Fix performance drop of iterating over lines and other stuff

- Fix 'STASHED' key and unsupported syntax in 5.0.2
- Optimise `if` statement to make it more idiomatic.

lib/git.zsh

@@ -150,15 +150,11 @@ function git_prompt_long_sha() {
 function git_prompt_status() {
   [[ "$(__git_prompt_git config --get oh-my-zsh.hide-status 2>/dev/null)" = 1 ]] && return
 
-  local status_prompt=""
-
-  # A lookup table of each git status encountered
-  local -A statuses_seen
-
   # Maps a git status prefix to an internal constant
   # This cannot use the prompt constants, as they may be empty
-  local -A prefix_constant_map=(
-    '?? '       'UNTRACKED'
+  local -A prefix_constant_map
+  prefix_constant_map=(
+    '\?\? '     'UNTRACKED'
     'A  '       'ADDED'
     'M  '       'ADDED'
     'MM '       'ADDED'
@@ -176,7 +172,8 @@ function git_prompt_status() {
   )
 
   # Maps the internal constant to the prompt theme
-  local -A constant_prompt_map=(
+  local -A constant_prompt_map
+  constant_prompt_map=(
     'UNTRACKED' "$ZSH_THEME_GIT_PROMPT_UNTRACKED"
     'ADDED'     "$ZSH_THEME_GIT_PROMPT_ADDED"
     'MODIFIED'  "$ZSH_THEME_GIT_PROMPT_MODIFIED"
@@ -190,25 +187,33 @@ function git_prompt_status() {
   )
 
   # The order that the prompt displays should be added to the prompt
-  local status_constants=(UNTRACKED ADDED MODIFIED RENAMED DELETED STASHED
-                          UNMERGED AHEAD BEHIND DIVERGED)
+  local status_constants
+  status_constants=(
+    UNTRACKED ADDED MODIFIED RENAMED DELETED
+    STASHED UNMERGED AHEAD BEHIND DIVERGED
+  )
 
-  local status_text=$(__git_prompt_git status --porcelain -b 2> /dev/null)
+  local status_text="$(__git_prompt_git status --porcelain -b 2> /dev/null)"
 
   # Don't continue on a catastrophic failure
   if [[ $? -eq 128 ]]; then
     return 1
   fi
 
-  if $(__git_prompt_git rev-parse --verify refs/stash >/dev/null 2>&1); then
-    statuses_seen['STASHED']=1
+  # A lookup table of each git status encountered
+  local -A statuses_seen
+
+  if __git_prompt_git rev-parse --verify refs/stash &>/dev/null; then
+    statuses_seen[STASHED]=1
   fi
 
-  local status_lines=("${(@f)${status_text}}");
+  local status_lines
+  status_lines=("${(@f)${status_text}}")
 
   # If the tracking line exists, get and parse it
-  if [[ $status_lines[1] =~ "^## [^ ]+ \[(.*)\]" ]]; then
-    local branch_statuses=("${(@s/,/)match}")
+  if [[ "$status_lines[1]" =~ "^## [^ ]+ \[(.*)\]" ]]; then
+    local branch_statuses
+    branch_statuses=("${(@s/,/)match}")
     for branch_status in $branch_statuses; do
       if [[ ! $branch_status =~ "(behind|diverged|ahead) ([0-9]+)?" ]]; then
         continue
@@ -216,29 +221,22 @@ function git_prompt_status() {
       local last_parsed_status=$prefix_constant_map[$match[1]]
       statuses_seen[$last_parsed_status]=$match[2]
     done
-    shift status_lines
   fi
 
-  # This not only gives us a status lookup, but the count of each type
-  for status_line in ${status_lines}; do
-    local status_prefix=${status_line[1, 3]}
-    local status_constant=${(v)prefix_constant_map[$status_prefix]}
+  # For each status prefix, do a regex comparison
+  for status_prefix in ${(k)prefix_constant_map}; do
+    local status_constant="${prefix_constant_map[$status_prefix]}"
+    local status_regex="(^|\n)$status_prefix"
 
-    if [[ -z $status_constant ]]; then
-      continue
+    if [[ "$status_text" =~ $status_regex ]]; then
+      statuses_seen[$status_constant]=1
     fi
-
-    (( statuses_seen[$status_constant]++ ))
   done
 
-  # At this point, the statuses_seen hash contains:
-  # - Tracking      => The difference between tracked and current
-  # - Modifications => The count of that type of modification
-  # - Stash         => Whether or not a stash exists
-  # Might be useful for someone?
-
+  # Display the seen statuses in the order specified
+  local status_prompt
   for status_constant in $status_constants; do
-    if [[ ${+statuses_seen[$status_constant]} -eq 1 ]]; then
+    if (( ${+statuses_seen[$status_constant]} )); then
       local next_display=$constant_prompt_map[$status_constant]
       status_prompt="$next_display$status_prompt"
     fi