/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=4 sts=4 sw=4 fenc=utf-8                               :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Python 3                                                                     │
│ https://docs.python.org/3/license.html                                       │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/mem/mem.h"
#include "third_party/python/Include/grammar.h"
#include "third_party/python/Include/objimpl.h"
#include "third_party/python/Include/pgenheaders.h"
#include "third_party/python/Include/pyerrors.h"
#include "libc/ctype.h"
#include "third_party/python/Include/token.h"

extern int Py_DebugFlag;

grammar *
newgrammar(int start)
{
    grammar *g;

    g = (grammar *)PyObject_MALLOC(sizeof(grammar));
    if (g == NULL)
        Py_FatalError("no mem for new grammar");
    g->g_ndfas = 0;
    g->g_dfa = NULL;
    g->g_start = start;
    g->g_ll.ll_nlabels = 0;
    g->g_ll.ll_label = NULL;
    g->g_accel = 0;
    return g;
}

void
freegrammar(grammar *g)
{
    int i;
    for (i = 0; i < g->g_ndfas; i++) {
        free(g->g_dfa[i].d_name);
        for (int j = 0; j < g->g_dfa[i].d_nstates; j++)
            PyObject_FREE(g->g_dfa[i].d_state[j].s_arc);
        PyObject_FREE(g->g_dfa[i].d_state);
    }
    PyObject_FREE(g->g_dfa);
    for (i = 0; i < g->g_ll.ll_nlabels; i++)
        free(g->g_ll.ll_label[i].lb_str);
    PyObject_FREE(g->g_ll.ll_label);
    PyObject_FREE(g);
}

dfa *
adddfa(grammar *g, int type, const char *name)
{
    dfa *d;

    g->g_dfa = (dfa *)PyObject_REALLOC(g->g_dfa,
                                        sizeof(dfa) * (g->g_ndfas + 1));
    if (g->g_dfa == NULL)
        Py_FatalError("no mem to resize dfa in adddfa");
    d = &g->g_dfa[g->g_ndfas++];
    d->d_type = type;
    d->d_name = strdup(name);
    d->d_nstates = 0;
    d->d_state = NULL;
    d->d_initial = -1;
    d->d_first = NULL;
    return d; /* Only use while fresh! */
}

int
addstate(dfa *d)
{
    state *s;

    d->d_state = (state *)PyObject_REALLOC(d->d_state,
                                  sizeof(state) * (d->d_nstates + 1));
    if (d->d_state == NULL)
        Py_FatalError("no mem to resize state in addstate");
    s = &d->d_state[d->d_nstates++];
    s->s_narcs = 0;
    s->s_arc = NULL;
    s->s_lower = 0;
    s->s_upper = 0;
    s->s_accel = NULL;
    s->s_accept = 0;
    return Py_SAFE_DOWNCAST(s - d->d_state, intptr_t, int);
}

void
addarc(dfa *d, int from, int to, int lbl)
{
    state *s;
    arc *a;

    assert(0 <= from && from < d->d_nstates);
    assert(0 <= to && to < d->d_nstates);

    s = &d->d_state[from];
    s->s_arc = (arc *)PyObject_REALLOC(s->s_arc, sizeof(arc) * (s->s_narcs + 1));
    if (s->s_arc == NULL)
        Py_FatalError("no mem to resize arc list in addarc");
    a = &s->s_arc[s->s_narcs++];
    a->a_lbl = lbl;
    a->a_arrow = to;
}

int
addlabel(labellist *ll, int type, const char *str)
{
    int i;
    label *lb;

    for (i = 0; i < ll->ll_nlabels; i++) {
        if (ll->ll_label[i].lb_type == type &&
            strcmp(ll->ll_label[i].lb_str, str) == 0)
            return i;
    }
    ll->ll_label = (label *)PyObject_REALLOC(ll->ll_label,
                                    sizeof(label) * (ll->ll_nlabels + 1));
    if (ll->ll_label == NULL)
        Py_FatalError("no mem to resize labellist in addlabel");
    lb = &ll->ll_label[ll->ll_nlabels++];
    lb->lb_type = type;
    lb->lb_str = strdup(str);
    if (Py_DebugFlag)
        printf("Label @ %8p, %d: %s\n", ll, ll->ll_nlabels,
               PyGrammar_LabelRepr(lb));
    return Py_SAFE_DOWNCAST(lb - ll->ll_label, intptr_t, int);
}

