Introduce LocalBuffer

Co-authored-by: Walt Karas <wkaras@verizonmedia.com>

Author: masaori335

include/tscpp/util/LocalBuffer.h

@@ -0,0 +1,49 @@
+/** @file
+
+   LocalBuffer
+
+   @section license License
+
+   Licensed to the Apache Software Foundation (ASF) under one
+   or more contributor license agreements.  See the NOTICE file
+   distributed with this work for additional information
+   regarding copyright ownership.  The ASF licenses this file
+   to you 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.
+ */
+
+#pragma once
+
+namespace ts
+{
+template <std::size_t EstSizeBound = 1024> class LocalBuffer
+{
+public:
+  LocalBuffer(std::size_t size) : _ptr(size == 0 ? nullptr : (size > EstSizeBound ? new uint8_t[size] : _buf)) {}
+  ~LocalBuffer()
+  {
+    if (_ptr && _ptr != _buf) {
+      delete[] _ptr;
+    }
+  }
+
+  uint8_t *
+  get() const
+  {
+    return _ptr;
+  }
+
+private:
+  uint8_t _buf[EstSizeBound];
+  uint8_t *const _ptr;
+};
+} // namespace ts

src/tscpp/util/Makefile.am

@@ -38,6 +38,7 @@ test_tscpputil_CXXFLAGS = -Wno-array-bounds $(AM_CXXFLAGS)
 test_tscpputil_LDADD = libtscpputil.la
 test_tscpputil_SOURCES = \
 	unit_tests/unit_test_main.cc \
+	unit_tests/test_LocalBuffer.cc \
 	unit_tests/test_MemSpan.cc \
 	unit_tests/test_PostScript.cc \
 	unit_tests/test_TextView.cc \

src/tscpp/util/unit_tests/test_LocalBuffer.cc

@@ -0,0 +1,105 @@
+/** @file
+
+    Unit tests for LocalBuffer
+
+    @section license License
+
+    Licensed to the Apache Software Foundation (ASF) under one
+    or more contributor license agreements.  See the NOTICE file
+    distributed with this work for additional information
+    regarding copyright ownership.  The ASF licenses this file
+    to you 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.
+ */
+
+#include "catch.hpp"
+#include "tscpp/util/LocalBuffer.h"
+
+#include <cstring>
+
+TEST_CASE("LocalBuffer", "[libts][LocalBuffer]")
+{
+  SECTION("EstSizeBound = default")
+  {
+    SECTION("size = 0")
+    {
+      const size_t len = 0;
+      LocalBuffer local_buffer(len);
+      uint8_t *buf = local_buffer.get();
+
+      CHECK(buf == nullptr);
+    }
+
+    SECTION("size = 1024")
+    {
+      const size_t len = 1024;
+      LocalBuffer local_buffer(len);
+      uint8_t *buf = local_buffer.get();
+
+      memset(buf, 0xAA, len);
+
+      CHECK(buf[0] == 0xAA);
+      CHECK(buf[len - 1] == 0xAA);
+    }
+
+    SECTION("size = 2048")
+    {
+      const size_t len = 2048;
+      LocalBuffer local_buffer(len);
+      uint8_t *buf = local_buffer.get();
+
+      memset(buf, 0xAA, len);
+
+      CHECK(buf[0] == 0xAA);
+      CHECK(buf[len - 1] == 0xAA);
+    }
+  }
+
+  SECTION("EstSizeBound = 2048")
+  {
+    SECTION("size = 1024")
+    {
+      const size_t len = 1024;
+      LocalBuffer<2048> local_buffer(len);
+      uint8_t *buf = local_buffer.get();
+
+      memset(buf, 0xAA, len);
+
+      CHECK(buf[0] == 0xAA);
+      CHECK(buf[len - 1] == 0xAA);
+    }
+
+    SECTION("size = 2048")
+    {
+      const size_t len = 2048;
+      LocalBuffer<2048> local_buffer(len);
+      uint8_t *buf = local_buffer.get();
+
+      memset(buf, 0xAA, len);
+
+      CHECK(buf[0] == 0xAA);
+      CHECK(buf[len - 1] == 0xAA);
+    }
+
+    SECTION("size = 4096")
+    {
+      const size_t len = 4096;
+      LocalBuffer<2048> local_buffer(len);
+      uint8_t *buf = local_buffer.get();
+
+      memset(buf, 0xAA, len);
+
+      CHECK(buf[0] == 0xAA);
+      CHECK(buf[len - 1] == 0xAA);
+    }
+  }
+}