/*
* Copyright 1999-2006 Sun Microsystems, Inc. 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. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
package java.util.regex;
/**
* An engine that performs match operations on a {@link java.lang.CharSequence
* </code>character sequence<code>} 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 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
* useAnchoringBounds} and {@link #useTransparentBounds 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 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;
/**
* 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;
/**
* 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];
// 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</code> with the state of this matcher
* @since 1.5
*/
public MatchResult toMatchResult() {
Matcher result = new Matcher(this.parentPattern, text.toString());
result.first = this.first;
result.last = this.last;
result.groups = (int[])(this.groups.clone());
return result;
}
/**
* Changes the <tt>Pattern</tt> that this <tt>Matcher</tt> 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 <tt>null</tt>
* @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;
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;
lastAppendPosition = 0;
from = 0;
to = getTextLength();
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. </p>
*
* @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><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) {
if (first < 0)
throw new IllegalStateException("No match available");
if (group > groupCount())
throw new IndexOutOfBoundsException("No group " + group);
return groups[group * 2];
}
/**
* Returns the offset after the last character matched. </p>
*
* @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><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) {
if (first < 0)
throw new IllegalStateException("No match available");
if (group > groupCount())
throw new IndexOutOfBoundsException("No group " + group);
return groups[group * 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><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() {
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><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) {
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 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
* <tt>start</tt>, <tt>end</tt>, and <tt>group</tt> methods. </p>
*
* @return <tt>true</tt> 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
* <tt>start</tt>, <tt>end</tt>, and <tt>group</tt> methods. </p>
*
* @return <tt>true</tt> 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
* <tt>start</tt>, <tt>end</tt>, and <tt>group</tt> methods, and subsequent
* invocations of the {@link #find()} method will start at the first
* character not matched by this match. </p>
*
* @throws IndexOutOfBoundsException
* If start is less than zero or if start is greater than the
* length of the input sequence.
*
* @return <tt>true</tt> 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
* <tt>start</tt>, <tt>end</tt>, and <tt>group</tt> methods. </p>
*
* @return <tt>true</tt> 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</code> for the specified
* <code>String</code>.
*
* This method produces a <code>String</code> that will work
* as a literal replacement <code>s</code> in the
* <code>appendReplacement</code> method of the {@link Matcher} class.
* The <code>String</code> produced will match the sequence of characters
* in <code>s</code> 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()} <tt>-</tt> <tt>1</tt>. </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
* <tt>$</tt><i>g</i><tt></tt> will be replaced by the result of
* evaluating {@link #group(int) group}<tt>(</tt><i>g</i><tt>)</tt>.
* The first number after the <tt>$</tt> 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 <tt>"foo"</tt>, for
* example, then passing the replacement string <tt>"$2bar"</tt> would
* cause <tt>"foobar"</tt> to be appended to the string buffer. A dollar
* sign (<tt>$</tt>) may be included as a literal in the replacement
* string by preceding it with a backslash (<tt>\$</tt>).
*
* <p> Note that backslashes (<tt>\</tt>) and dollar signs (<tt>$</tt>) in
* the replacement string may cause the results to be different than if it
* were being treated as a literal replacement string. Dollar signs may be
* treated as references to captured subsequences as described above, and
* backslashes are used to escape literal characters in the replacement
* string.
*
* <p> This method is intended to be used in a loop together with the
* {@link #appendTail appendTail} and {@link #find find} methods. The
* following code, for example, writes <tt>one dog two dogs in the
* yard</tt> to the standard-output stream: </p>
*
* <blockquote><pre>
* Pattern p = Pattern.compile("cat");
* Matcher m = p.matcher("one cat two cats in the yard");
* StringBuffer sb = new StringBuffer();
* while (m.find()) {
* m.appendReplacement(sb, "dog");
* }
* m.appendTail(sb);
* System.out.println(sb.toString());</pre></blockquote>
*
* @param sb
* The target string buffer
*
* @param replacement
* The replacement string
*
* @return This matcher
*
* @throws IllegalStateException
* If no match has yet been attempted,
* or if the previous match operation failed
*
* @throws IndexOutOfBoundsException
* If the replacement string refers to a capturing group
* that does not exist in the pattern
*/
public Matcher appendReplacement(StringBuffer sb, String replacement) {
// If no match, return error
if (first < 0)
throw new IllegalStateException("No match available");
// Process substitution string to replace group references with groups
int cursor = 0;
StringBuilder result = new StringBuilder();
while (cursor < replacement.length()) {
char nextChar = replacement.charAt(cursor);
if (nextChar == '\\') {
cursor++;
nextChar = replacement.charAt(cursor);
result.append(nextChar);
cursor++;
} else if (nextChar == '$') {
// Skip past $
cursor++;
// The first number is always a group
int refNum = (int)replacement.charAt(cursor) - '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++;
}
}
// Append the intervening text
sb.append(text, lastAppendPosition, first);
// Append the match substitution
sb.append(result);
lastAppendPosition = last;
return this;
}
/**
* 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 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;
}
/**
* 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 (<tt>\</tt>) and dollar signs (<tt>$</tt>) in
* the replacement string may cause the results to be different than if it
* were being treated as a literal replacement string. Dollar signs may be
* treated as references to captured subsequences as described above, and
* backslashes are used to escape literal characters in the replacement
* string.
