1 /*
2 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
3 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
4 *
5 *
6 *
7 *
8 *
9 *
10 *
11 *
12 *
13 *
14 *
15 *
16 *
17 *
18 *
19 *
20 *
21 *
22 *
23 *
24 */
25
26 package java.util.regex;
27
28 /**
29 * The result of a match operation.
30 *
31 * <p>This interface contains query methods used to determine the
32 * results of a match against a regular expression. The match boundaries,
33 * groups and group boundaries can be seen but not modified through
34 * a {@code MatchResult}.
35 *
36 * @author Michael McCloskey
37 * @see Matcher
38 * @since 1.5
39 */
40 public interface MatchResult {
41
42 /**
43 * Returns the start index of the match.
44 *
45 * @return The index of the first character matched
46 *
47 * @throws IllegalStateException
48 * If no match has yet been attempted,
49 * or if the previous match operation failed
50 */
51 public int start();
52
53 /**
54 * Returns the start index of the subsequence captured by the given group
55 * during this match.
56 *
57 * <p> <a href="Pattern.html#cg">Capturing groups</a> are indexed from left
58 * to right, starting at one. Group zero denotes the entire pattern, so
59 * the expression <i>m.</i>{@code start(0)} is equivalent to
60 * <i>m.</i>{@code start()}. </p>
61 *
62 * @param group
63 * The index of a capturing group in this matcher's pattern
64 *
65 * @return The index of the first character captured by the group,
66 * or {@code -1} if the match was successful but the group
67 * itself did not match anything
68 *
69 * @throws IllegalStateException
70 * If no match has yet been attempted,
71 * or if the previous match operation failed
72 *
73 * @throws IndexOutOfBoundsException
74 * If there is no capturing group in the pattern
75 * with the given index
76 */
77 public int start(int group);
78
79 /**
80 * Returns the offset after the last character matched.
81 *
82 * @return The offset after the last character matched
83 *
84 * @throws IllegalStateException
85 * If no match has yet been attempted,
86 * or if the previous match operation failed
87 */
88 public int end();
89
90 /**
91 * Returns the offset after the last character of the subsequence
92 * captured by the given group during this match.
93 *
94 * <p> <a href="Pattern.html#cg">Capturing groups</a> are indexed from left
95 * to right, starting at one. Group zero denotes the entire pattern, so
96 * the expression <i>m.</i>{@code end(0)} is equivalent to
97 * <i>m.</i>{@code end()}. </p>
98 *
99 * @param group
100 * The index of a capturing group in this matcher's pattern
101 *
102 * @return The offset after the last character captured by the group,
103 * or {@code -1} if the match was successful
104 * but the group itself did not match anything
105 *
106 * @throws IllegalStateException
107 * If no match has yet been attempted,
108 * or if the previous match operation failed
109 *
110 * @throws IndexOutOfBoundsException
111 * If there is no capturing group in the pattern
112 * with the given index
113 */
114 public int end(int group);
115
116 /**
117 * Returns the input subsequence matched by the previous match.
118 *
119 * <p> For a matcher <i>m</i> with input sequence <i>s</i>,
120 * the expressions <i>m.</i>{@code group()} and
121 * <i>s.</i>{@code substring(}<i>m.</i>{@code start(),} <i>m.</i>{@code end())}
122 * are equivalent. </p>
123 *
124 * <p> Note that some patterns, for example {@code a*}, match the empty
125 * string. This method will return the empty string when the pattern
126 * successfully matches the empty string in the input. </p>
127 *
128 * @return The (possibly empty) subsequence matched by the previous match,
129 * in string form
130 *
131 * @throws IllegalStateException
132 * If no match has yet been attempted,
133 * or if the previous match operation failed
134 */
135 public String group();
136
137 /**
138 * Returns the input subsequence captured by the given group during the
139 * previous match operation.
140 *
141 * <p> For a matcher <i>m</i>, input sequence <i>s</i>, and group index
142 * <i>g</i>, the expressions <i>m.</i>{@code group(}<i>g</i>{@code )} and
143 * <i>s.</i>{@code substring(}<i>m.</i>{@code start(}<i>g</i>{@code
144 * ),} <i>m.</i>{@code end(}<i>g</i>{@code ))}
145 * are equivalent. </p>
146 *
147 * <p> <a href="Pattern.html#cg">Capturing groups</a> are indexed from left
148 * to right, starting at one. Group zero denotes the entire pattern, so
149 * the expression {@code m.group(0)} is equivalent to {@code m.group()}.
150 * </p>
151 *
152 * <p> If the match was successful but the group specified failed to match
153 * any part of the input sequence, then {@code null} is returned. Note
154 * that some groups, for example {@code (a*)}, match the empty string.
155 * This method will return the empty string when such a group successfully
156 * matches the empty string in the input. </p>
157 *
158 * @param group
159 * The index of a capturing group in this matcher's pattern
160 *
161 * @return The (possibly empty) subsequence captured by the group
162 * during the previous match, or {@code null} if the group
163 * failed to match part of the input
164 *
165 * @throws IllegalStateException
166 * If no match has yet been attempted,
167 * or if the previous match operation failed
168 *
169 * @throws IndexOutOfBoundsException
170 * If there is no capturing group in the pattern
171 * with the given index
172 */
173 public String group(int group);
174
175 /**
176 * Returns the number of capturing groups in this match result's pattern.
177 *
178 * <p> Group zero denotes the entire pattern by convention. It is not
179 * included in this count.
180 *
181 * <p> Any non-negative integer smaller than or equal to the value
182 * returned by this method is guaranteed to be a valid group index for
183 * this matcher. </p>
184 *
185 * @return The number of capturing groups in this matcher's pattern
186 */
187 public int groupCount();
188
189 }
