Java tutorial
/* * Copyright (c) 1999, 2018, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.util.regex; import java.util.ConcurrentModificationException; import java.util.Iterator; import java.util.NoSuchElementException; import java.util.Objects; import java.util.Spliterator; import java.util.Spliterators; import java.util.function.Consumer; import java.util.function.Function; import java.util.stream.Stream; import java.util.stream.StreamSupport; /** * An engine that performs match operations on a {@linkplain * java.lang.CharSequence character sequence} by interpreting a {@link Pattern}. * * <p> A matcher is created from a pattern by invoking the pattern's {@link * Pattern#matcher matcher} method. Once created, a matcher can be used to * perform three different kinds of match operations: * * <ul> * * <li><p> The {@link #matches matches} method attempts to match the entire * input sequence against the pattern. </p></li> * * <li><p> The {@link #lookingAt lookingAt} method attempts to match the * input sequence, starting at the beginning, against the pattern. </p></li> * * <li><p> The {@link #find find} method scans the input sequence looking * for the next subsequence that matches the pattern. </p></li> * * </ul> * * <p> Each of these methods returns a boolean indicating success or failure. * More information about a successful match can be obtained by querying the * state of the matcher. * * <p> A matcher finds matches in a subset of its input called the * <i>region</i>. By default, the region contains all of the matcher's input. * The region can be modified via the {@link #region(int, int) region} method * and queried via the {@link #regionStart() regionStart} and {@link * #regionEnd() regionEnd} methods. The way that the region boundaries interact * with some pattern constructs can be changed. See {@link * #useAnchoringBounds(boolean) useAnchoringBounds} and {@link * #useTransparentBounds(boolean) useTransparentBounds} for more details. * * <p> This class also defines methods for replacing matched subsequences with * new strings whose contents can, if desired, be computed from the match * result. The {@link #appendReplacement appendReplacement} and {@link * #appendTail appendTail} methods can be used in tandem in order to collect * the result into an existing string buffer or string builder. Alternatively, * the more convenient {@link #replaceAll replaceAll} method can be used to * create a string in which every matching subsequence in the input sequence * is replaced. * * <p> The explicit state of a matcher includes the start and end indices of * the most recent successful match. It also includes the start and end * indices of the input subsequence captured by each <a * href="Pattern.html#cg">capturing group</a> in the pattern as well as a total * count of such subsequences. As a convenience, methods are also provided for * returning these captured subsequences in string form. * * <p> The explicit state of a matcher is initially undefined; attempting to * query any part of it before a successful match will cause an {@link * IllegalStateException} to be thrown. The explicit state of a matcher is * recomputed by every match operation. * * <p> The implicit state of a matcher includes the input character sequence as * well as the <i>append position</i>, which is initially zero and is updated * by the {@link #appendReplacement appendReplacement} method. * * <p> A matcher may be reset explicitly by invoking its {@link #reset()} * method or, if a new input sequence is desired, its {@link * #reset(java.lang.CharSequence) reset(CharSequence)} method. Resetting a * matcher discards its explicit state information and sets the append position * to zero. * * <p> Instances of this class are not safe for use by multiple concurrent * threads. </p> * * * @author Mike McCloskey * @author Mark Reinhold * @author JSR-51 Expert Group * @since 1.4 * @spec JSR-51 */ public final class Matcher implements MatchResult { /** * The Pattern object that created this Matcher. */ Pattern parentPattern; /** * The storage used by groups. They may contain invalid values if * a group was skipped during the matching. */ int[] groups; /** * The range within the sequence that is to be matched. Anchors * will match at these "hard" boundaries. Changing the region * changes these values. */ int from, to; /** * Lookbehind uses this value to ensure that the subexpression * match ends at the point where the lookbehind was encountered. */ int lookbehindTo; /** * The original string being matched. */ CharSequence text; /** * Matcher state used by the last node. NOANCHOR is used when a * match does not have to consume all of the input. ENDANCHOR is * the mode used for matching all the input. */ static final int ENDANCHOR = 1; static final int NOANCHOR = 0; int acceptMode = NOANCHOR; /** * The range of string that last matched the pattern. If the last * match failed then first is -1; last initially holds 0 then it * holds the index of the end of the last match (which is where the * next search starts). */ int first = -1, last = 0; /** * The end index of what matched in the last match operation. */ int oldLast = -1; /** * The index of the last position appended in a substitution. */ int lastAppendPosition = 0; /** * Storage used by nodes to tell what repetition they are on in * a pattern, and where groups begin. The nodes themselves are stateless, * so they rely on this field to hold state during a match. */ int[] locals; /** * Storage used by top greedy Loop node to store a specific hash set to * keep the beginning index of the failed repetition match. The nodes * themselves are stateless, so they rely on this field to hold state * during a match. */ IntHashSet[] localsPos; /** * Boolean indicating whether or not more input could change * the results of the last match. * * If hitEnd is true, and a match was found, then more input * might cause a different match to be found. * If hitEnd is true and a match was not found, then more * input could cause a match to be found. * If hitEnd is false and a match was found, then more input * will not change the match. * If hitEnd is false and a match was not found, then more * input will not cause a match to be found. */ boolean hitEnd; /** * Boolean indicating whether or not more input could change * a positive match into a negative one. * * If requireEnd is true, and a match was found, then more * input could cause the match to be lost. * If requireEnd is false and a match was found, then more * input might change the match but the match won't be lost. * If a match was not found, then requireEnd has no meaning. */ boolean requireEnd; /** * If transparentBounds is true then the boundaries