revset: abuse x:y syntax to specify line range of followlines()
This slightly complicates the parsing (see the previous patch), but the
overall result seems not bad.
I keep x:, :y and : for future extension.
revset: do not transform range* operators in parsed tree
This allows us to handle x:y range as a general range object. A primary user
of it is followlines().
revset: factor out getinteger() helper
We have 4 revset functions that take integer arguments, and they handle
their arguments in slightly different ways. This patch unifies them:
- getstring() in place of getsymbol(), which is more consistent with the
handling of integer revisions (both 1 and '1' are valid)
- say "expects" instead of "requires" for type errors
We don't need to catch TypeError since getstring() must return a string.
revset: rename rev argument of followlines() to startrev
The rev argument has the same meaning as startrev of follow(), and I think
startrev is more informative.
followlines() is new function, we can make BC now.
help: use :hg: role and canonical name to point to revset string patterns
Follows up
5dd67f0993ce. Now revisions.txt and revsets.txt has been merged,
so use revisions.* as a pointer.
util: compression APIs to support revlog decompression
Previously, compression engines had APIs for performing revlog
compression but no mechanism to perform revlog decompression. This
patch changes that.
Revlog decompression is slightly more complicated than compression
because in the compression case there is (currently) only a single
engine that can be used at a time. However for decompression, a
revlog could contain chunks from multiple compression engines. This
means decompression needs to map to multiple engines and
decompressors. This functionality is outside the scope of this patch.
But it drives the decision for engines to declare a byte header
sequence that identifies revlog data as belonging to an engine and
an API for obtaining an engine from a revlog header.