import first prototype

[code/topgit-ng.git] / tg-datastore-pcommits.inc

diff --git a/tg-datastore-pcommits.inc b/tg-datastore-pcommits.inc
new file mode 100644 (file)
index 0000000..f03ede5
--- /dev/null
+++ b/tg-datastore-pcommits.inc
@@ -0,0 +1,85 @@
+_get_empty_treeref()
+{
+  git mktree </dev/null
+}
+
+_make_pcommit()
+{
+  local timestamp; timestamp=$(date +'%s %z')
+  git hash-object -t commit -w --stdin <<-_commit_data
+       tree $(_get_empty_treeref)
+       author TopGit <> $timestamp
+       committer "$author"
+       x-topgit-data-node yes
+
+       TopGit data node
+
+       This commit is used internally by TopGit. Please just ignore it.
+
+       TopGit data follow:
+       $(cat)
+       _commit_data
+}
+
+_append_parentref_to_HEAD()
+{
+  local parent; parent="$1"
+  local ref; ref=$(git cat-file commit HEAD |
+                     sed -e "/^parent/aparent ${parent}" |
+                     git hash-object -t commit -w --stdin)
+  git update-ref HEAD $ref
+}
+
+_remove_parentref_from_HEAD()
+{
+  local parent; parent="$1"
+  local ref; ref=$(git cat-file commit HEAD |
+                     grep -v "^parent ${parent}" |
+                     git hash-object -t commit -w --stdin)
+  git update-ref HEAD $ref
+}
+
+# returns 0 if $1 is a valid TopGit pcommit
+_is_pcommit()
+{
+  local pcommit; pcommit="$1"
+  git cat-file commit $pcommit | grep -q '^x-topgit-data-node yes$'
+}
+
+# returns the ref of the pcommit attached to $1
+# returns 1 when none is found
+_find_pcommit()
+{
+  local commit; commit="$1"
+  local parentnr; parentnr=1
+
+  while :; do
+    ref=$(tg_ds_resolve_commit "${commit}^${parentnr}") || break
+    _is_pcommit "$ref" && printf "$ref\n" && return 0
+    parentnr=$(($parentnr + 1))
+  done
+  return 1
+}
+
+# expects data on stdin and adds to HEAD
+tg_ds_add_data()
+{
+  local author; author=$(git cat-file commit HEAD | sed -rne 's,^author ,,p')
+  _append_parentref_to_HEAD $(_make_pcommit "$author")
+}
+
+# removes data from HEAD
+tg_ds_remove_data()
+{
+  local pcommit; pcommit=$(_find_pcommit HEAD) || return   # no error
+  _remove_parentref_from_HEAD $pcommit
+}
+
+# lists data on a given commit
+tg_ds_list_data()
+{
+  local commit; commit="${1:-HEAD}"
+  ref=$(tg_ds_resolve_commit $commit) || die "tg_ds_list_data: invalid commit: $commit"
+  local pcommit; pcommit=$(_find_pcommit $commit) || return 1
+  git cat-file commit $pcommit | sed -e '0,/^TopGit data follow:$/d'
+}