21933: R. Ramkumar: three new styles for MIME handler

21935: documentation for same.

Functions/MIME/zsh-mime-setup

@@ -157,10 +157,40 @@ fi
   unfunction mime-setup-add-type >&/dev/null
 }
 
+local -a pats_prio o_prios
+local o_overwrite sentinel
+typeset -A type_prio_flags_map type_prio_src_map type_prio_mprio_map
+integer src_id prio mprio
+
+# A list of keywords indicating the methods used to break ties amongst multiple
+# entries. The following keywords are accepted:
+# files: The order of files read: Entries from files read earlier are preferred
+#   (The default value of the variable is a list with this keyword alone)
+# priority: The priority flag is matched in the entry. Can be a value from 0 to
+# 9. The default priority is 5. Higher priorities are preferred.
+# flags: See the mailcap-prio-flags option
+# place: Always overrides. Useful for specifying that entries read later are
+# preferred.
+#
+# As the program reads mailcap entries, if it encounters a duplicate
+# entry, each of the keywords in the list are checked to see if the new
+# entry can override the existing entry. If none of the keywords are able
+# to decide whether the new entry should be preferred to the older one, the
+# new entry is discarded.
+zstyle -a :mime: mailcap-priorities o_prios || o_prios=(files)
+
+# This style is used as an argument for the flags test in mailcap-priorities.
+# This is a list of patterns, each of which is tested against the flags for the
+# mailcap entry. An match with a pattern ahead in the list is preferred as
+# opposed to a match later in the list. An unmatched item is least preferred.
+zstyle -a :mime: mailcap-prio-flags pats_prio
+
 # Loop through files to find handlers for types.
+((src_id = 0))
 for file in $cap_files; do
   [[ -r $file ]] || continue
 
+  ((src_id = src_id + 1))
   # Oh, great.  We need to preserve backslashes inside the line,
   # but need to manage continuation lines.
   while read -r line; do
@@ -197,13 +227,66 @@ for file in $cap_files; do
       # and remove any surrounding white space --- this might
       # make the handler empty.
       line=${${line##[[:space:]]#}%%[[:space:]]}
-      if [[ -z $type_handler_map[$type] ]]; then
-        if [[ -n $o_verbose ]]; then
-          print -r "Adding handler for type $type:
+
+      ((prio = 0))
+      for i in $pats_prio; do
+	  # print -r "Comparing $i with '$flags'" >&2
+	[[ $flags = ${~i} ]] && break
+	  # print -r "Comparison failed" >&2
+	((prio = prio + 1))
+      done
+      ((mprio=5))
+      [[ $flags = (#b)*priority=([0-9])* ]] && mprio=$match[1]
+      sentinel=no
+      if [[ -n $type_handler_map[$type] ]]; then
+	for i in $o_prios; do
+	  case $i in
+	    (files)
+	    if [[ $src_id -lt $type_prio_src_map[$type] ]]; then
+	      sentinel=yes; break
+	    elif [[ $src_id -gt $type_prio_src_map[$type] ]]; then
+	      sentinel=no; break
+	    fi
+	    ;;
+	    (priority)
+	    if [[ $mprio -gt $type_prio_mprio_map[$type] ]]; then
+	      sentinel=yes; break
+	    elif [[ $mprio -lt $type_prio_mprio_map[$type] ]]; then
+	      sentinel=no; break
+	    fi
+	    ;;
+	    (flags)
+	    if [[ $prio -lt $type_prio_flags_map[$type] ]]; then
+	      sentinel=yes; break
+	    elif [[ $prio -gt $type_prio_flags_map[$type] ]]; then
+	      sentinel=no; break
+	    fi
+	    ;;
+	    (place)
+	    sentinel=yes
+	    break
+	    ;;
+	  esac
+	done
+      else
+	sentinel=yes
+      fi
+
+      if [[ $sentinel = yes ]]; then
+	if [[ -n $o_verbose ]]; then
+	  if [[ -n $type_handler_map[$type] ]]; then
+	    print -r "Overriding" >&2
+	  else
+	    print -r "Adding" >&2
+	  fi
+	  print -r " handler for type $type:
   $line" >&2
 	fi
 	type_handler_map[$type]=$line
 	type_flags_map[$type]=$flags
+	type_prio_src_map[$type]=$src_id
+	type_prio_flags_map[$type]=$prio
+	type_prio_mprio_map[$type]=$mprio
 	if [[ -n $flags && -n $o_verbose ]]; then
 	  print -r "  with flags $flags" >&2
 	fi