view mercurial/help/revisions.txt @ 18124:79db6d40bced

branchmap: store branchcache in a dedicated object

Value and key of branchcache would benefit from being hold by the same object.
Moreover some logic (update, write, validation) could be move on such object.

The creation of this object is the first step toward this move. The result will
clarify branchcache related code and hide most of the detail in the class
itself. This encapsulation will greatly helps implementation of branchcache for
filtered view of the repo.

Mercurial supports several ways to specify individual revisions.

A plain integer is treated as a revision number. Negative integers are
treated as sequential offsets from the tip, with -1 denoting the tip,
-2 denoting the revision prior to the tip, and so forth.

A 40-digit hexadecimal string is treated as a unique revision
identifier.

A hexadecimal string less than 40 characters long is treated as a
unique revision identifier and is referred to as a short-form
identifier. A short-form identifier is only valid if it is the prefix
of exactly one full-length identifier.

Any other string is treated as a bookmark, tag, or branch name. A
bookmark is a movable pointer to a revision. A tag is a permanent name
associated with a revision. A branch name denotes the tipmost revision
of that branch. Bookmark, tag, and branch names must not contain the ":"
character.

The reserved name "tip" always identifies the most recent revision.

The reserved name "null" indicates the null revision. This is the
revision of an empty repository, and the parent of revision 0.

The reserved name "." indicates the working directory parent. If no
working directory is checked out, it is equivalent to null. If an
uncommitted merge is in progress, "." is the revision of the first
parent.