Add RemovalTagsHandler

src/tags_handlers/removal_tags_handler.cc

@@ -0,0 +1,19 @@
+#include "tags_handlers/removal_tags_handler.h"
+#include "tags_handlers_errors.h"
+
+using namespace opustags;
+
+RemovalTagsHandler::RemovalTagsHandler(
+    const int streamno, const std::string &tag_key)
+    : StreamTagsHandler(streamno), tag_key(tag_key)
+{
+}
+
+bool RemovalTagsHandler::edit_impl(Tags &tags)
+{
+    if (tags.find(tag_key) == tags.end())
+        throw TagDoesNotExistError(tag_key);
+
+    tags.erase(tag_key);
+    return true;
+}

src/tags_handlers/removal_tags_handler.h

@@ -0,0 +1,19 @@
+#pragma once
+
+#include "tags_handlers/stream_tags_handler.h"
+
+namespace opustags {
+
+    class RemovalTagsHandler : public StreamTagsHandler
+    {
+    public:
+        RemovalTagsHandler(const int streamno, const std::string &tag_key);
+
+    protected:
+        bool edit_impl(Tags &) override;
+
+    private:
+        const std::string tag_key;
+    };
+
+}

src/tags_handlers_errors.cc

@@ -6,3 +6,8 @@ TagAlreadyExistsError::TagAlreadyExistsError(const std::string &tag_key)
     : std::runtime_error("Tag already exists: " + tag_key)
 {
 }
+
+TagDoesNotExistError::TagDoesNotExistError(const std::string &tag_key)
+    : std::runtime_error("Tag does not exist: " + tag_key)
+{
+}

src/tags_handlers_errors.h

@@ -9,4 +9,9 @@ namespace opustags {
         TagAlreadyExistsError(const std::string &tag_key);
     };
 
+    struct TagDoesNotExistError : std::runtime_error
+    {
+        TagDoesNotExistError(const std::string &tag_key);
+    };
+
 }

tests/tags_handlers/removal_tags_handler_test.cc

@@ -0,0 +1,20 @@
+#include "tags_handlers/removal_tags_handler.h"
+#include "catch.h"
+
+using namespace opustags;
+
+TEST_CASE("Removal tags handler test")
+{
+    const auto streamno = 1;
+    const auto expected_tag_key = "tag_key";
+    const auto other_tag_key = "other_tag_key";
+    const auto dummy_value = "dummy";
+    RemovalTagsHandler handler(streamno, expected_tag_key);
+
+    Tags tags = {{expected_tag_key, dummy_value}, {other_tag_key, dummy_value}};
+    REQUIRE(tags.size() == 2);
+    REQUIRE(handler.edit(streamno, tags));
+    REQUIRE(tags.size() == 1);
+    REQUIRE(tags.find(other_tag_key) != tags.end());
+    REQUIRE_THROWS(handler.edit(streamno, tags));
+}