/
tokenize.c
293 lines (250 loc) · 6.15 KB
/
tokenize.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
#include "chibicc.h"
char *filename;
char *user_input;
Token *token;
// Reports an error and exit.
void error(char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
fprintf(stderr, "\n");
exit(1);
}
// Reports an error message in the following format and exit.
//
// foo.c:10: x = y + 1;
// ^ <error message here>
void verror_at(char *loc, char *fmt, va_list ap) {
// Find a line containing `loc`.
char *line = loc;
while (user_input < line && line[-1] != '\n')
line--;
char *end = loc;
while (*end != '\n')
end++;
// Get a line number.
int line_num = 1;
for (char *p = user_input; p < line; p++)
if (*p == '\n')
line_num++;
// Print out the line.
int indent = fprintf(stderr, "%s:%d: ", filename, line_num);
fprintf(stderr, "%.*s\n", (int)(end - line), line);
// Show the error message.
int pos = loc - line + indent;
fprintf(stderr, "%*s", pos, ""); // print pos spaces.
fprintf(stderr, "^ ");
vfprintf(stderr, fmt, ap);
fprintf(stderr, "\n");
exit(1);
}
// Reports an error location and exit.
void error_at(char *loc, char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
verror_at(loc, fmt, ap);
}
// Reports an error location and exit.
void error_tok(Token *tok, char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
if (tok)
verror_at(tok->str, fmt, ap);
vfprintf(stderr, fmt, ap);
fprintf(stderr, "\n");
exit(1);
}
char *strndup(char *p, int len) {
char *buf = malloc(len + 1);
strncpy(buf, p, len);
buf[len] = '\0';
return buf;
}
// Returns true if the current token matches a given string.
Token *peek(char *s) {
if (token->kind != TK_RESERVED || strlen(s) != token->len ||
memcmp(token->str, s, token->len))
return NULL;
return token;
}
// Consumes the current token if it matches a given string.
Token *consume(char *s) {
if (!peek(s))
return NULL;
Token *t = token;
token = token->next;
return t;
}
// Consumes the current token if it is an identifier.
Token *consume_ident() {
if (token->kind != TK_IDENT)
return NULL;
Token *t = token;
token = token->next;
return t;
}
// Ensure that the current token is a given string
void expect(char *s) {
if (!peek(s))
error_tok(token, "expected \"%s\"", s);
token = token->next;
}
// Ensure that the current token is TK_NUM.
int expect_number() {
if (token->kind != TK_NUM)
error_tok(token, "expected a number");
int val = token->val;
token = token->next;
return val;
}
// Ensure that the current token is TK_IDENT.
char *expect_ident() {
if (token->kind != TK_IDENT)
error_tok(token, "expected an identifier");
char *s = strndup(token->str, token->len);
token = token->next;
return s;
}
bool at_eof() {
return token->kind == TK_EOF;
}
// Create a new token and add it as the next token of `cur`.
Token *new_token(TokenKind kind, Token *cur, char *str, int len) {
Token *tok = calloc(1, sizeof(Token));
tok->kind = kind;
tok->str = str;
tok->len = len;
cur->next = tok;
return tok;
}
bool startswith(char *p, char *q) {
return memcmp(p, q, strlen(q)) == 0;
}
bool is_alpha(char c) {
return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || c == '_';
}
bool is_alnum(char c) {
return is_alpha(c) || ('0' <= c && c <= '9');
}
char *starts_with_reserved(char *p) {
// Keyword
static char *kw[] = {"return", "if", "else", "while", "for", "int",
"char", "sizeof"};
for (int i = 0; i < sizeof(kw) / sizeof(*kw); i++) {
int len = strlen(kw[i]);
if (startswith(p, kw[i]) && !is_alnum(p[len]))
return kw[i];
}
// Multi-letter punctuator
static char *ops[] = {"==", "!=", "<=", ">="};
for (int i = 0; i < sizeof(ops) / sizeof(*ops); i++)
if (startswith(p, ops[i]))
return ops[i];
return NULL;
}
char get_escape_char(char c) {
switch (c) {
case 'a': return '\a';
case 'b': return '\b';
case 't': return '\t';
case 'n': return '\n';
case 'v': return '\v';
case 'f': return '\f';
case 'r': return '\r';
case 'e': return 27;
case '0': return 0;
default: return c;
}
}
Token *read_string_literal(Token *cur, char *start) {
char *p = start + 1;
char buf[1024];
int len = 0;
for (;;) {
if (len == sizeof(buf))
error_at(start, "string literal too large");
if (*p == '\0')
error_at(start, "unclosed string literal");
if (*p == '"')
break;
if (*p == '\\') {
p++;
buf[len++] = get_escape_char(*p++);
} else {
buf[len++] = *p++;
}
}
Token *tok = new_token(TK_STR, cur, start, p - start + 1);
tok->contents = malloc(len + 1);
memcpy(tok->contents, buf, len);
tok->contents[len] = '\0';
tok->cont_len = len + 1;
return tok;
}
// Tokenize `user_input` and returns new tokens.
Token *tokenize() {
char *p = user_input;
Token head;
head.next = NULL;
Token *cur = &head;
while (*p) {
// Skip whitespace characters.
if (isspace(*p)) {
p++;
continue;
}
// Skip line comments.
if (startswith(p, "//")) {
p += 2;
while (*p != '\n')
p++;
continue;
}
// Skip block comments.
if (startswith(p, "/*")) {
char *q = strstr(p + 2, "*/");
if (!q)
error_at(p, "unclosed block comment");
p = q + 2;
continue;
}
// Keyword or multi-letter punctuator
char *kw = starts_with_reserved(p);
if (kw) {
int len = strlen(kw);
cur = new_token(TK_RESERVED, cur, p, len);
p += len;
continue;
}
// Single-letter punctuator
if (strchr("+-*/()<>;={},&[]", *p)) {
cur = new_token(TK_RESERVED, cur, p++, 1);
continue;
}
// Identifier
if (is_alpha(*p)) {
char *q = p++;
while (is_alnum(*p))
p++;
cur = new_token(TK_IDENT, cur, q, p - q);
continue;
}
// String literal
if (*p == '"') {
cur = read_string_literal(cur, p);
p += cur->len;
continue;
}
// Integer literal
if (isdigit(*p)) {
cur = new_token(TK_NUM, cur, p, 0);
char *q = p;
cur->val = strtol(p, &p, 10);
cur->len = p - q;
continue;
}
error_at(p, "invalid token");
}
new_token(TK_EOF, cur, p, 0);
return head.next;
}