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#include <assert.h>
#include <ctype.h>
#include "lexer.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
void free_tokens(struct TOKEN *token) {
for (; token;) {
struct TOKEN *old = token;
token = token->next;
free(old);
}
}
int is_nonspecial_char(char c) {
if (!isprint(c))
return 0;
if (isspace(c))
return 0;
if (isalnum(c))
return 1;
return ('>' != c && '|' != c && '&' != c);
}
int parse_chars(const char **code_ptr, struct TOKEN *cur) {
const char *code = *code_ptr;
if (!is_nonspecial_char(*code))
return 0;
cur->type = TOKEN_CHARS;
int i = 0;
for (; *code; code++, i++) {
if (!is_nonspecial_char(*code)) {
break;
}
assert(i < 256);
cur->string_rep[i] = *code;
}
cur->string_rep[i] = '\0';
*code_ptr = code;
return 1;
}
// Operands such as: &, &&, |, || etc
// Is operands the right word?
int parse_operand(const char **code_ptr, struct TOKEN *cur) {
const char *code = *code_ptr;
#define TRY_PARSE_STRING(_s, _token) \
if (0 == strncmp(code, _s, strlen(_s))) { \
cur->type = _token; \
strcpy(cur->string_rep, _s); \
code += strlen(_s); \
goto complete_return; \
}
TRY_PARSE_STRING("&&", TOKEN_AND);
TRY_PARSE_STRING("||", TOKEN_NOT);
TRY_PARSE_STRING(">>", TOKEN_STREAM_APPEND);
TRY_PARSE_STRING(">", TOKEN_STREAM);
TRY_PARSE_STRING("|", TOKEN_PIPE);
// TODO: &
// Failed to parse
return 0;
complete_return:
*code_ptr = code;
return 1;
}
void skip_whitespace(const char **code_ptr) {
const char *code = *code_ptr;
for (; isspace(*code); code++)
;
*code_ptr = code;
}
struct TOKEN *lex(const char *code) {
struct TOKEN *head = NULL;
struct TOKEN *prev = NULL;
for (; *code;) {
skip_whitespace(&code);
if (!*code)
break;
struct TOKEN *cur = malloc(sizeof(struct TOKEN));
cur->next = NULL;
if (prev)
prev->next = cur;
if (parse_chars(&code, cur)) {
} else if (parse_operand(&code, cur)) {
} else {
free(cur);
printf("at: %s\n", code);
assert(0 && "Unknown token");
}
if (!head)
head = cur;
prev = cur;
}
return head;
}
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