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typedef enum TokenType {
TOKEN_UNKNOWN = 0,
TOKEN_LPAREN,
TOKEN_RPAREN,
TOKEN_FIXNUM,
TOKEN_SYMBOL,
TOKEN_BOOL,
TOKEN_STRING,
} TokenType;
typedef struct Token {
TokenType type;
StringView value;
} Token;
typedef struct Tokens {
Token *start;
size_t n;
} Tokens;
#define TRUE_TOKEN (StringView){"true", 4}
#define FALSE_TOKEN (StringView){"false", 5}
#define LPAREN_TOKEN (StringView){"(", 1}
#define RPAREN_TOKEN (StringView){")", 1}
TokenType
find_token_type(StringView value) {
bool is_fixnum = true;
for (size_t i = 0; i < value.n; i++) {
char c = value.start[i];
if (i == 0 && c == '-' && value.n > 1) {
continue;
}
if (!isdigit(c)) {
is_fixnum = false;
break;
}
}
if (is_fixnum) {
return TOKEN_FIXNUM;
}
if (sv_equal(value, TRUE_TOKEN) || sv_equal(value, FALSE_TOKEN)) {
return TOKEN_BOOL;
}
return TOKEN_SYMBOL;
}
Tokens
tokenize(StringView sv) {
// NOTE: Not allocating any memory for now, but we are limited by a maximum
// number of tokens we can process.
#define TOKENS_BUF_SIZE KB(64)
static Token tokens_buf[TOKENS_BUF_SIZE];
// Clear buffer.
for (size_t i = 0; i < TOKENS_BUF_SIZE; i++) {
tokens_buf[i] = (Token){0};
}
size_t n = 0;
size_t token_n = 0;
for (size_t i = 0; i < sv.n; i++) {
switch (sv.start[i]) {
case ' ':
case '\f':
case '\n':
case '\r':
case '\t':
case '\v': {
if (token_n != 0) {
Token token = (Token){
.type = TOKEN_UNKNOWN,
.value = (StringView){
.start = &sv.start[i - token_n],
.n = token_n,
}
};
token.type = find_token_type(token.value);
tokens_buf[n++] = token;
token_n = 0;
}
} break;
case ';': {
if (token_n != 0) {
Token token = (Token){
.type = TOKEN_UNKNOWN,
.value = (StringView){
.start = &sv.start[i - token_n],
.n = token_n,
}
};
token.type = find_token_type(token.value);
tokens_buf[n++] = token;
token_n = 0;
}
// Advance until the next newline.
do {
i++;
} while (i < sv.n && sv.start[(i + 1)] != '\n');
} break;
case '"': {
if (token_n != 0) {
fprintf(stderr, "error: string started inside symbol\n");
return (Tokens){0};
}
// Find end delimiter.
size_t string_start = i + 1;
size_t string_end = i + 1;
while (true) {
if (sv.start[string_end] == '"' && sv.start[string_end - 1] != '\\') {
break;
}
if (string_end >= sv.n) {
fprintf(stderr, "error: string delimiter not found\n");
return (Tokens){0};
}
string_end++;
}
Token token = (Token){
.type = TOKEN_STRING,
.value = (StringView){
.start = &sv.start[string_start],
.n = string_end - string_start,
}
};
tokens_buf[n++] = token;
token_n = 0;
i += string_end - string_start + 1;
} break;
case '(': {
if ((i + 1) < sv.n) {
char next_c = sv.start[i + 1];
if (isspace(next_c)) {
fprintf(stderr, "error: lparen delimiter followed by space\n");
return (Tokens){0};
}
}
if (token_n != 0) {
fprintf(stderr, "error: lparen delimiter within symbol name\n");
return (Tokens){0};
}
Token token = (Token){
.type = TOKEN_LPAREN,
.value = LPAREN_TOKEN,
};
tokens_buf[n++] = token;
} break;
case ')': {
if ((i + 1) < sv.n) {
char next_c = sv.start[i + 1];
if ((next_c != ')' && !isspace(next_c))) {
fprintf(stderr, "error: rparen delimiter within symbol name\n");
return (Tokens){0};
}
}
if (token_n != 0) {
// Push previous token.
Token token = (Token){
.type = TOKEN_UNKNOWN,
.value = (StringView){
.start = &sv.start[i - token_n],
.n = token_n,
}
};
token.type = find_token_type(token.value);
tokens_buf[n++] = token;
token_n = 0;
}
Token token = (Token){
.type = TOKEN_RPAREN,
.value = RPAREN_TOKEN,
};
tokens_buf[n++] = token;
} break;
case EOF: {
break;
} break;
default: {
token_n++;
} break;
}
}
if (token_n != 0) {
// End of line encountered.
Token token = (Token){
.type = TOKEN_UNKNOWN,
.value = (StringView){
.start = &sv.start[sv.n - token_n],
.n = token_n,
}
};
token.type = find_token_type(token.value);
tokens_buf[n++] = token;
}
return (Tokens){.start = (Token *)&tokens_buf, .n = n};
}
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