# Copyright (c) 1998-2002 John Aycock

#

# Permission is hereby granted, free of charge, to any person obtaining

# a copy of this software and associated documentation files (the

# "Software"), to deal in the Software without restriction, including

# without limitation the rights to use, copy, modify, merge, publish,

# distribute, sublicense, and/or sell copies of the Software, and to

# permit persons to whom the Software is furnished to do so, subject to

# the following conditions:

#

# The above copyright notice and this permission notice shall be

# included in all copies or substantial portions of the Software.

#

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,

# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

# IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY

# CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,

# TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

# SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

__version__ = 'SPARK-0.7 (pre-alpha-5)'

import re

import sys

# Compatability with older pythons.

def output(string='', end='\n'):

sys.stdout.write(string + end)

try:

sorted

except NameError:

def sorted(seq):

seq2 = seq[:]

seq2.sort()

return seq2

def _namelist(instance):

namelist, namedict, classlist = [], {}, [instance.__class__]

for c in classlist:

for b in c.__bases__:

classlist.append(b)

for name in c.__dict__.keys():

if name not in namedict:

namelist.append(name)

namedict[name] = 1

return namelist

class GenericScanner:

def __init__(self, flags=0):

pattern = self.reflect()

self.re = re.compile(pattern, re.VERBOSE|flags)

self.index2func = {}

for name, number in self.re.groupindex.items():

self.index2func[number-1] = getattr(self, 't_' + name)

def makeRE(self, name):

doc = getattr(self, name).__doc__

rv = '(?P<%s>%s)' % (name[2:], doc)

return rv

def reflect(self):

rv = []

for name in _namelist(self):

if name[:2] == 't_' and name != 't_default':

rv.append(self.makeRE(name))

rv.append(self.makeRE('t_default'))

return '|'.join(rv)

def error(self, s, pos):

output("Lexical error at position %s" % pos)

raise SystemExit

def tokenize(self, s):

pos = 0

n = len(s)

while pos < n:

m = self.re.match(s, pos)

if m is None:

self.error(s, pos)

groups = m.groups()

for i in range(len(groups)):

if groups[i] and i in self.index2func:

self.index2func[i](groups[i])

pos = m.end()

def t_default(self, s):

r'( . | \n )+'

output("Specification error: unmatched input")

raise SystemExit

#

# Extracted from GenericParser and made global so that [un]picking works.

#

class _State:

def __init__(self, stateno, items):

self.T, self.complete, self.items = [], [], items

self.stateno = stateno

class GenericParser:

#

# An Earley parser, as per J. Earley, "An Efficient Context-Free

# Parsing Algorithm", CACM 13(2), pp. 94-102. Also J. C. Earley,

# "An Efficient Context-Free Parsing Algorithm", Ph.D. thesis,

# Carnegie-Mellon University, August 1968. New formulation of

# the parser according to J. Aycock, "Practical Earley Parsing

# and the SPARK Toolkit", Ph.D. thesis, University of Victoria,

# 2001, and J. Aycock and R. N. Horspool, "Practical Earley

# Parsing", unpublished paper, 2001.

#

def __init__(self, start):

self.rules = {}

self.rule2func = {}

self.rule2name = {}

self.collectRules()

self.augment(start)

self.ruleschanged = 1

_NULLABLE = '\e_'

_START = 'START'

_BOF = '|-'

#

# When pickling, take the time to generate the full state machine;

# some information is then extraneous, too. Unfortunately we

# can't save the rule2func map.

#

def __getstate__(self):

if self.ruleschanged:

#

# XXX - duplicated from parse()

#

self.computeNull()

self.newrules = {}

self.new2old = {}

self.makeNewRules()

self.ruleschanged = 0

self.edges, self.cores = {}, {}

self.states = { 0: self.makeState0() }

self.makeState(0, self._BOF)

#

# XXX - should find a better way to do this..

#

changes = 1

while changes:

changes = 0

for k, v in self.edges.items():

if v is None:

state, sym = k

if state in self.states:

self.goto(state, sym)

changes = 1

rv = self.__dict__.copy()

for s in self.states.values():

del s.items

del rv['rule2func']

del rv['nullable']

del rv['cores']

return rv

def __setstate__(self, D):

self.rules = {}

self.rule2func = {}

self.rule2name = {}

self.collectRules()

start = D['rules'][self._START][0][1][1] # Blech.

