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+/*
+ * =========================================================================================
+ * Copyright 2013-2014 the kamon project <http://kamon.io/>
+ *
+ * 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 kamon.util;
+
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * Default implementation of PathFilter. Uses glob based includes and excludes to determine whether to export.
+ *
+ * @author John E. Bailey
+ * @author <a href="mailto:david.lloyd@redhat.com">David M. Lloyd</a>
+ */
+public final class GlobPathFilter implements PathFilter {
+ private static final Pattern GLOB_PATTERN = Pattern.compile("(\\*\\*?)|(\\?)|(\\\\.)|(/+)|([^*?]+)");
+
+ private final String glob;
+ private final Pattern pattern;
+
+ /**
+ * Construct a new instance.
+ *
+ * @param glob the path glob to match
+ */
+ public GlobPathFilter(final String glob) {
+ pattern = getGlobPattern(glob);
+ this.glob = glob;
+ }
+
+ /**
+ * Determine whether a path should be accepted.
+ *
+ * @param path the path to check
+ * @return true if the path should be accepted, false if not
+ */
+ public boolean accept(final String path) {
+ return pattern.matcher(path).matches();
+ }
+
+ /**
+ * Get a regular expression pattern which accept any path names which match the given glob. The glob patterns
+ * function similarly to {@code ant} file patterns. Valid metacharacters in the glob pattern include:
+ * <ul>
+ * <li><code>"\"</code> - escape the next character (treat it literally, even if it is itself a recognized metacharacter)</li>
+ * <li><code>"?"</code> - match any non-slash character</li>
+ * <li><code>"*"</code> - match zero or more non-slash characters</li>
+ * <li><code>"**"</code> - match zero or more characters, including slashes</li>
+ * <li><code>"/"</code> - match one or more slash characters. Consecutive {@code /} characters are collapsed down into one.</li>
+ * </ul>
+ * In addition, any glob pattern matches all subdirectories thereof. A glob pattern ending in {@code /} is equivalent
+ * to a glob pattern ending in <code>/**</code> in that the named directory is not itself included in the glob.
+ * <p/>
+ * <b>See also:</b> <a href="http://ant.apache.org/manual/dirtasks.html#patterns">"Patterns" in the Ant Manual</a>
+ *
+ * @param glob the glob to match
+ *
+ * @return the pattern
+ */
+ private static Pattern getGlobPattern(final String glob) {
+ StringBuilder patternBuilder = new StringBuilder();
+ final Matcher m = GLOB_PATTERN.matcher(glob);
+ boolean lastWasSlash = false;
+ while (m.find()) {
+ lastWasSlash = false;
+ String grp;
+ if ((grp = m.group(1)) != null) {
+ // match a * or **
+ if (grp.length() == 2) {
+ // it's a *workers are able to process multiple metrics*
+ patternBuilder.append(".*");
+ } else {
+ // it's a *
+ patternBuilder.append("[^/]*");
+ }
+ } else if ((grp = m.group(2)) != null) {
+ // match a '?' glob pattern; any non-slash character
+ patternBuilder.append("[^/]");
+ } else if ((grp = m.group(3)) != null) {
+ // backslash-escaped value
+ patternBuilder.append(Pattern.quote(m.group().substring(1)));
+ } else if ((grp = m.group(4)) != null) {
+ // match any number of / chars
+ patternBuilder.append("/+");
+ lastWasSlash = true;
+ } else {
+ // some other string
+ patternBuilder.append(Pattern.quote(m.group()));
+ }
+ }
+ if (lastWasSlash) {
+ // ends in /, append **
+ patternBuilder.append(".*");
+ }
+ return Pattern.compile(patternBuilder.toString());
+ }
+}