impl hex numbers

lexer.c

@@ -443,6 +443,57 @@ char lex_get_escaped_char(char c)
     return co;
 }
 
+void lexer_pop_token()
+{
+    vector_pop(lex_process->token_vec);
+}
+
+bool is_hex_char(char c)
+{
+    c = tolower(c);
+    return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f');
+}
+
+const char *
+read_hex_number_str()
+{
+    struct buffer *buffer = buffer_create();
+    char c = peekc();
+    LEX_GETC_IF(buffer, c, is_hex_char(c));
+    // write null terminator
+    buffer_write(buffer, 0x00);
+    return buffer_ptr(buffer);
+}
+
+struct token *
+token_make_special_number_hexadecimal()
+{
+    // skip the 'x'
+    nextc();
+
+    unsigned long number = 0;
+    const char *number_str = read_hex_number_str();
+    number = strtol(number_str, 0, 16);
+    return token_make_number_for_value(number);
+}
+
+struct token *
+token_make_special_number()
+{
+    struct token *token = NULL;
+    struct token *last_token = lexer_last_token();
+
+    lexer_pop_token(); // poping off the first 0
+
+    char c = peekc();
+    if (c == 'x')
+    {
+        token = token_make_special_number_hexadecimal();
+    }
+
+    return token;
+}
+
 struct token *
 token_make_quote()
 {
@@ -487,6 +538,10 @@ struct token *read_next_token()
         token = token_make_symbol();
         break;
 
+    case 'x': // '0' is already tokenized as a number
+        token = token_make_special_number();
+        break;
+
     case '"':
         token = token_make_string('"', '"');
         break;

test.c

@@ -6,3 +6,5 @@
     */
 
     'a' '\n' '\t'
+
+    0xFE12