001////////////////////////////////////////////////////////////////////////////////
002// checkstyle: Checks Java source code for adherence to a set of rules.
003// Copyright (C) 2001-2017 the original author or authors.
004//
005// This library is free software; you can redistribute it and/or
006// modify it under the terms of the GNU Lesser General Public
007// License as published by the Free Software Foundation; either
008// version 2.1 of the License, or (at your option) any later version.
009//
010// This library is distributed in the hope that it will be useful,
011// but WITHOUT ANY WARRANTY; without even the implied warranty of
012// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
013// Lesser General Public License for more details.
014//
015// You should have received a copy of the GNU Lesser General Public
016// License along with this library; if not, write to the Free Software
017// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
018////////////////////////////////////////////////////////////////////////////////
019
020package com.puppycrawl.tools.checkstyle.checks.javadoc.utils;
021
022import java.util.ArrayList;
023import java.util.List;
024import java.util.regex.Matcher;
025import java.util.regex.Pattern;
026
027import com.puppycrawl.tools.checkstyle.api.LineColumn;
028
029/**
030 * Tools for extracting inline tags from Javadoc comments.
031 *
032 * @author Nathan Naze
033 */
034public final class InlineTagUtils {
035
036    /**
037     * Inline tag pattern.
038     */
039    private static final Pattern INLINE_TAG_PATTERN = Pattern.compile(
040            ".*?\\{@(\\p{Alpha}+)\\b(.*?)}", Pattern.DOTALL);
041
042    /** Pattern to recognize leading "*" characters in Javadoc. */
043    private static final Pattern JAVADOC_PREFIX_PATTERN = Pattern.compile(
044        "^\\s*\\*", Pattern.MULTILINE);
045
046    /** Pattern matching whitespace, used by {@link InlineTagUtils#collapseWhitespace(String)}. */
047    private static final Pattern WHITESPACE_PATTERN = Pattern.compile("\\s+");
048
049    /** Pattern matching a newline. */
050    private static final Pattern NEWLINE_PATTERN = Pattern.compile("\\n");
051
052    /** Line feed character. */
053    private static final String LINE_FEED = "\n";
054
055    /** Carriage return character. */
056    private static final String CARRIAGE_RETURN = "\r";
057
058    /** Prevent instantiation. */
059    private InlineTagUtils() {
060    }
061
062    /**
063     * Extract inline Javadoc tags from the given comment.
064     * @param lines The Javadoc comment (as lines).
065     * @return The extracted inline Javadoc tags.
066     */
067    public static List<TagInfo> extractInlineTags(String... lines) {
068        for (String line : lines) {
069            if (line.contains(LINE_FEED) || line.contains(CARRIAGE_RETURN)) {
070                throw new IllegalArgumentException("comment lines cannot contain newlines");
071            }
072        }
073
074        final String commentText = convertLinesToString(lines);
075        final Matcher inlineTagMatcher = INLINE_TAG_PATTERN.matcher(commentText);
076
077        final List<TagInfo> tags = new ArrayList<>();
078
079        while (inlineTagMatcher.find()) {
080            final String tagName = inlineTagMatcher.group(1);
081
082            // Remove the leading asterisks (in case the tag spans a line) and collapse
083            // the whitespace.
084            String matchedTagValue = inlineTagMatcher.group(2);
085            matchedTagValue = removeLeadingJavaDoc(matchedTagValue);
086            matchedTagValue = collapseWhitespace(matchedTagValue);
087
088            final String tagValue = matchedTagValue;
089
090            final int startIndex = inlineTagMatcher.start(1);
091            final LineColumn position = getLineColumnOfIndex(commentText,
092                // correct start index offset
093                startIndex - 1);
094
095            tags.add(new TagInfo(tagName, tagValue, position));
096        }
097
098        return tags;
099    }
100
101    /**
102     * Convert array of string to single String.
103     * @param lines A number of lines, in order.
104     * @return The lines, joined together with newlines, as a single string.
105     */
106    private static String convertLinesToString(String... lines) {
107        final StringBuilder builder = new StringBuilder(1024);
108        for (String line : lines) {
109            builder.append(line);
110            builder.append(LINE_FEED);
111        }
112        return builder.toString();
113    }
114
115    /**
116     * Get LineColumn from string till index.
117     * @param source Source string.
118     * @param index An index into the string.
119     * @return A position in the source representing what line and column that index appears on.
120     */
121    private static LineColumn getLineColumnOfIndex(String source, int index) {
122        final String precedingText = source.subSequence(0, index).toString();
123        final String[] precedingLines = NEWLINE_PATTERN.split(precedingText);
124        final String lastLine = precedingLines[precedingLines.length - 1];
125        return new LineColumn(precedingLines.length, lastLine.length());
126    }
127
128    /**
129     * Collapse whitespaces.
130     * @param str Source string.
131     * @return The given string with all whitespace collapsed.
132     */
133    private static String collapseWhitespace(String str) {
134        final Matcher matcher = WHITESPACE_PATTERN.matcher(str);
135        return matcher.replaceAll(" ").trim();
136    }
137
138    /**
139     * Remove leading JavaDoc.
140     * @param source A string to remove leading Javadoc from.
141     * @return The given string with leading Javadoc "*" characters from each line removed.
142     */
143    private static String removeLeadingJavaDoc(String source) {
144        final Matcher matcher = JAVADOC_PREFIX_PATTERN.matcher(source);
145        return matcher.replaceAll("");
146    }
147}