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/*
* Copyright (c) 2026, Apollo Telephone Laboratories.
* Provided under the BSD-3 clause.
*/
#include <atas/lexer.h>
#include <atas/trace.h>
#include <stdio.h>
#include <stdbool.h>
/*
* Returns true if the given char is a whitespace
*
* @c: Character to compare against a set of whitespace
*/
static inline bool
lexer_is_ws(char c)
{
switch (c) {
case '\n':
case '\f':
case '\t':
case '\r':
case ' ':
return true;
}
return false;
}
/*
* Scan a single byte from the input source file
*
* @state: Assembler state
* @skip_ws: If true, skip whitespaces
*
* Returns the scanned byte on success, returns '\0'
* on failure.
*/
static char
lexer_scan_byte(struct atas_state *state, bool skip_ws)
{
char c;
if (state == NULL) {
return '\0';
}
if ((c = fgetc(state->in_file)) == EOF) {
return '\0';
}
while (lexer_is_ws(c) && skip_ws) {
if ((c = fgetc(state->in_file)) == EOF) {
return '\0';
}
}
return c;
}
int
atas_lexer_scan(struct atas_state *state, struct atas_token *token)
{
char c;
if (state == NULL || token == NULL) {
return -1;
}
c = lexer_scan_byte(state, true);
if (c == '\0') {
return -1;
}
switch (c) {
case ',':
token->type = TT_COMMA;
token->c = c;
return 0;
}
trace_fatal("unexpected token '%c' while scanning\n", c);
atas_fatal(state);
return -1;
}
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