Add syntax literals for signed and unsigned 64 bit integers.

Number literals can now take an optional "representation" suffix

- Use `:n` for normal numbers (IEEE-754 doubles)
- Use `:s` for signed 64 bit integers
- Use `:u` for unsigned 64 bit integers
- Other suffix will fallthrough the usual parseing logic. This means
  that they will only possibly resolve to symbols if they start with -,
  +, or .

The syntax does not collide with any existing valid Janet and is only
enabled with JANET_INTTYPES. This also leaves open a syntax for other
number types such as bignums, ratios, decimals, etc.

src/core/parse.c

@@ -467,8 +467,13 @@ static int tokenchar(JanetParser *p, JanetParseState *state, uint8_t c) {
             return 0;
         }
         ret = janet_keywordv(p->buf + 1, blen - 1);
+#ifdef JANET_INT_TYPES
+    } else if (start_num && !janet_scan_numeric(p->buf, blen, &ret)) {
+        (void) numval;
+#else
     } else if (start_num && !janet_scan_number(p->buf, blen, &numval)) {
         ret = janet_wrap_number(numval);
+#endif
     } else if (!check_str_const("nil", p->buf, blen)) {
         ret = janet_wrap_nil();
     } else if (!check_str_const("false", p->buf, blen)) {

src/core/strtod.c

@@ -489,6 +489,40 @@ int janet_scan_uint64(const uint8_t *str, int32_t len, uint64_t *out) {
     return 0;
 }
 
+/* Similar to janet_scan_number but allows for
+ * more numeric types with a given suffix. */
+int janet_scan_numeric(
+    const uint8_t *str,
+    int32_t len,
+    Janet *out) {
+    int result;
+    double num;
+    int64_t i64;
+    uint64_t u64;
+    if (len < 2 || str[len - 2] != ':') {
+        result = janet_scan_number_base(str, len, 0, &num);
+        *out = janet_wrap_number(num);
+        return result;
+    }
+    switch (str[len - 1]) {
+        default:
+            return 1;
+        case 'n':
+            result = janet_scan_number_base(str, len - 2, 0, &num);
+            *out = janet_wrap_number(num);
+            return result;
+        /* Condition is inverted janet_scan_int64 and janet_scan_uint64 */
+        case 's':
+            result = !janet_scan_int64(str, len - 2, &i64);
+            *out = janet_wrap_s64(i64);
+            return result;
+        case 'u':
+            result = !janet_scan_uint64(str, len - 2, &u64);
+            *out = janet_wrap_u64(u64);
+            return result;
+    }
+}
+
 #endif
 
 void janet_buffer_dtostr(JanetBuffer *buffer, double x) {

src/include/janet.h

@@ -1598,6 +1598,9 @@ JANET_API int janet_scan_number(const uint8_t *str, int32_t len, double *out);
 JANET_API int janet_scan_number_base(const uint8_t *str, int32_t len, int32_t base, double *out);
 JANET_API int janet_scan_int64(const uint8_t *str, int32_t len, int64_t *out);
 JANET_API int janet_scan_uint64(const uint8_t *str, int32_t len, uint64_t *out);
+#ifdef JANET_INT_TYPES
+JANET_API int janet_scan_numeric(const uint8_t *str, int32_t len, Janet *out);
+#endif
 
 /* Debugging */
 JANET_API void janet_debug_break(JanetFuncDef *def, int32_t pc);

test/suite-inttypes.janet

@@ -47,6 +47,14 @@
 (assert (= (int/to-number (i64 9007199254740991)) 9007199254740991))
 (assert (= (int/to-number (i64 -9007199254740991)) -9007199254740991))
 
+# New parser
+(assert (= (u64 "123") 123:u) "u64 parsing")
+(assert (= (u64 "0") 0:u) "u64 parsing")
+(assert (= (u64 "0xFFFF_FFFF_FFFF_FFFF") 0xFFFF_FFFF_FFFF_FFFF:u) "u64 parsing")
+(assert (= (i64 "123") 123:s) "s64 parsing")
+(assert (= (i64 "-123") -123:s) "s64 parsing")
+(assert (= (i64 "0") 0:s) "s64 parsing")
+
 (assert-error
   "u64 out of bounds for safe integer"
   (int/to-number (u64 "9007199254740993"))