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/*
* Copyright (c) 2026, Chloe M.
* Provided under the BSD-3 clause
*/
#include <errno.h>
#include <stdbool.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include "cescal/lexer.h"
#include "cescal/log.h"
#include "cescal/ptrbox.h"
static inline void
lexer_putback(struct cescal_state *state, char c)
{
if (state == NULL) {
return;
}
state->lex_putback = c;
}
static inline char
lexer_putback_pop(struct cescal_state *state)
{
char retc;
if (state == NULL) {
return '\0';
}
retc = state->lex_putback;
state->lex_putback = '\0';
return retc;
}
/*
* Returns true if the given character is a whitespace
*
* @c: Character to check
*/
static inline bool
lexer_is_ws(char c)
{
switch (c) {
case '\t':
case '\n':
case ' ':
case '\f':
case '\r':
return true;
}
return false;
}
/*
* Consume a single character from the input source file and
* optionally skip whitespace
*
* @state: Compiler state
* @skip_ws: If true skip whitespace
*/
static char
lexer_consume_single(struct cescal_state *state, bool skip_ws)
{
char c;
if (state == NULL) {
return '\0';
}
if ((c = lexer_putback_pop(state)) != '\0') {
if (!skip_ws) {
return c;
}
if (skip_ws && !lexer_is_ws(c)) {
return c;
}
}
while ((c = readbuf_read(&state->rb, state->in_fd)) != '\0') {
if (lexer_is_ws(c) && skip_ws) {
continue;
}
return c;
}
return '\0';
}
static int
lexer_scan_ident(struct cescal_state *state, char lc, struct token *res)
{
char *buf, c;
size_t bufsz, bufcap;
if (state == NULL || res == NULL) {
errno = EINVAL;
return -1;
}
bufsz = 0;
bufcap = 8;
if ((buf = malloc(bufcap)) == NULL) {
return -1;
}
if (lc != '_' && !isalpha(lc)) {
cc_error("bad identifier\n");
}
buf[bufsz++] = lc;
for (;;) {
c = lexer_consume_single(state, false);
if (c != '_' && !isalnum(c)) {
lexer_putback(state, c);
buf[bufsz] = '\0';
break;
}
buf[bufsz++] = c;
if (bufsz >= bufcap) {
bufcap += 8;
buf = realloc(buf, bufcap);
}
if (buf == NULL) {
return -1;
}
}
res->s = ptrbox_strdup(&state->ptrbox, buf);
res->type = TT_IDENT;
free(buf);
return 0;
}
/*
* Checks if an identifier token is actually a keyword
*
* @state: Compiler state
* @res: Token result
*/
static void
lexer_check_kw(struct cescal_state *state, struct token *res)
{
if (state == NULL || res == NULL) {
return;
}
switch (*res->s) {
case 'p':
if (strcmp(res->s, "pub") == 0) {
res->type = TT_PUB;
return;
}
if (strcmp(res->s, "proc") == 0) {
res->type = TT_PROC;
return;
}
break;
case 'b':
if (strcmp(res->s, "begin") == 0) {
res->type = TT_BEGIN;
return;
}
break;
case 'e':
if (strcmp(res->s, "end") == 0) {
res->type = TT_END;
return;
}
break;
}
}
int
lexer_nom(struct cescal_state *state, struct token *res)
{
char c;
if (state == NULL || res == NULL) {
errno = EINVAL;
return -1;
}
if ((c = lexer_consume_single(state, true)) == '\0') {
return -1;
}
switch (c) {
case '(':
res->type = TT_LPAREN;
res->c = c;
return 0;
case ')':
res->type = TT_RPAREN;
res->c = c;
return 0;
case ',':
res->type = TT_COMMA;
res->c = c;
return 0;
default:
if (lexer_scan_ident(state, c, res) == 0) {
lexer_check_kw(state, res);
return 0;
}
}
cc_error("got unknown token '%c'\n", c);
return -1;
}
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