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diff --git a/yapps/parsetree.py b/yapps/parsetree.py
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+# parsetree.py, part of Yapps 2 - yet another python parser system
+# Copyright 1999-2003 by Amit J. Patel <amitp@cs.stanford.edu>
+#
+# This version of the Yapps 2 Runtime can be distributed under the
+# terms of the MIT open source license, either found in the LICENSE file
+# included with the Yapps distribution
+# <http://theory.stanford.edu/~amitp/yapps/> or at
+# <http://www.opensource.org/licenses/mit-license.php>
+#
+
+"""Classes used to represent parse trees and generate output.
+
+This module defines the Generator class, which drives the generation
+of Python output from a grammar parse tree. It also defines nodes
+used to represent the parse tree; they are derived from class Node.
+
+The main logic of Yapps is in this module.
+"""
+
+import sys, re
+
+######################################################################
+INDENT = ' '*4
+class Generator:
+
+ # TODO: many of the methods here should be class methods, not instance methods
+
+ def __init__(self, name, options, tokens, rules):
+ self.change_count = 0
+ self.name = name
+ self.options = options
+ self.preparser = ''
+ self.postparser = None
+
+ self.tokens = {} # Map from tokens to regexps
+ self.ignore = {} # List of token names to ignore in parsing, map to statements
+ self.terminals = [] # List of token names (to maintain ordering)
+ for t in tokens:
+ if len(t) == 3:
+ n,t,s = t
+ else:
+ n,t = t
+ s = None
+
+ if n == '#ignore':
+ n = t
+ self.ignore[n] = s
+ if n in self.tokens.keys() and self.tokens[n] != t:
+ print >>sys.stderr, 'Warning: token %s defined more than once.' % n
+ self.tokens[n] = t
+ self.terminals.append(n)
+
+ self.rules = {} # Map from rule names to parser nodes
+ self.params = {} # Map from rule names to parameters
+ self.goals = [] # List of rule names (to maintain ordering)
+ for n,p,r in rules:
+ self.params[n] = p
+ self.rules[n] = r
+ self.goals.append(n)
+
+ self.output = sys.stdout
+
+ def has_option(self, name):
+ return self.options.get(name, 0)
+
+ def non_ignored_tokens(self):
+ return [x for x in self.terminals if x not in self.ignore]
+
+ def changed(self):
+ """Increments the change count.
+
+ >>> t = Generator('', [], [], [])
+ >>> old_count = t.change_count
+ >>> t.changed()
+ >>> assert t.change_count == old_count + 1
+ """
+ self.change_count = 1+self.change_count
+
+ def set_subtract(self, a, b):
+ """Returns the elements of a that are not in b.
+
+ >>> t = Generator('', [], [], [])
+ >>> t.set_subtract([], [])
+ []
+ >>> t.set_subtract([1, 2], [1, 2])
+ []
+ >>> t.set_subtract([1, 2, 3], [2])
+ [1, 3]
+ >>> t.set_subtract([1], [2, 3, 4])
+ [1]
+ """
+ result = []
+ for x in a:
+ if x not in b:
+ result.append(x)
+ return result
+
+ def subset(self, a, b):
+ """True iff all elements of sequence a are inside sequence b
+
+ >>> t = Generator('', [], [], [])
+ >>> t.subset([], [1, 2, 3])
+ 1
+ >>> t.subset([1, 2, 3], [])
+ 0
+ >>> t.subset([1], [1, 2, 3])
+ 1
+ >>> t.subset([3, 2, 1], [1, 2, 3])
+ 1
+ >>> t.subset([1, 1, 1], [1, 2, 3])
+ 1
+ >>> t.subset([1, 2, 3], [1, 1, 1])
+ 0
+ """
+ for x in a:
+ if x not in b:
+ return 0
+ return 1
+
+ def equal_set(self, a, b):
+ """True iff subset(a, b) and subset(b, a)
+
+ >>> t = Generator('', [], [], [])
+ >>> a_set = [1, 2, 3]
+ >>> t.equal_set(a_set, a_set)
+ 1
+ >>> t.equal_set(a_set, a_set[:])
+ 1
+ >>> t.equal_set([], a_set)
+ 0
+ >>> t.equal_set([1, 2, 3], [3, 2, 1])
+ 1
+ """
+ if len(a) != len(b): return 0
+ if a == b: return 1
+ return self.subset(a, b) and self.subset(b, a)
+
+ def add_to(self, parent, additions):
+ "Modify _parent_ to include all elements in _additions_"
+ for x in additions:
+ if x not in parent:
+ parent.append(x)
+ self.changed()
+
+ def equate(self, a, b):
+ """Extend (a) and (b) so that they contain each others' elements.
