STATIC bool is_whitespace(mp_lexer_t *lex) { return unichar_isspace(lex->chr0); }
// This function implements a simple non-recursive JSON parser. // // The JSON specification is at http://www.ietf.org/rfc/rfc4627.txt // The parser here will parse any valid JSON and return the correct // corresponding Python object. It allows through a superset of JSON, since // it treats commas and colons as "whitespace", and doesn't care if // brackets/braces are correctly paired. It will raise a ValueError if the // input is outside it's specs. // // Most of the work is parsing the primitives (null, false, true, numbers, // strings). It does 1 pass over the input string and so is easily extended to // being able to parse from a non-seekable stream. It tries to be fast and // small in code size, while not using more RAM than necessary. STATIC mp_obj_t mod_ujson_loads(mp_obj_t obj) { mp_uint_t len; const char *s = mp_obj_str_get_data(obj, &len); const char *top = s + len; vstr_t vstr; vstr_init(&vstr, 8); mp_obj_list_t stack; // we use a list as a simple stack for nested JSON stack.len = 0; stack.items = NULL; mp_obj_t stack_top = MP_OBJ_NULL; mp_obj_type_t *stack_top_type = NULL; mp_obj_t stack_key = MP_OBJ_NULL; for (;;) { cont: if (s == top) { break; } mp_obj_t next = MP_OBJ_NULL; bool enter = false; switch (*s) { case ',': case ':': case ' ': s += 1; goto cont; case 'n': if (s + 3 < top && s[1] == 'u' && s[2] == 'l' && s[3] == 'l') { s += 4; next = mp_const_none; } else { goto fail; } break; case 'f': if (s + 4 < top && s[1] == 'a' && s[2] == 'l' && s[3] == 's' && s[4] == 'e') { s += 5; next = mp_const_false; } else { goto fail; } break; case 't': if (s + 3 < top && s[1] == 'r' && s[2] == 'u' && s[3] == 'e') { s += 4; next = mp_const_true; } else { goto fail; } break; case '"': vstr_reset(&vstr); for (s++; s < top && *s != '"';) { byte c = *s; if (c == '\\') { s++; c = *s; switch (c) { case 'b': c = 0x08; break; case 'f': c = 0x0c; break; case 'n': c = 0x0a; break; case 'r': c = 0x0d; break; case 't': c = 0x09; break; case 'u': { if (s + 4 >= top) { goto fail; } mp_uint_t num = 0; for (int i = 0; i < 4; i++) { c = (*++s | 0x20) - '0'; if (c > 9) { c -= ('a' - ('9' + 1)); } num = (num << 4) | c; } vstr_add_char(&vstr, num); goto str_cont; } } } vstr_add_byte(&vstr, c); str_cont: s++; } if (s == top) { goto fail; } s++; next = mp_obj_new_str(vstr.buf, vstr.len, false); break; case '-': case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': case '8': case '9': { bool flt = false; vstr_reset(&vstr); for (; s < top; s++) { if (*s == '.' || *s == 'E' || *s == 'e') { flt = true; } else if (*s == '-' || unichar_isdigit(*s)) { // pass } else { break; } vstr_add_byte(&vstr, *s); } if (flt) { next = mp_parse_num_decimal(vstr.buf, vstr.len, false, false); } else { next = mp_parse_num_integer(vstr.buf, vstr.len, 10); } break; } case '[': next = mp_obj_new_list(0, NULL); enter = true; s += 1; break; case '{': next = mp_obj_new_dict(0); enter = true; s += 1; break; case '}': case ']': { s += 1; if (stack_top == MP_OBJ_NULL) { // no object at all goto fail; } if (stack.len == 0) { // finished; compound object goto success; } stack.len -= 1; stack_top = stack.items[stack.len]; stack_top_type = mp_obj_get_type(stack_top); goto cont; } default: goto fail; } if (stack_top == MP_OBJ_NULL) { stack_top = next; stack_top_type = mp_obj_get_type(stack_top); if (!enter) { // finished; single primitive only goto success; } } else { // append to list or dict if (stack_top_type == &mp_type_list) { mp_obj_list_append(stack_top, next); } else { if (stack_key == MP_OBJ_NULL) { stack_key = next; if (enter) { goto fail; } } else { mp_obj_dict_store(stack_top, stack_key, next); stack_key = MP_OBJ_NULL; } } if (enter) { if (stack.items == NULL) { mp_obj_list_init(&stack, 1); stack.items[0] = stack_top; } else { mp_obj_list_append(&stack, stack_top); } stack_top = next; stack_top_type = mp_obj_get_type(stack_top); } } } success: // eat trailing whitespace while (s < top && unichar_isspace(*s)) { s++; } if (s < top) { // unexpected chars goto fail; } if (stack.len != 0) { goto fail; } vstr_clear(&vstr); return stack_top; fail: nlr_raise(mp_obj_new_exception_msg(&mp_type_ValueError, "syntax error in JSON")); }