templater: define interface for objects requiring unwraphybrid() Prepares for introducing another hybrid-like data type. show() takes context as an argument so a wrapper class may render its items by pre-configured template: def show(self, context, mapping): return (context.expand(self._tmpl, mapping + lm) for lm in self._mappings)

templater: pass (context, mapping) down to unwraphybrid() See the subsequent patches for why. I initially thought it would be wrong to pass a mapping to flatten() and stringify() since these functions may be applied to a tree of generators, where each node should be bound to the mapping when it was evaluated. But, actually that isn't a problem. If an intermediate node has to override a mapping dict, it can do on unwraphybrid() and yield "unwrapped" generator of byte strings: "{f(g(v))}" # literal template example. ^^^^ # g() want to override a mapping, so it returns a wrapped # object 'G{V}' with partial mapping 'lm' attached. ^^^^^^^ # f() stringifies 'G{V}', starting from a mapping 'm'. # when unwrapping 'G{}', it updates 'm' with 'lm', and # passes it to 'V'. This structure is important for the formatter (and the hgweb) to build a static template keyword, which can't access a mapping dict until evaluation phase.

scmutil: add method for looking up a context given a revision symbol changectx's constructor currently supports a mix if inputs: * integer revnums * binary nodeids * '.', 'tip', 'null' * stringified revnums * namespaced identifiers (e.g. bookmarks and tags) * hex nodeids * partial hex nodeids The first two are always internal [1]. The other five can be specified by the user. The third type ('.', 'tip', 'null') often comes from either the user or internal callers. We probably have some internal callers that pass hex nodeids too, perhaps even partial ones (histedit?). There are only a few callers that pass user-supplied strings: revsets.stringset, peer.lookup, webutil.changeidctx, and maybe one or two more. Supporting this mix of things in the constructor is convenient, but a bit strange, IMO. For example, if repo[node] is given a node that's not in the repo, it will first check if it's bookmark etc before raising an exception. Of course, the risk of it being a bookmark is extremely small, but it just feels ugly. Also, a problem with having this code in the constructor (whether it supports a mix of types or not) is that it's harder to override (I'd like to override it, and that's how this series started). This patch starts moving out the handling of user-supplied strings by introducing scmutil.revsymbol(). So far, that just checks that the input is indeed a string, and then delegates to repo[symbol]. The patch also calls it from revsets.stringset to prove that it works. [1] Well, you probably can enter a 20-byte binary nodeid on the command line, but I don't think we should care to preserve support for that. Differential Revision: https://phab.mercurial-scm.org/D3024