+
+ >>> t = Generator('', [], [], [])
+ >>> a = [1, 2]
+ >>> b = [2, 3]
+ >>> t.equate(a, b)
+ >>> a
+ [1, 2, 3]
+ >>> b
+ [2, 3, 1]
+ """
+ self.add_to(a, b)
+ self.add_to(b, a)
+
+ def write(self, *args):
+ for a in args:
+ self.output.write(a)
+
+ def in_test(self, expr, full, set):
+ """Generate a test of (expr) being in (set), where (set) is a subset of (full)
+
+ expr is a string (Python expression)
+ set is a list of values (which will be converted with repr)
+ full is the list of all values expr could possibly evaluate to
+
+ >>> t = Generator('', [], [], [])
+ >>> t.in_test('x', [1,2,3,4], [])
+ '0'
+ >>> t.in_test('x', [1,2,3,4], [1,2,3,4])
+ '1'
+ >>> t.in_test('x', [1,2,3,4], [1])
+ 'x == 1'
+ >>> t.in_test('a+b', [1,2,3,4], [1,2])
+ 'a+b in [1, 2]'
+ >>> t.in_test('x', [1,2,3,4,5], [1,2,3])
+ 'x not in [4, 5]'
+ >>> t.in_test('x', [1,2,3,4,5], [1,2,3,4])
+ 'x != 5'
+ """
+
+ if not set: return '0'
+ if len(set) == 1: return '%s == %s' % (expr, repr(set[0]))
+ if full and len(set) > len(full)/2:
+ # Reverse the sense of the test.
+ not_set = [x for x in full if x not in set]
+ return self.not_in_test(expr, full, not_set)
+ return '%s in %s' % (expr, repr(set))
+
+ def not_in_test(self, expr, full, set):
+ """Like in_test, but the reverse test."""
+ if not set: return '1'
+ if len(set) == 1: return '%s != %s' % (expr, repr(set[0]))
+ return '%s not in %s' % (expr, repr(set))
+
+ def peek_call(self, a):
+ """Generate a call to scan for a token in the set 'a'"""
+ assert type(a) == type([])
+ a_set = (repr(a)[1:-1])
+ if self.equal_set(a, self.non_ignored_tokens()): a_set = ''
+ if self.has_option('context-insensitive-scanner'): a_set = ''
+ if a_set: a_set += ","
+
+ return 'self._peek(%s context=_context)' % a_set
+
+ def peek_test(self, a, b):
+ """Generate a call to test whether the next token (which could be any of
+ the elements in a) is in the set b."""
+ if self.subset(a, b): return '1'
+ if self.has_option('context-insensitive-scanner'): a = self.non_ignored_tokens()
+ return self.in_test(self.peek_call(a), a, b)
+
+ def not_peek_test(self, a, b):
+ """Like peek_test, but the opposite sense."""
+ if self.subset(a, b): return '0'
+ return self.not_in_test(self.peek_call(a), a, b)
+
+ def calculate(self):
+ """The main loop to compute the epsilon, first, follow sets.
+ The loop continues until the sets converge. This works because
+ each set can only get larger, so when they stop getting larger,
+ we're done."""
