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# parser.py - simple top-down operator precedence parser for mercurial
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#
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# Copyright 2010 Matt Mackall <mpm@selenic.com>
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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# see http://effbot.org/zone/simple-top-down-parsing.htm and
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# http://eli.thegreenplace.net/2010/01/02/top-down-operator-precedence-parsing/
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# for background
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# takes a tokenizer and elements
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# tokenizer is an iterator that returns (type, value, pos) tuples
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# elements is a mapping of types to binding strength, primary, prefix, infix
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# and suffix actions
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# an action is a tree node name, a tree label, and an optional match
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# __call__(program) parses program into a labeled tree
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from __future__ import absolute_import
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from .i18n import _
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from . import error
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class parser(object):
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def __init__(self, elements, methods=None):
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self._elements = elements
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self._methods = methods
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self.current = None
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def _advance(self):
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'advance the tokenizer'
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t = self.current
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self.current = next(self._iter, None)
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return t
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def _hasnewterm(self):
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'True if next token may start new term'
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return any(self._elements[self.current[0]][1:3])
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def _match(self, m):
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'make sure the tokenizer matches an end condition'
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if self.current[0] != m:
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raise error.ParseError(_("unexpected token: %s") % self.current[0],
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self.current[2])
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self._advance()
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def _parseoperand(self, bind, m=None):
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'gather right-hand-side operand until an end condition or binding met'
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if m and self.current[0] == m:
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expr = None
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else:
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expr = self._parse(bind)
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if m:
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self._match(m)
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return expr
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def _parse(self, bind=0):
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token, value, pos = self._advance()
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# handle prefix rules on current token, take as primary if unambiguous
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primary, prefix = self._elements[token][1:3]
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if primary and not (prefix and self._hasnewterm()):
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expr = (primary, value)
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elif prefix:
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expr = (prefix[0], self._parseoperand(*prefix[1:]))
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else:
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raise error.ParseError(_("not a prefix: %s") % token, pos)
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# gather tokens until we meet a lower binding strength
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while bind < self._elements[self.current[0]][0]:
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token, value, pos = self._advance()
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# handle infix rules, take as suffix if unambiguous
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infix, suffix = self._elements[token][3:]
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if suffix and not (infix and self._hasnewterm()):
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expr = (suffix[0], expr)
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elif infix:
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expr = (infix[0], expr, self._parseoperand(*infix[1:]))
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else:
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raise error.ParseError(_("not an infix: %s") % token, pos)
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return expr
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def parse(self, tokeniter):
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'generate a parse tree from tokens'
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self._iter = tokeniter
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self._advance()
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res = self._parse()
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token, value, pos = self.current
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return res, pos
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def eval(self, tree):
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'recursively evaluate a parse tree using node methods'
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if not isinstance(tree, tuple):
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return tree
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return self._methods[tree[0]](*[self.eval(t) for t in tree[1:]])
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def __call__(self, tokeniter):
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'parse tokens into a parse tree and evaluate if methods given'
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t = self.parse(tokeniter)
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if self._methods:
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return self.eval(t)
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return t
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def buildargsdict(trees, funcname, keys, keyvaluenode, keynode):
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"""Build dict from list containing positional and keyword arguments
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Invalid keywords or too many positional arguments are rejected, but
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missing arguments are just omitted.
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"""
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if len(trees) > len(keys):
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raise error.ParseError(_("%(func)s takes at most %(nargs)d arguments")
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% {'func': funcname, 'nargs': len(keys)})
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args = {}
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# consume positional arguments
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for k, x in zip(keys, trees):
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if x[0] == keyvaluenode:
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break
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args[k] = x
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# remainder should be keyword arguments
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for x in trees[len(args):]:
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if x[0] != keyvaluenode or x[1][0] != keynode:
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raise error.ParseError(_("%(func)s got an invalid argument")
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% {'func': funcname})
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k = x[1][1]
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if k not in keys:
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raise error.ParseError(_("%(func)s got an unexpected keyword "
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"argument '%(key)s'")
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% {'func': funcname, 'key': k})
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if k in args:
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raise error.ParseError(_("%(func)s got multiple values for keyword "
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"argument '%(key)s'")
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% {'func': funcname, 'key': k})
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args[k] = x[2]
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return args
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def unescapestr(s):
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try:
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return s.decode("string_escape")
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except ValueError as e:
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# mangle Python's exception into our format
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raise error.ParseError(str(e).lower())
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def _prettyformat(tree, leafnodes, level, lines):
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if not isinstance(tree, tuple) or tree[0] in leafnodes:
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lines.append((level, str(tree)))
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else:
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lines.append((level, '(%s' % tree[0]))
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for s in tree[1:]:
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_prettyformat(s, leafnodes, level + 1, lines)
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lines[-1:] = [(lines[-1][0], lines[-1][1] + ')')]
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def prettyformat(tree, leafnodes):
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lines = []
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_prettyformat(tree, leafnodes, 0, lines)
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output = '\n'.join((' ' * l + s) for l, s in lines)
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return output
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def simplifyinfixops(tree, targetnodes):
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"""Flatten chained infix operations to reduce usage of Python stack
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>>> def f(tree):
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... print prettyformat(simplifyinfixops(tree, ('or',)), ('symbol',))
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>>> f(('or',
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... ('or',
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... ('symbol', '1'),
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... ('symbol', '2')),
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... ('symbol', '3')))
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(or
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('symbol', '1')
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('symbol', '2')
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('symbol', '3'))
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>>> f(('func',
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... ('symbol', 'p1'),
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... ('or',
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... ('or',
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... ('func',
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... ('symbol', 'sort'),
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... ('list',
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... ('or',
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... ('or',
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... ('symbol', '1'),
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... ('symbol', '2')),
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... ('symbol', '3')),
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... ('negate',
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... ('symbol', 'rev')))),
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... ('and',
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... ('symbol', '4'),
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... ('group',
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... ('or',
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... ('or',
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... ('symbol', '5'),
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... ('symbol', '6')),
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... ('symbol', '7'))))),
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... ('symbol', '8'))))
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(func
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('symbol', 'p1')
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(or
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(func
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('symbol', 'sort')
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(list
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(or
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('symbol', '1')
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('symbol', '2')
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('symbol', '3'))
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(negate
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('symbol', 'rev'))))
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(and
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('symbol', '4')
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(group
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(or
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('symbol', '5')
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('symbol', '6')
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('symbol', '7'))))
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('symbol', '8')))
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"""
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if not isinstance(tree, tuple):
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return tree
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op = tree[0]
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if op not in targetnodes:
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return (op,) + tuple(simplifyinfixops(x, targetnodes) for x in tree[1:])
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# walk down left nodes taking each right node. no recursion to left nodes
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# because infix operators are left-associative, i.e. left tree is deep.
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# e.g. '1 + 2 + 3' -> (+ (+ 1 2) 3) -> (+ 1 2 3)
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simplified = []
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x = tree
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while x[0] == op:
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l, r = x[1:]
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simplified.append(simplifyinfixops(r, targetnodes))
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x = l
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simplified.append(simplifyinfixops(x, targetnodes))
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simplified.append(op)
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return tuple(reversed(simplified))
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def parseerrordetail(inst):
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"""Compose error message from specified ParseError object
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"""
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if len(inst.args) > 1:
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return _('at %s: %s') % (inst.args[1], inst.args[0])
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else:
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return inst.args[0]
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class alias(object):
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"""Parsed result of alias"""
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def __init__(self, name, args, err, replacement):
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self.name = name
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self.args = args
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self.error = err
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self.replacement = replacement
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# whether own `error` information is already shown or not.
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# this avoids showing same warning multiple times at each
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# `expandaliases`.
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self.warned = False
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class basealiasrules(object):
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"""Parsing and expansion rule set of aliases
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This is a helper for fileset/revset/template aliases. A concrete rule set
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should be made by sub-classing this and implementing class/static methods.
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It supports alias expansion of symbol and funciton-call styles::
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# decl = defn
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h = heads(default)
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b($1) = ancestors($1) - ancestors(default)
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"""
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# typically a config section, which will be included in error messages
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_section = None
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# tag of symbol node
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_symbolnode = 'symbol'
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def __new__(cls):
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raise TypeError("'%s' is not instantiatable" % cls.__name__)
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@staticmethod
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def _parse(spec):
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"""Parse an alias name, arguments and definition"""
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raise NotImplementedError
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@staticmethod
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def _trygetfunc(tree):
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"""Return (name, args) if tree is a function; otherwise None"""
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raise NotImplementedError
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@classmethod
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def _builddecl(cls, decl):
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"""Parse an alias declaration into ``(name, args, errorstr)``
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This function analyzes the parsed tree. The parsing rule is provided
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by ``_parse()``.
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- ``name``: of declared alias (may be ``decl`` itself at error)
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- ``args``: list of argument names (or None for symbol declaration)
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- ``errorstr``: detail about detected error (or None)
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>>> sym = lambda x: ('symbol', x)
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>>> symlist = lambda *xs: ('list',) + tuple(sym(x) for x in xs)
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>>> func = lambda n, a: ('func', sym(n), a)
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>>> parsemap = {
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... 'foo': sym('foo'),
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... '$foo': sym('$foo'),
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... 'foo::bar': ('dagrange', sym('foo'), sym('bar')),
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... 'foo()': func('foo', None),
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... '$foo()': func('$foo', None),
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... 'foo($1, $2)': func('foo', symlist('$1', '$2')),
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... 'foo(bar_bar, baz.baz)':
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... func('foo', symlist('bar_bar', 'baz.baz')),
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... 'foo(bar($1, $2))':
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... func('foo', func('bar', symlist('$1', '$2'))),
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... 'foo($1, $2, nested($1, $2))':
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... func('foo', (symlist('$1', '$2') +
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... (func('nested', symlist('$1', '$2')),))),
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... 'foo("bar")': func('foo', ('string', 'bar')),
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... 'foo($1, $2': error.ParseError('unexpected token: end', 10),
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... 'foo("bar': error.ParseError('unterminated string', 5),
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... 'foo($1, $2, $1)': func('foo', symlist('$1', '$2', '$1')),
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... }
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>>> def parse(expr):
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... x = parsemap[expr]
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... if isinstance(x, Exception):
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... raise x
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... return x
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>>> def trygetfunc(tree):
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... if not tree or tree[0] != 'func' or tree[1][0] != 'symbol':
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... return None
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... if not tree[2]:
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... return tree[1][1], []
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... if tree[2][0] == 'list':
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... return tree[1][1], list(tree[2][1:])
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... return tree[1][1], [tree[2]]
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>>> class aliasrules(basealiasrules):
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... _parse = staticmethod(parse)
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... _trygetfunc = staticmethod(trygetfunc)
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>>> builddecl = aliasrules._builddecl
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>>> builddecl('foo')
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('foo', None, None)
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>>> builddecl('$foo')
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('$foo', None, "invalid symbol '$foo'")
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>>> builddecl('foo::bar')
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('foo::bar', None, 'invalid format')
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>>> builddecl('foo()')
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('foo', [], None)
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>>> builddecl('$foo()')
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('$foo()', None, "invalid function '$foo'")
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>>> builddecl('foo($1, $2)')
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('foo', ['$1', '$2'], None)
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>>> builddecl('foo(bar_bar, baz.baz)')
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('foo', ['bar_bar', 'baz.baz'], None)
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>>> builddecl('foo($1, $2, nested($1, $2))')
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('foo($1, $2, nested($1, $2))', None, 'invalid argument list')
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>>> builddecl('foo(bar($1, $2))')
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('foo(bar($1, $2))', None, 'invalid argument list')
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>>> builddecl('foo("bar")')
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('foo("bar")', None, 'invalid argument list')
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>>> builddecl('foo($1, $2')
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('foo($1, $2', None, 'at 10: unexpected token: end')
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>>> builddecl('foo("bar')
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('foo("bar', None, 'at 5: unterminated string')
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>>> builddecl('foo($1, $2, $1)')
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('foo', None, 'argument names collide with each other')
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"""
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try:
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tree = cls._parse(decl)
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except error.ParseError as inst:
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return (decl, None, parseerrordetail(inst))
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if tree[0] == cls._symbolnode:
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# "name = ...." style
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name = tree[1]
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if name.startswith('$'):
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return (decl, None, _("invalid symbol '%s'") % name)
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return (name, None, None)
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func = cls._trygetfunc(tree)
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if func:
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# "name(arg, ....) = ...." style
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name, args = func
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if name.startswith('$'):
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return (decl, None, _("invalid function '%s'") % name)
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if any(t[0] != cls._symbolnode for t in args):
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return (decl, None, _("invalid argument list"))
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if len(args) != len(set(args)):
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return (name, None, _("argument names collide with each other"))
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return (name, [t[1] for t in args], None)
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return (decl, None, _("invalid format"))
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@classmethod
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def _relabelargs(cls, tree, args):
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"""Mark alias arguments as ``_aliasarg``"""
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if not isinstance(tree, tuple):
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return tree
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op = tree[0]
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if op != cls._symbolnode:
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return (op,) + tuple(cls._relabelargs(x, args) for x in tree[1:])
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assert len(tree) == 2
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sym = tree[1]
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if sym in args:
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op = '_aliasarg'
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elif sym.startswith('$'):
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raise error.ParseError(_("invalid symbol '%s'") % sym)
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return (op, sym)
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@classmethod
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def _builddefn(cls, defn, args):
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"""Parse an alias definition into a tree and marks substitutions
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This function marks alias argument references as ``_aliasarg``. The
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parsing rule is provided by ``_parse()``.
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``args`` is a list of alias argument names, or None if the alias
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is declared as a symbol.
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>>> parsemap = {
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... '$1 or foo': ('or', ('symbol', '$1'), ('symbol', 'foo')),
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... '$1 or $bar': ('or', ('symbol', '$1'), ('symbol', '$bar')),
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... '$10 or baz': ('or', ('symbol', '$10'), ('symbol', 'baz')),
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... '"$1" or "foo"': ('or', ('string', '$1'), ('string', 'foo')),
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... }
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>>> class aliasrules(basealiasrules):
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... _parse = staticmethod(parsemap.__getitem__)
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... _trygetfunc = staticmethod(lambda x: None)
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>>> builddefn = aliasrules._builddefn
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|
>>> def pprint(tree):
|
|
|
... print prettyformat(tree, ('_aliasarg', 'string', 'symbol'))
|
|
|
>>> args = ['$1', '$2', 'foo']
|
|
|
>>> pprint(builddefn('$1 or foo', args))
|
|
|
(or
|
|
|
('_aliasarg', '$1')
|
|
|
('_aliasarg', 'foo'))
|
|
|
>>> try:
|
|
|
... builddefn('$1 or $bar', args)
|
|
|
... except error.ParseError as inst:
|
|
|
... print parseerrordetail(inst)
|
|
|
invalid symbol '$bar'
|
|
|
>>> args = ['$1', '$10', 'foo']
|
|
|
>>> pprint(builddefn('$10 or baz', args))
|
|
|
(or
|
|
|
('_aliasarg', '$10')
|
|
|
('symbol', 'baz'))
|
|
|
>>> pprint(builddefn('"$1" or "foo"', args))
|
|
|
(or
|
|
|
('string', '$1')
|
|
|
('string', 'foo'))
|
|
|
"""
|
|
|
tree = cls._parse(defn)
|
|
|
if args:
|
|
|
args = set(args)
|
|
|
else:
|
|
|
args = set()
|
|
|
return cls._relabelargs(tree, args)
|
|
|
|
|
|
@classmethod
|
|
|
def build(cls, decl, defn):
|
|
|
"""Parse an alias declaration and definition into an alias object"""
|
|
|
repl = efmt = None
|
|
|
name, args, err = cls._builddecl(decl)
|
|
|
if err:
|
|
|
efmt = _('bad declaration of %(section)s "%(name)s": %(error)s')
|
|
|
else:
|
|
|
try:
|
|
|
repl = cls._builddefn(defn, args)
|
|
|
except error.ParseError as inst:
|
|
|
err = parseerrordetail(inst)
|
|
|
efmt = _('bad definition of %(section)s "%(name)s": %(error)s')
|
|
|
if err:
|
|
|
err = efmt % {'section': cls._section, 'name': name, 'error': err}
|
|
|
return alias(name, args, err, repl)
|
|
|
|
|
|
@classmethod
|
|
|
def buildmap(cls, items):
|
|
|
"""Parse a list of alias (name, replacement) pairs into a dict of
|
|
|
alias objects"""
|
|
|
aliases = {}
|
|
|
for decl, defn in items:
|
|
|
a = cls.build(decl, defn)
|
|
|
aliases[a.name] = a
|
|
|
return aliases
|
|
|
|
|
|
@classmethod
|
|
|
def _getalias(cls, aliases, tree):
|
|
|
"""If tree looks like an unexpanded alias, return (alias, pattern-args)
|
|
|
pair. Return None otherwise.
|
|
|
"""
|
|
|
if not isinstance(tree, tuple):
|
|
|
return None
|
|
|
if tree[0] == cls._symbolnode:
|
|
|
name = tree[1]
|
|
|
a = aliases.get(name)
|
|
|
if a and a.args is None:
|
|
|
return a, None
|
|
|
func = cls._trygetfunc(tree)
|
|
|
if func:
|
|
|
name, args = func
|
|
|
a = aliases.get(name)
|
|
|
if a and a.args is not None:
|
|
|
return a, args
|
|
|
return None
|
|
|
|
|
|
@classmethod
|
|
|
def _expandargs(cls, tree, args):
|
|
|
"""Replace _aliasarg instances with the substitution value of the
|
|
|
same name in args, recursively.
|
|
|
"""
|
|
|
if not isinstance(tree, tuple):
|
|
|
return tree
|
|
|
if tree[0] == '_aliasarg':
|
|
|
sym = tree[1]
|
|
|
return args[sym]
|
|
|
return tuple(cls._expandargs(t, args) for t in tree)
|
|
|
|
|
|
@classmethod
|
|
|
def _expand(cls, aliases, tree, expanding, cache):
|
|
|
if not isinstance(tree, tuple):
|
|
|
return tree
|
|
|
r = cls._getalias(aliases, tree)
|
|
|
if r is None:
|
|
|
return tuple(cls._expand(aliases, t, expanding, cache)
|
|
|
for t in tree)
|
|
|
a, l = r
|
|
|
if a.error:
|
|
|
raise error.Abort(a.error)
|
|
|
if a in expanding:
|
|
|
raise error.ParseError(_('infinite expansion of %(section)s '
|
|
|
'"%(name)s" detected')
|
|
|
% {'section': cls._section, 'name': a.name})
|
|
|
# get cacheable replacement tree by expanding aliases recursively
|
|
|
expanding.append(a)
|
|
|
if a.name not in cache:
|
|
|
cache[a.name] = cls._expand(aliases, a.replacement, expanding,
|
|
|
cache)
|
|
|
result = cache[a.name]
|
|
|
expanding.pop()
|
|
|
if a.args is None:
|
|
|
return result
|
|
|
# substitute function arguments in replacement tree
|
|
|
if len(l) != len(a.args):
|
|
|
raise error.ParseError(_('invalid number of arguments: %d')
|
|
|
% len(l))
|
|
|
l = [cls._expand(aliases, t, [], cache) for t in l]
|
|
|
return cls._expandargs(result, dict(zip(a.args, l)))
|
|
|
|
|
|
@classmethod
|
|
|
def expand(cls, aliases, tree):
|
|
|
"""Expand aliases in tree, recursively.
|
|
|
|
|
|
'aliases' is a dictionary mapping user defined aliases to alias objects.
|
|
|
"""
|
|
|
return cls._expand(aliases, tree, [], {})
|
|
|
|
