Finish Git rework

The final output of the Git formatting should be identical. But not only
is it faster, it is broken into multiple data functions that can be used
to format Git repo data any way that a theme wants.

The API isn't stable yet, as I'm sure things will need to change when I
do the other VCS functions. I want all VCSs to return data with the same
API so that themes can theme VCS data only once instead of once per VCS.

liquidprompt

@@ -960,28 +960,53 @@ _lp_smart_mark() {
 
 # GIT #
 
-# Get the branch name of the current directory
-_lp_git_branch() {
-    (( LP_ENABLE_GIT )) || return
-
-    \git rev-parse --is-inside-work-tree >/dev/null 2>&1 || return
+# Check if Git is enabled in Liquidprompt and the current directory is a valid
+# Git repository. This check should be done before running any other _lp_git_*
+# data functions.
+# return: false if Git disabled (2) or not a valid repo (1), true otherwise.
+_lp_git_active() {
+    (( LP_ENABLE_GIT )) || return 2
+    \git rev-parse --is-inside-work-tree >/dev/null 2>&1 || return 1
+}
 
+# Get the branch name of the repo in the current directory.
+# return: true if a valid Git branch is checked out.
+#         lp_vcs_branch; the name of the current branch.
+_lp_git_branch() {
     local branch ret
     # Recent versions of Git support the --short option for symbolic-ref, but
     # not 1.7.9 (Ubuntu 12.04)
-    if branch="$(\git symbolic-ref -q HEAD)"; then
+    if branch="$(\git symbolic-ref -q HEAD 2>/dev/null)"; then
         __lp_escape "${branch#refs/heads/}"
         lp_vcs_branch="$ret"
     else
-        # In detached head state, use commit instead
-        # No escape needed
-        lp_vcs_branch="$(\git rev-parse --short -q HEAD)"
+        return 1
+    fi
+}
+
+# Get a tag name of the repo in the current directory.
+# return: true if a valid Git tag matches the HEAD commit.
+#         lp_vcs_tag; the name of (one of) the current tag(s).
+_lp_git_tag() {
+    local tag ret
+    if tag="$(\git describe --tags --exact-match 2>/dev/null)"; then
+        __lp_escape "$tag"
+        lp_vcs_tag="$ret"
+    else
+        return 1
     fi
 }
 
+# Get the current full commit hash of the repo in the current directory.
+# return: lp_vcs_commit_id; the hash of the HEAD commit.
+_lp_git_commit_id() {
+    lp_vcs_commit_id="$(\git rev-parse -q HEAD 2>/dev/null)"
+}
 
-# Display additional information if HEAD is in merging, rebasing
-# or cherry-picking state
+# Get additional information if HEAD is in merging, rebasing
+# or cherry-picking state.
+# return: true if any extra state is found.
+#         lp_vcs_head_status; the extra repo state.
 _lp_git_head_status() {
     local gitdir="${lp_vcs_root}/.git"
     if [[ -f "${gitdir}/MERGE_HEAD" ]]; then
@@ -995,9 +1020,12 @@ _lp_git_head_status() {
     fi
 }
 
+# Get the number of Git stashes in the repo.
+# return: true if any stashes are found.
+#         lp_vcs_stash_count; the number of stashes.
 _lp_git_stash_count() {
     local stashes count
-    stashes="$(\git rev-parse --verify -q refs/stash; printf x)"
+    stashes="$(\git rev-parse --verify -q refs/stash 2>/dev/null; printf x)"
     __lp_line_count "${stashes%x}"
     lp_vcs_stash_count=$count
     (( lp_vcs_stash_count ))
@@ -1017,20 +1045,82 @@ _lp_git_commits_off_remote() {
     (( lp_vcs_commit_behind || lp_vcs_commit_ahead ))
 }
 
+# Get the number of untracked files in the repo.
+# return: true if any untracked files exist.
+#         lp_vcs_untracked_files: the number of untracked files.
 _lp_git_untracked_files() {
     lp_vcs_untracked_files="$(LC_ALL=C \git status --porcelain 2>/dev/null | \grep -c '^??')"
     (( lp_vcs_untracked_files ))
 }
 