+ # First we determine whether a rule accepts epsilon (the empty sequence)
+ while 1:
+ for r in self.goals:
+ self.rules[r].setup(self)
+ if self.change_count == 0: break
+ self.change_count = 0
+
+ # Now we compute the first/follow sets
+ while 1:
+ for r in self.goals:
+ self.rules[r].update(self)
+ if self.change_count == 0: break
+ self.change_count = 0
+
+ def dump_information(self):
+ """Display the grammar in somewhat human-readable form."""
+ self.calculate()
+ for r in self.goals:
+ print ' _____' + '_'*len(r)
+ print ('___/Rule '+r+'\\' + '_'*80)[:79]
+ queue = [self.rules[r]]
+ while queue:
+ top = queue[0]
+ del queue[0]
+
+ print 'Rule', repr(top), 'of class', top.__class__.__name__
+ top.first.sort()
+ top.follow.sort()
+ eps = []
+ if top.accepts_epsilon: eps = ['(null)']
+ print ' FIRST:', ', '.join(top.first+eps)
+ print ' FOLLOW:', ', '.join(top.follow)
+ for x in top.get_children(): queue.append(x)
+
+ def repr_ignore(self):
+ out="{"
+ for t,s in self.ignore.iteritems():
+ if s is None: s=repr(s)
+ out += "%s:%s," % (repr(t),s)
+ out += "}"
+ return out
+
+ def generate_output(self):
+ self.calculate()
+ self.write(self.preparser)
+ self.write("# Begin -- grammar generated by Yapps\n")
+ self.write("import sys, re\n")
+ self.write("from yapps import runtime\n")
+ self.write("\n")
+ self.write("class ", self.name, "Scanner(runtime.Scanner):\n")
+ self.write(" patterns = [\n")
+ for p in self.terminals:
+ self.write(" (%s, re.compile(%s)),\n" % (
+ repr(p), repr(self.tokens[p])))
+ self.write(" ]\n")
+ self.write(" def __init__(self, str,*args,**kw):\n")
+ self.write(" runtime.Scanner.__init__(self,None,%s,str,*args,**kw)\n" %
+ self.repr_ignore())
+ self.write("\n")
+
+ self.write("class ", self.name, "(runtime.Parser):\n")
+ self.write(INDENT, "Context = runtime.Context\n")
+ for r in self.goals:
+ self.write(INDENT, "def ", r, "(self")
+ if self.params[r]: self.write(", ", self.params[r])
+ self.write(", _parent=None):\n")
+ self.write(INDENT+INDENT, "_context = self.Context(_parent, self._scanner, %s, [%s])\n" %
+ (repr(r), self.params.get(r, '')))
+ self.rules[r].output(self, INDENT+INDENT)
+ self.write("\n")
+
+ self.write("\n")
+ self.write("def parse(rule, text):\n")
+ self.write(" P = ", self.name, "(", self.name, "Scanner(text))\n")
+ self.write(" return runtime.wrap_error_reporter(P, rule)\n")
+ self.write("\n")
+ if self.postparser is not None:
+ self.write("# End -- grammar generated by Yapps\n")
+ self.write(self.postparser)
+ else:
+ self.write("if __name__ == '__main__':\n")
+ self.write(INDENT, "from sys import argv, stdin\n")
+ self.write(INDENT, "if len(argv) >= 2:\n")
+ self.write(INDENT*2, "if len(argv) >= 3:\n")
+ self.write(INDENT*3, "f = open(argv[2],'r')\n")
+ self.write(INDENT*2, "else:\n")
+ self.write(INDENT*3, "f = stdin\n")
+ self.write(INDENT*2, "print parse(argv[1], f.read())\n")
+ self.write(INDENT, "else: print >>sys.stderr, 'Args: <rule> [<filename>]'\n")
+ self.write("# End -- grammar generated by Yapps\n")
+
+######################################################################
+class Node:
+ """This is the base class for all components of a grammar."""