/* Same, but rather dies than adds */

int
findlabel(labellist *ll, int type, const char *str)
{
    int i;

    for (i = 0; i < ll->ll_nlabels; i++) {
        if (ll->ll_label[i].lb_type == type /*&&
            strcmp(ll->ll_label[i].lb_str, str) == 0*/)
            return i;
    }
    fprintf(stderr, "Label %d/'%s' not found\n", type, str);
    Py_FatalError("grammar.c:findlabel()");

    /* Py_FatalError() is declared with __attribute__((__noreturn__)).
       GCC emits a warning without "return 0;" (compiler bug!), but Clang is
       smarter and emits a warning on the return... */
#ifndef __clang__
    return 0; /* Make gcc -Wall happy */
#endif
}

/* Forward */
static void translabel(grammar *, label *);

void
translatelabels(grammar *g)
{
    int i;

#ifdef Py_DEBUG
    printf("Translating labels ...\n");
#endif
    /* Don't translate EMPTY */
    for (i = EMPTY+1; i < g->g_ll.ll_nlabels; i++)
        translabel(g, &g->g_ll.ll_label[i]);
}

static void
translabel(grammar *g, label *lb)
{
    int i;

    if (Py_DebugFlag)
        printf("Translating label %s ...\n", PyGrammar_LabelRepr(lb));

    if (lb->lb_type == NAME) {
        for (i = 0; i < g->g_ndfas; i++) {
            if (strcmp(lb->lb_str, g->g_dfa[i].d_name) == 0) {
                if (Py_DebugFlag)
                    printf(
                        "Label %s is non-terminal %d.\n",
                        lb->lb_str,
                        g->g_dfa[i].d_type);
                lb->lb_type = g->g_dfa[i].d_type;
                free(lb->lb_str);
                lb->lb_str = NULL;
                return;
            }
        }
        for (i = 0; i < (int)N_TOKENS; i++) {
            if (strcmp(lb->lb_str, _PyParser_TokenNames[i]) == 0) {
                if (Py_DebugFlag)
                    printf("Label %s is terminal %d.\n",
                        lb->lb_str, i);
                lb->lb_type = i;
                free(lb->lb_str);
                lb->lb_str = NULL;
                return;
            }
        }
        printf("Can't translate NAME label '%s'\n", lb->lb_str);
        return;
    }

    if (lb->lb_type == STRING) {
        if (isalpha(Py_CHARMASK(lb->lb_str[1])) ||
            lb->lb_str[1] == '_') {
            char *p;
            char *src;
            char *dest;
            size_t name_len;
            if (Py_DebugFlag)
                printf("Label %s is a keyword\n", lb->lb_str);
            lb->lb_type = NAME;
            src = lb->lb_str + 1;
            p = strchr(src, '\'');
            if (p)
                name_len = p - src;
            else
                name_len = strlen(src);
            dest = (char *)malloc(name_len + 1);
            if (!dest) {
                printf("Can't alloc dest '%s'\n", src);
                return;
            }
            strncpy(dest, src, name_len);
            dest[name_len] = '\0';
            free(lb->lb_str);
            lb->lb_str = dest;
        }
        else if (lb->lb_str[2] == lb->lb_str[0]) {
            int type = (int) PyToken_OneChar(lb->lb_str[1]);
            if (type != OP) {
                lb->lb_type = type;
                free(lb->lb_str);
                lb->lb_str = NULL;
            }
            else
                printf("Unknown OP label %s\n",
                    lb->lb_str);
        }
        else if (lb->lb_str[2] && lb->lb_str[3] == lb->lb_str[0]) {
            int type = (int) PyToken_TwoChars(lb->lb_str[1],
                                       lb->lb_str[2]);
            if (type != OP) {
                lb->lb_type = type;
                free(lb->lb_str);
                lb->lb_str = NULL;
            }
            else
                printf("Unknown OP label %s\n",
                    lb->lb_str);
        }
        else if (lb->lb_str[2] && lb->lb_str[3] && lb->lb_str[4] == lb->lb_str[0]) {
            int type = (int) PyToken_ThreeChars(lb->lb_str[1],
                                                lb->lb_str[2],
                                                lb->lb_str[3]);
            if (type != OP) {
                lb->lb_type = type;
                free(lb->lb_str);
                lb->lb_str = NULL;
            }
            else
                printf("Unknown OP label %s\n",
                    lb->lb_str);
        }
        else
            printf("Can't translate STRING label %s\n",
                lb->lb_str);
    }
    else
        printf("Can't translate label '%s'\n",
               PyGrammar_LabelRepr(lb));
}
