from __future__ import division
#  Copyright (c) 1998-2000 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-0.6.1'

import re
import sys
import string

def _namelist(instance):
        namelist, namedict, classlist = [], {}, [instance.__class__]
        for c in classlist:
                for b in c.__bases__:
                        classlist.append(b)
                for name in dir(c):
                        if name not in namedict:
                                namelist.append(name)
                                namedict[name] = 1
        return namelist

class GenericScanner:
        def __init__(self):
                pattern = self.reflect()
                self.re = re.compile(pattern, re.VERBOSE)

                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 string.join(rv, '|')

        def error(self, s, pos):
                print "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 )+'
                pass

class GenericParser:
        def __init__(self, start):
                self.rules = {}
                self.rule2func = {}
                self.rule2name = {}
                self.collectRules()
                self.startRule = self.augment(start)
                self.ruleschanged = 1

        _START = 'START'
        _EOF = 'EOF'

        #
        #  A hook for GenericASTBuilder and GenericASTMatcher.
        #
        def preprocess(self, rule, func):       return rule, func

        def addRule(self, doc, func):
                rules = string.split(doc)

                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))

                        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):
                #
                #  Tempting though it is, this isn't made into a call
                #  to self.addRule() because the start rule shouldn't
                #  be subject to preprocessing.
                #
                startRule = (self._START, ( start, self._EOF ))
                self.rule2func[startRule] = lambda args: args[0]
                self.rules[self._START] = [ startRule ]
                self.rule2name[startRule] = ''
                return startRule

        def makeFIRST(self):
                union = {}
                self.first = {}
                
                for rulelist in self.rules.values():
                        for lhs, rhs in rulelist:
                                if lhs not in self.first:
                                        self.first[lhs] = {}

                                if len(rhs) == 0:
                                        self.first[lhs][None] = 1
                                        continue

                                sym = rhs[0]
                                if sym not in self.rules:
                                        self.first[lhs][sym] = 1
                                else:
                                        union[(sym, lhs)] = 1
                changes = 1
                while changes:
                        changes = 0
                        for src, dest in union.keys():
                                destlen = len(self.first[dest])
                                self.first[dest].update(self.first[src])
                                if len(self.first[dest]) != destlen:
                                        changes = 1

        #
        #  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, p. 27.
        #
        
        def typestring(self, token):
                return None

        def error(self, token):
                s = "Pysynphot syntax error at or near '%s' token" % token
                raise ValueError(s)

        def parse(self, tokens):
                tree = {}
                tokens.append(self._EOF)
                states = { 0: [ (self.startRule, 0, 0) ] }
                
                if self.ruleschanged:
                        self.makeFIRST()

                for i in xrange(len(tokens)):
                        states[i+1] = []

                        if states[i] == []:
                                break                           
                        self.buildState(tokens[i], states, i, tree)

                #_dump(tokens, states)

                if i < len(tokens)-1 or states[i+1] != [(self.startRule, 2, 0)]:
                        del tokens[-1]
                        self.error(tokens[i-1])
                rv = self.buildTree(tokens, tree, ((self.startRule, 2, 0), i+1))
                del tokens[-1]
                return rv

        def buildState(self, token, states, i, tree):
                needsCompletion = {}
                state = states[i]
                predicted = {}
                
                for item in state:
                        rule, pos, parent = item
                        lhs, rhs = rule

                        #
                        #  A -> a . (completer)
                        #
                        if pos == len(rhs):
                                if len(rhs) == 0:
                                        needsCompletion[lhs] = (item, i)

                                for pitem in states[parent]:
                                        if pitem is item:
                                                break

                                        prule, ppos, pparent = pitem
                                        plhs, prhs = prule

                                        if prhs[ppos:ppos+1] == (lhs,):
                                                new = (prule,
                                                       ppos+1,
                                                       pparent)
                                                if new not in state:
                                                        state.append(new)
                                                        tree[(new, i)] = [(item, i)]
                                                else:
                                                        tree[(new, i)].append((item, i))
                                continue

                        nextSym = rhs[pos]

                        #
                        #  A -> a . B (predictor)
                        #
                        if nextSym in self.rules:
                                #
                                #  Work on completer step some more; for rules
                                #  with empty RHS, the "parent state" is the
                                #  current state we're adding Earley items to,
                                #  so the Earley items the completer step needs
                                #  may not all be present when it runs.
                                #
                                if nextSym in needsCompletion:
                                        new = (rule, pos+1, parent)
                                        olditem_i = needsCompletion[nextSym]
                                        if new not in state:
                                                state.append(new)
                                                tree[(new, i)] = [olditem_i]
                                        else:
                                                tree[(new, i)].append(olditem_i)