self.augment(start)

D['rule2func'] = self.rule2func

D['makeSet'] = self.makeSet_fast

self.__dict__ = D

#

# A hook for GenericASTBuilder and GenericASTMatcher. Mess

# thee not with this; nor shall thee toucheth the _preprocess

# argument to addRule.

#

def preprocess(self, rule, func): return rule, func

def addRule(self, doc, func, _preprocess=1):

fn = func

rules = doc.split()

index = []

for i in range(len(rules)):

if rules[i] == '::=':

index.append(i-1)

index.append(len(rules))

for i in range(len(index)-1):

lhs = rules[index[i]]

rhs = rules[index[i]+2:index[i+1]]

rule = (lhs, tuple(rhs))

if _preprocess:

rule, fn = self.preprocess(rule, func)

if lhs in self.rules:

self.rules[lhs].append(rule)

else:

self.rules[lhs] = [ rule ]

self.rule2func[rule] = fn

self.rule2name[rule] = func.__name__[2:]

self.ruleschanged = 1

def collectRules(self):

for name in _namelist(self):

if name[:2] == 'p_':

func = getattr(self, name)

doc = func.__doc__

self.addRule(doc, func)

def augment(self, start):

rule = '%s ::= %s %s' % (self._START, self._BOF, start)

self.addRule(rule, lambda args: args[1], 0)

def computeNull(self):

self.nullable = {}

tbd = []

for rulelist in self.rules.values():

lhs = rulelist[0][0]

self.nullable[lhs] = 0

for rule in rulelist:

rhs = rule[1]

if len(rhs) == 0:

self.nullable[lhs] = 1

continue

#

# We only need to consider rules which

# consist entirely of nonterminal symbols.

# This should be a savings on typical

# grammars.

#

for sym in rhs:

if sym not in self.rules:

break

else:

tbd.append(rule)

changes = 1

while changes:

changes = 0

for lhs, rhs in tbd:

if self.nullable[lhs]:

continue

for sym in rhs:

if not self.nullable[sym]:

break

else:

self.nullable[lhs] = 1

changes = 1

def makeState0(self):

s0 = _State(0, [])

for rule in self.newrules[self._START]:

s0.items.append((rule, 0))

return s0

def finalState(self, tokens):

#

# Yuck.

#

if len(self.newrules[self._START]) == 2 and len(tokens) == 0:

return 1

start = self.rules[self._START][0][1][1]

return self.goto(1, start)

def makeNewRules(self):

worklist = []

for rulelist in self.rules.values():

for rule in rulelist:

worklist.append((rule, 0, 1, rule))

for rule, i, candidate, oldrule in worklist:

lhs, rhs = rule

n = len(rhs)

while i < n:

sym = rhs[i]

if sym not in self.rules or \

not self.nullable[sym]:

candidate = 0

i = i + 1

continue

newrhs = list(rhs)

newrhs[i] = self._NULLABLE+sym

newrule = (lhs, tuple(newrhs))

worklist.append((newrule, i+1,

candidate, oldrule))

candidate = 0

i = i + 1

else:

if candidate:

lhs = self._NULLABLE+lhs

rule = (lhs, rhs)

if lhs in self.newrules:

self.newrules[lhs].append(rule)

else:

self.newrules[lhs] = [ rule ]

self.new2old[rule] = oldrule

def typestring(self, token):

return None

def error(self, token):

output("Syntax error at or near `%s' token" % token)

raise SystemExit

def parse(self, tokens):

sets = [ [(1,0), (2,0)] ]

self.links = {}

if self.ruleschanged:

self.computeNull()

self.newrules = {}

self.new2old = {}

self.makeNewRules()

self.ruleschanged = 0

self.edges, self.cores = {}, {}

self.states = { 0: self.makeState0() }

self.makeState(0, self._BOF)

for i in range(len(tokens)):

sets.append([])

if sets[i] == []:

break

self.makeSet(tokens[i], sets, i)

else:

sets.append([])

self.makeSet(None, sets, len(tokens))

