OpcodeFixer.cpp

/* -*- mode: c++; -*- */
#include "absl/strings/string_view.h"
#include "absl/strings/str_cat.h"
#include <string>
#include <cstdint>

enum OpcodeFixScope {
    kOpcodeFixGeneric,
    kOpcodeFixRegion,
};

static std::string fixOpcode(absl::string_view rawOpcode, OpcodeFixScope scope)
{
    std::string opcode { rawOpcode };

    /*!re2c
    re2c:flags:posix-captures = 1;
    re2c:define:YYCTYPE = char;
    re2c:yyfill:enable = 0;
    */
    /*!maxnmatch:re2c*/

    const char* YYCURSOR;
    const char* YYMARKER;
    const char* yypmatch[2 * YYMAXNMATCH];
    uint32_t yynmatch;

    /*!stags:re2c format = "const char* @@; "; */

    auto group = [&yypmatch](size_t i) -> absl::string_view {
        const char *beg = yypmatch[2 * i];
        const char *end = yypmatch[2 * i + 1];
        return absl::string_view(beg, end - beg);
    };

    /*!re2c
    digit  = [0-9];
    number = digit+;
    END = [\x00];
    */

    //--------------------------------------------------------------------------

    YYCURSOR = opcode.c_str();

    /*!re2c

    (.*) '_cc' (number) END {
        opcode = absl::StrCat(group(1), "_oncc", group(2));
        goto end_generic;
    }

    * {
        goto end_generic;
    }

    */

end_generic:
    /* end */;

    //--------------------------------------------------------------------------

    if (scope == kOpcodeFixRegion) {

    YYCURSOR = opcode.c_str();

    /*!re2c

    lfoV1 = 'amplfo'|'fillfo'|'pitchlfo';
    egV1 = 'ampeg'|'fileg'|'pitcheg';
    eqV1 = 'eq' number;

    lfoV2 = 'lfo' number;

    (lfoV1) '_' ('depth'|'freq'|'fade') 'cc' (number) END {
        opcode = absl::StrCat(group(1), "_", group(2), "_oncc", group(3));
        goto end_region;
    }
    (eqV1) '_' ('bw'|'freq'|'gain') 'cc' (number) END {
        opcode = absl::StrCat(group(1), "_", group(2), "_oncc", group(3));
        goto end_region;
    }
    (egV1) '_' ('delay'|'start'|'attack'|'hold'|'decay'|'sustain'|'release') 'cc' (number) END {
        opcode = absl::StrCat(group(1), "_", group(2), "_oncc", group(3));
        goto end_region;
    }

    (lfoV2) '_' ('wave'|'offset'|'ratio'|'scale') END {
        opcode = absl::StrCat(group(1), "_", group(2), "1");
        goto end_region;
    }

    'loop' ('mode'|'start'|'end') END {
        opcode = absl::StrCat("loop_", group(1));
        goto end_region;
    }
    'off' ('by'|'mode') END {
        opcode = absl::StrCat("off_", group(1));
        goto end_region;
    }
    'bend' ('up'|'down') END {
        opcode = absl::StrCat("bend_", group(1));
        goto end_region;
    }
    'filtype' END {
        opcode = absl::StrCat("fil1_type");
        goto end_region;
    }
    'fil' (number) 'type' END {
        opcode = absl::StrCat("fil", group(1), "_type");
        goto end_region;
    }

    'polyphony_group' END {
        opcode = "group";
        goto end_region;
     }

     'gain' ('_' .*)? END {
         opcode = absl::StrCat("volume", group(1));
         goto end_region;
     }
     'tune' ('_' .*)? END {
         opcode = absl::StrCat("pitch", group(1));
         goto end_region;
     }

     'fil_' (.*) END {
         opcode = absl::StrCat("fil1_", group(1));
         goto end_region;
     }

    'on_' ('hi'|'lo') 'cc' (number) END {
        opcode = absl::StrCat("start_", group(1), "cc", group(2));
        goto end_region;
    }

    * { goto end_region; }

    */

end_region:
    /* end */;

    } // scope == kOpcodeFixRegion

    //--------------------------------------------------------------------------

    #undef YYMAXNMATCH

    return opcode;
}

#include <stdio.h>

int main(int argc, char *argv[])
{
    if (argc != 2) return 1;
    std::string r = fixOpcode(argv[1], kOpcodeFixRegion);
    printf("Result: %s\n", r.c_str());
    return 0;
}