Add shrink-path plugin to shorten directory paths (e.g. ~/f/b/quux) (#5262)

* Add shrink-path plugin to shorten directory paths (e.g. ~/f/b/quux)

* Add a README

plugins/shrink-path/README.md

+# A plugin to shrink directory paths for brevity and pretty-printing
+
+
+## Examples
+
+For this directory tree:
+```
+    /home/
+      me/
+        foo/
+          bar/
+            quux/
+          biz/     # The prefix b is ambiguous between bar and biz.
+```
+here are the results of calling `shrink_path <option> /home/me/foo/bar/quux`:
+```
+    Option        Result
+    <none>        /h/m/f/ba/q
+    -l|--last     /h/m/f/ba/quux
+    -s|--short    /h/m/f/b/q
+    -t|--tilde    ~/f/ba/q
+    -f|--fish     ~/f/b/quux
+```
+
+
+## Usage
+
+For a fish-style working directory in your command prompt, add the following to
+your theme or zshrc:
+
+```
+    setopt prompt_subst
+    PS1='%n@%m $(shrink_path -f)>'
+```
+
+The following options are available:
+
+```
+    -f, --fish       fish simulation, equivalent to -l -s -t.
+    -l, --last       Print the last directory's full name.
+    -s, --short      Truncate directory names to the first character. Without
+                     -s, names are truncated without making them ambiguous.
+    -t, --tilde      Substitute ~ for the home directory.
+    -T, --nameddirs  Substitute named directories as well.
+```
+
+The long options can also be set via zstyle, like
+```
+    zstyle :prompt:shrink_path fish yes
+```
+
+Note: Directory names containing two or more consecutive spaces are not yet
+supported.
+
+
+## License
+
+Copyright (C) 2008 by Daniel Friesel <derf@xxxxxxxxxxxxxxxxxx>
+
+License: WTFPL <http://sam.zoy.org/wtfpl>
+
+Ref: http://www.zsh.org/mla/workers/2009/msg00415.html
+     http://www.zsh.org/mla/workers/2009/msg00419.html
+
+
+## Misc
+
+Keywords: prompt directory truncate shrink collapse fish

plugins/shrink-path/shrink-path.plugin.zsh

+# Shrink directory paths, e.g. /home/me/foo/bar/quux -> ~/f/b/quux.
+#
+# For a fish-style working directory in your command prompt, add the following
+# to your theme or zshrc:
+#
+#   setopt prompt_subst
+#   PS1='%n@%m $(shrink_path -f)>'
+#
+# The following options are available:
+#
+#   -f, --fish       fish simulation, equivalent to -l -s -t.
+#   -l, --last       Print the last directory's full name.
+#   -s, --short      Truncate directory names to the first character. Without
+#                    -s, names are truncated without making them ambiguous.
+#   -t, --tilde      Substitute ~ for the home directory.
+#   -T, --nameddirs  Substitute named directories as well.
+#
+# The long options can also be set via zstyle, like
+#   zstyle :prompt:shrink_path fish yes
+#
+# Note: Directory names containing two or more consecutive spaces are not yet
+# supported.
+#
+# Keywords: prompt directory truncate shrink collapse fish
+#
+# Copyright (C) 2008 by Daniel Friesel <derf@xxxxxxxxxxxxxxxxxx>
+# License: WTFPL <http://sam.zoy.org/wtfpl>
+#
+# Ref: http://www.zsh.org/mla/workers/2009/msg00415.html
+#      http://www.zsh.org/mla/workers/2009/msg00419.html
+
+shrink_path () {
+        setopt localoptions
+        setopt rc_quotes null_glob
+
+        typeset -i lastfull=0
+        typeset -i short=0
+        typeset -i tilde=0
+        typeset -i named=0
+
+        if zstyle -t ':prompt:shrink_path' fish; then
+                lastfull=1
+                short=1
+                tilde=1
+        fi
+        if zstyle -t ':prompt:shrink_path' nameddirs; then
+                tilde=1
+                named=1
+        fi
+        zstyle -t ':prompt:shrink_path' last && lastfull=1
+        zstyle -t ':prompt:shrink_path' short && short=1
+        zstyle -t ':prompt:shrink_path' tilde && tilde=1
+
+        while [[ $1 == -* ]]; do
+                case $1 in
+                        -f|--fish)
+                                lastfull=1
+                                short=1
+                                tilde=1
+                        ;;
+                        -h|--help)
+                                print 'Usage: shrink_path [-f -l -s -t] [directory]'
+                                print ' -f, --fish      fish-simulation, like -l -s -t'
+                                print ' -l, --last      Print the last directory''s full name'
+                                print ' -s, --short     Truncate directory names to the first character'
+                                print ' -t, --tilde     Substitute ~ for the home directory'
+                                print ' -T, --nameddirs Substitute named directories as well'
+                                print 'The long options can also be set via zstyle, like'
+                                print '  zstyle :prompt:shrink_path fish yes'
+                                return 0
+                        ;;
+                        -l|--last) lastfull=1 ;;
+                        -s|--short) short=1 ;;
+                        -t|--tilde) tilde=1 ;;
+                        -T|--nameddirs)
+                                tilde=1
+                                named=1
+                        ;;
+                esac
+                shift
+        done
+
+        typeset -a tree expn
+        typeset result part dir=${1-$PWD}
+        typeset -i i
+
+        [[ -d $dir ]] || return 0
+
+        if (( named )) {
+                for part in ${(k)nameddirs}; {
+                        [[ $dir == ${nameddirs[$part]}(/*|) ]] && dir=${dir/${nameddirs[$part]}/\~$part}
+                }
+        }
+        (( tilde )) && dir=${dir/$HOME/\~}
+        tree=(${(s:/:)dir})
+        (
+                unfunction chpwd 2> /dev/null
+                if [[ $tree[1] == \~* ]] {
+                        cd ${~tree[1]}
+                        result=$tree[1]
+                        shift tree
+                } else {
+                        cd /
+                }
+                for dir in $tree; {
+                        if (( lastfull && $#tree == 1 )) {
+                                result+="/$tree"
+                                break
+                        }
+                        expn=(a b)
+                        part=''
+                        i=0
+                        until [[ (( ${#expn} == 1 )) || $dir = $expn || $i -gt 99 ]]  do
+                                (( i++ ))
+                                part+=$dir[$i]
+                                expn=($(echo ${part}*(-/)))
+                                (( short )) && break
+                        done
+                        result+="/$part"
+                        cd $dir
+                        shift tree
+                }
+                echo ${result:-/}
+        )
+}
+
+## vim:ft=zsh