+ def __init__(self, rule):
+ self.rule = rule # name of the rule containing this node
+ self.first = []
+ self.follow = []
+ self.accepts_epsilon = 0
+
+ def setup(self, gen):
+ # Setup will change accepts_epsilon,
+ # sometimes from 0 to 1 but never 1 to 0.
+ # It will take a finite number of steps to set things up
+ pass
+
+ def used(self, vars):
+ "Return two lists: one of vars used, and the other of vars assigned"
+ return vars, []
+
+ def get_children(self):
+ "Return a list of sub-nodes"
+ return []
+
+ def __repr__(self):
+ return str(self)
+
+ def update(self, gen):
+ if self.accepts_epsilon:
+ gen.add_to(self.first, self.follow)
+
+ def output(self, gen, indent):
+ "Write out code to _gen_ with _indent_:string indentation"
+ gen.write(indent, "assert 0 # Invalid parser node\n")
+
+class Terminal(Node):
+ """This class stores terminal nodes, which are tokens."""
+ def __init__(self, rule, token):
+ Node.__init__(self, rule)
+ self.token = token
+ self.accepts_epsilon = 0
+
+ def __str__(self):
+ return self.token
+
+ def update(self, gen):
+ Node.update(self, gen)
+ if self.first != [self.token]:
+ self.first = [self.token]
+ gen.changed()
+
+ def output(self, gen, indent):
+ gen.write(indent)
+ if re.match('[a-zA-Z_][a-zA-Z_0-9]*$', self.token):
+ gen.write(self.token, " = ")
+ gen.write("self._scan(%s, context=_context)\n" % repr(self.token))
+
+class Eval(Node):
+ """This class stores evaluation nodes, from {{ ... }} clauses."""
+ def __init__(self, rule, expr):
+ Node.__init__(self, rule)
+ self.expr = expr
+
+ def setup(self, gen):
+ Node.setup(self, gen)
+ if not self.accepts_epsilon:
+ self.accepts_epsilon = 1
+ gen.changed()
+
+ def __str__(self):
+ return '{{ %s }}' % self.expr.strip()
+
+ def output(self, gen, indent):
+ gen.write(indent, self.expr.strip(), '\n')
+
+class NonTerminal(Node):
+ """This class stores nonterminal nodes, which are rules with arguments."""
+ def __init__(self, rule, name, args):
+ Node.__init__(self, rule)
+ self.name = name
+ self.args = args
+
+ def setup(self, gen):
+ Node.setup(self, gen)
+ try:
+ self.target = gen.rules[self.name]
+ if self.accepts_epsilon != self.target.accepts_epsilon:
+ self.accepts_epsilon = self.target.accepts_epsilon
+ gen.changed()
+ except KeyError: # Oops, it's nonexistent
+ print >>sys.stderr, 'Error: no rule <%s>' % self.name
+ self.target = self
+
+ def __str__(self):
+ return '%s' % self.name
+
+ def update(self, gen):
+ Node.update(self, gen)
+ gen.equate(self.first, self.target.first)
+ gen.equate(self.follow, self.target.follow)
+
+ def output(self, gen, indent):
+ gen.write(indent)
+ gen.write(self.name, " = ")
+ args = self.args
+ if args: args += ', '
+ args += '_context'
+ gen.write("self.", self.name, "(", args, ")\n")
+
+class Sequence(Node):
+ """This class stores a sequence of nodes (A B C ...)"""
+ def __init__(self, rule, *children):
+ Node.__init__(self, rule)
+ self.children = children
+
+ def setup(self, gen):
+ Node.setup(self, gen)
+ for c in self.children: c.setup(gen)
+
+ if not self.accepts_epsilon:
+ # If it's not already accepting epsilon, it might now do so.