of this * matcher's region are transparent to lookahead, lookbehind, * and boundary matching constructs that try to see beyond them. */ boolean transparentBounds = false; /** * If anchoringBounds is true then the boundaries of this * matcher's region match anchors such as ^ and $. */ boolean anchoringBounds = true; /** * Number of times this matcher's state has been modified */ int modCount; /** * No default constructor. */ Matcher() { } /** * All matchers have the state used by Pattern during a match. */ Matcher(Pattern parent, CharSequence text) { this.parentPattern = parent; this.text = text; // Allocate state storage int parentGroupCount = Math.max(parent.capturingGroupCount, 10); groups = new int[parentGroupCount * 2]; locals = new int[parent.localCount]; localsPos = new IntHashSet[parent.localTCNCount]; // Put fields into initial states reset(); } /** * Returns the pattern that is interpreted by this matcher. * * @return The pattern for which this matcher was created */ public Pattern pattern() { return parentPattern; } /** * Returns the match state of this matcher as a {@link MatchResult}. * The result is unaffected by subsequent operations performed upon this * matcher. * * @return a {@code MatchResult} with the state of this matcher * @since 1.5 */ public MatchResult toMatchResult() { return toMatchResult(text.toString()); } private MatchResult toMatchResult(String text) { return new ImmutableMatchResult(this.first, this.last, groupCount(), this.groups.clone(), text); } private static class ImmutableMatchResult implements MatchResult { private final int first; private final int last; private final int[] groups; private final int groupCount; private final String text; ImmutableMatchResult(int first, int last, int groupCount, int groups[], String text) { this.first = first; this.last = last; this.groupCount = groupCount; this.groups = groups; this.text = text; } @Override public int start() { checkMatch(); return first; } @Override public int start(int group) { checkMatch(); if (group < 0 || group > groupCount) throw new IndexOutOfBoundsException("No group " + group); return groups[group * 2]; } @Override public int end() { checkMatch(); return last; } @Override public int end(int group) { checkMatch(); if (group < 0 || group > groupCount) throw new IndexOutOfBoundsException("No group " + group); return groups[group * 2 + 1]; } @Override public int groupCount() { return groupCount; } @Override public String group() { checkMatch(); return group(0); } @Override public String group(int group) { checkMatch(); if (group < 0 || group > groupCount) throw new IndexOutOfBoundsException("No group " + group); if ((groups[group * 2] == -1) || (groups[group * 2 + 1] == -1)) return null; return text.subSequence(groups[group * 2], groups[group * 2 + 1]).toString(); } private void checkMatch() { if (first < 0) throw new IllegalStateException("No match found"); } } /** * Changes the {@code Pattern} that this {@code Matcher} uses to * find matches with. * * <p> This method causes this matcher to lose information * about the groups of the last match that occurred. The * matcher's position in the input is maintained and its * last append position is unaffected.</p> * * @param newPattern * The new pattern used by this matcher * @return This matcher * @throws IllegalArgumentException * If newPattern is {@code null} * @since 1.5 */ public Matcher usePattern(Pattern newPattern) { if (newPattern == null) throw new IllegalArgumentException("Pattern cannot be null"); parentPattern = newPattern; // Reallocate state storage int parentGroupCount = Math.max(newPattern.capturingGroupCount, 10); groups = new int[parentGroupCount * 2]; locals = new int[newPattern.localCount]; for (int i = 0; i < groups.length; i++) groups[i] = -1; for (int i = 0; i < locals.length; i++) locals[i] = -1; localsPos = new IntHashSet[parentPattern.localTCNCount]; modCount++; return this; } /** * Resets this matcher. * * <p> Resetting a matcher discards all of its explicit state information * and sets its append position to zero. The matcher's region is set to the * default region, which is its entire character sequence. The anchoring * and transparency of this matcher's region boundaries are unaffected. * * @return This matcher */ public Matcher reset() { first = -1; last = 0; oldLast = -1; for (int i = 0; i < groups.length; i++) groups[i] = -1; for (int i = 0; i < locals.length; i++) locals[i] = -1; for (int i = 0; i < localsPos.length; i++) { if (localsPos[i] != null) localsPos[i].clear(); } lastAppendPosition = 0; from = 0; to = getTextLength(); modCount++; return this; } /** * Resets this matcher with a new input sequence. * * <p> Resetting a matcher discards all of its explicit state information * and sets its append position to zero. The matcher's region is set to * the default region, which is its entire character sequence. The * anchoring and transparency of this matcher's region boundaries are * unaffected. * * @param input * The new input character sequence * * @return This matcher */ public Matcher reset(CharSequence input) { text = input; return reset(); } /** * Returns the start index of the previous 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() { if (first < 0) throw new IllegalStateException("No match available"); return first; } /** * Returns the start index of the subsequence captured by the given group * during the previous match operation. * * <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>{@code start(0)} is equivalent to * <i>m.</i>{@code start()}. </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 {@code -1} 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) { if (first < 0) throw new IllegalStateException("No match available"); if (group < 0 || group > groupCount()) throw new IndexOutOfBoundsException("No group " + group); return groups[group * 2]; } /** * Returns the start index of the subsequence captured by the given * <a href="Pattern.html#groupname">named-capturing group</a> during the * previous match operation. * * @param name * The name of a named-capturing group in this matcher's pattern * * @return The index of the first character captured by the group, * or {@code -1} 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 IllegalArgumentException * If there is no capturing group in the pattern * with the given name * @since 1.8 */ public int start(String name) { return groups[getMatchedGroupIndex(name) * 2]; } /** * Returns the offset after the last character matched. * * @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() { if (first < 0) throw new IllegalStateException("No match available"); return last; } /** * Returns the offset after the last character of the subsequence * captured by the given group during the previous match operation. * * <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>{@code end(0)} is equivalent to * <i>m.