+# Get the number of changed lines compared to HEAD
+# return: true if any lines differ from HEAD
+#         lp_vcs_uncommitted_i_lines; the number of lines inserted
+#         lp_vcs_uncommitted_d_lines; the number of lines deleted
+_lp_git_uncommitted_lines() {
+    local stat
+    stat="$(LC_ALL=C \git diff --shortstat HEAD -- 2>/dev/null)"
+
+    stat=${stat/*changed, /} # removing "n file(s) changed"
+
+    if [[ "$stat" = *insertion* ]]; then
+        lp_vcs_uncommitted_i_lines=${stat/ inser*}
+    else
+        lp_vcs_uncommitted_i_lines=0
+    fi
+
+    if [[ "$stat" = *deletion* ]]; then
+        stat=${stat/*\(+\), }
+        lp_vcs_uncommitted_d_lines=${stat/ del*/}
+    else
+        lp_vcs_uncommitted_d_lines=0
+    fi
+
+    (( lp_vcs_uncommitted_i_lines || lp_vcs_uncommitted_d_lines ))
+}
+
+# Get the number of changed lines compared to staging
+# return: true if any lines differ from staging
+#         lp_vcs_unstaged_i_lines; the number of lines inserted
+#         lp_vcs_unstaged_d_lines; the number of lines deleted
+_lp_git_unstaged_lines() {
+    local stat
+    stat="$(LC_ALL=C \git diff --shortstat 2>/dev/null)"
+
+    stat=${stat/*changed, /} # removing "n file(s) changed"
+
+    if [[ "$stat" = *insertion* ]]; then
+        lp_vcs_unstaged_i_lines=${stat/ inser*}
+    else
+        lp_vcs_unstaged_i_lines=0
+    fi
+
+    if [[ "$stat" = *deletion* ]]; then
+        stat=${stat/*\(+\), }
+        lp_vcs_unstaged_d_lines=${stat/ del*/}
+    else
+        lp_vcs_unstaged_d_lines=0
+    fi
+
+    (( lp_vcs_unstaged_i_lines || lp_vcs_unstaged_d_lines ))
+}
+
 # Set a color depending on the branch state:
 # - green if the repository is up to date
 # - yellow if there is some commits not pushed
 # - red if there is changes to commit
-#
 # Add the number of pending commits and the impacted lines.
+# return: lp_vcs_branch_color; the detailed formatted string of repo details
 _lp_git_branch_color() {
-    _lp_git_branch || return $?
-    local branch="$lp_vcs_branch"
+    local branch
+    if _lp_git_branch; then
+        branch="$lp_vcs_branch"
+    elif _lp_git_tag; then
+        branch="tag: $lp_vcs_tag"
+    else
+        _lp_git_commit_id
+        branch="${lp_vcs_commit_id:0:7}"
+    fi
 
     local end="$NO_COL"
     if _lp_git_head_status; then
@@ -1057,31 +1147,11 @@ _lp_git_branch_color() {
     fi
 
     local ret
-    local shortstat # only to check for uncommitted changes
-    shortstat="$(LC_ALL=C \git diff --shortstat HEAD -- 2>/dev/null)"
-
-    if [[ -n "$shortstat" ]]; then
-        local u_stat # shorstat of *unstaged* changes
-        u_stat="$(LC_ALL=C \git diff --shortstat 2>/dev/null)"
-        u_stat=${u_stat/*changed, /} # removing "n file(s) changed"
-
-        local i_lines # inserted lines
-        if [[ "$u_stat" = *insertion* ]]; then
-            i_lines=${u_stat/ inser*}
-        else
-            i_lines=0
-        fi
-
-        local d_lines # deleted lines
-        if [[ "$u_stat" = *deletion* ]]; then
-            d_lines=${u_stat/*\(+\), }
-            d_lines=${d_lines/ del*/}
-        else
-            d_lines=0
-        fi
+    if _lp_git_uncommitted_lines; then
+        _lp_git_unstaged_lines
 
         local has_lines
-        has_lines="+$i_lines/-$d_lines"
+        has_lines="+$lp_vcs_unstaged_i_lines/-$lp_vcs_unstaged_d_lines"
 
         if [[ -n "$has_commit" ]]; then
             # Changes to commit and commits to push
@@ -1091,7 +1161,7 @@ _lp_git_branch_color() {
         fi
     elif [[ -n "$has_commit" ]]; then
         # some commit(s) to push
-        if [[ "$commit_behind" -gt "0" ]]; then
+        if [[ "$lp_vcs_commit_behind" -gt "0" ]]; then
             ret="${LP_COLOR_COMMITS_BEHIND}${branch}${NO_COL}($has_commit)"
         else
             ret="${LP_COLOR_COMMITS}${branch}${NO_COL}($has_commit)"