[GitHub] [arrow] dragosmg commented on a change in pull request #12353: ARROW-14471: [R] Implement lubridate's date/time parsing functions

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dragosmg commented on a change in pull request #12353:
URL: https://github.com/apache/arrow/pull/12353#discussion_r803882802



##########
File path: r/R/dplyr-funcs-datetime.R
##########
@@ -148,4 +148,56 @@ register_bindings_datetime <- function() {
     !call_binding("am", x)
   })
 
+  register_binding("ymd", function(x) {
+    format_map <-
+      list(
+        ymd_hyphen1 = "%Y-%m-%d",
+        ymd_hyphen2 = "%y-%m-%d",
+        ymd_hyphen3 = "%Y-%B-%d",
+        ymd_hyphen4 = "%y-%B-%d",
+        ymd_hyphen5 = "%Y-%b-%d",
+        ymd_hyphen6 = "%y-%b-%d",

Review comment:
       Reducing the formats works (I might have to implement it in several steps to handle `" "` and multiple instances of the same separator). There are a couple of outstanding issues:
   
   * `coalesce()` needs the first call to `call_binding("strptime")` to return `NA` in order to move on to the second one and so on. Instead the first call errors and the second one never get evaluated. `tryCatch()` doesn't seem to work in this context.
   * short (`"%y"`) vs long (`"%Y"`) years. If the string contains a short year (e.g. "19") libarrrow will not error for the first format, but instead return `0019`.  




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