merge: use constants for merge record state Named constants are easier to read than short string values. Differential Revision: https://phab.mercurial-scm.org/D2700

merge: use constants for merge driver state Named constants are superior to magic values. Differential Revision: https://phab.mercurial-scm.org/D2699

merge: use constants for merge state record types merge.py is using multiple discrete sets of 1 and 2 letter constants to define types and behavior. To the uninitiated, the code is very difficult to reason about. I didn't even realize there were multiple sets of constants in play initially! We begin our sanity injection with merge state records. The record types (which are serialized to disk) are now defined in RECORD_* constants. Differential Revision: https://phab.mercurial-scm.org/D2698

histedit: always define update results Before, we had a branch that could return None for the update stats. Let's just return an updateresult instance instead. Differential Revision: https://phab.mercurial-scm.org/D2693

merge: return an attrs class from update() and applyupdates() Previously, we returned a tuple containing counts. The result of an update is kind of complex and the use of tuples with nameless fields made the code a bit harder to read and constrained future expansion of the return value. Let's invent an attrs-defined class for representing the result of an update operation. We provide __getitem__ and __len__ implementations for backwards compatibility as a container type to minimize code churn. In (at least) Python 2, the % operator seems to insist on using tuples. So we had to update a consumer using the % operator. .. api:: merge.update() and merge.applyupdates() now return a class with named attributes instead of a tuple. Switch consumers to access elements by name instead of by offset. Differential Revision: https://phab.mercurial-scm.org/D2692

histedit: make histedit's commands accept revsets (issue5746) Earlier the code was only looking for rulehashes and neglecting all other revision identifiers, this code intercepts the fromrule function and calls scmutil.revsingle() on anything that is not a rulehash and then obtains the rulehash from the changectx object returned, rest of the pipeline follows as it was Differential Revision: https://phab.mercurial-scm.org/D2394

formatter: make 'originalnode' a thing in log-like templates mapping['node'] doesn't work since {node} is computed dynamically in non-web templates.

formatter: port handling of 'originalnode' to populatemap() hook This isn't a pure templating business, so let's move out of the templater module. Note that this works only in web templates where mapping['node'] is a static value.

templater: switch 'revcache' based on new mapping items It was pretty easy to leave a stale 'revcache' when switching 'ctx'. Let's make it be automatically replaced.

templater: add hook point to populate additional mapping items The 'revcache' dict will be inserted by this hook.