📚 Update #search documentation

Author: nevans

lib/net/imap.rb

@@ -1930,15 +1930,35 @@ def uid_expunge(uid_set)
     end
 
     # Sends a {SEARCH command [IMAP4rev1 §6.4.4]}[https://www.rfc-editor.org/rfc/rfc3501#section-6.4.4]
-    # to search the mailbox for messages that match the given searching
-    # criteria, and returns message sequence numbers.  +keys+ can either be a
-    # string holding the entire search string, or a single-dimension array of
-    # search keywords and arguments.
-    #
-    # Returns a SearchResult object.  SearchResult inherits from Array (for
+    # to search the mailbox for messages that match the given search +criteria+,
+    # and returns a SearchResult.  SearchResult inherits from Array (for
     # backward compatibility) but adds SearchResult#modseq when the +CONDSTORE+
     # capability has been enabled.
     #
+    # +criteria+ is one or more search keys and their arguments, which may be
+    # provided as an array or a string.
+    #
+    #  * When +criteria+ is an array, any array members will be converted into
+    #    a SequenceSet.  _NOTE:_ this means that a parenthesized list cannot be
+    #    sent when +criteria+ is an array.
+    #
+    #  * When +criteria+ is a string, it will be sent directly to the server
+    #    <em>without any validation</em>.  *WARNING:* This is vulnerable to
+    #    injection attacks when external inputs are used.
+    #
+    # +charset+ is the name of the {registered character
+    # set}[https://www.iana.org/assignments/character-sets/character-sets.xhtml]
+    # used by strings in the search +criteria+.  When +charset+ isn't specified,
+    # either <tt>"US-ASCII"</tt> or <tt"UTF-8"</tt> is assumed, depending on the
+    # server's capabilities.
+    #
+    # _NOTE:_ +charset+ may be sent as part of +criteria+.
+    # Do not use the +charset+ argument when it is embedded in +criteria+.
+    # For example:
+    #
+    #    imap.search("CHARSET UTF-8 OR UNSEEN FLAGGED")
+    #    imap.search(%w[CHARSET UTF-8 OR UNSEEN FLAGGED])
+    #
     # Related: #uid_search
     #
     # ===== Search criteria
@@ -1989,11 +2009,14 @@ def uid_expunge(uid_set)
     #
     # ===== Capabilities
     #
-    # If [CONDSTORE[https://www.rfc-editor.org/rfc/rfc7162.html]] is supported
+    # When +IMAP4rev2+ is enabled, or when the server supports +IMAP4rev2+ but
+    # not +IMAP4rev1+, ESearchResult is always returned instead of SearchResult.
+    #
+    # If CONDSTORE[https://www.rfc-editor.org/rfc/rfc7162.html] is supported
     # and enabled for the selected mailbox, a non-empty SearchResult will
     # include a +MODSEQ+ value.
     #   imap.select("mbox", condstore: true)
-    #   result = imap.search(["SUBJECT", "hi there", "not", "new")
+    #   result = imap.search(["SUBJECT", "hi there", "not", "new"])
     #   #=> Net::IMAP::SearchResult[1, 6, 7, 8, modseq: 5594]
     #   result.modseq # => 5594
     def search(keys, charset = nil)
@@ -2008,7 +2031,7 @@ def search(keys, charset = nil)
     # backward compatibility) but adds SearchResult#modseq when the +CONDSTORE+
     # capability has been enabled.
     #
-    # See #search for documentation of search criteria.
+    # See #search for documentation of parameters.
     def uid_search(keys, charset = nil)
       return search_internal("UID SEARCH", keys, charset)
     end