</i>{@code end()}. </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 {@code -1} 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) { if (first < 0) throw new IllegalStateException("No match available"); if (group < 0 || group > groupCount()) throw new IndexOutOfBoundsException("No group " + group); return groups[group * 2 + 1]; } /** * Returns the offset after the last character of the subsequence * captured by the given <a href="Pattern.html#groupname">named-capturing * group</a> during the previous match operation. * * @param name * The name of a named-capturing group in this matcher's pattern * * @return The offset after the last character captured by the group, * or {@code -1} 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 IllegalArgumentException * If there is no capturing group in the pattern * with the given name * @since 1.8 */ public int end(String name) { return groups[getMatchedGroupIndex(name) * 2 + 1]; } /** * 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>{@code group()} and * <i>s.</i>{@code substring(}<i>m.</i>{@code start(),} <i>m.</i> * {@code end())} are equivalent. </p> * * <p> Note that some patterns, for example {@code a*}, 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() { return group(0); } /** * 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>{@code group(}<i>g</i>{@code )} and * <i>s.</i>{@code substring(}<i>m.</i>{@code start(}<i>g</i>{@code * ),} <i>m.</i>{@code end(}<i>g</i>{@code ))} * 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 {@code m.group(0)} is equivalent to {@code m.group()}. * </p> * * <p> If the match was successful but the group specified failed to match * any part of the input sequence, then {@code null} is returned. Note * that some groups, for example {@code (a*)}, 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 {@code null} 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) { if (first < 0) throw new IllegalStateException("No match found"); if (group < 0 || group > groupCount()) throw new IndexOutOfBoundsException("No group " + group); if ((groups[group * 2] == -1) || (groups[group * 2 + 1] == -1)) return null; return getSubSequence(groups[group * 2], groups[group * 2 + 1]).toString(); } /** * Returns the input subsequence captured by the given * <a href="Pattern.html#groupname">named-capturing group</a> during the * previous match operation. * * <p> If the match was successful but the group specified failed to match * any part of the input sequence, then {@code null} is returned. Note * that some groups, for example {@code (a*)}, 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 name * The name of a named-capturing group in this matcher's pattern * * @return The (possibly empty) subsequence captured by the named group * during the previous match, or {@code null} 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 IllegalArgumentException * If there is no capturing group in the pattern * with the given name * @since 1.7 */ public String group(String name) { int group = getMatchedGroupIndex(name); if ((groups[group * 2] == -1) || (groups[group * 2 + 1] == -1)) return null; return getSubSequence(groups[group * 2], groups[group * 2 + 1]).toString(); } /** * Returns the number of capturing groups in this matcher'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() { return parentPattern.capturingGroupCount - 1; } /** * Attempts to match the entire region against the pattern. * * <p> If the match succeeds then more information can be obtained via the * {@code start}, {@code end}, and {@code group} methods. </p> * * @return {@code true} if, and only if, the entire region sequence * matches this matcher's pattern */ public boolean matches() { return match(from, ENDANCHOR); } /** * Attempts to find the next subsequence of the input sequence that matches * the pattern. * * <p> This method starts at the beginning of this matcher's region, or, if * a previous invocation of the method was successful and the matcher has * not since been reset, at the first character not matched by the previous * match. * * <p> If the match succeeds then more information can be obtained via the * {@code start}, {@code end}, and {@code group} methods. </p> * * @return {@code true} if, and only if, a subsequence of the input * sequence matches this matcher's pattern */ public boolean find() { int nextSearchIndex = last; if (nextSearchIndex == first) nextSearchIndex++; // If next search starts before region, start it at region if (nextSearchIndex < from) nextSearchIndex = from; // If next search starts beyond region then it fails if (nextSearchIndex > to) { for (int i = 0; i < groups.length; i++) groups[i] = -1; return false; } return search(nextSearchIndex); } /** * Resets this matcher and then attempts to find the next subsequence of * the input sequence that matches the pattern, starting at the specified * index. * * <p> If the match succeeds then more information can be obtained via the * {@code start}, {@code end}, and {@code group} methods, and subsequent * invocations of the {@link #find()} method will start at the first * character not matched by this match. </p> * * @param start the index to start searching for a match * @throws IndexOutOfBoundsException * If start is less than zero or if start is greater than the * length of the input sequence. * * @return {@code true} if, and only if, a subsequence of the input * sequence starting at the given index matches this matcher's * pattern */ public boolean find(int start) { int limit = getTextLength(); if ((start < 0) || (start > limit)) throw new IndexOutOfBoundsException("Illegal start index"); reset(); return search(start); } /** * Attempts to match the input sequence, starting at the beginning of the * region, against the pattern. * * <p> Like the {@link #matches matches} method, this method always starts * at the beginning of the region; unlike that method, it does not * require that the entire region be matched. * * <p> If the match succeeds then more information can be obtained via the * {@code start}, {@code end}, and {@code group} methods. </p> * * @return {@code true} if, and only if, a prefix of the input * sequence matches this matcher's pattern */ public boolean lookingAt() { return match(from, NOANCHOR); } /** * Returns a literal replacement {@code String} for the specified * {@code String}. * * This method produces a {@code String} that will work * as a literal replacement {@code s} in the * {@code appendReplacement} method of the {@link Matcher} class. * The {@code