Fix documentation that implies pattern argument can be empty

Fixes tidyverse#508

R/count.R

@@ -4,6 +4,20 @@
 #' of `string.`
 #'
 #' @inheritParams str_detect
+#' @param pattern Pattern to look for.
+#'
+#'   The default interpretation is a regular expression, as described in
+#'   `vignette("regular-expressions")`. Use [regex()] for finer control of the
+#'   matching behaviour.
+#'
+#'   Match a fixed string (i.e. by comparing only bytes), using
+#'   [fixed()]. This is fast, but approximate. Generally,
+#'   for matching human text, you'll want [coll()] which
+#'   respects character matching rules for the specified locale.
+#'
+#'   Match character, word, line and sentence boundaries with
+#'   [boundary()]. An empty pattern, "", is equivalent to
+#'   `boundary("character")`.
 #' @return An integer vector the same length as `string`/`pattern`.
 #' @seealso [stringi::stri_count()] which this function wraps.
 #'

R/detect.R

@@ -17,9 +17,8 @@
 #'   for matching human text, you'll want [coll()] which
 #'   respects character matching rules for the specified locale.
 #'
-#'   Match character, word, line and sentence boundaries with
-#'   [boundary()]. An empty pattern, "", is equivalent to
-#'   `boundary("character")`.
+#'   Pattern cannot be a character, word, line, or sentence boundary. An empty
+#'   pattern, "", is equivalent to `boundary("character")`.
 #'
 #' @param negate If `TRUE`, inverts the resulting boolean vector.
 #' @return A logical vector the same length as `string`/`pattern`.

R/extract.R

@@ -3,7 +3,7 @@
 #' `str_extract()` extracts the first complete match from each string,
 #' `str_extract_all()`extracts all matches from each string.
 #'
-#' @inheritParams str_detect
+#' @inheritParams str_count
 #' @param group If supplied, instead of returning the complete match, will
 #'   return the matched text from the specified capturing group.
 #' @seealso [str_match()] to extract matched groups;

R/locate.R

@@ -7,7 +7,7 @@
 #' Because the `start` and `end` values are inclusive, zero-length matches
 #' (e.g. `$`, `^`, `\\b`) will have an `end` that is smaller than `start`.
 #'
-#' @inheritParams str_detect
+#' @inheritParams str_count
 #' @returns
 #' * `str_locate()` returns an integer matrix with two columns and
 #'   one row for each element of `string`. The first column, `start`,

R/split.R

@@ -16,7 +16,6 @@
 #' * `str_split_fixed()` splits each string in a character vector into a
 #'    fixed number of pieces, returning a character matrix.
 #'
-#' @inheritParams str_detect
 #' @inheritParams str_extract
 #' @param n Maximum number of pieces to return. Default (Inf) uses all
 #'   possible split positions.