[api-common-java] Handle "-", _deleted-topic_ patterns

src/main/java/com/google/api/pathtemplate/PathTemplate.java

@@ -869,8 +869,17 @@ private static ImmutableList<Segment> parseTemplate(String template) {
     int pathWildCardBound = 0;
 
     for (String seg : Splitter.on('/').trimResults().split(template)) {
-      if (COMPLEX_DELIMITER_PATTERN.matcher(seg.substring(0, 1)).find()
-          || COMPLEX_DELIMITER_PATTERN.matcher(seg.substring(seg.length() - 1)).find()) {
+      // Handle _deleted-topic_ for PubSub.
+      if (seg.equals("_deleted-topic_")) {
+        builder.add(Segment.create(SegmentKind.LITERAL, seg));
+        continue;
+      }
+
+      boolean isLastSegment = (template.indexOf(seg) + seg.length()) == template.length();
+      boolean isCollectionWildcard = !isLastSegment && (seg.equals("-") || seg.equals("-}"));
+      if (!isCollectionWildcard
+          && (COMPLEX_DELIMITER_PATTERN.matcher(seg.substring(0, 1)).find()
+              || COMPLEX_DELIMITER_PATTERN.matcher(seg.substring(seg.length() - 1)).find())) {
         throw new ValidationException("parse error: invalid begin or end character in '%s'", seg);
       }
       // Disallow zero or multiple delimiters between variable names.
@@ -896,7 +905,7 @@ private static ImmutableList<Segment> parseTemplate(String template) {
         }
 
         Matcher complexPatternDelimiterMatcher = END_SEGMENT_COMPLEX_DELIMITER_PATTERN.matcher(seg);
-        complexDelimiterFound = complexPatternDelimiterMatcher.find();
+        complexDelimiterFound = !isCollectionWildcard && complexPatternDelimiterMatcher.find();
 
         // Look for complex resource names.
         // Need to handle something like "{user_a}~{user_b}".
@@ -915,6 +924,8 @@ private static ImmutableList<Segment> parseTemplate(String template) {
               throw new ValidationException(
                   "parse error: invalid binding syntax in '%s'", template);
             }
+          } else if (seg.indexOf('-') <= 0 && isCollectionWildcard) {
+            implicitWildcard = true;
           } else {
             // Looking at something like "{name=wildcard}".
             varName = seg.substring(0, i).trim();
@@ -957,6 +968,10 @@ private static ImmutableList<Segment> parseTemplate(String template) {
             }
             // If the wildcard is implicit, seg will be empty. Just continue.
             break;
+          case "-":
+            builder.add(Segment.WILDCARD);
+            implicitWildcard = false;
+            break;
           default:
             builder.add(Segment.create(SegmentKind.LITERAL, seg));
         }

src/test/java/com/google/api/pathtemplate/PathTemplateTest.java

@@ -317,6 +317,31 @@ public void complexResourceIdMixedSeparators() {
     Truth.assertThat(match.get("zone_d")).isEqualTo("europe-west2-b");
   }
 
+  @Test
+  public void collectionWildcardMatchingInParent() {
+    PathTemplate template = PathTemplate.create("v1/publishers/-/books/{book}");
+    Map<String, String> match =
+        template.match(
+            "https://example.googleapis.com/v1/publishers/publisher-abc/books/blockchain_for_babies");
+    Truth.assertThat(match).isNotNull();
+
+    template = PathTemplate.create("/v1/{parent=rooms/-}/blurbs/{blurb}");
+    match = template.match("https://example.googleapis.com/v1/rooms/den/blurbs/asdf");
+    Truth.assertThat(match).isNotNull();
+  }
+
+  @Test
+  public void collectionWildcardMatchingInvalid() {
+    thrown.expect(ValidationException.class);
+    PathTemplate.create("v1/publishers/{publisher}/books/-");
+  }
+
+  @Test
+  public void complexResourceIdPubSubDeletedTopic() {
+    PathTemplate template = PathTemplate.create("_deleted-topic_");
+    Truth.assertThat(template).isNotNull();
+  }
+
   @Test
   public void complexResourceIdInParent() {
     // One parent has a complex resource ID.