String} produced will match the sequence of characters * in {@code s} treated as a literal sequence. Slashes ('\') and * dollar signs ('$') will be given no special meaning. * * @param s The string to be literalized * @return A literal string replacement * @since 1.5 */ public static String quoteReplacement(String s) { if ((s.indexOf('\\') == -1) && (s.indexOf('$') == -1)) return s; StringBuilder sb = new StringBuilder(); for (int i = 0; i < s.length(); i++) { char c = s.charAt(i); if (c == '\\' || c == '$') { sb.append('\\'); } sb.append(c); } return sb.toString(); } /** * Implements a non-terminal append-and-replace step. * * <p> This method performs the following actions: </p> * * <ol> * * <li><p> It reads characters from the input sequence, starting at the * append position, and appends them to the given string buffer. It * stops after reading the last character preceding the previous match, * that is, the character at index {@link * #start()} {@code -} {@code 1}. </p></li> * * <li><p> It appends the given replacement string to the string buffer. * </p></li> * * <li><p> It sets the append position of this matcher to the index of * the last character matched, plus one, that is, to {@link #end()}. * </p></li> * * </ol> * * <p> The replacement string may contain references to subsequences * captured during the previous match: Each occurrence of * <code>${</code><i>name</i><code>}</code> or {@code $}<i>g</i> * will be replaced by the result of evaluating the corresponding * {@link #group(String) group(name)} or {@link #group(int) group(g)} * respectively. For {@code $}<i>g</i>, * the first number after the {@code $} is always treated as part of * the group reference. Subsequent numbers are incorporated into g if * they would form a legal group reference. Only the numerals '0' * through '9' are considered as potential components of the group * reference. If the second group matched the string {@code "foo"}, for * example, then passing the replacement string {@code "$2bar"} would * cause {@code "foobar"} to be appended to the string buffer. A dollar * sign ({@code $}) may be included as a literal in the replacement * string by preceding it with a backslash ({@code \$}). * * <p> Note that backslashes ({@code \}) and dollar signs ({@code $}) in * the replacement string may cause the results to be different than if it * were being treated as a literal replacement string. Dollar signs may be * treated as references to captured subsequences as described above, and * backslashes are used to escape literal characters in the replacement * string. * * <p> This method is intended to be used in a loop together with the * {@link #appendTail(StringBuffer) appendTail} and {@link #find() find} * methods. The following code, for example, writes {@code one dog two dogs * in the yard} to the standard-output stream: </p> * * <blockquote><pre> * Pattern p = Pattern.compile("cat"); * Matcher m = p.matcher("one cat two cats in the yard"); * StringBuffer sb = new StringBuffer(); * while (m.find()) { * m.appendReplacement(sb, "dog"); * } * m.appendTail(sb); * System.out.println(sb.toString());</pre></blockquote> * * @param sb * The target string buffer * * @param replacement * The replacement string * * @return This matcher * * @throws IllegalStateException * If no match has yet been attempted, * or if the previous match operation failed * * @throws IllegalArgumentException * If the replacement string refers to a named-capturing * group that does not exist in the pattern * * @throws IndexOutOfBoundsException * If the replacement string refers to a capturing group * that does not exist in the pattern */ public Matcher appendReplacement(StringBuffer sb, String replacement) { // If no match, return error if (first < 0) throw new IllegalStateException("No match available"); StringBuilder result = new StringBuilder(); appendExpandedReplacement(replacement, result); // Append the intervening text sb.append(text, lastAppendPosition, first); // Append the match substitution sb.append(result); lastAppendPosition = last; modCount++; return this; } /** * Implements a non-terminal append-and-replace step. * * <p> This method performs the following actions: </p> * * <ol> * * <li><p> It reads characters from the input sequence, starting at the * append position, and appends them to the given string builder. It * stops after reading the last character preceding the previous match, * that is, the character at index {@link * #start()} {@code -} {@code 1}. </p></li> * * <li><p> It appends the given replacement string to the string builder. * </p></li> * * <li><p> It sets the append position of this matcher to the index of * the last character matched, plus one, that is, to {@link #end()}. * </p></li> * * </ol> * * <p> The replacement string may contain references to subsequences * captured during the previous match: Each occurrence of * {@code $}<i>g</i> will be replaced by the result of * evaluating {@link #group(int) group}{@code (}<i>g</i>{@code )}. * The first number after the {@code $} is always treated as part of * the group reference. Subsequent numbers are incorporated into g if * they would form a legal group reference. Only the numerals '0' * through '9' are considered as potential components of the group * reference. If the second group matched the string {@code "foo"}, for * example, then passing the replacement string {@code "$2bar"} would * cause {@code "foobar"} to be appended to the string builder. A dollar * sign ({@code $}) may be included as a literal in the replacement * string by preceding it with a backslash ({@code \$}). * * <p> Note that backslashes ({@code \}) and dollar signs ({@code $}) in * the replacement string may cause the results to be different than if it * were being treated as a literal replacement string. Dollar signs may be * treated as references to captured subsequences as described above, and * backslashes are used to escape literal characters in the replacement * string. * * <p> This method is intended to be used in a loop together with the * {@link #appendTail(StringBuilder) appendTail} and * {@link #find() find} methods. The following code, for example, writes * {@code one dog two dogs in the yard} to the standard-output stream: </p> * * <blockquote><pre> * Pattern p = Pattern.compile("cat"); * Matcher m = p.matcher("one cat two cats in the yard"); * StringBuilder sb = new StringBuilder(); * while (m.find()) { * m.appendReplacement(sb, "dog"); * } * m.appendTail(sb); * System.out.println(sb.toString());</pre></blockquote> * * @param sb * The target string builder * @param replacement * The replacement string * @return This matcher * * @throws IllegalStateException * If no match has yet been