lib/yajl/Gen: new class

src/lib/yajl/Gen.hxx

+/*
+ * Copyright 2021 Max Kellermann <max.kellermann@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef YAJL_GEN_HXX
+#define YAJL_GEN_HXX
+
+#include "util/ConstBuffer.hxx"
+
+#include <yajl/yajl_gen.h>
+
+#include <algorithm>
+#include <string_view>
+
+namespace Yajl {
+
+/**
+ * OO wrapper for #yajl_gen.
+ */
+class Gen {
+	yajl_gen gen = nullptr;
+
+public:
+	Gen() = default;
+
+	explicit Gen(const yajl_alloc_funcs *allocFuncs) noexcept
+		:gen(yajl_gen_alloc(allocFuncs)) {}
+
+	Gen(Gen &&src) noexcept
+		:gen(std::exchange(src.gen, nullptr)) {}
+
+	~Gen() noexcept {
+		if (gen != nullptr)
+			yajl_gen_free(gen);
+	}
+
+	Gen &operator=(Gen &&src) noexcept {
+		using std::swap;
+		swap(gen, src.gen);
+		return *this;
+	}
+
+	void Integer(long long int number) noexcept {
+		yajl_gen_integer(gen, number);
+	}
+
+	void String(std::string_view s) noexcept {
+		yajl_gen_string(gen, (const unsigned char *)s.data(), s.size());
+	}
+
+	void OpenMap() noexcept {
+		yajl_gen_map_open(gen);
+	}
+
+	void CloseMap() noexcept {
+		yajl_gen_map_close(gen);
+	}
+
+	void OpenArray() noexcept {
+		yajl_gen_array_open(gen);
+	}
+
+	void CloseArray() noexcept {
+		yajl_gen_array_close(gen);
+	}
+
+	ConstBuffer<char> GetBuffer() const noexcept {
+		const unsigned char *buf;
+		size_t len;
+		auto status = yajl_gen_get_buf(gen, &buf, &len);
+		if (status != yajl_gen_status_ok)
+			return nullptr;
+
+		return {(const char *)buf, len};
+	}
+};
+
+} // namespace Yajl
+
+#endif