#_dump(tokens, sets, self.states)

finalitem = (self.finalState(tokens), 0)

if finalitem not in sets[-2]:

if len(tokens) > 0:

self.error(tokens[i-1])

else:

self.error(None)

return self.buildTree(self._START, finalitem,

tokens, len(sets)-2)

def isnullable(self, sym):

#

# For symbols in G_e only. If we weren't supporting 1.5,

# could just use sym.startswith().

#

return self._NULLABLE == sym[0:len(self._NULLABLE)]

def skip(self, hs, pos=0):

n = len(hs[1])

while pos < n:

if not self.isnullable(hs[1][pos]):

break

pos = pos + 1

return pos

def makeState(self, state, sym):

assert sym is not None

#

# Compute \epsilon-kernel state's core and see if

# it exists already.

#

kitems = []

for rule, pos in self.states[state].items:

lhs, rhs = rule

if rhs[pos:pos+1] == (sym,):

kitems.append((rule, self.skip(rule, pos+1)))

core = kitems

core.sort()

tcore = tuple(core)

if tcore in self.cores:

return self.cores[tcore]

#

# Nope, doesn't exist. Compute it and the associated

# \epsilon-nonkernel state together; we'll need it right away.

#

k = self.cores[tcore] = len(self.states)

K, NK = _State(k, kitems), _State(k+1, [])

self.states[k] = K

predicted = {}

edges = self.edges

rules = self.newrules

for X in K, NK:

worklist = X.items

for item in worklist:

rule, pos = item

lhs, rhs = rule

if pos == len(rhs):

X.complete.append(rule)

continue

nextSym = rhs[pos]

key = (X.stateno, nextSym)

if nextSym not in rules:

if key not in edges:

edges[key] = None

X.T.append(nextSym)

else:

edges[key] = None

if nextSym not in predicted:

predicted[nextSym] = 1

for prule in rules[nextSym]:

ppos = self.skip(prule)

new = (prule, ppos)

NK.items.append(new)

#

# Problem: we know K needs generating, but we

# don't yet know about NK. Can't commit anything

# regarding NK to self.edges until we're sure. Should

# we delay committing on both K and NK to avoid this

# hacky code? This creates other problems..

#

if X is K:

edges = {}

if NK.items == []:

return k

#

# Check for \epsilon-nonkernel's core. Unfortunately we

# need to know the entire set of predicted nonterminals

# to do this without accidentally duplicating states.

#

core = sorted(predicted.keys())

tcore = tuple(core)

if tcore in self.cores:

self.edges[(k, None)] = self.cores[tcore]

return k

nk = self.cores[tcore] = self.edges[(k, None)] = NK.stateno

self.edges.update(edges)

self.states[nk] = NK

return k

def goto(self, state, sym):

key = (state, sym)

if key not in self.edges:

#

# No transitions from state on sym.

#

return None

rv = self.edges[key]

if rv is None:

#

# Target state isn't generated yet. Remedy this.

#

rv = self.makeState(state, sym)

self.edges[key] = rv

return rv

def gotoT(self, state, t):

return [self.goto(state, t)]

def gotoST(self, state, st):

rv = []

for t in self.states[state].T:

if st == t:

rv.append(self.goto(state, t))

return rv

def add(self, set, item, i=None, predecessor=None, causal=None):

if predecessor is None:

if item not in set:

set.append(item)

else:

key = (item, i)

if item not in set:

self.links[key] = []

set.append(item)

self.links[key].append((predecessor, causal))

def makeSet(self, token, sets, i):

cur, next = sets[i], sets[i+1]

ttype = token is not None and self.typestring(token) or None

if ttype is not None:

fn, arg = self.gotoT, ttype

else:

fn, arg = self.gotoST, token

for item in cur:

ptr = (item, i)

state, parent = item

add = fn(state, arg)

for k in add:

if k is not None:

self.add(next, (k, parent), i+1, ptr)

nk = self.goto(k, None)

if nk is not None:

self.add(next, (nk, i+1))

if parent == i:

continue

for rule in self.states[state].complete:

lhs, rhs = rule

for pitem in sets[parent]:

pstate, pparent = pitem

k = self.goto(pstate, lhs)

if k is not None:

why = (item, i, rule)

pptr = (pitem, parent)

self.add(cur, (k, pparent),

i, pptr, why)

nk = self.goto(k, None)

if nk is not None:

self.add(cur, (nk, i))

def makeSet_fast(self, token, sets, i):

