escape_sequence_parser.h

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#pragma once
 
#include "di/container/string/string.h"
#include "di/container/string/string_view.h"
#include "di/function/container/function.h"
#include "di/reflect/prelude.h"
#include "di/vocab/variant/prelude.h"
#include "ttx/features.h"
#include "ttx/params.h"
 
namespace ttx {
struct PrintableCharacter {
    c32 code_point = 0;
 
    auto operator==(PrintableCharacter const&) const -> bool = default;
 
    constexpr friend auto tag_invoke(di::Tag<di::reflect>, di::InPlaceType<PrintableCharacter>) {
        return di::make_fields<"PrintableCharacter">(di::field<"code_point", &PrintableCharacter::code_point>);
    }
};
 
struct DCS {
    di::String intermediate;
    Params params;
    di::String data;
 
    auto operator==(DCS const&) const -> bool = default;
 
    constexpr friend auto tag_invoke(di::Tag<di::reflect>, di::InPlaceType<DCS>) {
        return di::make_fields<"DCS">(di::field<"intermediate", &DCS::intermediate>, di::field<"params", &DCS::params>,
                                      di::field<"data", &DCS::data>);
    }
};
 
struct OSC {
    di::String data;
    di::StringView terminator; // Either BEL (\a) or ST (ESC \‍)
 
    auto operator==(OSC const&) const -> bool = default;
 
    constexpr friend auto tag_invoke(di::Tag<di::reflect>, di::InPlaceType<OSC>) {
        return di::make_fields<"OSC">(di::field<"data", &OSC::data>, di::field<"terminator", &OSC::terminator>);
    }
};
 
struct APC {
    di::String data;
 
    auto operator==(APC const&) const -> bool = default;
 
    constexpr friend auto tag_invoke(di::Tag<di::reflect>, di::InPlaceType<APC>) {
        return di::make_fields<"APC">(di::field<"data", &APC::data>);
    }
};
 
struct CSI {
    di::String intermediate {};
    Params params {};
    c32 terminator = 0;
 
    auto operator==(CSI const&) const -> bool = default;
 
    constexpr friend auto tag_invoke(di::Tag<di::reflect>, di::InPlaceType<CSI>) {
        return di::make_fields<"CSI">(di::field<"intermediate", &CSI::intermediate>, di::field<"params", &CSI::params>,
                                      di::field<"terminator", &CSI::terminator>);
    }
};
 
struct Escape {
    di::String intermediate;
    c32 terminator = 0;
 
    auto operator==(Escape const&) const -> bool = default;
 
    constexpr friend auto tag_invoke(di::Tag<di::reflect>, di::InPlaceType<Escape>) {
        return di::make_fields<"Escape">(di::field<"intermediate", &Escape::intermediate>,
                                         di::field<"terminator", &Escape::terminator>);
    }
};
 
struct ControlCharacter {
    u32 code_point { 0 };         // Not a c32, so that it will be printed as a decimal.
    bool was_in_escape { false }; // This is true if the control character occurred in the middle of an escape sequence.
 
    auto operator==(ControlCharacter const&) const -> bool = default;
 
    constexpr friend auto tag_invoke(di::Tag<di::reflect>, di::InPlaceType<ControlCharacter>) {
        return di::make_fields<"ControlCharacter">(di::field<"code_point", &ControlCharacter::code_point>,
                                                   di::field<"was_in_escape", &ControlCharacter::was_in_escape>);
    }
};
 
using ParserResult = di::Variant<PrintableCharacter, DCS, OSC, APC, CSI, Escape, ControlCharacter>;
 
class EscapeSequenceParser {
public:
    enum class Mode {
        Application,
        Input,
    };
 
    auto parse_application_escape_sequences(di::StringView data) -> di::Span<ParserResult>;
    auto parse_input_escape_sequences(di::StringView data, Feature features = Feature::None, bool flush = true)
        -> di::Span<ParserResult>;
 
private:
// VT500-Series parser states from https://vt100.net/emu/dec_ansi_parser
// For parsing input escape sequences, the following state is added:
//   - SS3
// Additionally, non CSI related states are ignored when parsing input
// sequences.
#define __ENUMERATE_STATES(M)                  \
    M(Ground, ground)                          \
    M(Escape, escape)                          \
    M(EscapeIntermediate, escape_intermediate) \
    M(CsiEntry, csi_entry)                     \
    M(CsiParam, csi_param)                     \
    M(CsiIntermediate, csi_intermediate)       \
    M(CsiIgnore, csi_ignore)                   \
    M(Ss3, ss3)                                \
    M(DcsEntry, dcs_entry)                     \
    M(DcsParam, dcs_param)                     \
    M(DcsIntermediate, dcs_intermediate)       \
    M(DcsPassthrough, dcs_passthrough)         \
    M(DcsIgnore, dcs_ignore)                   \
    M(OscString, osc_string)                   \
    M(ApcString, apc_string)                   \
    M(SosPmString, sos_pm_string)
 
    enum class State {
#define __ENUMERATE_STATE(N, n) N,
        __ENUMERATE_STATES(__ENUMERATE_STATE)
#undef __ENUMERATE_STATE
    };
 
#define __ENUMERATE_STATE(N, n) void n##_state(c32 code_point);
    __ENUMERATE_STATES(__ENUMERATE_STATE)
#undef __ENUMERATE_STATE
 
    void ignore(c32 code_point);
    void print(c32 code_point);
    void execute(c32 code_point);
    void clear();
    void collect(c32 code_point);
    void param(c32 code_point);
    void esc_dispatch(c32 code_point);
    void csi_dispatch(c32 code_point);
    void hook();
    void put(c32 code_point);
    void unhook();
    void osc_start();
    void osc_put(c32 code_point);
    void osc_end();
    void apc_start();
    void apc_put(c32 code_point);
    void apc_end();
    void output_ss3(c32 code_point);
 
    void transition(State state);
 
    void on_input(c32 code_point);
 
    void add_param(di::Optional<u32> param);
 
    State m_last_state { State::Ground };
    State m_next_state { State::Ground };
    di::Function<void()> m_on_state_exit;
 
    di::String m_intermediate;
    di::String m_current_param;
    di::String m_data;
    Params m_params;
    bool m_last_separator_was_colon { false };
    bool m_saw_legacy_string_terminator { false };
    c32 m_prev {};
    Mode m_mode { Mode::Application };
    di::Vector<ParserResult> m_result;
};
}