All Downloads are FREE. Search and download functionalities are using the official Maven repository.

java.util.regex.Matcher Maven / Gradle / Ivy

There is a newer version: 1.2.9
Show newest version
/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package java.util.regex;

/**
 * The result of applying a {@code Pattern} to a given input. See {@link Pattern} for
 * example uses.
 */
public final class Matcher implements MatchResult {

    /**
     * Holds the pattern, that is, the compiled regular expression.
     */
    private Pattern pattern;

    /**
     * The address of the native peer.
     * Uses of this must be manually synchronized to avoid native crashes.
     */
    private long address;

    /**
     * Holds the input text.
     */
    private String input;

    /**
     * Holds the start of the region, or 0 if the matching should start at the
     * beginning of the text.
     */
    private int regionStart;

    /**
     * Holds the end of the region, or input.length() if the matching should
     * go until the end of the input.
     */
    private int regionEnd;

    /**
     * Holds the position where the next append operation will take place.
     */
    private int appendPos;

    /**
     * Reflects whether a match has been found during the most recent find
     * operation.
     */
    private boolean matchFound;

    /**
     * Holds the offsets for the most recent match.
     */
    private int[] matchOffsets;

    /**
     * Reflects whether the bounds of the region are anchoring.
     */
    private boolean anchoringBounds = true;

    /**
     * Reflects whether the bounds of the region are transparent.
     */
    private boolean transparentBounds;

    /**
     * Creates a matcher for a given combination of pattern and input. Both
     * elements can be changed later on.
     *
     * @param pattern
     *            the pattern to use.
     * @param input
     *            the input to use.
     */
    Matcher(Pattern pattern, CharSequence input) {
        usePattern(pattern);
        reset(input);
    }

    /**
     * Appends a literal part of the input plus a replacement for the current
     * match to a given {@link StringBuffer}. The literal part is exactly the
     * part of the input between the previous match and the current match. The
     * method can be used in conjunction with {@link #find()} and
     * {@link #appendTail(StringBuffer)} to walk through the input and replace
     * all occurrences of the {@code Pattern} with something else.
     *
     * @param buffer
     *            the {@code StringBuffer} to append to.
     * @param replacement
     *            the replacement text.
     * @return the {@code Matcher} itself.
     * @throws IllegalStateException
     *             if no successful match has been made.
     */
    public Matcher appendReplacement(StringBuffer buffer, String replacement) {
        buffer.append(input.substring(appendPos, start()));
        appendEvaluated(buffer, replacement);
        appendPos = end();

        return this;
    }

    /**
     * Internal helper method to append a given string to a given string buffer.
     * If the string contains any references to groups, these are replaced by
     * the corresponding group's contents.
     *
     * @param buffer
     *            the string buffer.
     * @param s
     *            the string to append.
     */
    private void appendEvaluated(StringBuffer buffer, String s) {
        boolean escape = false;
        boolean dollar = false;

        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (c == '\\' && !escape) {
                escape = true;
            } else if (c == '$' && !escape) {
                dollar = true;
            } else if (c >= '0' && c <= '9' && dollar) {
                buffer.append(group(c - '0'));
                dollar = false;
            } else {
                buffer.append(c);
                dollar = false;
                escape = false;
            }
        }

        // This seemingly stupid piece of code reproduces a JDK bug.
        if (escape) {
            throw new ArrayIndexOutOfBoundsException(s.length());
        }
    }

    /**
     * Resets the {@code Matcher}. This results in the region being set to the
     * whole input. Results of a previous find get lost. The next attempt to
     * find an occurrence of the {@link Pattern} in the string will start at the
     * beginning of the input.
     *
     * @return the {@code Matcher} itself.
     */
    public Matcher reset() {
        return reset(input, 0, input.length());
    }

    /**
     * Provides a new input and resets the {@code Matcher}. This results in the
     * region being set to the whole input. Results of a previous find get lost.
     * The next attempt to find an occurrence of the {@link Pattern} in the
     * string will start at the beginning of the input.
     *
     * @param input
     *            the new input sequence.
     *
     * @return the {@code Matcher} itself.
     */
    public Matcher reset(CharSequence input) {
        return reset(input, 0, input.length());
    }

