/* Native functions for string operations.

Copyright (C) 2016, 2017 Paul Boddie <paul@boddie.org.uk>

This program is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free Software

Foundation; either version 3 of the License, or (at your option) any later

version.

This program is distributed in the hope that it will be useful, but WITHOUT

ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more

details.

You should have received a copy of the GNU General Public License along with

this program.  If not, see <http://www.gnu.org/licenses/>.

*/

#include <string.h> /* strcmp, memcpy */

#include "native/common.h"

#include "types.h"

#include "exceptions.h"

#include "ops.h"

#include "progconsts.h"

#include "progops.h"

#include "progtypes.h"

#include "main.h"

/* String operations. */

__attr __fn_native_str_str_add(__attr __args[])

{

    __attr * const _data = &__args[1];

    __attr * const other = &__args[2];

    __attr * const _size = &__args[3];

    __attr * const othersize = &__args[4];

    /* _data, other interpreted as string */

    char *s = _data->strvalue;

    char *o = other->strvalue;

    int ss = _size->intvalue, os = othersize->intvalue;

    int n = ss + os;

    char *r = (char *) __ALLOCATE(n + 1, sizeof(char));

    memcpy(r, s, ss);

    memcpy(r + ss, o, os);

    /* Return a new string. */

    return __new_str(r, n);

}

__attr __fn_native_str_str_chr(__attr __args[])

{

    __attr * const _data = &__args[1];

    /* _data interpreted as int */

    int n = _data->intvalue;

    char *s = (char *) __ALLOCATE(2, sizeof(char));

    s[0] = (char) n;

    return __new_str(s, 1);

}

__attr __fn_native_str_str_lt(__attr __args[])

{

    __attr * const _data = &__args[1];

    __attr * const other = &__args[2];

    /* _data, other interpreted as string */

    char *s = _data->strvalue;

    char *o = other->strvalue;

    /* NOTE: Using simple byte-level string operations. */

    return strcmp(s, o) < 0 ? __builtins___boolean_True : __builtins___boolean_False;

}

__attr __fn_native_str_str_gt(__attr __args[])

{

    __attr * const _data = &__args[1];

    __attr * const other = &__args[2];

    /* _data, other interpreted as string */

    char *s = _data->strvalue;

    char *o = other->strvalue;

    /* NOTE: Using simple byte-level string operations. */

    return strcmp(s, o) > 0 ? __builtins___boolean_True : __builtins___boolean_False;

}

__attr __fn_native_str_str_eq(__attr __args[])

{

    __attr * const _data = &__args[1];

    __attr * const other = &__args[2];

    /* _data, other interpreted as string */

    char *s = _data->strvalue;

    char *o = other->strvalue;

    /* NOTE: Using simple byte-level string operations. */

    return strcmp(s, o) == 0 ? __builtins___boolean_True : __builtins___boolean_False;

}

__attr __fn_native_str_str_ord(__attr __args[])

{

    __attr * const _data = &__args[1];

    /* _data interpreted as string */

    char *s = _data->strvalue;

    return __new_int((unsigned int) s[0]);

}

__attr __fn_native_str_str_substr(__attr __args[])

{

    __attr * const _data = &__args[1];

    __attr * const start = &__args[2];

    __attr * const end = &__args[3];

    __attr * const step = &__args[4];

    /* _data interpreted as string */

    char *s = _data->strvalue, *sub;

    /* start.__data__ interpreted as int */

    int istart = __load_via_object(start->value, __pos___data__).intvalue;

    /* end.__data__ interpreted as int */

    int iend = __load_via_object(end->value, __pos___data__).intvalue;

    /* step.__data__ interpreted as int */

    int istep = __load_via_object(step->value, __pos___data__).intvalue;

    /* Calculate the size of the substring. */

    size_t resultsize = ((iend - istart - (istep > 0 ? 1 : -1)) / istep) + 1;

    int to, from;

    /* Reserve space for a new string. */

    sub = (char *) __ALLOCATE(resultsize + 1, sizeof(char));

    /* Does not null terminate but final byte should be zero. */

    if (istep > 0)

        for (from = istart, to = 0; from < iend; from += istep, to++)

            sub[to] = s[from];

    else if (istep < 0)

        for (from = istart, to = 0; from > iend; from += istep, to++)

            sub[to] = s[from];

    return __new_str(sub, resultsize);

}

/* Module initialisation. */

void __main_native_str()

{

}