templater: add subsetparents(rev, revset) function
Naming suggestions are welcome. And this could be flagged as an (ADVANCED)
function since the primary use case is to draw a graph.
This provides all data needed for drawing revisions graph filtered by revset,
and allows us to implement a GUI graph viewer in some languages better than
Python. A frontend grapher will be quite similar to our graphmod since
subsetparents() just returns parent-child relations in the filtered sub graph.
Frontend example:
https://hg.sr.ht/~yuja/hgv/browse/default/core/hgchangesetgrapher.cpp
However, the resulting graph will be simpler than the one "hg log -G" would
generate because redundant edges are eliminated. This should be the same graph
rendering strategy as TortoiseHg.
This function could be implemented as a revset predicate, but that would mean
the scanning state couldn't be cached and thus slow.
Test cases are split to new file since test-template-functions.t is quite
big and we'll need a new branchy repository anyway.
@echo off
rem Windows Driver script for Mercurial
setlocal
set HG=%~f0
rem Use a full path to Python (relative to this script) if it exists,
rem as the standard Python install does not put python.exe on the PATH...
rem Otherwise, expect that python.exe can be found on the PATH.
rem %~dp0 is the directory of this script
if exist "%~dp0..\python.exe" (
"%~dp0..\python" "%~dp0hg" %*
) else (
python "%~dp0hg" %*
)
endlocal
exit /b %ERRORLEVEL%