    /**
     * Resets the Matcher. A new input sequence and a new region can be
     * specified. Results of a previous find get lost. The next attempt to find
     * an occurrence of the Pattern in the string will start at the beginning of
     * the region. This is the internal version of reset() to which the several
     * public versions delegate.
     *
     * @param input
     *            the input sequence.
     * @param start
     *            the start of the region.
     * @param end
     *            the end of the region.
     *
     * @return the matcher itself.
     */
    private Matcher reset(CharSequence input, int start, int end) {
        if (input == null) {
            throw new IllegalArgumentException("input == null");
        }

        if (start < 0 || end < 0 || start > input.length() || end > input.length() || start > end) {
            throw new IndexOutOfBoundsException();
        }

        this.input = input.toString();
        this.regionStart = start;
        this.regionEnd = end;
        resetForInput();

        matchFound = false;
        appendPos = 0;

        return this;
    }

    /**
     * Sets a new pattern for the {@code Matcher}. Results of a previous find
     * get lost. The next attempt to find an occurrence of the {@link Pattern}
     * in the string will start at the beginning of the input.
     *
     * @param pattern
     *            the new {@code Pattern}.
     *
     * @return the {@code Matcher} itself.
     */
    public Matcher usePattern(Pattern pattern) {
        if (pattern == null) {
            throw new IllegalArgumentException("pattern == null");
        }

        this.pattern = pattern;

        synchronized (this) {
            if (address != 0) {
                closeImpl(address);
                address = 0; // In case openImpl throws.
            }
            address = openImpl(pattern.address);
        }

        if (input != null) {
            resetForInput();
        }

        matchOffsets = new int[(groupCount() + 1) * 2];
        matchFound = false;
        return this;
    }

    private void resetForInput() {
        synchronized (this) {
            setInputImpl(address, input, regionStart, regionEnd);
            useAnchoringBoundsImpl(address, anchoringBounds);
            useTransparentBoundsImpl(address, transparentBounds);
        }
    }

    /**
     * Resets this matcher and sets a region. Only characters inside the region
     * are considered for a match.
     *
     * @param start
     *            the first character of the region.
     * @param end
     *            the first character after the end of the region.
     * @return the {@code Matcher} itself.
     */
    public Matcher region(int start, int end) {
        return reset(input, start, end);
    }

    /**
     * Appends the (unmatched) remainder of the input to the given
     * {@link StringBuffer}. The method can be used in conjunction with
     * {@link #find()} and {@link #appendReplacement(StringBuffer, String)} to
     * walk through the input and replace all matches of the {@code Pattern}
     * with something else.
     *
     * @param buffer
     *            the {@code StringBuffer} to append to.
     * @return the {@code StringBuffer}.
     * @throws IllegalStateException
     *             if no successful match has been made.
     */
    public StringBuffer appendTail(StringBuffer buffer) {
        if (appendPos < regionEnd) {
            buffer.append(input.substring(appendPos, regionEnd));
        }
        return buffer;
    }

    /**
     * Replaces the first occurrence of this matcher's pattern in the input with
     * a given string.
     *
     * @param replacement
     *            the replacement text.
     * @return the modified input string.
     */
    public String replaceFirst(String replacement) {
        reset();
        StringBuffer buffer = new StringBuffer(input.length());
        if (find()) {
            appendReplacement(buffer, replacement);
        }
        return appendTail(buffer).toString();
    }

    /**
     * Replaces all occurrences of this matcher's pattern in the input with a
     * given string.
     *
     * @param replacement
     *            the replacement text.
     * @return the modified input string.
     */
    public String replaceAll(String replacement) {
        reset();
        StringBuffer buffer = new StringBuffer(input.length());
        while (find()) {
            appendReplacement(buffer, replacement);
        }
        return appendTail(buffer).toString();
    }

