/*
* @(#)MatchResult.java 1.5 04/06/28
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package java.util.regex;
/**
* The result of a match operation.
*
* <p>This interface contains query methods used to determine the
* results of a match against a regular expression. The match boundaries,
* groups and group boundaries can be seen but not modified through
* a <code>MatchResult</code>.
*
* @author Michael McCloskey
* @version 1.5 06/28/04
* @see Matcher
* @since 1.5
*/
public interface MatchResult {
/**
* Returns the start index of the match.
*
* @return The index of the first character matched
*
* @throws IllegalStateException
* If no match has yet been attempted,
* or if the previous match operation failed
*/
public int start();
/**
* Returns the start index of the subsequence captured by the given group
* during this match.
*
* <p> <a href="Pattern.html#cg">Capturing groups</a> are indexed from left
* to right, starting at one. Group zero denotes the entire pattern, so
* the expression <i>m.</i><tt>start(0)</tt> is equivalent to
* <i>m.</i><tt>start()</tt>. </p>
*
* @param group
* The index of a capturing group in this matcher's pattern
*
* @return The index of the first character captured by the group,
* or <tt>-1</tt> if the match was successful but the group
* itself did not match anything
*
* @throws IllegalStateException
* If no match has yet been attempted,
* or if the previous match operation failed
*
* @throws IndexOutOfBoundsException
* If there is no capturing group in the pattern
* with the given index
*/
public int start(int group);
/**
* Returns the offset after the last character matched. </p>
*
* @return @return The offset after the last character matched
*
* @throws IllegalStateException
* If no match has yet been attempted,
* or if the previous match operation failed
*/
public int end();
/**
* Returns the offset after the last character of the subsequence
* captured by the given group during this match.
*
* <p> <a href="Pattern.html#cg">Capturing groups</a> are indexed from left
* to right, starting at one. Group zero denotes the entire pattern, so
* the expression <i>m.</i><tt>end(0)</tt> is equivalent to
* <i>m.</i><tt>end()</tt>. </p>
*
* @param group
* The index of a capturing group in this matcher's pattern
*
* @return The offset after the last character captured by the group,
* or <tt>-1</tt> if the match was successful
* but the group itself did not match anything
*
* @throws IllegalStateException
* If no match has yet been attempted,
* or if the previous match operation failed
*
* @throws IndexOutOfBoundsException
* If there is no capturing group in the pattern
* with the given index
*/
public int end(int group);
/**
* Returns the input subsequence matched by the previous match.
*
* <p> For a matcher <i>m</i> with input sequence <i>s</i>,
* the expressions <i>m.</i><tt>group()</tt> and
* <i>s.</i><tt>substring(</tt><i>m.</i><tt>start(),</tt> <i>m.</i><tt>end())</tt>
* are equivalent. </p>
*
* <p> Note that some patterns, for example <tt>a*</tt>, match the empty
* string. This method will return the empty string when the pattern
* successfully matches the empty string in the input. </p>
*
* @return The (possibly empty) subsequence matched by the previous match,
* in string form
*
* @throws IllegalStateException
* If no match has yet been attempted,
* or if the previous match operation failed
*/
public String group();
/**
* Returns the input subsequence captured by the given group during the
* previous match operation.
*
* <p> For a matcher <i>m</i>, input sequence <i>s</i>, and group index
* <i>g</i>, the expressions <i>m.</i><tt>group(</tt><i>g</i><tt>)</tt> and
* <i>s.</i><tt>substring(</tt><i>m.</i><tt>start(</tt><i>g</i><tt>),</tt> <i>m.</i><tt>end(</tt><i>g</i><tt>))</tt>
* are equivalent. </p>
*
* <p> <a href="Pattern.html#cg">Capturing groups</a> are indexed from left
* to right, starting at one. Group zero denotes the entire pattern, so
* the expression <tt>m.group(0)</tt> is equivalent to <tt>m.group()</tt>.
* </p>
*
* <p> If the match was successful but the group specified failed to match
* any part of the input sequence, then <tt>null</tt> is returned. Note
* that some groups, for example <tt>(a*)</tt>, match the empty string.
* This method will return the empty string when such a group successfully
* matches the empty string in the input. </p>
*
* @param group
* The index of a capturing group in this matcher's pattern
*
* @return The (possibly empty) subsequence captured by the group
* during the previous match, or <tt>null</tt> if the group
* failed to match part of the input
*
* @throws IllegalStateException
* If no match has yet been attempted,
* or if the previous match operation failed
*
* @throws IndexOutOfBoundsException
* If there is no capturing group in the pattern
* with the given index
*/
public String group(int group);
/**
* Returns the number of capturing groups in this match result's pattern.
*
* <p> Group zero denotes the entire pattern by convention. It is not
* included in this count.
*
* <p> Any non-negative integer smaller than or equal to the value
* returned by this method is guaranteed to be a valid group index for
* this matcher. </p>
*
* @return The number of capturing groups in this matcher's pattern
*/
public int groupCount();
}
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