attempted, * or if the previous match operation failed * @throws IllegalArgumentException * If the replacement string refers to a named-capturing * group that does not exist in the pattern * @throws IndexOutOfBoundsException * If the replacement string refers to a capturing group * that does not exist in the pattern * @since 9 */ public Matcher appendReplacement(StringBuilder sb, String replacement) { // If no match, return error if (first < 0) throw new IllegalStateException("No match available"); StringBuilder result = new StringBuilder(); appendExpandedReplacement(replacement, result); // Append the intervening text sb.append(text, lastAppendPosition, first); // Append the match substitution sb.append(result); lastAppendPosition = last; modCount++; return this; } /** * Processes replacement string to replace group references with * groups. */ private StringBuilder appendExpandedReplacement(String replacement, StringBuilder result) { int cursor = 0; while (cursor < replacement.length()) { char nextChar = replacement.charAt(cursor); if (nextChar == '\\') { cursor++; if (cursor == replacement.length()) throw new IllegalArgumentException("character to be escaped is missing"); nextChar = replacement.charAt(cursor); result.append(nextChar); cursor++; } else if (nextChar == '$') { // Skip past $ cursor++; // Throw IAE if this "$" is the last character in replacement if (cursor == replacement.length()) throw new IllegalArgumentException("Illegal group reference: group index is missing"); nextChar = replacement.charAt(cursor); int refNum = -1; if (nextChar == '{') { cursor++; StringBuilder gsb = new StringBuilder(); while (cursor < replacement.length()) { nextChar = replacement.charAt(cursor); if (ASCII.isLower(nextChar) || ASCII.isUpper(nextChar) || ASCII.isDigit(nextChar)) { gsb.append(nextChar); cursor++; } else { break; } } if (gsb.length() == 0) throw new IllegalArgumentException("named capturing group has 0 length name"); if (nextChar != '}') throw new IllegalArgumentException("named capturing group is missing trailing '}'"); String gname = gsb.toString(); if (ASCII.isDigit(gname.charAt(0))) throw new IllegalArgumentException( "capturing group name {" + gname + "} starts with digit character"); if (!parentPattern.namedGroups().containsKey(gname)) throw new IllegalArgumentException("No group with name {" + gname + "}"); refNum = parentPattern.namedGroups().get(gname); cursor++; } else { // The first number is always a group refNum = nextChar - '0'; if ((refNum < 0) || (refNum > 9)) throw new IllegalArgumentException("Illegal group reference"); cursor++; // Capture the largest legal group string boolean done = false; while (!done) { if (cursor >= replacement.length()) { break; } int nextDigit = replacement.charAt(cursor) - '0'; if ((nextDigit < 0) || (nextDigit > 9)) { // not a number break; } int newRefNum = (refNum * 10) + nextDigit; if (groupCount() < newRefNum) { done = true; } else { refNum = newRefNum; cursor++; } } } // Append group if (start(refNum) != -1 && end(refNum) != -1) result.append(text, start(refNum), end(refNum)); } else { result.append(nextChar); cursor++; } } return result; } /** * Implements a terminal append-and-replace step. * * <p> This method reads characters from the input sequence, starting at * the append position, and appends them to the given string buffer. It is * intended to be invoked after one or more invocations of the {@link * #appendReplacement(StringBuffer, String) appendReplacement} method in * order to copy the remainder of the input sequence. </p> * * @param sb * The target string buffer * * @return The target string buffer */ public StringBuffer appendTail(StringBuffer sb) { sb.append(text, lastAppendPosition, getTextLength()); return sb; } /** * Implements a terminal append-and-replace step. * * <p> This method reads characters from the input sequence, starting at * the append position, and appends them to the given string builder. It is * intended to be invoked after one or more invocations of the {@link * #appendReplacement(StringBuilder, String) * appendReplacement} method in order to copy the remainder of the input * sequence. </p> * * @param sb * The target string builder * * @return The target string builder * * @since 9 */ public StringBuilder appendTail(StringBuilder sb) { sb.append(text, lastAppendPosition, getTextLength()); return sb; } /** * Replaces every subsequence of the input sequence that matches the * pattern with the given replacement string. * * <p> This method first resets this matcher. It then scans the input * sequence looking for matches of the pattern. Characters that are not * part of any match are appended directly to the result string; each match * is replaced in the result by the replacement string. The replacement * string may contain references to captured subsequences as in the {@link * #appendReplacement appendReplacement} method. * * <p> Note that backslashes ({@code \}) and dollar signs ({@code $}) in * the replacement string may cause the results to be different than if it * were being treated as a literal replacement string. Dollar signs may be * treated as references to captured subsequences as described above, and * backslashes are used to escape literal characters in the replacement * string. * * <p> Given the regular expression {@code a*b}, the input * {@code "aabfooaabfooabfoob"}, and the replacement string * {@code "-"}, an invocation of this method on a matcher for that * expression would yield the string {@code "-foo-foo-foo-"}. * * <p> Invoking this method changes this matcher's state. If the matcher * is to be used in further matching operations then it should first be * reset. </p> * * @param replacement * The replacement string * * @return The string constructed by replacing each matching subsequence * by the replacement string, substituting captured subsequences * as needed */ public String replaceAll(String replacement) { reset(); boolean result = find(); if (result) { StringBuilder sb = new StringBuilder(); do { appendReplacement(sb, replacement); result = find(); } while (result); appendTail(sb); return sb.toString(); } return text.toString(); } /** * Replaces every subsequence of the input sequence that matches the * pattern with the result of applying the given replacer function to the * match result of this matcher corresponding to that subsequence. * Exceptions thrown by the function are relayed to the caller. * * <p> This method first resets this matcher. It then scans the input * sequence looking for matches of the pattern. Characters that are not * part of any match are appended directly to the result string; each match * is replaced in the result by the applying the replacer function