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parser: add helper function that constructs parsed tree from template

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This function will be used as follows:

  build('only(_, _)', x, y)

See the next patch for details.
This commit is contained in:
Yuya Nishihara 2016-02-17 21:30:04 +09:00
parent 5caf86603b
commit ee31d80d0f
1 changed files with 27 additions and 0 deletions
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27
mercurial/parser.py
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@ -285,6 +285,33 @@ def simplifyinfixops(tree, targetnodes):
simplified.append(op)
return tuple(reversed(simplified))
def _buildtree(template, placeholder, replstack):
if template == placeholder:
return replstack.pop()
if not isinstance(template, tuple):
return template
return tuple(_buildtree(x, placeholder, replstack) for x in template)
def buildtree(template, placeholder, *repls):
"""Create new tree by substituting placeholders by replacements
>>> _ = ('symbol', '_')
>>> def f(template, *repls):
... return buildtree(template, _, *repls)
>>> f(('func', ('symbol', 'only'), ('list', _, _)),
... ('symbol', '1'), ('symbol', '2'))
('func', ('symbol', 'only'), ('list', ('symbol', '1'), ('symbol', '2')))
>>> f(('and', _, ('not', _)), ('symbol', '1'), ('symbol', '2'))
('and', ('symbol', '1'), ('not', ('symbol', '2')))
"""
if not isinstance(placeholder, tuple):
raise error.ProgrammingError('placeholder must be a node tuple')
replstack = list(reversed(repls))
r = _buildtree(template, placeholder, replstack)
if replstack:
raise error.ProgrammingError('too many replacements')
return r
def parseerrordetail(inst):
"""Compose error message from specified ParseError object
"""