emit_ostream.hpp

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#ifndef C4_YML_EMIT_OSTREAM_HPP_
#define C4_YML_EMIT_OSTREAM_HPP_

/** @file emit_ostream.hpp emit to STL-like ostreams */

#ifndef C4_YML_NODE_HPP_
#include "c4/yml/node.hpp"
#endif
#ifndef C4_YML_EMITTER_HPP_
#include "c4/yml/emitter.hpp"
#endif
#ifndef C4_YML_EMITTER_DEF_HPP_
#include "c4/yml/emitter.def.hpp"
#endif
#ifndef C4_YML_WRITER_OSTREAM_HPP_
#include "c4/yml/writer_ostream.hpp"
#endif


namespace c4 {
namespace yml {


/** @addtogroup doc_emit_to_ostream
 *
 * @{
 */

template<class OStream>
using EmitterOStream = Emitter<WriterOStream<OStream>>;


/** tag type to mark a tree or node to be emitted as yaml when using
 * @ref operator<<, with options. For example:
 *
 * ```cpp
 * Tree t = parse_in_arena("{foo: bar}");
 * std::cout << t; // emits YAML
 * std::cout << as_yaml(t, id); // emits YAML from nested node
 * std::cout << as_yaml(t, EmitOptions{}.flow_spc(true)); // emits YAML forcing spaces after flow commas
 * ```
 */
struct as_json
{
    Tree const* tree;
    id_type node;
    EmitOptions options;
    as_json(Tree const& t,             EmitOptions const& opts={}) noexcept : tree(&t), node(t.root_id_maybe()), options(opts) {}
    as_json(Tree const& t, id_type id, EmitOptions const& opts={}) noexcept : tree(&t), node(id), options(opts) {}
    as_json(ConstNodeRef const& n,     EmitOptions const& opts={}) noexcept : tree(n.tree()), node(n.id()), options(opts) {}
};


/** tag type to mark a tree or node to be emitted as yaml when using
 * @ref operator<< . For example:
 *
 * ```cpp
 * Tree t = parse_in_arena("{foo: bar}");
 * std::cout << t; // emits YAML
 * std::cout << as_yaml(t); // emits JSON
 * std::cout << as_yaml(t, id); // emits JSON from nested node
 * std::cout << as_json(t, EmitOptions{}.flow_spc(true)); // emits JSON forcing spaces after commas
 * ```
 */
struct as_yaml
{
    Tree const* tree;
    id_type node;
    EmitOptions options;
    as_yaml(Tree const& t,             EmitOptions const& opts={}) noexcept : tree(&t), node(t.root_id_maybe()), options(opts) {}
    as_yaml(Tree const& t, id_type id, EmitOptions const& opts={}) noexcept : tree(&t), node(id), options(opts) {}
    as_yaml(ConstNodeRef const& n,     EmitOptions const& opts={}) noexcept : tree(n.tree()), node(n.id()), options(opts) {}
};


/** emit YAML to an STL-like ostream */
template<class OStream>
OStream& operator<< (OStream& stream, Tree const& tree)
{
    EmitterOStream<OStream> em(EmitOptions{}, &stream);
    em.emit_as(EMIT_YAML, &tree);
    return stream;
}


/** emit YAML to an STL-like ostream
 * @overload */
template<class OStream>
OStream& operator<< (OStream& stream, ConstNodeRef const& node)
{
    EmitterOStream<OStream> em(EmitOptions{}, &stream);
    em.emit_as(EMIT_YAML, node.tree(), node.id());
    return stream;
}


/** emit JSON to an STL-like ostream */
template<class OStream>
OStream& operator<< (OStream& stream, as_json const& json_spec)
{
    if(json_spec.tree && !json_spec.tree->empty())
    {
        EmitterOStream<OStream> em(json_spec.options, &stream);
        id_type node_id = json_spec.node != NONE ? json_spec.node : json_spec.tree->root_id();
        em.emit_as(EMIT_JSON, json_spec.tree, node_id);
    }
    return stream;
}


/** emit YAML to an STL-like ostream */
template<class OStream>
OStream& operator<< (OStream& stream, as_yaml const& yaml_spec)
{
    if(yaml_spec.tree && !yaml_spec.tree->empty())
    {
        EmitterOStream<OStream> em(yaml_spec.options, &stream);
        id_type node_id = yaml_spec.node != NONE ? yaml_spec.node : yaml_spec.tree->root_id();
        em.emit_as(EMIT_YAML, yaml_spec.tree, node_id);
    }
    return stream;
}

/** @} */


} // namespace yml
} // namespace c4

#endif /* C4_YML_EMIT_OSTREAM_HPP_ */