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#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "types.h"
#include "lexer.h"
#include "parser.h"
#include "runtime.h"
static pit_lex_token peek(pit_parser *st) {
if (!st) return PIT_LEX_TOKEN_ERROR;
return st->next.token;
}
static pit_lex_token advance(pit_parser *st) {
if (!st) return PIT_LEX_TOKEN_ERROR;
st->cur = st->next;
st->next.token = pit_lex_next(st->lexer);
st->next.start = st->lexer->start;
st->next.end = st->lexer->end;
st->next.line = st->lexer->start_line;
st->next.column = st->lexer->start_column;
return st->cur.token;
}
static bool match(pit_parser *st, pit_lex_token t) {
if (peek(st) == t) {
advance(st);
return true;
} else return false;
}
static void get_token_string(pit_parser *st, char *buf, i64 len) {
i64 diff = st->cur.end - st->cur.start;
i64 tlen = diff >= len ? len - 1 : diff;
memcpy(buf, st->lexer->input + st->cur.start, tlen);
buf[tlen] = 0;
}
void pit_parser_from_lexer(pit_parser *ret, pit_lexer *lex) {
ret->lexer = lex;
ret->cur.token = ret->next.token = PIT_LEX_TOKEN_ERROR;
ret->cur.start = ret->next.start = 0;
ret->cur.end = ret->next.end = 0;
ret->cur.line = ret->next.line = -1;
ret->cur.column = ret->next.column = -1;
advance(ret);
}
// parse a single expression
pit_value pit_parse(pit_runtime *rt, pit_parser *st, bool *eof) {
char buf[256] = {0};
pit_lex_token t = advance(st);
rt->source_line = st->cur.line;
rt->source_column = st->cur.column;
switch (t) {
case PIT_LEX_TOKEN_ERROR:
pit_error(rt, "encountered an error while lexing: %s", st->lexer->error);
return PIT_NIL;
case PIT_LEX_TOKEN_EOF:
if (eof != NULL) {
*eof = true;
} else {
pit_error(rt, "end-of-file while parsing");
}
return PIT_NIL;
case PIT_LEX_TOKEN_LPAREN: {
// to construct a cons-list, we need the arguments "backwards"
// we could reverse or build up a temporary list
// (or use non-tail recursion, which is basically the temporary list on the stack)
// we choose to build a temporary list on the scratch arena
i64 scratch_reset = rt->scratch->next;
while (!match(st, PIT_LEX_TOKEN_RPAREN)) {
pit_value *cell = pit_arena_alloc_bulk(rt->scratch, sizeof(pit_value));
*cell = pit_parse(rt, st, eof);
if (rt->error != PIT_NIL) return PIT_NIL; // if we hit an error, stop!
}
pit_value ret = PIT_NIL;
for (i64 i = rt->scratch->next - sizeof(pit_value); i >= scratch_reset; i -= sizeof(pit_value)) {
pit_value *v = pit_arena_idx(rt->scratch, i);
ret = pit_cons(rt, *v, ret);
}
rt->scratch->next = scratch_reset;
return ret;
}
case PIT_LEX_TOKEN_QUOTE:
return pit_list(rt, 2, pit_intern_cstr(rt, "quote"), pit_parse(rt, st, eof));
case PIT_LEX_TOKEN_INTEGER_LITERAL:
get_token_string(st, buf, sizeof(buf));
return pit_integer_new(rt, atoi(buf));
case PIT_LEX_TOKEN_STRING_LITERAL:
get_token_string(st, buf, sizeof(buf));
i64 len = strlen(buf);
i64 cur = 0;
for (i64 i = 1; i < len; ++i) {
if (buf[i] == '\\' && i + 1 < len) buf[cur++] = buf[++i];
else if (buf[i] != '"') buf[cur++] = buf[i];
else break;
}
return pit_bytes_new(rt, (u8 *) buf, cur);
case PIT_LEX_TOKEN_SYMBOL:
get_token_string(st, buf, sizeof(buf));
return pit_intern_cstr(rt, buf);
default:
pit_error(rt, "unexpected token: %s", pit_lex_token_name(t));
return PIT_NIL;
}
}
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