*abc*" with leading and trailing stars, position of "abc"
	 * is returned. For a pattern like"*??*" in text "abcdf", (1,3) is returned
	 */
	public StringMatcher.Position find(String text, int start, int end) {
		if (text == null)
			throw new IllegalArgumentException();

		int tlen= text.length();
		if (start < 0)
			start= 0;
		if (end > tlen)
			end= tlen;
		if (end < 0 ||start >= end )
			return null;
		if (fLength == 0)
			return new Position(start, start);
		if (fIgnoreWildCards) {
			int x= posIn(text, start, end);
			if (x < 0)
				return null;
			return new Position(x, x+fLength);
		}

		int segCount= fSegments.length;
		if (segCount == 0)//pattern contains only '*'(s)
			return new Position (start, end);

		int curPos= start;
		int matchStart= -1;
		int i;
		for (i= 0; i < segCount && curPos < end; ++i) {
			String current= fSegments[i];
			int nextMatch= regExpPosIn(text, curPos, end, current);
			if (nextMatch < 0 )
				return null;
			if(i == 0)
				matchStart= nextMatch;
			curPos= nextMatch + current.length();
		}
		if (i < segCount)
			return null;
		return new Position(matchStart, curPos);
	}
	
match the given text with the pattern
Params:
text – a String object
Returns:
true if matched eitherwise false/**
	 * match the given <code>text</code> with the pattern
	 * @return true if matched eitherwise false
	 * @param text a String object
	 */
	public boolean match(String text) {
		return match(text, 0, text.length());
	}
	
Given the starting (inclusive) and the ending (exclusive) positions in the
text, determine if the given substring matches with aPattern
Params:
text – a String object that contains the substring to match
start – marks the starting position (inclusive) of the substring
end – marks the ending index (exclusive) of the substring
Returns:
true if the specified portion of the text matches the pattern/**
	 * Given the starting (inclusive) and the ending (exclusive) positions in the
	 * <code>text</code>, determine if the given substring matches with aPattern
	 * @return true if the specified portion of the text matches the pattern
	 * @param text a String object that contains the substring to match
	 * @param start marks the starting position (inclusive) of the substring
	 * @param end marks the ending index (exclusive) of the substring
	 */
	public boolean match(String text, int start, int end) {
		if (null == text)
			throw new IllegalArgumentException();

		if (start > end)
			return false;

		if (fIgnoreWildCards)
			return (end - start == fLength) && fPattern.regionMatches(fIgnoreCase, 0, text, start, fLength);
		int segCount= fSegments.length;
		if (segCount == 0 && (fHasLeadingStar || fHasTrailingStar))  // pattern contains only '*'(s)
			return true;
		if (start == end)
			return fLength == 0;
		if (fLength == 0)
			return start == end;

		int tlen= text.length();
		if (start < 0)
			start= 0;
		if (end > tlen)
			end= tlen;

		int tCurPos= start;
		int bound= end - fBound;
		if ( bound < 0)
			return false;
		int i=0;
		String current= fSegments[i];
		int segLength= current.length();

		/* process first segment */
		if (!fHasLeadingStar){
			if(!regExpRegionMatches(text, start, current, 0, segLength)) {
				return false;
			} else {
				++i;
				tCurPos= tCurPos + segLength;
			}
		}
		if ((fSegments.length == 1) && (!fHasLeadingStar) && (!fHasTrailingStar)) {
			// only one segment to match, no wildcards specified
			return tCurPos == end;
		}
		/* process middle segments */
		while (i < segCount) {
			current= fSegments[i];
			int currentMatch;
			int k= current.indexOf(fSingleWildCard);
			if (k < 0) {
				currentMatch= textPosIn(text, tCurPos, end, current);
				if (currentMatch < 0)
					return false;
			} else {
				currentMatch= regExpPosIn(text, tCurPos, end, current);
				if (currentMatch < 0)
					return false;
			}
			tCurPos= currentMatch + current.length();
			i++;
		}

		/* process final segment */
		if (!fHasTrailingStar && tCurPos != end) {
			int clen= current.length();
			return regExpRegionMatches(text, end - clen, current, 0, clen);
		}
		return i == segCount ;
	}

	
This method parses the given pattern into segments seperated by wildcard '*' characters.
Since wildcards are not being used in this case, the pattern consists of a single segment.
/**
	 * This method parses the given pattern into segments seperated by wildcard '*' characters.
	 * Since wildcards are not being used in this case, the pattern consists of a single segment.
	 */
	private void parseNoWildCards() {
		fSegments= new String[1];
		fSegments[0]= fPattern;
		fBound= fLength;
	}
	
