two version of R2R are hereHEADmaster

1 files changed, 345 insertions, 0 deletions

diff --git a/.venv/lib/python3.12/site-packages/lark/parsers/cyk.py b/.venv/lib/python3.12/site-packages/lark/parsers/cyk.py
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+"""This module implements a CYK parser."""
+
+# Author: https://github.com/ehudt (2018)
+#
+# Adapted by Erez
+
+
+from collections import defaultdict
+import itertools
+
+from ..exceptions import ParseError
+from ..lexer import Token
+from ..tree import Tree
+from ..grammar import Terminal as T, NonTerminal as NT, Symbol
+
+try:
+    xrange
+except NameError:
+    xrange = range
+
+def match(t, s):
+    assert isinstance(t, T)
+    return t.name == s.type
+
+
+class Rule(object):
+    """Context-free grammar rule."""
+
+    def __init__(self, lhs, rhs, weight, alias):
+        super(Rule, self).__init__()
+        assert isinstance(lhs, NT), lhs
+        assert all(isinstance(x, NT) or isinstance(x, T) for x in rhs), rhs
+        self.lhs = lhs
+        self.rhs = rhs
+        self.weight = weight
+        self.alias = alias
+
+    def __str__(self):
+        return '%s -> %s' % (str(self.lhs), ' '.join(str(x) for x in self.rhs))
+
+    def __repr__(self):
+        return str(self)
+
+    def __hash__(self):
+        return hash((self.lhs, tuple(self.rhs)))
+
+    def __eq__(self, other):
+        return self.lhs == other.lhs and self.rhs == other.rhs
+
+    def __ne__(self, other):
+        return not (self == other)
+
+
+class Grammar(object):
+    """Context-free grammar."""
+
+    def __init__(self, rules):
+        self.rules = frozenset(rules)
+
+    def __eq__(self, other):
+        return self.rules == other.rules
+
+    def __str__(self):
+        return '\n' + '\n'.join(sorted(repr(x) for x in self.rules)) + '\n'
+
+    def __repr__(self):
+        return str(self)
+
+
+# Parse tree data structures
+class RuleNode(object):
+    """A node in the parse tree, which also contains the full rhs rule."""
+
+    def __init__(self, rule, children, weight=0):
+        self.rule = rule
+        self.children = children
+        self.weight = weight
+
+    def __repr__(self):
+        return 'RuleNode(%s, [%s])' % (repr(self.rule.lhs), ', '.join(str(x) for x in self.children))
+
+
+
+class Parser(object):
+    """Parser wrapper."""
+
+    def __init__(self, rules):
+        super(Parser, self).__init__()
+        self.orig_rules = {rule: rule for rule in rules}
+        rules = [self._to_rule(rule) for rule in rules]
+        self.grammar = to_cnf(Grammar(rules))
+
+    def _to_rule(self, lark_rule):
+        """Converts a lark rule, (lhs, rhs, callback, options), to a Rule."""
+        assert isinstance(lark_rule.origin, NT)
+        assert all(isinstance(x, Symbol) for x in lark_rule.expansion)
+        return Rule(
+            lark_rule.origin, lark_rule.expansion,
+            weight=lark_rule.options.priority if lark_rule.options.priority else 0,
+            alias=lark_rule)
+
+    def parse(self, tokenized, start):  # pylint: disable=invalid-name
+        """Parses input, which is a list of tokens."""
+        assert start
+        start = NT(start)
+
+        table, trees = _parse(tokenized, self.grammar)
+        # Check if the parse succeeded.
+        if all(r.lhs != start for r in table[(0, len(tokenized) - 1)]):
+            raise ParseError('Parsing failed.')
+        parse = trees[(0, len(tokenized) - 1)][start]
+        return self._to_tree(revert_cnf(parse))
+
+    def _to_tree(self, rule_node):
+        """Converts a RuleNode parse tree to a lark Tree."""
+        orig_rule = self.orig_rules[rule_node.rule.alias]
+        children = []
+        for child in rule_node.children:
+            if isinstance(child, RuleNode):
+                children.append(self._to_tree(child))
+            else:
+                assert isinstance(child.name, Token)
+                children.append(child.name)
+        t = Tree(orig_rule.origin, children)
+        t.rule=orig_rule
+        return t
+
+
+def print_parse(node, indent=0):
+    if isinstance(node, RuleNode):
+        print(' ' * (indent * 2) + str(node.rule.lhs))
+        for child in node.children:
+            print_parse(child, indent + 1)
+    else:
+        print(' ' * (indent * 2) + str(node.s))
+
+
+def _parse(s, g):
+    """Parses sentence 's' using CNF grammar 'g'."""