+ for c in self.children:
+ # any non-epsilon means all is non-epsilon
+ if not c.accepts_epsilon: break
+ else:
+ self.accepts_epsilon = 1
+ gen.changed()
+
+ def get_children(self):
+ return self.children
+
+ def __str__(self):
+ return '( %s )' % ' '.join(map(str, self.children))
+
+ def update(self, gen):
+ Node.update(self, gen)
+ for g in self.children:
+ g.update(gen)
+
+ empty = 1
+ for g_i in range(len(self.children)):
+ g = self.children[g_i]
+
+ if empty: gen.add_to(self.first, g.first)
+ if not g.accepts_epsilon: empty = 0
+
+ if g_i == len(self.children)-1:
+ next = self.follow
+ else:
+ next = self.children[1+g_i].first
+ gen.add_to(g.follow, next)
+
+ if self.children:
+ gen.add_to(self.follow, self.children[-1].follow)
+
+ def output(self, gen, indent):
+ if self.children:
+ for c in self.children:
+ c.output(gen, indent)
+ else:
+ # Placeholder for empty sequences, just in case
+ gen.write(indent, 'pass\n')
+
+class Choice(Node):
+ """This class stores a choice between nodes (A | B | C | ...)"""
+ def __init__(self, rule, *children):
+ Node.__init__(self, rule)
+ self.children = children
+
+ def setup(self, gen):
+ Node.setup(self, gen)
+ for c in self.children: c.setup(gen)
+
+ if not self.accepts_epsilon:
+ for c in self.children:
+ if c.accepts_epsilon:
+ self.accepts_epsilon = 1
+ gen.changed()
+
+ def get_children(self):
+ return self.children
+
+ def __str__(self):
+ return '( %s )' % ' | '.join(map(str, self.children))
+
+ def update(self, gen):
+ Node.update(self, gen)
+ for g in self.children:
+ g.update(gen)
+
+ for g in self.children:
+ gen.add_to(self.first, g.first)
+ gen.add_to(self.follow, g.follow)
+ for g in self.children:
+ gen.add_to(g.follow, self.follow)
+ if self.accepts_epsilon:
+ gen.add_to(self.first, self.follow)
+
+ def output(self, gen, indent):
+ test = "if"
+ gen.write(indent, "_token = ", gen.peek_call(self.first), "\n")
+ tokens_seen = []
+ tokens_unseen = self.first[:]
+ if gen.has_option('context-insensitive-scanner'):
+ # Context insensitive scanners can return ANY token,
+ # not only the ones in first.
+ tokens_unseen = gen.non_ignored_tokens()
+ for c in self.children:
+ testset = c.first[:]
+ removed = []
+ for x in testset:
+ if x in tokens_seen:
+ testset.remove(x)
+ removed.append(x)
+ if x in tokens_unseen: tokens_unseen.remove(x)
+ tokens_seen = tokens_seen + testset
+ if removed:
+ if not testset:
+ print >>sys.stderr, 'Error in rule', self.rule+':'
+ else:
+ print >>sys.stderr, 'Warning in rule', self.rule+':'
+ print >>sys.stderr, ' *', self
+ print >>sys.stderr, ' * These tokens could be matched by more than one clause:'
+ print >>sys.stderr, ' *', ' '.join(removed)
+
+ if testset:
+ if not tokens_unseen: # context sensitive scanners only!
+ if test == 'if':
+ # if it's the first AND last test, then
+ # we can simply put the code without an if/else
+ c.output(gen, indent)
+ else:
+ gen.write(indent, "else:")
+ t = gen.in_test('', [], testset)
+ if len(t) < 70-len(indent):
+ gen.write(' #', t)
+ gen.write("\n")
+ c.output(gen, indent+INDENT)
+ else:
+ gen.write(indent, test, " ",
+ gen.in_test('_token', tokens_unseen, testset),
+ ":\n")
+ c.output(gen, indent+INDENT)
+ test = "elif"
+
+ if tokens_unseen:
+ gen.write(indent, "else:\n")
+ gen.write(indent, INDENT, "raise runtime.SyntaxError(_token[0], ")
+ gen.write("'Could not match ", self.rule, "')\n")
+
+class Wrapper(Node):
+ """This is a base class for nodes that modify a single child."""
