templater: factor out generator of join()-ed items Prepares for defining join() behavior per wrapped types and getting rid of the public joinfmt attribute.

templater: pass context to itermaps() for future extension Unlike show() and tovalue(), a base mapping isn't passed to itermaps() since it is the function to generate a partial mapping.

templater: define interface for objects which act as iterator of mappings

stringutil: drop escapedata() in favor of escapestr() They are quite similar. Let's choose one that uses standard Python escape.

peer: make ui an attribute With abc interfaces, instance attributes could not satisfy @abc.abstractproperty requirements because interface conformance was tested at type creation time. When we created the abc peer interfaces, we had to make "ui" a @property to satisfy abc. Now that peer interfaces are using zope.interface and there is no import time validation (but there are tests validating instances conform to the interface), we can go back to using regular object attributes. Differential Revision: https://phab.mercurial-scm.org/D3069

repository: port peer interfaces to zope.interface zope.interface is superior. Let's switch to it. Unlike abc, which defines interfaces through a base class, zope.interface uses different types for interfaces and for implementations. So, we had to invent some new types to hold the interfaces in order to separate the interface from its default implementation. The names here could probably be better. I've been wanting to overhaul the peer interface for a while. And wire protocol version 2 will force that work. So anticipate a refactoring of these interfaces in later commits. With this commit, we no longer test abc interfaces in test-check-interfaces.py, so code for that has been removed. Differential Revision: https://phab.mercurial-scm.org/D3068 # no-check-commit because of stream_out()