Mercurial > hg
view mercurial/parser.py @ 39506:b66ea3fc3a86
sparse-revlog: set max delta chain length to on thousand
The new snapshot system used in the sparse-revlog case gave us some small size
benefit so far. However its most important property is to gracefully handle
harder limit on delta chainlength.
Long delta chain has a very detrimental impact on read (and write) performance
in revlog. Being able to shorter them provide a great boost. However, shorting
delta used to result significantly lower compression ratio. The intermediate
snapshots effectively suppress most of this effect (even all in some case).
# Effect on the test repository
The repository we use for test is not "realistic" but can still show this in
action using an unreasonably low chain limit. Limiting the chain length show a
sizeable increase but stay under control: +6% for limit=15; +15% for limit=10.
Without the snapshot system the increase is significantly bigger: +45% for
limit=15; +80% for limit=10. Even slightly larger than without delta chain
limit, the resulting size is still smaller than before we started doing
snapshots.
Here is a table for comparison. *Since the repository is not branchy, the
initial sparse-revlog version does not bring much benefit compare to the
non-sparse one):
chain length limit | none | limit=15 | limit=10 |
without sparse-revlog | 62 818 987 | 112 664 615 | 131 222 574 |
without snapshot | 74 365 490 | 108 211 410 | 133 857 764 |
with snapshot | 59 230 936 | 63 002 924 | 68 415 329 |
# Effect On Real Life Repositories
The series provides significant benefits on all kind of repositories.
Using `hg debugupgraderepo -o redeltaparent --run`, we recomputed delta chain
for various repositories with different settings:
- delta chain length: unlimited or 1000 limit
- sparse-revlog: enabled or disabled
- this series: applied or not applied
We can observe multiple types of effect:
- On very branchy repositories:
* The delta chain limit as low impact on the repo size.
* Intermediate snapshot greatly reduces manifest size:
- pypy: -80%
- netbeans: -95%
* The delta chain limit is effective, without a size impact:
- netbeans average: 613 -> 282
- private #1 average: 1 068 -> 307
- On more linear repository:
* Intermediate snapshot limit the impact of delta chain limit:
- mozilla:
without the series: +360%
with the series: +25%
* The delta chain limit provides large improvement:
- mozilla's average chain length:
unlimited: 15 338
limited: 469
* Despite the chain length limit, the manifest size is reduced:
- mercurial: -25%
- mozilla: -30%
It is clear that the use of chains of intermediate snapshots provide large
benefits both in storage size and delta chains quality. We should now switch our
effort toward making sure the write performance are acceptable. Then,
`sparse-revlog` will be a suitable format for all new repository.
# Raw Statistic
* no-sparse: general delta repository not using sparse-revlog
* no-snapshot: sparse-revlog repository not using this series
* snapshot: sparse-revlog repository using this series
mercurial
Manifest Size:
limit | none | 1000
------------|-------------|------------
no-sparse | 8 021 373 | 8 199 366
no-snapshot | 8 103 561 | 8 259 719
snapshot | 6 137 116 | 6 126 433
Manifest Chain length data
limit || none || 1000 ||
value || average | max || average | max ||
------------||---------|---------||---------|---------||
no-sparse || 307 | 1456 || 279 | 1000 ||
no-snapshot || 312 | 1456 || 283 | 1000 ||
snapshot || 248 | 1208 || 241 | 1000 ||
Full Store Size
limit | none | 1000
------------|-------------|------------
no-sparse | 51 013 198 | 51 201 574
no-snapshot | 50 930 795 | 51 141 006
snapshot | 48 072 037 | 48 093 572
pypy
Manifest Size:
limit | none | 1000
------------|-------------|------------
no-sparse | 193 987 784 | 193 987 784
no-snapshot | 163 171 745 | 163 312 229
snapshot | 34 605 900 | 34 600 750
Manifest Chain length data
limit || none || 1000 ||
value || average | max || average | max ||
------------||---------|---------||---------|---------||
