22573: smooth interface to history-beginning-search-menu

document how to quote metacharacters for reverse array subscript

1 files changed, 12 insertions, 0 deletions

diff --git a/Doc/Zsh/params.yo b/Doc/Zsh/params.yo
index 9212f8593..fe005ed21 100644
--- a/Doc/Zsh/params.yo
+++ b/Doc/Zsh/params.yo
@@ -211,6 +211,18 @@ example (assuming the option tt(KSH_ARRAYS) is not in effect):
 example([[ ${array[(i)pattern]} -le ${#array} ]])
 
 If tt(KSH_ARRAYS) is in effect, the tt(-le) should be replaced by tt(-lt).
+
+Note that in subscripts with both `tt(r)' and `tt(R)' pattern characters
+are active even if they were substituted for a parameter (regardless
+of the setting of tt(GLOB_SUBST) which controls this feature in normal
+pattern matching).  It is therefore necessary to quote pattern characters
+for an exact string match.  Given a string in tt($key), and assuming
+the tt(EXTENDED_GLOB) option is set, the following is sufficient to
+match an element of an array tt($array) containing exactly the value of
+tt($key):
+
+example(key2=${key//(#m)[\][+LPAR()+RPAR()\\*?#<>]/\\$MATCH}
+print ${array[(R)$key2]})
 )
 item(tt(R))(
 Like `tt(r)', but gives the last match.  For associative arrays, gives