1 files changed, 95 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/docgen/DocCheckerUtils.java b/src/main/java/com/google/devtools/build/docgen/DocCheckerUtils.java
new file mode 100644
index 0000000000..3b64362b51
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+++ b/src/main/java/com/google/devtools/build/docgen/DocCheckerUtils.java
@@ -0,0 +1,95 @@
+// Copyright 2014 Google Inc. All rights reserved.
+//
+// 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 com.google.devtools.build.docgen;
+
+import com.google.common.collect.ImmutableSet;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+/**
+ * A utility class to check the generated documentations.
+ */
+public class DocCheckerUtils {
+
+  // TODO(bazel-team): remove elements from this list and clean up the tested documentations.
+  private static final ImmutableSet<String> UNCHECKED_HTML_TAGS = ImmutableSet.<String>of(
+      "br", "li", "ul", "p");
+
+  private static final Pattern TAG_PATTERN = Pattern.compile(
+        "<([/]?[a-z0-9_]+)"
+      + "([^>]*)"
+      + ">",
+      Pattern.CASE_INSENSITIVE);
+
+  private static final Pattern COMMENT_PATTERN = Pattern.compile(
+      "<!--.*?-->",
+      Pattern.CASE_INSENSITIVE);
+
+  /**
+   * Returns the first unmatched html tag of srcs or null if no such tag exists.
+   * Note that this check is not performed on br, ul, li and p tags. The method also
+   * prints some help in case an unmatched tag is found. The check is performed
+   * inside comments too.
+   */
+  public static String getFirstUnclosedTagAndPrintHelp(String src) {
+    return getFirstUnclosedTag(src, true);
+  }
+
+  static String getFirstUnclosedTag(String src) {
+    return getFirstUnclosedTag(src, false);
+  }
+
+  // TODO(bazel-team): run this on the Skylark docs too.
+  private static String getFirstUnclosedTag(String src, boolean printHelp) {
+    Matcher commentMatcher = COMMENT_PATTERN.matcher(src);
+    src = commentMatcher.replaceAll("");
+    Matcher tagMatcher = TAG_PATTERN.matcher(src);
+    Deque<String> tagStack = new ArrayDeque<>();
+    while (tagMatcher.find()) {
+      String tag = tagMatcher.group(1);
+      String rest = tagMatcher.group(2);
+      String strippedTag = tag.substring(1);
+
+      // Ignoring self closing tags.
+      if (!rest.endsWith("/")
+          // Ignoring unchecked tags.
+          && !UNCHECKED_HTML_TAGS.contains(tag) && !UNCHECKED_HTML_TAGS.contains(strippedTag)) {
+        if (tag.startsWith("/")) {
+          // Closing tag. Removing '/' from the beginning.
+          tag = strippedTag;
+          String lastTag = tagStack.removeLast();
+          if (!lastTag.equals(tag)) {
+            if (printHelp) {
+              System.err.println(
+                    "Unclosed tag: " + lastTag + "\n"
+                  + "Trying to close with: " + tag + "\n"
+                  + "Stack of open tags: " + tagStack + "\n"
+                  + "Last 200 characters:\n"
+                  + src.substring(Math.max(tagMatcher.start() - 200, 0), tagMatcher.start()));
+            }
+            return lastTag;
+          }
+        } else {
+          // Starting tag.
+          tagStack.addLast(tag);
+        }
+      }
+    }
+    return null;
+  }
+}