no-sparse || 101 | 692 || 101 | 692 ||
no-snapshot || 151 | 1307 || 148 | 1000 ||
snapshot || 128 | 1309 || 125 | 1000 ||
Full Store Size
limit | none | 1000
------------|-------------|------------
no-sparse | 495 931 473 | 495 931 473
no-snapshot | 465 441 017 | 465 581 501
snapshot | 355 467 301 | 355 472 451
Mozilla
Manifest Size:
limit | none | 1000
------------|----------------|---------------
no-sparse | 416 757 148 | 1 869 009 668
no-snapshot | 401 592 370 | 1 843 493 795
snapshot | 224 359 521 | 284 615 500
Manifest Chain length data
limit || none || 1000 ||
value || average | max || average | max ||
------------||---------|---------||---------|---------||
no-sparse || 15 333 | 58 980 || 468 | 1 000 ||
no-snapshot || 15 336 | 58 980 || 469 | 1 000 ||
snapshot || 15 338 | 58 983 || 469 | 1 000 ||
Full Store Size
limit | none | 1000
------------|----------------|---------------
no-sparse | 2 712 477 887 | 4 164 995 451
no-snapshot | 2 698 887 835 | 4 141 054 304
snapshot | 2 518 130 385 | 2 578 587 596
Netbeans
Manifest Size:
limit | none | 1000
------------|----------------|---------------
no-sparse | 4 766 794 101 | 4 870 642 687
no-snapshot | 4 334 806 082 | 4 428 681 309
snapshot | 232 659 666 | 240 330 665
Manifest Chain length data
limit || none || 1000 ||
value || average | max || average | max ||
------------||---------|---------||---------|---------||
no-sparse || 597 | 6802 || 254 | 1 000 ||
no-snapshot || 648 | 6 802 || 305 | 1 000 ||
snapshot || 613 | 6 804 || 282 | 1 000 ||
Full Store Size
limit | none | 1000
------------|----------------|---------------
no-sparse | 5 807 347 998 | 5 911 196 584
no-snapshot | 5 375 398 602 | 5 469 273 829
snapshot | 1 282 519 928 | 1 290 190 927
Private repo #1
Manifest Size:
limit | none | 1000
------------|-----------------|---------------
no-sparse | 41 389 010 840 | 41 398 162 091
no-snapshot | 9 737 319 435 | 10 223 773 150
snapshot | 744 215 807 | 747 961 822
Manifest Chain length data
limit || none || 1000 ||
value || average | max || average | max ||
------------||---------|---------||---------|---------||
no-sparse || 245 | 8 885 || 81 | 1 000 ||
no-snapshot || 1 225 | 8 885 || 336 | 1 000 ||
snapshot || 1 068 | 7 909 || 307 | 1 000 ||
Full Store Size
limit | none | 1000
------------|----------------|---------------
no-sparse | 49 646 065 126 | 49 655 216 377
no-snapshot | 17 924 862 856 | 18 411 316 571
snapshot | 9 009 024 710 | 9 012 770 725
Private repo #2
We currently have less data available for that repository.
* Before is a sparse-revlog repository without this series
* After is a sparse-revlog repository with this series + 1000 chain limit
Manifest Size:
Before: 1 531 485 040 bytes
After: 1 091 422 451 bytes
Manifest Chain:
Before: 2 218 avg; 6 575 Max
After: 442 avg; 1 000 Max
Full Store Size
Before: 15 203 955 615
after: 8 207 180 693
author | Boris Feld <boris.feld@octobus.net> |
---|---|
date | Fri, 07 Sep 2018 11:18:45 -0400 |
parents | 0a2ce5b43574 |
children | 29798c9ba5c9 |
line wrap: on
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# 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, print_function from .i18n import _ from . import ( error, pycompat, util, ) from .utils import ( stringutil, ) 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, 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 splitargspec(spec): """Parse spec of function arguments into (poskeys, varkey, keys, optkey) >>> splitargspec(b'') ([], None, [], None) >>> splitargspec(b'foo bar') ([], None, ['foo', 'bar'], None) >>> splitargspec(b'foo *bar baz **qux') (['foo'], 'bar', ['baz'], 'qux') >>> splitargspec(b'*foo') ([], 'foo', [], None) >>> splitargspec(b'**foo') ([], None, [], 'foo') """ optkey = None pre, sep, post = spec.partition('**') if sep: posts = post.split() if not posts: raise error.ProgrammingError('no **optkey name provided') if len(posts) > 1: raise error.ProgrammingError('excessive **optkey names provided') optkey = posts[0] pre, sep, post = pre.partition('*') pres = pre.split() posts = post.split() if sep: if not posts: raise error.ProgrammingError('no *varkey name provided') return pres, posts[0], posts[1:], optkey return [], None, pres, optkey def buildargsdict(trees, funcname, argspec, keyvaluenode, keynode): """Build dict from list containing positional and keyword arguments Arguments are specified by a tuple of ``(poskeys, varkey, keys, optkey)`` where - ``poskeys``: list of names of positional arguments - ``varkey``: optional argument name that takes up remainder - ``keys``: list of names that can be either positional or keyword arguments - ``optkey``: optional argument name that takes up excess keyword arguments If ``varkey`` specified, all ``keys`` must be given as keyword arguments. Invalid keywords, too few positional arguments, or too many positional arguments are rejected, but missing keyword arguments are just omitted. """ poskeys, varkey, keys, optkey = argspec kwstart = next((i for i, x in enumerate(trees) if x[0] == keyvaluenode), len(trees)) if kwstart < len(poskeys): raise error.ParseError(_("%(func)s takes at least %(nargs)d positional " "arguments") % {'func': funcname, 'nargs': len(poskeys)}) if not varkey and kwstart > len(poskeys) + len(keys): raise error.ParseError(_("%(func)s takes at most %(nargs)d positional " "arguments") % {'func': funcname, 'nargs': len(poskeys) + len(keys)}) args = util.sortdict() # consume positional arguments for k, x in zip(poskeys, trees[:kwstart]): args[k] = x if varkey: args[varkey] = trees[len(args):kwstart] else: for k, x in zip(keys, trees[len(args):kwstart]): args[k] = x # remainder should be keyword arguments if optkey: args[optkey] = util.sortdict() for x in trees[kwstart:]: 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 in keys: d = args elif not optkey: raise error.ParseError(_("%(func)s got an unexpected keyword " "argument '%(key)s'") % {'func': funcname, 'key': k}) else: d = args[optkey] if k in d: raise error.ParseError(_("%(func)s got multiple values for keyword " "argument '%(key)s'") % {'func': funcname, 'key': k}) d[k] = x[2] return args def unescapestr(s): try: return stringutil.unescapestr(s) except ValueError as e: # mangle Python's exception into our format raise error.ParseError(pycompat.bytestr(e).lower()) def _prettyformat(tree, leafnodes, level, lines): if not isinstance(tree, tuple): lines.append((level, stringutil.pprint(tree))) elif tree[0] in leafnodes: rs = map(stringutil.pprint, tree[1:]) lines.append((level, '(%s %s)' % (tree[0], ' '.join(rs)))) 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 >>> from . import pycompat >>> def f(tree): ... s = prettyformat(simplifyinfixops(tree, (b'or',)), (b'symbol',)) ... print(pycompat.sysstr(s)) >>> f((b'or', ... (b'or', ... (b'symbol', b'1'), ... (b'symbol', b'2')), ... (b'symbol', b'3'))) (or (symbol '1') (symbol '2') (symbol '3')) >>> f((b'func', ... (b'symbol', b'p1'), ... (b'or', ... (b'or', ... (b'func', ... (b'symbol', b'sort'), ... (b'list', ... (b'or', ... (b'or', ... (b'symbol', b'1'), ... (b'symbol', b'2')), ... (b'symbol', b'3')), ... (b'negate', ... (b'symbol', b'rev')))), ... (b'and', ... (b'symbol', b'4'), ... (b'group', ... (b'or', ... (b'or', ... (b'symbol', b'5'), ... (b'symbol', b'6')), ... (b'symbol', b'7'))))), ... (b'symbol', b'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 _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 >>> _ = (b'symbol', b'_') >>> def f(template, *repls): ... return buildtree(template, _, *repls) >>> f((b'func', (b'symbol', b'only'), (b'list', _, _)), ... ('symbol', '1'), ('symbol', '2')) ('func', ('symbol', 'only'), ('list', ('symbol', '1'), ('symbol', '2'))) >>> f((b'and', _, (b'not', _)), (b'symbol', b'1'), (b'symbol', b'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 _matchtree(pattern, tree, placeholder, incompletenodes, matches): if pattern == tree: return True if not isinstance(pattern, tuple) or not isinstance(tree, tuple): return False if pattern == placeholder and tree[0] not in incompletenodes: matches.append(tree) return True if len(pattern) != len(tree): return False return all(_matchtree(p, x, placeholder, incompletenodes, matches) for p, x in zip(pattern, tree)) def matchtree(pattern, tree, placeholder=None, incompletenodes=()): """If a tree matches the pattern, return a list of the tree and nodes matched with the placeholder; Otherwise None >>> def f(pattern, tree): ... m = matchtree(pattern, tree, _, {b'keyvalue', b'list'}) ... if m: ... return m[1:] >>> _ = (b'symbol', b'_') >>> f((b'func', (b'symbol', b'ancestors'), _), ... (b'func', (b'symbol', b'ancestors'), (b'symbol', b'1'))) [('symbol', '1')] >>> f((b'func', (b'symbol', b'ancestors'), _), ... (b'func', (b'symbol', b'ancestors'), None)) >>> f((b'range', (b'dagrange', _, _), _), ... (b'range', ... (b'dagrange', (b'symbol', b'1'), (b'symbol', b'2')), ... (b'symbol', b'3'))) [('symbol', '1'), ('symbol', '2'), ('symbol', '3')] The placeholder does not match the specified incomplete nodes because an incomplete node (e.g. argument list) cannot construct an expression. >>> f((b'func', (b'symbol', b'ancestors'), _), ... (b'func', (b'symbol', b'ancestors'), ... (b'list', (b'symbol', b'1'), (b'symbol', b'2')))) The placeholder may be omitted, but which shouldn't match a None node. >>> _ = None >>> f((b'func', (b'symbol', b'ancestors'), None), ... (b'func', (b'symbol', b'ancestors'), (b'symbol', b'0'))) """ if placeholder is not None and not isinstance(placeholder, tuple): raise error.ProgrammingError('placeholder must be a node tuple') matches = [tree] if _matchtree(pattern, tree, placeholder, incompletenodes, matches): return matches def parseerrordetail(inst): """Compose error message from specified ParseError object """ if len(inst.args) > 1: return _('at %d: %s') % (inst.args[1], inst.args[0]) else: return inst.args[0] class alias(object): """Parsed result of alias""" def __init__(self, name, args, err, replacement): self.name = name self.args = args self.error = err self.replacement = replacement # whether own `error` information is already shown or not. # this avoids showing same warning multiple times at each # `expandaliases`. self.warned = False 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 function-call styles:: # decl = defn h = heads(default) b($1) = ancestors($1) - ancestors(default) """ # typically a config section, which will be included in error messages _section = None # tag of symbol node _symbolnode = 'symbol' def __new__(cls): raise TypeError("'%s' is not instantiatable" % cls.__name__) @staticmethod def _parse(spec): """Parse an alias name, arguments and definition""" raise NotImplementedError @staticmethod def _trygetfunc(tree): """Return (name, args) if tree is a function; otherwise None""" raise NotImplementedError @classmethod def _builddecl(cls, decl): """Parse an alias declaration into ``(name, args, errorstr)`` This function analyzes the parsed tree. The parsing rule is provided by ``_parse()``. - ``name``: of declared alias (may be ``decl`` itself at error) - ``args``: list of argument names (or None for symbol declaration) - ``errorstr``: detail about detected error (or None) >>> sym = lambda x: (b'symbol', x) >>> symlist = lambda *xs: (b'list',) + tuple(sym(x) for x in xs) >>> func = lambda n, a: (b'func', sym(n), a) >>> parsemap = { ... b'foo': sym(b'foo'), ... b'$foo': sym(b'$foo'), ... b'foo::bar': (b'dagrange', sym(b'foo'), sym(b'bar')), ... b'foo()': func(b'foo', None), ... b'$foo()': func(b'$foo', None), ... b'foo($1, $2)': func(b'foo', symlist(b'$1', b'$2')), ... b'foo(bar_bar, baz.baz)': ... func(b'foo', symlist(b'bar_bar', b'baz.baz')), ... b'foo(bar($1, $2))': ... func(b'foo', func(b'bar', symlist(b'$1', b'$2'))), ... b'foo($1, $2, nested($1, $2))': ... func(b'foo', (symlist(b'$1', b'$2') + ... (func(b'nested', symlist(b'$1', b'$2')),))), ... b'foo("bar")': func(b'foo', (b'string', b'bar')), ... b'foo($1, $2': error.ParseError(b'unexpected token: end', 10), ... b'foo("bar': error.ParseError(b'unterminated string', 