+    # The CYK table. Indexed with a 2-tuple: (start pos, end pos)
+    table = defaultdict(set)
+    # Top-level structure is similar to the CYK table. Each cell is a dict from
+    # rule name to the best (lightest) tree for that rule.
+    trees = defaultdict(dict)
+    # Populate base case with existing terminal production rules
+    for i, w in enumerate(s):
+        for terminal, rules in g.terminal_rules.items():
+            if match(terminal, w):
+                for rule in rules:
+                    table[(i, i)].add(rule)
+                    if (rule.lhs not in trees[(i, i)] or
+                        rule.weight < trees[(i, i)][rule.lhs].weight):
+                        trees[(i, i)][rule.lhs] = RuleNode(rule, [T(w)], weight=rule.weight)
+
+    # Iterate over lengths of sub-sentences
+    for l in xrange(2, len(s) + 1):
+        # Iterate over sub-sentences with the given length
+        for i in xrange(len(s) - l + 1):
+            # Choose partition of the sub-sentence in [1, l)
+            for p in xrange(i + 1, i + l):
+                span1 = (i, p - 1)
+                span2 = (p, i + l - 1)
+                for r1, r2 in itertools.product(table[span1], table[span2]):
+                    for rule in g.nonterminal_rules.get((r1.lhs, r2.lhs), []):
+                        table[(i, i + l - 1)].add(rule)
+                        r1_tree = trees[span1][r1.lhs]
+                        r2_tree = trees[span2][r2.lhs]
+                        rule_total_weight = rule.weight + r1_tree.weight + r2_tree.weight
+                        if (rule.lhs not in trees[(i, i + l - 1)]
+                            or rule_total_weight < trees[(i, i + l - 1)][rule.lhs].weight):
+                            trees[(i, i + l - 1)][rule.lhs] = RuleNode(rule, [r1_tree, r2_tree], weight=rule_total_weight)
+    return table, trees
+
+
+# This section implements context-free grammar converter to Chomsky normal form.
+# It also implements a conversion of parse trees from its CNF to the original
+# grammar.
+# Overview:
+# Applies the following operations in this order:
+# * TERM: Eliminates non-solitary terminals from all rules
+# * BIN: Eliminates rules with more than 2 symbols on their right-hand-side.
+# * UNIT: Eliminates non-terminal unit rules
+#
+# The following grammar characteristics aren't featured:
+# * Start symbol appears on RHS
+# * Empty rules (epsilon rules)
+
+
+class CnfWrapper(object):
+    """CNF wrapper for grammar.
+
+  Validates that the input grammar is CNF and provides helper data structures.
+  """
+
+    def __init__(self, grammar):
+        super(CnfWrapper, self).__init__()
+        self.grammar = grammar
+        self.rules = grammar.rules
+        self.terminal_rules = defaultdict(list)
+        self.nonterminal_rules = defaultdict(list)
+        for r in self.rules:
+            # Validate that the grammar is CNF and populate auxiliary data structures.
+            assert isinstance(r.lhs, NT), r
+            if len(r.rhs) not in [1, 2]:
+                raise ParseError("CYK doesn't support empty rules")
+            if len(r.rhs) == 1 and isinstance(r.rhs[0], T):
+                self.terminal_rules[r.rhs[0]].append(r)
+            elif len(r.rhs) == 2 and all(isinstance(x, NT) for x in r.rhs):
+                self.nonterminal_rules[tuple(r.rhs)].append(r)
+            else:
+                assert False, r
+
+    def __eq__(self, other):
+        return self.grammar == other.grammar
+
+    def __repr__(self):
+        return repr(self.grammar)
+
+
+class UnitSkipRule(Rule):
+    """A rule that records NTs that were skipped during transformation."""
+
+    def __init__(self, lhs, rhs, skipped_rules, weight, alias):
+        super(UnitSkipRule, self).__init__(lhs, rhs, weight, alias)
+        self.skipped_rules = skipped_rules
+
+    def __eq__(self, other):
+        return isinstance(other, type(self)) and self.skipped_rules == other.skipped_rules
+
+    __hash__ = Rule.__hash__
+
+
+def build_unit_skiprule(unit_rule, target_rule):
+    skipped_rules = []
+    if isinstance(unit_rule, UnitSkipRule):
+        skipped_rules += unit_rule.skipped_rules
+    skipped_rules.append(target_rule)
+    if isinstance(target_rule, UnitSkipRule):
+        skipped_rules += target_rule.skipped_rules
+    return UnitSkipRule(unit_rule.lhs, target_rule.rhs, skipped_rules,
+                      weight=unit_rule.weight + target_rule.weight, alias=unit_rule.alias)
+
+
+def get_any_nt_unit_rule(g):
+    """Returns a non-terminal unit rule from 'g', or None if there is none."""