#

# Call *only* when the entire state machine has been built!

# It relies on self.edges being filled in completely, and

# then duplicates and inlines code to boost speed at the

# cost of extreme ugliness.

#

cur, next = sets[i], sets[i+1]

ttype = token is not None and self.typestring(token) or None

for item in cur:

ptr = (item, i)

state, parent = item

if ttype is not None:

k = self.edges.get((state, ttype), None)

if k is not None:

#self.add(next, (k, parent), i+1, ptr)

#INLINED --v

new = (k, parent)

key = (new, i+1)

if new not in next:

self.links[key] = []

next.append(new)

self.links[key].append((ptr, None))

#INLINED --^

#nk = self.goto(k, None)

nk = self.edges.get((k, None), None)

if nk is not None:

#self.add(next, (nk, i+1))

#INLINED --v

new = (nk, i+1)

if new not in next:

next.append(new)

#INLINED --^

else:

add = self.gotoST(state, token)

for k in add:

if k is not None:

self.add(next, (k, parent), i+1, ptr)

#nk = self.goto(k, None)

nk = self.edges.get((k, None), None)

if nk is not None:

self.add(next, (nk, i+1))

if parent == i:

continue

for rule in self.states[state].complete:

lhs, rhs = rule

for pitem in sets[parent]:

pstate, pparent = pitem

#k = self.goto(pstate, lhs)

k = self.edges.get((pstate, lhs), None)

if k is not None:

why = (item, i, rule)

pptr = (pitem, parent)

#self.add(cur, (k, pparent),

# i, pptr, why)

#INLINED --v

new = (k, pparent)

key = (new, i)

if new not in cur:

self.links[key] = []

cur.append(new)

self.links[key].append((pptr, why))

#INLINED --^

#nk = self.goto(k, None)

nk = self.edges.get((k, None), None)

if nk is not None:

#self.add(cur, (nk, i))

#INLINED --v

new = (nk, i)

if new not in cur:

cur.append(new)

#INLINED --^

def predecessor(self, key, causal):

for p, c in self.links[key]:

if c == causal:

return p

assert 0

def causal(self, key):

links = self.links[key]

if len(links) == 1:

return links[0][1]

choices = []

rule2cause = {}

for p, c in links:

rule = c[2]

choices.append(rule)

rule2cause[rule] = c

return rule2cause[self.ambiguity(choices)]

def deriveEpsilon(self, nt):

if len(self.newrules[nt]) > 1:

rule = self.ambiguity(self.newrules[nt])

else:

rule = self.newrules[nt][0]

#output(rule)

rhs = rule[1]

attr = [None] * len(rhs)

for i in range(len(rhs)-1, -1, -1):

attr[i] = self.deriveEpsilon(rhs[i])

return self.rule2func[self.new2old[rule]](attr)

def buildTree(self, nt, item, tokens, k):

state, parent = item

choices = []

for rule in self.states[state].complete:

if rule[0] == nt:

choices.append(rule)

rule = choices[0]

if len(choices) > 1:

rule = self.ambiguity(choices)

#output(rule)

rhs = rule[1]

attr = [None] * len(rhs)

for i in range(len(rhs)-1, -1, -1):

sym = rhs[i]

if sym not in self.newrules:

if sym != self._BOF:

attr[i] = tokens[k-1]

key = (item, k)

item, k = self.predecessor(key, None)

#elif self.isnullable(sym):

elif self._NULLABLE == sym[0:len(self._NULLABLE)]:

attr[i] = self.deriveEpsilon(sym)

else:

key = (item, k)

why = self.causal(key)

attr[i] = self.buildTree(sym, why[0],

tokens, why[1])

item, k = self.predecessor(key, why)

return self.rule2func[self.new2old[rule]](attr)

def ambiguity(self, rules):

#

# XXX - problem here and in collectRules() if the same rule

# appears in >1 method. Also undefined results if rules

# causing the ambiguity appear in the same method.

#

sortlist = []

name2index = {}

for i in range(len(rules)):

lhs, rhs = rule = rules[i]

name = self.rule2name[self.new2old[rule]]

sortlist.append((len(rhs), name))

name2index[name] = i

sortlist.sort()

list = [b for a, b in sortlist]

return rules[name2index[self.resolve(list)]]

def resolve(self, list):