*
* <p> Given the regular expression <tt>a*b</tt>, the input
* <tt>"aabfooaabfooabfoob"</tt>, and the replacement string
* <tt>"-"</tt>, an invocation of this method on a matcher for that
* expression would yield the string <tt>"-foo-foo-foo-"</tt>.
*
* <p> Invoking this method changes this matcher's state. If the matcher
* is to be used in further matching operations then it should first be
* reset. </p>
*
* @param replacement
* The replacement string
*
* @return The string constructed by replacing each matching subsequence
* by the replacement string, substituting captured subsequences
* as needed
*/
public String replaceAll(String replacement) {
reset();
boolean result = find();
if (result) {
StringBuffer sb = new StringBuffer();
do {
appendReplacement(sb, replacement);
result = find();
} while (result);
appendTail(sb);
return sb.toString();
}
return text.toString();
}
/**
* Replaces the first subsequence of the input sequence that matches the
* pattern with the given replacement string.
*
* <p> This method first resets this matcher. It then scans the input
* sequence looking for a match of the pattern. Characters that are not
* part of the match are appended directly to the result string; the match
* is replaced in the result by the replacement string. The replacement
* string may contain references to captured subsequences as in the {@link
* #appendReplacement appendReplacement} method.
*
* <p>Note that backslashes (<tt>\</tt>) and dollar signs (<tt>$</tt>) 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 <tt>dog</tt>, the input
* <tt>"zzzdogzzzdogzzz"</tt>, and the replacement string
* <tt>"cat"</tt>, an invocation of this method on a matcher for that
* expression would yield the string <tt>"zzzcatzzzdogzzz"</tt>. </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();
StringBuffer sb = new StringBuffer();
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</code> parameter and end at the
* index specified by the <code>end</code> parameter.
*
* <p>Depending on the transparency and anchoring being used (see
* {@link #useTransparentBounds useTransparentBounds} and
* {@link #useAnchoringBounds 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 <tt>true</tt> if this matcher uses
* <i>transparent</i> bounds, <tt>false</tt> if it uses <i>opaque</i>
* bounds.
*
* <p> See {@link #useTransparentBounds useTransparentBounds} for a
* description of transparent and opaque bounds.
*
* <p> By default, a matcher uses opaque region boundaries.
*
* @return <tt>true</tt> iff this matcher is using transparent bounds,
* <tt>false</tt> 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 <tt>true</tt> will set this
* matcher to use <i>transparent</i> bounds. If the boolean
* argument is <tt>false</tt>, 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 <tt>true</tt> if this matcher uses
* <i>anchoring</i> bounds, <tt>false</tt> otherwise.
*
* <p> See {@link #useAnchoringBounds useAnchoringBounds} for a
* description of anchoring bounds.
*
* <p> By default, a matcher uses anchoring region boundaries.
*
* @return <tt>true</tt> iff this matcher is using anchoring bounds,
* <tt>false</tt> 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 <tt>true</tt> will set this
* matcher to use <i>anchoring</i> bounds. If the boolean
* argument is <tt>false</tt>, 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</code> 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");
sb.append("[pattern=" + pattern());
sb.append(" region=");
sb.append(regionStart() + "," + regionEnd());
sb.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;
acceptMode = NOANCHOR;
boolean result = parentPattern.root.match(this, from, text);
if (!result)
this.first = -1;
this.oldLast = this.last;
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;
acceptMode = anchor;
boolean result = parentPattern.matchRoot.match(this, from, text);
if (!result)
this.first = -1;
this.oldLast = this.last;
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);
}
}