BiteTheDDDDt commented on code in PR #18565:
URL: https://github.com/apache/doris/pull/18565#discussion_r1171066642
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be/src/vec/functions/function_cast.h:
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@@ -62,7 +65,91 @@ inline UInt32 extract_to_decimal_scale(const
ColumnWithTypeAndName& named_column
named_column.column->get(0, field);
return field.get<UInt32>();
}
+/** Cast from string or number to Time.
+ * In Doris, the underlying storage type of the Time class is Float64.
+ */
+struct TimeCast {
+ // Cast from string
+ // Some examples of conversions.
+ // '300' -> 00:03:00 '20:23' -> 20:23:00 '20:23:24' -> 20:23:24
+ template <typename T>
+ static bool try_parse_time(char* s, size_t len, T& x) {
+ char* first_char = s;
+ char* end_char = s + len;
+ int hour = 0, minute = 0, second = 0;
+ auto parse_from_str_to_int = [](char* begin, size_t len, auto& num) {
+ StringParser::ParseResult parse_result =
StringParser::PARSE_SUCCESS;
+ auto int_value = StringParser::string_to_unsigned_int<uint64_t>(
+ reinterpret_cast<char*>(begin), len, &parse_result);
+ if (UNLIKELY(parse_result != StringParser::PARSE_SUCCESS)) {
+ return false;
+ }
+ num = int_value;
+ return true;
+ };
+ char *first_colon {nullptr}, *second_colon {nullptr};
+ if ((first_colon = (char*)memchr(first_char, ':', len)) != nullptr) {
+ if ((second_colon = (char*)memchr(first_colon + 1, ':', end_char -
first_colon - 1)) !=
+ nullptr) {
+ // find tow colon
+ // parse hour
+ if (!parse_from_str_to_int(first_char, first_colon -
first_char, hour)) {
+ // hour failed
+ return false;
+ }
+ // parse minute
+ if (!parse_from_str_to_int(first_colon + 1, second_colon -
first_colon - 1,
+ minute)) {
+ return false;
+ }
+ // parse second
+ if (!parse_from_str_to_int(second_colon + 1, end_char -
second_colon - 1, second)) {
+ return false;
+ }
+ } else {
+ // find one colon
+ // parse hour
+ if (!parse_from_str_to_int(first_char, first_colon -
first_char, hour)) {
+ return false;
+ }
+ // parse minute
+ if (!parse_from_str_to_int(first_colon + 1, end_char -
first_colon - 1, minute)) {
+ return false;
+ }
+ }
+ } else {
+ // no colon ,so try to parse as a number
+ size_t from {};
+ if (!parse_from_str_to_int(first_char, len, from)) {
+ return false;
+ }
+ return try_parse_time(from, x);
+ }
+ // minute second must be < 60
+ if (minute >= 60 || second >= 60) {
+ return false;
+ }
+ x = hour * 3600 + minute * 60 + second;
+ return true;
+ }
+ // Cast from number
+ template <typename T, typename S>
+ static bool try_parse_time(T from, S& x) {
+ int64 seconds = from;
+ int64 hour = 0, minute = 0, second = 0;
+ second = seconds % 100;
+ seconds /= 100;
Review Comment:
```
seconds=from/100
second=from-seconds*100
```
Maybe performance will be better this way
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