that * returns a replacement string. Each replacement string may contain * references to captured subsequences as in the {@link #appendReplacement * appendReplacement} method. * * <p> Note that backslashes ({@code \}) and dollar signs ({@code $}) in * a replacement string may cause the results to be different than if it * were being treated as a literal replacement string. Dollar signs may be * treated as references to captured subsequences as described above, and * backslashes are used to escape literal characters in the replacement * string. * * <p> Given the regular expression {@code dog}, the input * {@code "zzzdogzzzdogzzz"}, and the function * {@code mr -> mr.group().toUpperCase()}, an invocation of this method on * a matcher for that expression would yield the string * {@code "zzzDOGzzzDOGzzz"}. * * <p> Invoking this method changes this matcher's state. If the matcher * is to be used in further matching operations then it should first be * reset. </p> * * <p> The replacer function should not modify this matcher's state during * replacement. This method will, on a best-effort basis, throw a * {@link java.util.ConcurrentModificationException} if such modification is * detected. * * <p> The state of each match result passed to the replacer function is * guaranteed to be constant only for the duration of the replacer function * call and only if the replacer function does not modify this matcher's * state. * * @implNote * This implementation applies the replacer function to this matcher, which * is an instance of {@code MatchResult}. * * @param replacer * The function to be applied to the match result of this matcher * that returns a replacement string. * @return The string constructed by replacing each matching subsequence * with the result of applying the replacer function to that * matched subsequence, substituting captured subsequences as * needed. * @throws NullPointerException if the replacer function is null * @throws ConcurrentModificationException if it is detected, on a * best-effort basis, that the replacer function modified this * matcher's state * @since 9 */ public String replaceAll(Function<MatchResult, String> replacer) { Objects.requireNonNull(replacer); reset(); boolean result = find(); if (result) { StringBuilder sb = new StringBuilder(); do { int ec = modCount; String replacement = replacer.apply(this); if (ec != modCount) throw new ConcurrentModificationException(); appendReplacement(sb, replacement); result = find(); } while (result); appendTail(sb); return sb.toString(); } return text.toString(); } /** * Returns a stream of match results for each subsequence of the input * sequence that matches the pattern. The match results occur in the * same order as the matching subsequences in the input sequence. * * <p> Each match result is produced as if by {@link #toMatchResult()}. * * <p> This method does not reset this matcher. Matching starts on * initiation of the terminal stream operation either at the beginning of * this matcher's region, or, if the matcher has not since been reset, at * the first character not matched by a previous match. * * <p> If the matcher is to be used for further matching operations after * the terminal stream operation completes then it should be first reset. * * <p> This matcher's state should not be modified during execution of the * returned stream's pipeline. The returned stream's source * {@code Spliterator} is <em>fail-fast</em> and will, on a best-effort * basis, throw a {@link java.util.ConcurrentModificationException} if such * modification is detected. * * @return a sequential stream of match results. * @since 9 */ public Stream<MatchResult> results() { class MatchResultIterator implements Iterator<MatchResult> { // -ve for call to find, 0 for not found, 1 for found int state = -1; // State for concurrent modification checking // -1 for uninitialized int expectedCount = -1; // The input sequence as a string, set once only after first find // Avoids repeated conversion from CharSequence for each match String textAsString; @Override public MatchResult next() { if (expectedCount >= 0 && expectedCount != modCount) throw new ConcurrentModificationException(); if (!hasNext()) throw new NoSuchElementException(); state = -1; return toMatchResult(textAsString); } @Override public boolean hasNext() { if (state >= 0) return state == 1; // Defer throwing ConcurrentModificationException to when next // or forEachRemaining is called. The is consistent with other // fail-fast implementations. if (expectedCount >= 0 && expectedCount != modCount) return true; boolean found = find(); // Capture the input sequence as a string on first find if (found && state < 0) textAsString = text.toString(); state = found ? 1 : 0; expectedCount = modCount; return found; } @Override public void forEachRemaining(Consumer<? super MatchResult> action) { if (expectedCount >= 0 && expectedCount != modCount) throw new ConcurrentModificationException(); int s = state; if (s == 0) return; // Set state to report no more elements on further operations state = 0; expectedCount = -1; // Perform a first find if required if (s < 0 && !find()) return; // Capture the input sequence as a string on first find textAsString = text.toString(); do { int ec = modCount; action.accept(toMatchResult(textAsString)); if (ec != modCount) throw new ConcurrentModificationException(); } while (find()); } } return StreamSupport.stream(Spliterators.spliteratorUnknownSize(new MatchResultIterator(), Spliterator.ORDERED | Spliterator.NONNULL), false); } /** * Replaces the first subsequence of the input sequence that matches the * pattern with the given replacement string. * * <p> This method first resets this matcher. It then scans the input * sequence looking for a match of the pattern. Characters that are not * part of the match are appended directly to the result string; the match * is replaced in the result by the replacement string. The replacement * string may contain references to captured subsequences as in the {@link * #appendReplacement appendReplacement} method. * * <p>Note that backslashes ({@code \}) and dollar signs ({@code $}) in * the replacement string may cause the results to be different than if it * were being treated as a literal replacement string. Dollar signs may be * treated as references to captured subsequences as described above, and * backslashes are used to escape literal characters in the replacement * string. * * <p> Given the regular expression {@code dog}, the input * {@code "zzzdogzzzdogzzz"}, and the replacement string * {@code "cat"}, an invocation of this method on a matcher for that * expression would yield the string {@code "zzzcatzzzdogzzz"}. </p> * * <p> Invoking