[GitHub] [arrow] dragosmg commented on a diff in pull request #13196: ARROW-16407: [R] Extend `parse_date_time` to cover hour, dates, and minutes components

[GitBox <gi...@apache.org>]

dragosmg commented on code in PR #13196:
URL: https://github.com/apache/arrow/pull/13196#discussion_r878249552


##########
r/R/dplyr-funcs-datetime.R:
##########
@@ -488,105 +488,28 @@ register_bindings_duration_helpers <- function() {
 register_bindings_datetime_parsers <- function() {
   register_binding("parse_date_time", function(x,
                                                orders,
-                                               tz = "UTC") {
-
-    # each order is translated into possible formats
-    formats <- build_formats(orders)
-
-    x <- x$cast(string())
-
-    # make all separators (non-letters and non-numbers) into "-"
-    x <- call_binding("gsub", "[^A-Za-z0-9]", "-", x)
-    # collapse multiple separators into a single one
-    x <- call_binding("gsub", "-{2,}", "-", x)
-
-    # we need to transform `x` when orders are `ym`, `my`, and `yq`
-    # for `ym` and `my` orders we add a day ("01")
-    augmented_x <- NULL
-    if (any(orders %in% c("ym", "my"))) {
-      augmented_x <- call_binding("paste0", x, "-01")
-    }
-
-    # for `yq` we need to transform the quarter into the start month (lubridate
-    # behaviour) and then add 01 to parse to the first day of the quarter
-    augmented_x2 <- NULL
-    if (any(orders == "yq")) {
-      # extract everything that comes after the `-` separator, i.e. the quarter
-      # (e.g. 4 from 2022-4)
-      quarter_x <- call_binding("gsub", "^.*?-", "", x)
-      # we should probably error if quarter is not in 1:4
-      # extract everything that comes before the `-`, i.e. the year (e.g. 2002
-      # in 2002-4)
-      year_x <- call_binding("gsub", "-.*$", "", x)
-      quarter_x <- quarter_x$cast(int32())
-      month_x <- (quarter_x - 1) * 3 + 1
-      augmented_x2 <- call_binding("paste0", year_x, "-", month_x, "-01")
-    }
-
-    # TODO figure out how to parse strings that have no separators
-    # https://issues.apache.org/jira/browse/ARROW-16446
-    # we could insert separators at the "likely" positions, but it might be
-    # tricky given the possible combinations between dmy formats + locale
-
-    # build a list of expressions for each format
-    parse_attempt_expressions <- map(
-      formats,
-      ~ build_expr(
-        "strptime",
-        x,
-        options = list(
-          format = .x,
-          unit = 0L,
-          error_is_null = TRUE
-        )
-      )
-    )
-
-    # build separate expression lists of parsing attempts for the orders that
-    # need an augmented `x`
-    # list for attempts when orders %in% c("ym", "my")
-    parse_attempt_exp_augmented_x <- list()
-
-    if (!is.null(augmented_x)) {
-      parse_attempt_exp_augmented_x <- map(
-        formats,
-        ~ build_expr(
-          "strptime",
-          augmented_x,
-          options = list(
-            format = .x,
-            unit = 0L,
-            error_is_null = TRUE
-          )
-        )
-      )
+                                               tz = "UTC",
+                                               truncated = 0,
+                                               quiet = TRUE,
+                                               exact = FALSE) {
+    if (!quiet) {
+      arrow_not_supported("`quiet = FALSE`")
     }
 
-    # list for attempts when orders %in% c("yq")
-    parse_attempt_exp_augmented_x2 <- list()
-    if (!is.null(augmented_x2)) {
-      parse_attempt_exp_augmented_x2 <- map(
-        formats,
-        ~ build_expr(
-          "strptime",
-          augmented_x2,
-          options = list(
-            format = .x,
-            unit = 0L,
-            error_is_null = TRUE
-          )
-        )
-      )
+    if (truncated != 0) {
+      # build several orders for truncated formats
+      orders <- map_chr(0:truncated, ~ substr(orders, start = 1, stop = nchar(orders) - .x))

Review Comment:
   Nope. I was thinking to maybe limit `truncated` to 3 (i.e. error if greater). What do you think?



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