Parses the given pattern into segments seperated by wildcard '*' characters.
/**
	 * Parses the given pattern into segments seperated by wildcard '*' characters.
	 */
	private void parseWildCards() {
		if(fPattern.startsWith("*"))//$NON-NLS-1$
			fHasLeadingStar= true;
		if(fPattern.endsWith("*")) {//$NON-NLS-1$
			/* make sure it's not an escaped wildcard */
			if (fLength > 1 && fPattern.charAt(fLength - 2) != '\\') {
				fHasTrailingStar= true;
			}
		}

		Vector<String> temp= new Vector<>();

		int pos= 0;
		StringBuilder buf= new StringBuilder();
		while (pos < fLength) {
			char c= fPattern.charAt(pos++);
			switch (c) {
				case '\\':
					if (pos >= fLength) {
						buf.append(c);
					} else {
						char next= fPattern.charAt(pos++);
						/* if it's an escape sequence */
						if (next == '*' || next == '?' || next == '\\') {
							buf.append(next);
						} else {
							/* not an escape sequence, just insert literally */
							buf.append(c);
							buf.append(next);
						}
					}
				break;
				case '*':
					if (buf.length() > 0) {
						/* new segment */
						temp.addElement(buf.toString());
						fBound += buf.length();
						buf.setLength(0);
					}
				break;
				case '?':
					/* append special character representing single match wildcard */
					buf.append(fSingleWildCard);
				break;
				default:
					buf.append(c);
			}
		}

		/* add last buffer to segment list */
		if (buf.length() > 0) {
			temp.addElement(buf.toString());
			fBound += buf.length();
		}

		fSegments= new String[temp.size()];
		temp.copyInto(fSegments);
	}
	
Params:
text – a string which contains no wildcard
start – the starting index in the text for search, inclusive
end – the stopping point of search, exclusive
Returns:
the starting index in the text of the pattern , or -1 if not found/**
	 * @param text a string which contains no wildcard
	 * @param start the starting index in the text for search, inclusive
	 * @param end the stopping point of search, exclusive
	 * @return the starting index in the text of the pattern , or -1 if not found
	 */
	protected int posIn(String text, int start, int end) {//no wild card in pattern
		int max= end - fLength;

		if (!fIgnoreCase) {
			int i= text.indexOf(fPattern, start);
			if (i == -1 || i > max)
				return -1;
			return i;
		}

		for (int i= start; i <= max; ++i) {
			if (text.regionMatches(true, i, fPattern, 0, fLength))
				return i;
		}

		return -1;
	}
	
Params:
text – a simple regular expression that may only contain '?'(s)
start – the starting index in the text for search, inclusive
end – the stopping point of search, exclusive
p – a simple regular expression that may contains '?'
Returns:
the starting index in the text of the pattern , or -1 if not found/**
	 * @param text a simple regular expression that may only contain '?'(s)
	 * @param start the starting index in the text for search, inclusive
	 * @param end the stopping point of search, exclusive
	 * @param p a simple regular expression that may contains '?'
	 * @return the starting index in the text of the pattern , or -1 if not found
	 */
	protected int regExpPosIn(String text, int start, int end, String p) {
		int plen= p.length();

		int max= end - plen;
		for (int i= start; i <= max; ++i) {
			if (regExpRegionMatches(text, i, p, 0, plen))
				return i;
		}
		return -1;
	}


	protected boolean regExpRegionMatches(String text, int tStart, String p, int pStart, int plen) {
		while (plen-- > 0) {
			char tchar= text.charAt(tStart++);
			char pchar= p.charAt(pStart++);

			/* process wild cards */
			if (!fIgnoreWildCards) {
				/* skip single wild cards */
				if (pchar == fSingleWildCard) {
					continue;
				}
			}
			if (pchar == tchar)
				continue;
			if (fIgnoreCase) {
				if (Character.toUpperCase(tchar) == Character.toUpperCase(pchar))
					continue;
				// comparing after converting to upper case doesn't handle all cases;
				// also compare after converting to lower case
				if (Character.toLowerCase(tchar) == Character.toLowerCase(pchar))
					continue;
			}
			return false;
		}
		return true;
	}
	
Params:
text – the string to match
start – the starting index in the text for search, inclusive
end – the stopping point of search, exclusive
p – a string that has no wildcard
Returns:
the starting index in the text of the pattern , or -1 if not found/**
	 * @param text the string to match
	 * @param start the starting index in the text for search, inclusive
	 * @param end the stopping point of search, exclusive
	 * @param p a string that has no wildcard
	 * @return the starting index in the text of the pattern , or -1 if not found
	 */
	protected int textPosIn(String text, int start, int end, String p) {

		int plen= p.length();
		int max= end - plen;

		if (!fIgnoreCase) {
			int i= text.indexOf(p, start);
			if (i == -1 || i > max)
				return -1;
			return i;
		}

		for (int i= start; i <= max; ++i) {
			if (text.regionMatches(true, i, p, 0, plen))
				return i;
		}

		return -1;
	}
}