    /**
     * Returns the {@link Pattern} instance used inside this matcher.
     *
     * @return the {@code Pattern} instance.
     */
    public Pattern pattern() {
        return pattern;
    }

    /**
     * Returns the text that matched a given group of the regular expression.
     * Explicit capturing groups in the pattern are numbered left to right in order
     * of their opening parenthesis, starting at 1.
     * The special group 0 represents the entire match (as if the entire pattern is surrounded
     * by an implicit capturing group).
     * For example, "a((b)c)" matching "abc" would give the following groups:
     * 
     * 0 "abc"
     * 1 "bc"
     * 2 "b"
     * 
* *

An optional capturing group that failed to match as part of an overall * successful match (for example, "a(b)?c" matching "ac") returns null. * A capturing group that matched the empty string (for example, "a(b?)c" matching "ac") * returns the empty string. * * @throws IllegalStateException * if no successful match has been made. */ public String group(int group) { ensureMatch(); int from = matchOffsets[group * 2]; int to = matchOffsets[(group * 2) + 1]; if (from == -1 || to == -1) { return null; } else { return input.substring(from, to); } } /** * Returns the text that matched the whole regular expression. * * @return the text. * @throws IllegalStateException * if no successful match has been made. */ public String group() { return group(0); } /** * Returns true if there is another match in the input, starting * from the given position. The region is ignored. * * @throws IndexOutOfBoundsException if {@code start < 0 || start > input.length()} */ public boolean find(int start) { if (start < 0 || start > input.length()) { throw new IndexOutOfBoundsException("start=" + start + "; length=" + input.length()); } synchronized (this) { matchFound = findImpl(address, input, start, matchOffsets); } return matchFound; } /** * Returns the next occurrence of the {@link Pattern} in the input. If a * previous match was successful, the method continues the search from the * first character following that match in the input. Otherwise it searches * either from the region start (if one has been set), or from position 0. * * @return true if (and only if) a match has been found. */ public boolean find() { synchronized (this) { matchFound = findNextImpl(address, input, matchOffsets); } return matchFound; } /** * Tries to match the {@link Pattern}, starting from the beginning of the * region (or the beginning of the input, if no region has been set). * Doesn't require the {@code Pattern} to match against the whole region. * * @return true if (and only if) the {@code Pattern} matches. */ public boolean lookingAt() { synchronized (this) { matchFound = lookingAtImpl(address, input, matchOffsets); } return matchFound; } /** * Tries to match the {@link Pattern} against the entire region (or the * entire input, if no region has been set). * * @return true if (and only if) the {@code Pattern} matches the entire * region. */ public boolean matches() { synchronized (this) { matchFound = matchesImpl(address, input, matchOffsets); } return matchFound; } /** * Returns the index of the first character of the text that matched a given * group. * * @param group * the group, ranging from 0 to groupCount() - 1, with 0 * representing the whole pattern. * @return the character index. * @throws IllegalStateException * if no successful match has been made. */ public int start(int group) throws IllegalStateException { ensureMatch(); return matchOffsets[group * 2]; } /** * Returns the index of the first character following the text that matched * a given group. * * @param group * the group, ranging from 0 to groupCount() - 1, with 0 * representing the whole pattern. * @return the character index. * @throws IllegalStateException * if no successful match has been made. */ public int end(int group) { ensureMatch(); return matchOffsets[(group * 2) + 1]; } /** * Returns a replacement string for the given one that has all backslashes * and dollar signs escaped. * * @param s * the input string. * @return the input string, with all backslashes and dollar signs having * been escaped. */ public static String quoteReplacement(String s) { StringBuilder result = new StringBuilder(s.length()); for (int i = 0; i < s.length(); i++) { char c = s.charAt(i); if (c == '\\' || c == '$') { result.append('\\'); } result.append(c); } return result.toString(); } /** * Returns the index of the first character of the text that matched the * whole regular expression. * * @return the character index. * @throws IllegalStateException * if no successful match has been made. */ public int start() { return start(0); } /** * Returns the number of groups in the results, which is always equal to * the number of groups in the original regular expression. * * @return the number of groups. */ public