Add ModificationTagsHandler

src/tags_handlers/modification_tags_handler.cc

@@ -0,0 +1,18 @@
+#include "tags_handlers/modification_tags_handler.h"
+#include "tags_handlers_errors.h"
+
+using namespace opustags;
+
+ModificationTagsHandler::ModificationTagsHandler(
+    const int streamno,
+    const std::string &tag_key,
+    const std::string &tag_value)
+    : StreamTagsHandler(streamno), tag_key(tag_key), tag_value(tag_value)
+{
+}
+
+bool ModificationTagsHandler::edit_impl(Tags &tags)
+{
+    tags[tag_key] = tag_value;
+    return true;
+}

src/tags_handlers/modification_tags_handler.h

@@ -0,0 +1,23 @@
+#pragma once
+
+#include "tags_handlers/stream_tags_handler.h"
+
+namespace opustags {
+
+    class ModificationTagsHandler : public StreamTagsHandler
+    {
+    public:
+        ModificationTagsHandler(
+            const int streamno,
+            const std::string &tag_key,
+            const std::string &tag_value);
+
+    protected:
+        bool edit_impl(Tags &) override;
+
+    private:
+        const std::string tag_key;
+        const std::string tag_value;
+    };
+
+}

tests/tags_handlers/modification_tags_handler_test.cc

@@ -0,0 +1,28 @@
+#include "tags_handlers/modification_tags_handler.h"
+#include "catch.h"
+
+using namespace opustags;
+
+TEST_CASE("Modification tags handler test")
+{
+    const auto streamno = 1;
+    const auto first_tag_key = "tag_key";
+    const auto other_tag_key = "other_tag_key";
+    const auto dummy_value = "dummy";
+    const auto new_value = "dummy 2";
+
+    Tags tags = {{first_tag_key, dummy_value}};
+    REQUIRE(tags.size() == 1);
+
+    // setting nonexistent keys adds them
+    ModificationTagsHandler handler1(streamno, other_tag_key, dummy_value);
+    REQUIRE(handler1.edit(streamno, tags));
+    REQUIRE(tags.size() == 2);
+    REQUIRE(tags[other_tag_key] == dummy_value);
+
+    // setting existing keys overrides their values
+    ModificationTagsHandler handler2(streamno, other_tag_key, new_value);
+    REQUIRE(handler2.edit(streamno, tags));
+    REQUIRE(tags.size() == 2);
+    REQUIRE(tags[other_tag_key] == new_value);
+}