Add a method to get the value of a specific tag.

Fix #258

include/reader.h

@@ -235,6 +235,27 @@ class Reader
    */
   string getTags(bool original=false) const;
 
+  /**
+   * Get the value (as a string) of a specific tag.
+   *
+   * According to https://wiki.openzim.org/wiki/Tags
+   *
+   * @return The value of the specified tag.
+   * @throw  std::out_of_range if the specified tag is not found.
+   */
+  string getTagStr(const std::string& tagName) const;
+
+  /**
+   * Get the boolean value of a specific tag.
+   *
+   * According to https://wiki.openzim.org/wiki/Tags
+   *
+   * @return The boolean value of the specified tag.
+   * @throw  std::out_of_range if the specified tag is not found.
+   *         std::domain_error if the value of the tag cannot be convert to bool.
+   */
+  bool getTagBool(const std::string& tagName) const;
+
   /**
    * Get the relations of the zim file.
    *

src/reader.cpp

@@ -400,6 +400,48 @@ string Reader::getTags(bool original) const
   return join(tags, ";");
 }
 
+string getTagValueFromTagList(const std::vector<std::string>& tagList, const std::string& tagName)
+{
+  for (auto tag: tagList) {
+    if (tag[0] == '_') {
+      auto delimPos = tag.find(':');
+      if (delimPos == string::npos) {
+        // No delimiter... what to do ?
+        continue;
+      }
+      auto cTagName = tag.substr(1, delimPos-1);
+      auto cTagValue = tag.substr(delimPos+1);
+      if (cTagName == tagName) {
+        return cTagValue;
+      }
+    }
+  }
+  std::stringstream ss;
+  ss << tagName << " cannot be found";
+  throw std::out_of_range(ss.str());
+}
+
+string Reader::getTagStr(const std::string& tagName) const
+{
+  string tags_str;
+  getMetadata("Tags", tags_str);
+  return getTagValueFromTagList(convertTags(tags_str), tagName);
+}
+
+bool Reader::getTagBool(const std::string& tagName) const
+{
+  auto tagValue = getTagStr(tagName);
+  if (tagValue == "yes") {
+    return true;
+  } else if (tagValue == "no") {
+    return false;
+  } else {
+    std::stringstream ss;
+    ss << "Tag value '" << tagValue << "' for " << tagName << " cannot be converted to bool.";
+    throw std::domain_error(ss.str());
+  }
+}
+
 string Reader::getRelation() const
 {
   METADATA("Relation")

test/tagParsing.cpp

@@ -60,6 +60,40 @@ TEST(ParseTagTest, convert)
   }
 }
 
+TEST(ParseTagTest, valid)
+{
+  std::string tagStr = "_ftindex:yes;_pictures:no;_videos:no;_details:yes;_category:foo;bar";
+  auto tagList = convertTags(tagStr);
+
+  ASSERT_EQ(parse_tag(tagList, "ftindex"), "yes");
+  ASSERT_EQ(parse_tag(tagList, "pictures"), "no");
+  ASSERT_EQ(parse_tag(tagList, "category"), "foo");
+  ASSERT_EQ(parse_tag(tagList, "details"), "yes");
+  ASSERT_THROW(parse_tag(tagList, "detail"), std::out_of_range);
+}
+
+TEST(ParseTagTest, compat)
+{
+  std::string tagStr = "_ftindex;nopic;foo;bar";
+  auto tagList = convertTags(tagStr);
+
+  ASSERT_EQ(parse_tag(tagList, "ftindex"), "yes");
+  ASSERT_EQ(parse_tag(tagList, "pictures"), "no");
+  ASSERT_EQ(parse_tag(tagList, "videos"), "yes");
+  ASSERT_EQ(parse_tag(tagList, "details"), "yes");
+}
+
+TEST(ParseTagTest, invalid)
+{
+  std::string tagStr = "_ftindex:y;_pictures;_videos:;_details:yes;_details:no;_category:foo;bar";
+  auto tagList = convertTags(tagStr);
+
+  ASSERT_EQ(parse_tag(tagList, "ftindex"), "y");
+  ASSERT_EQ(parse_tag(tagList, "pictures"), "yes");
+  ASSERT_EQ(parse_tag(tagList, "videos"), "");
+  ASSERT_EQ(parse_tag(tagList, "details"), "yes");
+}
+
 };
 int main(int argc, char** argv)
 {