+    for rule in g.rules:
+        if len(rule.rhs) == 1 and isinstance(rule.rhs[0], NT):
+            return rule
+    return None
+
+
+def _remove_unit_rule(g, rule):
+    """Removes 'rule' from 'g' without changing the langugage produced by 'g'."""
+    new_rules = [x for x in g.rules if x != rule]
+    refs = [x for x in g.rules if x.lhs == rule.rhs[0]]
+    new_rules += [build_unit_skiprule(rule, ref) for ref in refs]
+    return Grammar(new_rules)
+
+
+def _split(rule):
+    """Splits a rule whose len(rhs) > 2 into shorter rules."""
+    rule_str = str(rule.lhs) + '__' + '_'.join(str(x) for x in rule.rhs)
+    rule_name = '__SP_%s' % (rule_str) + '_%d'
+    yield Rule(rule.lhs, [rule.rhs[0], NT(rule_name % 1)], weight=rule.weight, alias=rule.alias)
+    for i in xrange(1, len(rule.rhs) - 2):
+        yield Rule(NT(rule_name % i), [rule.rhs[i], NT(rule_name % (i + 1))], weight=0, alias='Split')
+    yield Rule(NT(rule_name % (len(rule.rhs) - 2)), rule.rhs[-2:], weight=0, alias='Split')
+
+
+def _term(g):
+    """Applies the TERM rule on 'g' (see top comment)."""
+    all_t = {x for rule in g.rules for x in rule.rhs if isinstance(x, T)}
+    t_rules = {t: Rule(NT('__T_%s' % str(t)), [t], weight=0, alias='Term') for t in all_t}
+    new_rules = []
+    for rule in g.rules:
+        if len(rule.rhs) > 1 and any(isinstance(x, T) for x in rule.rhs):
+            new_rhs = [t_rules[x].lhs if isinstance(x, T) else x for x in rule.rhs]
+            new_rules.append(Rule(rule.lhs, new_rhs, weight=rule.weight, alias=rule.alias))
+            new_rules.extend(v for k, v in t_rules.items() if k in rule.rhs)
+        else:
+            new_rules.append(rule)
+    return Grammar(new_rules)
+
+
+def _bin(g):
+    """Applies the BIN rule to 'g' (see top comment)."""
+    new_rules = []
+    for rule in g.rules:
+        if len(rule.rhs) > 2:
+            new_rules += _split(rule)
+        else:
+            new_rules.append(rule)
+    return Grammar(new_rules)
+
+
+def _unit(g):
+    """Applies the UNIT rule to 'g' (see top comment)."""
+    nt_unit_rule = get_any_nt_unit_rule(g)
+    while nt_unit_rule:
+        g = _remove_unit_rule(g, nt_unit_rule)
+        nt_unit_rule = get_any_nt_unit_rule(g)
+    return g
+
+
+def to_cnf(g):
+    """Creates a CNF grammar from a general context-free grammar 'g'."""
+    g = _unit(_bin(_term(g)))
+    return CnfWrapper(g)
+
+
+def unroll_unit_skiprule(lhs, orig_rhs, skipped_rules, children, weight, alias):
+    if not skipped_rules:
+        return RuleNode(Rule(lhs, orig_rhs, weight=weight, alias=alias), children, weight=weight)
+    else:
+        weight = weight - skipped_rules[0].weight
+        return RuleNode(
+            Rule(lhs, [skipped_rules[0].lhs], weight=weight, alias=alias), [
+                unroll_unit_skiprule(skipped_rules[0].lhs, orig_rhs,
+                                skipped_rules[1:], children,
+                                skipped_rules[0].weight, skipped_rules[0].alias)
+            ], weight=weight)
+
+
+def revert_cnf(node):
+    """Reverts a parse tree (RuleNode) to its original non-CNF form (Node)."""
+    if isinstance(node, T):
+        return node
+    # Reverts TERM rule.
+    if node.rule.lhs.name.startswith('__T_'):
+        return node.children[0]
+    else:
+        children = []
+        for child in map(revert_cnf, node.children):
+            # Reverts BIN rule.
+            if isinstance(child, RuleNode) and child.rule.lhs.name.startswith('__SP_'):
+                children += child.children
+            else:
+                children.append(child)
+        # Reverts UNIT rule.
+        if isinstance(node.rule, UnitSkipRule):
+            return unroll_unit_skiprule(node.rule.lhs, node.rule.rhs,
+                                    node.rule.skipped_rules, children,
+                                    node.rule.weight, node.rule.alias)
+        else:
+            return RuleNode(node.rule, children)