this method changes this matcher's state. If the matcher * is to be used in further matching operations then it should first be * reset. </p> * * @param replacement * The replacement string * @return The string constructed by replacing the first matching * subsequence by the replacement string, substituting captured * subsequences as needed */ public String replaceFirst(String replacement) { if (replacement == null) throw new NullPointerException("replacement"); reset(); if (!find()) return text.toString(); StringBuilder sb = new StringBuilder(); appendReplacement(sb, replacement); appendTail(sb); return sb.toString(); } /** * Replaces the first subsequence of the input sequence that matches the * pattern with the result of applying the given replacer function to the * match result of this matcher corresponding to that subsequence. * Exceptions thrown by the replace function are relayed to the caller. * * <p> This method first resets this matcher. It then scans the input * sequence looking for a match of the pattern. Characters that are not * part of the match are appended directly to the result string; the match * is replaced in the result by the applying the replacer function that * returns a replacement string. The replacement string may contain * references to captured subsequences as in the {@link #appendReplacement * appendReplacement} method. * * <p>Note that backslashes ({@code \}) and dollar signs ({@code $}) in * the replacement string may cause the results to be different than if it * were being treated as a literal replacement string. Dollar signs may be * treated as references to captured subsequences as described above, and * backslashes are used to escape literal characters in the replacement * string. * * <p> Given the regular expression {@code dog}, the input * {@code "zzzdogzzzdogzzz"}, and the function * {@code mr -> mr.group().toUpperCase()}, an invocation of this method on * a matcher for that expression would yield the string * {@code "zzzDOGzzzdogzzz"}. * * <p> Invoking this method changes this matcher's state. If the matcher * is to be used in further matching operations then it should first be * reset. * * <p> The replacer function should not modify this matcher's state during * replacement. This method will, on a best-effort basis, throw a * {@link java.util.ConcurrentModificationException} if such modification is * detected. * * <p> The state of the match result passed to the replacer function is * guaranteed to be constant only for the duration of the replacer function * call and only if the replacer function does not modify this matcher's * state. * * @implNote * This implementation applies the replacer function to this matcher, which * is an instance of {@code MatchResult}. * * @param replacer * The function to be applied to the match result of this matcher * that returns a replacement string. * @return The string constructed by replacing the first matching * subsequence with the result of applying the replacer function to * the matched subsequence, substituting captured subsequences as * needed. * @throws NullPointerException if the replacer function is null * @throws ConcurrentModificationException if it is detected, on a * best-effort basis, that the replacer function modified this * matcher's state * @since 9 */ public String replaceFirst(Function<MatchResult, String> replacer) { Objects.requireNonNull(replacer); reset(); if (!find()) return text.toString(); StringBuilder sb = new StringBuilder(); int ec = modCount; String replacement = replacer.apply(this); if (ec != modCount) throw new ConcurrentModificationException(); appendReplacement(sb, replacement); appendTail(sb); return sb.toString(); } /** * Sets the limits of this matcher's region. The region is the part of the * input sequence that will be searched to find a match. Invoking this * method resets the matcher, and then sets the region to start at the * index specified by the {@code start} parameter and end at the * index specified by the {@code end} parameter. * * <p>Depending on the transparency and anchoring being used (see * {@link #useTransparentBounds(boolean) useTransparentBounds} and * {@link #useAnchoringBounds(boolean) useAnchoringBounds}), certain * constructs such as anchors may behave differently at or around the * boundaries of the region. * * @param start * The index to start searching at (inclusive) * @param end * The index to end searching at (exclusive) * @throws IndexOutOfBoundsException * If start or end is less than zero, if * start is greater than the length of the input sequence, if * end is greater than the length of the input sequence, or if * start is greater than end. * @return this matcher * @since 1.5 */ public Matcher region(int start, int end) { if ((start < 0) || (start > getTextLength())) throw new IndexOutOfBoundsException("start"); if ((end < 0) || (end > getTextLength())) throw new IndexOutOfBoundsException("end"); if (start > end) throw new IndexOutOfBoundsException("start > end"); reset(); from = start; to = end; return this; } /** * Reports the start index of this matcher's region. The * searches this matcher conducts are limited to finding matches * within {@link #regionStart() regionStart} (inclusive) and * {@link #regionEnd() regionEnd} (exclusive). * * @return The starting point of this matcher's region * @since 1.5 */ public int regionStart() { return from; } /** * Reports the end index (exclusive) of this matcher's region. * The searches this matcher conducts are limited to finding matches * within {@link #regionStart() regionStart} (inclusive) and * {@link #regionEnd() regionEnd} (exclusive). * * @return the ending point of this matcher's region * @since 1.5 */ public int regionEnd() { return to; } /** * Queries the transparency of region bounds for this matcher. * * <p> This method returns {@code true} if this matcher uses * <i>transparent</i> bounds, {@code false} if it uses <i>opaque</i> * bounds. * * <p> See {@link #useTransparentBounds(boolean) useTransparentBounds} for a * description of transparent and opaque bounds. * * <p> By default, a matcher uses opaque region boundaries. * * @return {@code true} iff this matcher is using transparent bounds, * {@code false} otherwise. * @see java.util.regex.Matcher#useTransparentBounds(boolean) * @since 1.5 */ public boolean hasTransparentBounds() { return transparentBounds; } /** * Sets the transparency of region bounds for this matcher. * * <p> Invoking this method with an argument of {@code true} will set this * matcher to use <i>transparent</i> bounds. If the boolean * argument is {@code false}, then <i>opaque</i> bounds will be used. * * <p> Using transparent bounds, the boundaries of this * matcher's region are transparent to lookahead, lookbehind, * and boundary matching constructs. Those constructs can see beyond the * boundaries of the region to see if a match is appropriate. * * <p> Using opaque bounds, the boundaries of this matcher's * region are opaque to lookahead, lookbehind, and boundary matching * constructs that may try to see beyond them. Those constructs cannot * look past the boundaries so they will fail to match anything outside * of the region. * * <p> By default, a matcher uses opaque bounds. * * @param b a boolean indicating whether to use opaque or transparent * regions * @return this matcher * @see java.util.regex.Matcher#hasTransparentBounds * @since 1.5 */ public Matcher useTransparentBounds(boolean b) { transparentBounds = b; return this; } /** * Queries the anchoring of region bounds for this matcher. * * <p> This method returns {@code true} if this matcher uses * <i>anchoring</i> bounds, {@code false} otherwise. * * <p> See {@link #useAnchoringBounds(boolean) useAnchoringBounds} for a * description of anchoring bounds. * * <p> By default, a matcher uses anchoring region boundaries. * * @return {@code true} iff this matcher is using anchoring bounds, * {@code false} otherwise. * @see java.util.regex.Matcher#useAnchoringBounds(boolean) * @since 1.5 */ public boolean hasAnchoringBounds() { return anchoringBounds; } /** * Sets the anchoring of region bounds for this matcher. * * <p> Invoking this method with an argument of {@code true} will set this * matcher to use <i>anchoring</i> bounds. If the boolean * argument is {@code false}, then <i>non-anchoring</i> bounds will be * used. * * <p> Using anchoring bounds, the boundaries of this * matcher's region match anchors such as ^ and $. * * <p> Without anchoring bounds, the boundaries of this * matcher's region will not match anchors such as ^ and $. * * <p> By default, a matcher uses anchoring region boundaries. * * @param b a boolean indicating whether or not to use anchoring bounds. * @return this matcher * @see java.util.regex.Matcher#hasAnchoringBounds * @since 1.5 */ public Matcher useAnchoringBounds(boolean b) { anchoringBounds = b; return this; } /** * <p>Returns the string representation of this matcher. The * string representation of a {@code Matcher} contains information * that may be useful for debugging. The exact format is unspecified. * * @return The string representation of this matcher * @since 1.5 */ public String toString() { StringBuilder sb = new StringBuilder(); sb.append("java.util.regex.Matcher").append("[pattern=").append(pattern()).append(" region=") .append(regionStart()).append(',').append(regionEnd()).append(" lastmatch="); if ((first >= 0) && (group() != null)) { sb.append(group()); } sb.append(']'); return sb.toString(); } /** * <p>Returns true if the end of input was hit by the search engine in * the last match operation performed by this matcher. * * <p>When this method returns true, then it is possible that more input * would have changed the result of the last search. * * @return true iff the end of input was hit in the last match; false * otherwise * @since 1.5 */ public boolean hitEnd() { return hitEnd; } /** * <p>Returns true if more input could change a positive match into a * negative one. * * <p>If this method returns true, and a match was found, then more * input could cause the match to be lost. If this method returns false * and a match was found, then more input might change the match but the * match won't be lost. If a match was not found, then requireEnd has no * meaning. * * @return true iff more input could change a positive match into a * negative one. * @since 1.5 */ public boolean requireEnd() { return requireEnd; } /** * Initiates a search to find a Pattern within the given bounds. * The groups are filled with default values and the match of the root * of the state machine is called. The state machine will hold the state * of the match as it proceeds in this matcher. * * Matcher.from is not set here, because it is the "hard" boundary * of the start of the search which anchors will set to. The from param * is the "soft" boundary of the start of the search, meaning that the * regex tries to match at that index but ^ won't match there. Subsequent * calls to the search methods start at a new "soft" boundary which is * the end of the previous match. */ boolean search(int from) { this.hitEnd = false; this.requireEnd = false; from = from < 0 ? 0 : from; this.first = from; this.oldLast = oldLast < 0 ? from : oldLast; for (int i = 0; i < groups.length; i++) groups[i] = -1; for (int i = 0; i < localsPos.length; i++) { if (localsPos[i] != null) localsPos[i].clear(); } acceptMode = NOANCHOR; boolean result = parentPattern.root.match(this, from, text); if (!result) this.first = -1; this.oldLast = this.last; this.modCount++; return result; } /** * Initiates a search for an anchored match to a Pattern within the given * bounds. The groups are filled with default values and the match of the * root of the state machine is called. The state machine will hold the * state of the match as it proceeds in this matcher. */ boolean match(int from, int anchor) { this.hitEnd = false; this.requireEnd = false; from = from < 0 ? 0 : from; this.first = from; this.oldLast = oldLast < 0 ? from : oldLast; for (int i = 0; i < groups.length; i++) groups[i] = -1; for (int i = 0; i < localsPos.length; i++) { if (localsPos[i] != null) localsPos[i].clear(); } acceptMode = anchor; boolean result = parentPattern.matchRoot.match(this, from, text); if (!result) this.first = -1; this.oldLast = this.last; this.modCount++; return result; } /** * Returns the end index of the text. * * @return the index after the last character in the text */ int getTextLength() { return text.length(); } /** * Generates a String from this matcher's input in the specified range. * * @param beginIndex the beginning index, inclusive * @param endIndex the ending index, exclusive * @return A String generated from this matcher's input */ CharSequence getSubSequence(int beginIndex, int endIndex) { return text.subSequence(beginIndex, endIndex); } /** * Returns this matcher's input character at index i. * * @return A char from the specified index */ char charAt(int i) { return text.charAt(i); } /** * Returns the group index of the matched capturing group. * * @return the index of the named-capturing group */ int getMatchedGroupIndex(String name) { Objects.requireNonNull(name, "Group name"); if (first < 0) throw new IllegalStateException("No match found"); if (!parentPattern.namedGroups().containsKey(name)) throw new IllegalArgumentException("No group with name <" + name + ">"); return parentPattern.namedGroups().get(name); } }