5), ... b'foo($1, $2, $1)': func(b'foo', symlist(b'$1', b'$2', b'$1')), ... } >>> def parse(expr): ... x = parsemap[expr] ... if isinstance(x, Exception): ... raise x ... return x >>> def trygetfunc(tree): ... if not tree or tree[0] != b'func' or tree[1][0] != b'symbol': ... return None ... if not tree[2]: ... return tree[1][1], [] ... if tree[2][0] == b'list': ... return tree[1][1], list(tree[2][1:]) ... return tree[1][1], [tree[2]] >>> class aliasrules(basealiasrules): ... _parse = staticmethod(parse) ... _trygetfunc = staticmethod(trygetfunc) >>> builddecl = aliasrules._builddecl >>> builddecl(b'foo') ('foo', None, None) >>> builddecl(b'$foo') ('$foo', None, "invalid symbol '$foo'") >>> builddecl(b'foo::bar') ('foo::bar', None, 'invalid format') >>> builddecl(b'foo()') ('foo', [], None) >>> builddecl(b'$foo()') ('$foo()', None, "invalid function '$foo'") >>> builddecl(b'foo($1, $2)') ('foo', ['$1', '$2'], None) >>> builddecl(b'foo(bar_bar, baz.baz)') ('foo', ['bar_bar', 'baz.baz'], None) >>> builddecl(b'foo($1, $2, nested($1, $2))') ('foo($1, $2, nested($1, $2))', None, 'invalid argument list') >>> builddecl(b'foo(bar($1, $2))') ('foo(bar($1, $2))', None, 'invalid argument list') >>> builddecl(b'foo("bar")') ('foo("bar")', None, 'invalid argument list') >>> builddecl(b'foo($1, $2') ('foo($1, $2', None, 'at 10: unexpected token: end') >>> builddecl(b'foo("bar') ('foo("bar', None, 'at 5: unterminated string') >>> builddecl(b'foo($1, $2, $1)') ('foo', None, 'argument names collide with each other') """ try: tree = cls._parse(decl) except error.ParseError as inst: return (decl, None, parseerrordetail(inst)) if tree[0] == cls._symbolnode: # "name = ...." style name = tree[1] if name.startswith('$'): return (decl, None, _("invalid symbol '%s'") % name) return (name, None, None) func = cls._trygetfunc(tree) if func: # "name(arg, ....) = ...." style name, args = func if name.startswith('$'): return (decl, None, _("invalid function '%s'") % name) if any(t[0] != cls._symbolnode for t in args): return (decl, None, _("invalid argument list")) if len(args) != len(set(args)): return (name, None, _("argument names collide with each other")) return (name, [t[1] for t in args], None) return (decl, None, _("invalid format")) @classmethod def _relabelargs(cls, tree, args): """Mark alias arguments as ``_aliasarg``""" if not isinstance(tree, tuple): return tree op = tree[0] if op != cls._symbolnode: return (op,) + tuple(cls._relabelargs(x, args) for x in tree[1:]) assert len(tree) == 2 sym = tree[1] if sym in args: op = '_aliasarg' elif sym.startswith('$'): raise error.ParseError(_("invalid symbol '%s'") % sym) return (op, sym) @classmethod def _builddefn(cls, defn, args): """Parse an alias definition into a tree and marks substitutions This function marks alias argument references as ``_aliasarg``. The parsing rule is provided by ``_parse()``. ``args`` is a list of alias argument names, or None if the alias is declared as a symbol. >>> from . import pycompat >>> parsemap = { ... b'$1 or foo': (b'or', (b'symbol', b'$1'), (b'symbol', b'foo')), ... b'$1 or $bar': ... (b'or', (b'symbol', b'$1'), (b'symbol', b'$bar')), ... b'$10 or baz': ... (b'or', (b'symbol', b'$10'), (b'symbol', b'baz')), ... b'"$1" or "foo"': ... (b'or', (b'string', b'$1'), (b'string', b'foo')), ... } >>> class aliasrules(basealiasrules): ... _parse = staticmethod(parsemap.__getitem__) ... _trygetfunc = staticmethod(lambda x: None) >>> builddefn = aliasrules._builddefn >>> def pprint(tree): ... s = prettyformat(tree, (b'_aliasarg', b'string', b'symbol')) ... print(pycompat.sysstr(s)) >>> args = [b'$1', b'$2', b'foo'] >>> pprint(builddefn(b'$1 or foo', args)) (or (_aliasarg '$1') (_aliasarg 'foo')) >>> try: ... builddefn(b'$1 or $bar', args) ... except error.ParseError as inst: ... print(pycompat.sysstr(parseerrordetail(inst))) invalid symbol '$bar' >>> args = [b'$1', b'$10', b'foo'] >>> pprint(builddefn(b'$10 or baz', args)) (or (_aliasarg '$10') (symbol 'baz')) >>> pprint(builddefn(b'"$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, [], {})