From 2f58f5d883f04e62b6d8869c0c3a14ba785371df Mon Sep 17 00:00:00 2001
From: "martin f. krafft" <madduck@madduck.net>
Date: Tue, 6 May 2008 23:35:34 +0100
Subject: [PATCH] rework the vcs prompt

---
 .zsh/zshrc/85_vcs_prompt | 121 +++++++++++++++++++++++++--------------
 1 file changed, 78 insertions(+), 43 deletions(-)

diff --git a/.zsh/zshrc/85_vcs_prompt b/.zsh/zshrc/85_vcs_prompt
index e0fbbd0..e96b772 100644
--- a/.zsh/zshrc/85_vcs_prompt
+++ b/.zsh/zshrc/85_vcs_prompt
@@ -10,8 +10,9 @@
 # Shamelessly based on http://glandium.org/blog/?p=170
 #
 
-__git_get_repo_root()
+__git_get_reporoot()
 {
+  # return the full path to the root of the current git repository
   local relroot
   relroot="$(git rev-parse --show-cdup 2>/dev/null)" || return 1
   if [ -n "$relroot" ]; then
@@ -23,63 +24,96 @@ __git_get_repo_root()
 
 __git_get_branch()
 {
+  # return the name of the git branch we're on
   local ref
   ref=$(git symbolic-ref -q HEAD 2>/dev/null \
-     || git-name-rev --name-only HEAD 2>/dev/null)
+     || git-name-rev --name-only HEAD 2>/dev/null) || return 1
   echo "${ref#refs/heads/}"
 }
 
-__get_root_offsets()
+__vcs_get_repo_type()
 {
-  local pwda reporoot loc
-  pwda=(${(s:/:)PWD})
-  reporoot=(${(s:/:)1})
-  echo $((1 - $#reporoot)) $(($#pwda - $#reporoot))
+  # return the type of the closest repository in the path hierarchy
+  local dir
+  while true; do
+    [ -d ${dir}.git ] && echo git && break
+    [ -d ${dir}.bzr ] && echo bzr && break
+    [ -d ${dir}.hg ] && echo hg && break
+    [ -d ${dir}.svn ] && echo svn && break
+    [ -d ${dir}.svk ] && echo svk && break
+    [ -d ${dir}CVS ] && echo cvs && break
+    [ "$(readlink -f ${dir:-.})" = / ] && echo NONE && break
+    dir="../$dir"
+  done
 }
 
-__get_prompt_path_components()
+__vcs_get_prompt_path_components()
 {
-  local reporoot
-  reporoot="$1"
+  # return formatted path components (prefix branch postfix) given
+  # the repository root and the branch.
 
-  set -- $(__get_root_offsets "$reporoot")
-  if [ "$2" -le 0 ]; then
-    echo %~
-  else
-    echo "%${1}~" "%${2}~"
+  # shortcut: if there are no arguments, return a default prompt
+  if [ -z "${1:-}" ]; then
+    pwdnamed="%${_PROMPT_PATH_MAXLEN}<..<%~%<<"
+    pwdnamed="${(%)pwdnamed}"
+    echo "$pwdnamed"
+    return
   fi
-}
 
-__vcs_get_repo_type()
-{
-  while true; do
-    [ -d .git ] && echo git && break
-    [ -d .bzr ] && echo bzr && break
-    [ -d .hg ] && echo hg && break
-    [ -d .svn ] && echo svn && break
-    [ -d .svk ] && echo svk && break
-    [ -d CVS ] && echo cvs && break
-    [ "$PWD" = / ] && echo NONE && return 1
-    cd ..
-  done
+  local reporoot branch
+  reporoot="${1%%/}"
+  branch="$2"
+
+  # replace named directories in the PWD, we need thi for the proper component
+  # count later
+  local pwdnamed="%~"
+  pwdnamed="${(%)pwdnamed}"
+
+  # store paths in arrays for component count calculation
+  typeset -la apwd apwdnamed areporoot
+  apwd=(${(s:/:)PWD})
+  apwdnamed=(${(s:/:)pwdnamed})
+  areporoot=(${(s:/:)reporoot})
+
+  # get the number of leading and trailing path components. Since we're using
+  # %~ later and then /home/madduck suddenly becomes ~, which is 1, not
+  # 2 components, we calculate the leading component count by using the named
+  # path and the number of post components
+  local precomps postcomps
+  postcomps=$(($#apwd - $#areporoot))
+  precomps=$(($#apwdnamed - $postcomps))
+
+  local postfix
+  if (( $postcomps > 0 )); then
+    postfix="%${postcomps}~"
+    postfix="${(%)postfix}"
+  fi
+
+  # we don't want the prompt to get too long, so keep the total prompt length
+  # under $_PROMPT_PATH_MAXLEN (25), but ensure that the prefix is not shorter
+  # than $_PROMPT_PATH_MINLEN (10), no matter what
+  local prelen minlen prefix
+  prelen=$((${_PROMPT_PATH_MAXLEN:-25} - $#branch - $#postfix))
+  minlen=${_PROMPT_PATH_MINLEN:-10}
+  (( $prelen < $minlen )) && prelen=$minlen
+  prefix="%${prelen}<..<%-${precomps}~%<<"
+  prefix="${(%)prefix}"
+
+  echo "$prefix" "$branch" "$postfix"
 }
 
 __vcs_set_prompt_variables()
 {
-  local pre branch post
-  local MAXLEN=25
-  local repotype="${1:-$(__vcs_get_repo_type)}"
+  # set psvar[1..3] depending on repo type, or just psvar[1] if no repo found
+  local reporoot branch repotype
+  repotype="${1:-$(__vcs_get_repo_type)}"
 
   case "$repotype" in
     git)
-      local reporoot="$(__git_get_repo_root)"
-      set -- $(__get_prompt_path_components "$reporoot")
-      branch="$(__git_get_branch)"
-      post="${(%)2}"
-      local prelen="$((MAXLEN - $#post - $#branch))"
-      [ $prelen -lt 10 ] && prelen=10
-      pre="%${prelen}<..<${1}%<<"
-      pre="${(%)pre}"
+      reporoot="$(__git_get_reporoot)" ||
+        { error "could not determine git repository root"; return 1 }
+      branch="$(__git_get_branch)" ||
+        { error "could not determine git branch"; return 1 }
       ;;
     *)
       case "$repotype" in
@@ -94,9 +128,10 @@ __vcs_set_prompt_variables()
       return
   esac
 
-  psvar[1]="$pre"
-  psvar[2]="$branch"
-  psvar[3]="$post"
+  set -- $(__vcs_get_prompt_path_components "$reporoot" "$branch")
+  psvar[1]="$1"
+  psvar[2]="$2"
+  psvar[3]="$3"
 }
 
 if ! is_root; then
@@ -106,7 +141,7 @@ if ! is_root; then
     local vcs="$(__vcs_get_repo_type)"
     case "$(history $(($HISTCMD - 1)))" in
       # $vcs appeared in last command, so be sure to update
-      *${vcs}*) __vcs_set_prompt_variables
+      *${vcs}*) __vcs_set_prompt_variables "$vcs"
     esac
   }
   precmd_functions+=_update_vcs_prompt_vars_if_vcs_ran
-- 
2.39.2