#

# Resolve ambiguity in favor of the shortest RHS.

# Since we walk the tree from the top down, this

# should effectively resolve in favor of a "shift".

#

return list[0]

#

# GenericASTBuilder automagically constructs a concrete/abstract syntax tree

# for a given input. The extra argument is a class (not an instance!)

# which supports the "__setslice__" and "__len__" methods.

#

# XXX - silently overrides any user code in methods.

#

class GenericASTBuilder(GenericParser):

def __init__(self, AST, start):

GenericParser.__init__(self, start)

self.AST = AST

def preprocess(self, rule, func):

rebind = lambda lhs, self=self: \

lambda args, lhs=lhs, self=self: \

self.buildASTNode(args, lhs)

lhs, rhs = rule

return rule, rebind(lhs)

def buildASTNode(self, args, lhs):

children = []

for arg in args:

if isinstance(arg, self.AST):

children.append(arg)

else:

children.append(self.terminal(arg))

return self.nonterminal(lhs, children)

def terminal(self, token): return token

def nonterminal(self, type, args):

rv = self.AST(type)

rv[:len(args)] = args

return rv

#

# GenericASTTraversal is a Visitor pattern according to Design Patterns. For

# each node it attempts to invoke the method n_<node type>, falling

# back onto the default() method if the n_* can't be found. The preorder

# traversal also looks for an exit hook named n_<node type>_exit (no default

# routine is called if it's not found). To prematurely halt traversal

# of a subtree, call the prune() method -- this only makes sense for a

# preorder traversal. Node type is determined via the typestring() method.

#

class GenericASTTraversalPruningException:

pass

class GenericASTTraversal:

def __init__(self, ast):

self.ast = ast

def typestring(self, node):

return node.type

def prune(self):

raise GenericASTTraversalPruningException

def preorder(self, node=None):

if node is None:

node = self.ast

try:

name = 'n_' + self.typestring(node)

if hasattr(self, name):

func = getattr(self, name)

func(node)

else:

self.default(node)

except GenericASTTraversalPruningException:

return

for kid in node:

self.preorder(kid)

name = name + '_exit'

if hasattr(self, name):

func = getattr(self, name)

func(node)

def postorder(self, node=None):

if node is None:

node = self.ast

for kid in node:

self.postorder(kid)

name = 'n_' + self.typestring(node)

if hasattr(self, name):

func = getattr(self, name)

func(node)

else:

self.default(node)

def default(self, node):

pass

#

# GenericASTMatcher. AST nodes must have "__getitem__" and "__cmp__"

# implemented.

#

# XXX - makes assumptions about how GenericParser walks the parse tree.

#

class GenericASTMatcher(GenericParser):

def __init__(self, start, ast):

GenericParser.__init__(self, start)

self.ast = ast

def preprocess(self, rule, func):

rebind = lambda func, self=self: \

lambda args, func=func, self=self: \

self.foundMatch(args, func)

lhs, rhs = rule

rhslist = list(rhs)

rhslist.reverse()

return (lhs, tuple(rhslist)), rebind(func)

def foundMatch(self, args, func):

func(args[-1])

return args[-1]

def match_r(self, node):

self.input.insert(0, node)

children = 0

for child in node:

if children == 0:

self.input.insert(0, '(')

children = children + 1

self.match_r(child)

if children > 0:

self.input.insert(0, ')')

def match(self, ast=None):

if ast is None:

ast = self.ast

self.input = []

self.match_r(ast)

self.parse(self.input)

def resolve(self, list):

#

# Resolve ambiguity in favor of the longest RHS.

#

return list[-1]

def _dump(tokens, sets, states):

for i in range(len(sets)):

output('set %d' % i)

for item in sets[i]:

output('\t', item)

for (lhs, rhs), pos in states[item[0]].items:

output('\t\t', lhs, '::=', end='')

output(' '.join(rhs[:pos]), end='')

output('.', end='')

output(' '.join(rhs[pos:]))

if i < len(tokens):

output()

output('token %s' % str(tokens[i]))

output()