int groupCount() { synchronized (this) { return groupCountImpl(address); } } /** * Returns the index of the first character following the text that matched * the whole regular expression. * * @return the character index. * @throws IllegalStateException * if no successful match has been made. */ public int end() { return end(0); } /** * Converts the current match into a separate {@link MatchResult} instance * that is independent from this matcher. The new object is unaffected when * the state of this matcher changes. * * @return the new {@code MatchResult}. * @throws IllegalStateException * if no successful match has been made. */ public MatchResult toMatchResult() { ensureMatch(); return new MatchResultImpl(input, matchOffsets); } /** * Determines whether this matcher has anchoring bounds enabled or not. When * anchoring bounds are enabled, the start and end of the input match the * '^' and '$' meta-characters, otherwise not. Anchoring bounds are enabled * by default. * * @param value * the new value for anchoring bounds. * @return the {@code Matcher} itself. */ public Matcher useAnchoringBounds(boolean value) { synchronized (this) { anchoringBounds = value; useAnchoringBoundsImpl(address, value); } return this; } /** * Returns true if this matcher has anchoring bounds enabled. When * anchoring bounds are enabled, the start and end of the input match the * '^' and '$' meta-characters, otherwise not. Anchoring bounds are enabled * by default. */ public boolean hasAnchoringBounds() { return anchoringBounds; } /** * Determines whether this matcher has transparent bounds enabled or not. * When transparent bounds are enabled, the parts of the input outside the * region are subject to lookahead and lookbehind, otherwise they are not. * Transparent bounds are disabled by default. * * @param value * the new value for transparent bounds. * @return the {@code Matcher} itself. */ public Matcher useTransparentBounds(boolean value) { synchronized (this) { transparentBounds = value; useTransparentBoundsImpl(address, value); } return this; } /** * Makes sure that a successful match has been made. Is invoked internally * from various places in the class. * * @throws IllegalStateException * if no successful match has been made. */ private void ensureMatch() { if (!matchFound) { throw new IllegalStateException("No successful match so far"); } } /** * Returns true if this matcher has transparent bounds enabled. When * transparent bounds are enabled, the parts of the input outside the region * are subject to lookahead and lookbehind, otherwise they are not. * Transparent bounds are disabled by default. */ public boolean hasTransparentBounds() { return transparentBounds; } /** * Returns this matcher's region start, that is, the index of the first character that is * considered for a match. */ public int regionStart() { return regionStart; } /** * Returns this matcher's region end, that is, the index of the first character that is * not considered for a match. */ public int regionEnd() { return regionEnd; } /** * Returns true if the most recent match succeeded and additional input could cause * it to fail. 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. */ public boolean requireEnd() { synchronized (this) { return requireEndImpl(address); } } /** * Returns true if the most recent matching operation attempted to access * additional text beyond the available input, meaning that additional input * could change the results of the match. */ public boolean hitEnd() { synchronized (this) { return hitEndImpl(address); } } @Override protected void finalize() throws Throwable { try { synchronized (this) { closeImpl(address); } } finally { super.finalize(); } } /** * Returns a string representing this {@code Matcher}. * The format of this string is unspecified. */ @Override public String toString() { return getClass().getName() + "[pattern=" + pattern() + " region=" + regionStart() + "," + regionEnd() + " lastmatch=" + (matchFound ? group() : "") + "]"; } private static native void closeImpl(long addr); private static native boolean findImpl(long addr, String s, int startIndex, int[] offsets); private static native boolean findNextImpl(long addr, String s, int[] offsets); private static native int groupCountImpl(long addr); private static native boolean hitEndImpl(long addr); private static native boolean lookingAtImpl(long addr, String s, int[] offsets); private static native boolean matchesImpl(long addr, String s, int[] offsets); private static native long openImpl(long patternAddr); private static native boolean requireEndImpl(long addr); private static native void setInputImpl(long addr, String s, int start, int end); private static native void useAnchoringBoundsImpl(long addr, boolean value); private static native void useTransparentBoundsImpl(long addr, boolean value); }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy