parser: move alias declaration parser to common rule-set class
The original _parsealiasdecl() function is split into common _builddecl()
and revset-specific _parsealiasdecl(). And the original _parsealiasdecl()
call is temporarily replaced by rules._builddecl(), which should be eliminated
later.
The doctests are mostly ported by using the dummy parse(), but the test for
'foo bar' is kept in _parsealiasdecl() as it checks if "pos != len(decl)" is
working. Also, 'foo($1)' test is added to make sure the alias tokenizer can
handle '$1' symbol, which is the only reason why we need _parsealiasdecl().
# parser.py - simple top-down operator precedence parser for mercurial
#
# Copyright 2010 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
# see http://effbot.org/zone/simple-top-down-parsing.htm and
# http://eli.thegreenplace.net/2010/01/02/top-down-operator-precedence-parsing/
# for background
# takes a tokenizer and elements
# tokenizer is an iterator that returns (type, value, pos) tuples
# elements is a mapping of types to binding strength, primary, prefix, infix
# and suffix actions
# an action is a tree node name, a tree label, and an optional match
# __call__(program) parses program into a labeled tree
from __future__ import absolute_import
from .i18n import _
from . import error
class parser(object):
def __init__(self, elements, methods=None):
self._elements = elements
self._methods = methods
self.current = None
def _advance(self):
'advance the tokenizer'
t = self.current
self.current = next(self._iter, None)
return t
def _hasnewterm(self):
'True if next token may start new term'
return any(self._elements[self.current[0]][1:3])
def _match(self, m):
'make sure the tokenizer matches an end condition'
if self.current[0] != m:
raise error.ParseError(_("unexpected token: %s") % self.current[0],
self.current[2])
self._advance()
def _parseoperand(self, bind, m=None):
'gather right-hand-side operand until an end condition or binding met'
if m and self.current[0] == m:
expr = None
else:
expr = self._parse(bind)
if m:
self._match(m)
return expr
def _parse(self, bind=0):
token, value, pos = self._advance()
# handle prefix rules on current token, take as primary if unambiguous
primary, prefix = self._elements[token][1:3]
if primary and not (prefix and self._hasnewterm()):
expr = (primary, value)
elif prefix:
expr = (prefix[0], self._parseoperand(*prefix[1:]))
else:
raise error.ParseError(_("not a prefix: %s") % token, pos)
# gather tokens until we meet a lower binding strength
while bind < self._elements[self.current[0]][0]:
token, value, pos = self._advance()
# handle infix rules, take as suffix if unambiguous
infix, suffix = self._elements[token][3:]
if suffix and not (infix and self._hasnewterm()):
expr = (suffix[0], expr)
elif infix:
expr = (infix[0], expr, self._parseoperand(*infix[1:]))
else:
raise error.ParseError(_("not an infix: %s") % token, pos)
return expr
def parse(self, tokeniter):
'generate a parse tree from tokens'
self._iter = tokeniter
self._advance()
res = self._parse()
token, value, pos = self.current
return res, pos
def eval(self, tree):
'recursively evaluate a parse tree using node methods'
if not isinstance(tree, tuple):
return tree
return self._methods[tree[0]](*[self.eval(t) for t in tree[1:]])
def __call__(self, tokeniter):
'parse tokens into a parse tree and evaluate if methods given'
t = self.parse(tokeniter)
if self._methods:
return self.eval(t)
return t
def buildargsdict(trees, funcname, keys, keyvaluenode, keynode):
"""Build dict from list containing positional and keyword arguments
Invalid keywords or too many positional arguments are rejected, but
missing arguments are just omitted.
"""
if len(trees) > len(keys):
raise error.ParseError(_("%(func)s takes at most %(nargs)d arguments")
% {'func': funcname, 'nargs': len(keys)})
args = {}
# consume positional arguments
for k, x in zip(keys, trees):
if x[0] == keyvaluenode:
break
args[k] = x
# remainder should be keyword arguments
for x in trees[len(args):]:
if x[0] != keyvaluenode or x[1][0] != keynode:
raise error.ParseError(_("%(func)s got an invalid argument")
% {'func': funcname})
k = x[1][1]
if k not in keys:
raise error.ParseError(_("%(func)s got an unexpected keyword "
"argument '%(key)s'")
% {'func': funcname, 'key': k})
if k in args:
raise error.ParseError(_("%(func)s got multiple values for keyword "
"argument '%(key)s'")
% {'func': funcname, 'key': k})
args[k] = x[2]
return args
def unescapestr(s):
try:
return s.decode("string_escape")
except ValueError as e:
# mangle Python's exception into our format
raise error.ParseError(str(e).lower())
def _prettyformat(tree, leafnodes, level, lines):
if not isinstance(tree, tuple) or tree[0] in leafnodes:
lines.append((level, str(tree)))
else:
lines.append((level, '(%s' % tree[0]))
for s in tree[1:]:
_prettyformat(s, leafnodes, level + 1, lines)
lines[-1:] = [(lines[-1][0], lines[-1][1] + ')')]
def prettyformat(tree, leafnodes):
lines = []
_prettyformat(tree, leafnodes, 0, lines)
output = '\n'.join((' ' * l + s) for l, s in lines)
return output
def simplifyinfixops(tree, targetnodes):
"""Flatten chained infix operations to reduce usage of Python stack
>>> def f(tree):
... print prettyformat(simplifyinfixops(tree, ('or',)), ('symbol',))
>>> f(('or',
... ('or',
... ('symbol', '1'),
... ('symbol', '2')),
... ('symbol', '3')))
(or
('symbol', '1')
('symbol', '2')
('symbol', '3'))
>>> f(('func',
... ('symbol', 'p1'),
... ('or',
... ('or',
... ('func',
... ('symbol', 'sort'),
... ('list',
... ('or',
... ('or',
... ('symbol', '1'),
... ('symbol', '2')),
... ('symbol', '3')),
... ('negate',
... ('symbol', 'rev')))),
... ('and',
... ('symbol', '4'),
... ('group',
... ('or',
... ('or',
... ('symbol', '5'),
... ('symbol', '6')),
... ('symbol', '7'))))),
... ('symbol', '8'))))
(func
('symbol', 'p1')
(or
(func
('symbol', 'sort')
(list
(or
('symbol', '1')
('symbol', '2')
('symbol', '3'))
(negate
('symbol', 'rev'))))
(and
('symbol', '4')
(group
(or
('symbol', '5')
('symbol', '6')
('symbol', '7'))))
('symbol', '8')))
"""
if not isinstance(tree, tuple):
return tree
op = tree[0]
if op not in targetnodes:
return (op,) + tuple(simplifyinfixops(x, targetnodes) for x in tree[1:])
# walk down left nodes taking each right node. no recursion to left nodes
# because infix operators are left-associative, i.e. left tree is deep.
# e.g. '1 + 2 + 3' -> (+ (+ 1 2) 3) -> (+ 1 2 3)
simplified = []
x = tree
while x[0] == op:
l, r = x[1:]
simplified.append(simplifyinfixops(r, targetnodes))
x = l
simplified.append(simplifyinfixops(x, targetnodes))
simplified.append(op)
return tuple(reversed(simplified))
def parseerrordetail(inst):
"""Compose error message from specified ParseError object
"""
if len(inst.args) > 1:
return _('at %s: %s') % (inst.args[1], inst.args[0])
else:
return inst.args[0]
class basealiasrules(object):
"""Parsing and expansion rule set of aliases
This is a helper for fileset/revset/template aliases. A concrete rule set
should be made by sub-classing this and implementing class/static methods.
It supports alias expansion of symbol and funciton-call styles::
# decl = defn
h = heads(default)
b($1) = ancestors($1) - ancestors(default)
"""
# typically a config section, which will be included in error messages
_section = None
# tags of symbol and function nodes
_symbolnode = 'symbol'
_funcnode = 'func'
def __new__(cls):
raise TypeError("'%s' is not instantiatable" % cls.__name__)
@staticmethod
def _parsedecl(spec):
"""Parse an alias name and arguments"""
raise NotImplementedError
@staticmethod
def _parsedefn(spec):
"""Parse an alias definition"""
raise NotImplementedError
@staticmethod
def _getlist(tree):
"""Extract a list of arguments from parsed tree"""
raise NotImplementedError
@classmethod
def _builddecl(cls, decl):
"""Parse an alias declaration into ``(name, tree, args, errorstr)``
This function analyzes the parsed tree. The parsing rule is provided
by ``_parsedecl()``.
- ``name``: of declared alias (may be ``decl`` itself at error)
- ``tree``: parse result (or ``None`` at error)
- ``args``: list of argument names (or None for symbol declaration)
- ``errorstr``: detail about detected error (or None)
>>> sym = lambda x: ('symbol', x)
>>> symlist = lambda *xs: ('list',) + tuple(sym(x) for x in xs)
>>> func = lambda n, a: ('func', sym(n), a)
>>> parsemap = {
... 'foo': sym('foo'),
... '$foo': sym('$foo'),
... 'foo::bar': ('dagrange', sym('foo'), sym('bar')),
... 'foo()': func('foo', None),
... '$foo()': func('$foo', None),
... 'foo($1, $2)': func('foo', symlist('$1', '$2')),
... 'foo(bar_bar, baz.baz)':
... func('foo', symlist('bar_bar', 'baz.baz')),
... 'foo(bar($1, $2))':
... func('foo', func('bar', symlist('$1', '$2'))),
... 'foo($1, $2, nested($1, $2))':
... func('foo', (symlist('$1', '$2') +
... (func('nested', symlist('$1', '$2')),))),
... 'foo("bar")': func('foo', ('string', 'bar')),
... 'foo($1, $2': error.ParseError('unexpected token: end', 10),
... 'foo("bar': error.ParseError('unterminated string', 5),
... 'foo($1, $2, $1)': func('foo', symlist('$1', '$2', '$1')),
... }
>>> def parse(expr):
... x = parsemap[expr]
... if isinstance(x, Exception):
... raise x
... return x
>>> def getlist(tree):
... if not tree:
... return []
... if tree[0] == 'list':
... return list(tree[1:])
... return [tree]
>>> class aliasrules(basealiasrules):
... _parsedecl = staticmethod(parse)
... _getlist = staticmethod(getlist)
>>> builddecl = aliasrules._builddecl
>>> builddecl('foo')
('foo', ('symbol', 'foo'), None, None)
>>> builddecl('$foo')
('$foo', None, None, "'$' not for alias arguments")
>>> builddecl('foo::bar')
('foo::bar', None, None, 'invalid format')
>>> builddecl('foo()')
('foo', ('func', ('symbol', 'foo')), [], None)
>>> builddecl('$foo()')
('$foo()', None, None, "'$' not for alias arguments")
>>> builddecl('foo($1, $2)')
('foo', ('func', ('symbol', 'foo')), ['$1', '$2'], None)
>>> builddecl('foo(bar_bar, baz.baz)')
('foo', ('func', ('symbol', 'foo')), ['bar_bar', 'baz.baz'], None)
>>> builddecl('foo($1, $2, nested($1, $2))')
('foo($1, $2, nested($1, $2))', None, None, 'invalid argument list')
>>> builddecl('foo(bar($1, $2))')
('foo(bar($1, $2))', None, None, 'invalid argument list')
>>> builddecl('foo("bar")')
('foo("bar")', None, None, 'invalid argument list')
>>> builddecl('foo($1, $2')
('foo($1, $2', None, None, 'at 10: unexpected token: end')
>>> builddecl('foo("bar')
('foo("bar', None, None, 'at 5: unterminated string')
>>> builddecl('foo($1, $2, $1)')
('foo', None, None, 'argument names collide with each other')
"""
try:
tree = cls._parsedecl(decl)
except error.ParseError as inst:
return (decl, None, None, parseerrordetail(inst))
if tree[0] == cls._symbolnode:
# "name = ...." style
name = tree[1]
if name.startswith('$'):
return (decl, None, None, _("'$' not for alias arguments"))
return (name, tree, None, None)
if tree[0] == cls._funcnode and tree[1][0] == cls._symbolnode:
# "name(arg, ....) = ...." style
name = tree[1][1]
if name.startswith('$'):
return (decl, None, None, _("'$' not for alias arguments"))
args = []
for arg in cls._getlist(tree[2]):
if arg[0] != cls._symbolnode:
return (decl, None, None, _("invalid argument list"))
args.append(arg[1])
if len(args) != len(set(args)):
return (name, None, None,
_("argument names collide with each other"))
return (name, tree[:2], args, None)
return (decl, None, None, _("invalid format"))