                                #
                                #  Has this been predicted already?
                                #
                                if nextSym in predicted:
                                        continue
                                predicted[nextSym] = 1

                                ttype = token is not self._EOF and \
                                        self.typestring(token) or \
                                        None
                                if ttype is not None:
                                        #
                                        #  Even smarter predictor, when the
                                        #  token's type is known.  The code is
                                        #  grungy, but runs pretty fast.  Three
                                        #  cases are looked for: rules with
                                        #  empty RHS; first symbol on RHS is a
                                        #  terminal; first symbol on RHS is a
                                        #  nonterminal (and isn't nullable).
                                        #
                                        for prule in self.rules[nextSym]:
                                                new = (prule, 0, i)
                                                prhs = prule[1]
                                                if len(prhs) == 0:
                                                        state.append(new)
                                                        continue
                                                prhs0 = prhs[0]
                                                if prhs0 not in self.rules:
                                                        if prhs0 != ttype:
                                                                continue
                                                        else:
                                                                state.append(new)
                                                                continue
                                                first = self.first[prhs0]
                                                if None not in first and \
                                                   ttype not in first:
                                                        continue
                                                state.append(new)
                                        continue

                                for prule in self.rules[nextSym]:
                                        #
                                        #  Smarter predictor, as per Grune &
                                        #  Jacobs' _Parsing Techniques_.  Not
                                        #  as good as FIRST sets though.
                                        #
                                        prhs = prule[1]
                                        if len(prhs) > 0 and \
                                           prhs[0] not in self.rules and \
                                           token != prhs[0]:
                                                continue
                                        state.append((prule, 0, i))

                        #
                        #  A -> a . c (scanner)
                        #
                        elif token == nextSym:
                                #assert new not in states[i+1]
                                states[i+1].append((rule, pos+1, parent))

        def buildTree(self, tokens, tree, root):
                stack = []
                self.buildTree_r(stack, tokens, -1, tree, root)
                return stack[0]

        def buildTree_r(self, stack, tokens, tokpos, tree, root):
                (rule, pos, parent), state = root
                
                while pos > 0:
                        want = ((rule, pos, parent), state)
                        if want not in tree:
                                #
                                #  Since pos > 0, it didn't come from closure,
                                #  and if it isn't in tree[], then there must
                                #  be a terminal symbol to the left of the dot.
                                #  (It must be from a "scanner" step.)
                                #
                                pos = pos - 1
                                state = state - 1
                                stack.insert(0, tokens[tokpos])
                                tokpos = tokpos - 1
                        else:
                                #
                                #  There's a NT to the left of the dot.
                                #  Follow the tree pointer recursively (>1
                                #  tree pointers from it indicates ambiguity).
                                #  Since the item must have come about from a
                                #  "completer" step, the state where the item
                                #  came from must be the parent state of the
                                #  item the tree pointer points to.
                                #
                                children = tree[want]
                                if len(children) > 1:
                                        child = self.ambiguity(children)
                                else:
                                        child = children[0]
                                
                                tokpos = self.buildTree_r(stack,
                                                          tokens, tokpos,
                                                          tree, child)
                                pos = pos - 1
                                (crule, cpos, cparent), cstate = child
                                state = cparent
                                
                lhs, rhs = rule
                result = self.rule2func[rule](stack[:len(rhs)])
                stack[:len(rhs)] = [result]
                return tokpos

        def ambiguity(self, children):
                #
                #  XXX - problem here and in collectRules() if the same
                #        rule appears in >1 method.  But in that case the
                #        user probably gets what they deserve :-)  Also
                #        undefined results if rules causing the ambiguity
                #        appear in the same method.
                #
                sortlist = []
                name2index = {}
                for i in range(len(children)):
                        ((rule, pos, parent), index) = children[i]
                        lhs, rhs = rule
                        name = self.rule2name[rule]
                        sortlist.append((len(rhs), name))
                        name2index[name] = i
                sortlist.sort()
                list = map(lambda (a,b): b, sortlist)
                return children[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, states):
        for i in range(len(states)):
                print 'state', i
                for (lhs, rhs), pos, parent in states[i]:
                        print '\t', lhs, '::=',
                        print string.join(rhs[:pos]),
                        print '.',
                        print string.join(rhs[pos:]),
                        print ',', parent
                if i < len(tokens):
                        print
                        print 'token', str(tokens[i])
                        print