+ def __init__(self, rule, child):
+ Node.__init__(self, rule)
+ self.child = child
+
+ def setup(self, gen):
+ Node.setup(self, gen)
+ self.child.setup(gen)
+
+ def get_children(self):
+ return [self.child]
+
+ def update(self, gen):
+ Node.update(self, gen)
+ self.child.update(gen)
+ gen.add_to(self.first, self.child.first)
+ gen.equate(self.follow, self.child.follow)
+
+class Option(Wrapper):
+ """This class represents an optional clause of the form [A]"""
+ def setup(self, gen):
+ Wrapper.setup(self, gen)
+ if not self.accepts_epsilon:
+ self.accepts_epsilon = 1
+ gen.changed()
+
+ def __str__(self):
+ return '[ %s ]' % str(self.child)
+
+ def output(self, gen, indent):
+ if self.child.accepts_epsilon:
+ print >>sys.stderr, 'Warning in rule', self.rule+': contents may be empty.'
+ gen.write(indent, "if %s:\n" %
+ gen.peek_test(self.first, self.child.first))
+ self.child.output(gen, indent+INDENT)
+
+ if gen.has_option('context-insensitive-scanner'):
+ gen.write(indent, "if %s:\n" %
+ gen.not_peek_test(gen.non_ignored_tokens(), self.follow))
+ gen.write(indent+INDENT, "raise runtime.SyntaxError(pos=self._scanner.get_pos(), context=_context, msg='Need one of ' + ', '.join(%s))\n" %
+ repr(self.first))
+
+
+class Plus(Wrapper):
+ """This class represents a 1-or-more repetition clause of the form A+"""
+ def setup(self, gen):
+ Wrapper.setup(self, gen)
+ if self.accepts_epsilon != self.child.accepts_epsilon:
+ self.accepts_epsilon = self.child.accepts_epsilon
+ gen.changed()
+
+ def __str__(self):
+ return '%s+' % str(self.child)
+
+ def update(self, gen):
+ Wrapper.update(self, gen)
+ gen.add_to(self.child.follow, self.child.first)
+
+ def output(self, gen, indent):
+ if self.child.accepts_epsilon:
+ print >>sys.stderr, 'Warning in rule', self.rule+':'
+ print >>sys.stderr, ' * The repeated pattern could be empty. The resulting parser may not work properly.'
+ gen.write(indent, "while 1:\n")
+ self.child.output(gen, indent+INDENT)
+ union = self.first[:]
+ gen.add_to(union, self.follow)
+ gen.write(indent+INDENT, "if %s: break\n" %
+ gen.not_peek_test(union, self.child.first))
+
+ if gen.has_option('context-insensitive-scanner'):
+ gen.write(indent, "if %s:\n" %
+ gen.not_peek_test(gen.non_ignored_tokens(), self.follow))
+ gen.write(indent+INDENT, "raise runtime.SyntaxError(pos=self._scanner.get_pos(), context=_context, msg='Need one of ' + ', '.join(%s))\n" %
+ repr(self.first))
+
+
+class Star(Wrapper):
+ """This class represents a 0-or-more repetition clause of the form A*"""
+ def setup(self, gen):
+ Wrapper.setup(self, gen)
+ if not self.accepts_epsilon:
+ self.accepts_epsilon = 1
+ gen.changed()
+
+ def __str__(self):
+ return '%s*' % str(self.child)
+
+ def update(self, gen):
+ Wrapper.update(self, gen)
+ gen.add_to(self.child.follow, self.child.first)
+
+ def output(self, gen, indent):
+ if self.child.accepts_epsilon:
+ print >>sys.stderr, 'Warning in rule', self.rule+':'
+ print >>sys.stderr, ' * The repeated pattern could be empty. The resulting parser probably will not work properly.'
+ gen.write(indent, "while %s:\n" %
+ gen.peek_test(self.follow, self.child.first))
+ self.child.output(gen, indent+INDENT)
+
+ # TODO: need to generate tests like this in lots of rules
+ if gen.has_option('context-insensitive-scanner'):
+ gen.write(indent, "if %s:\n" %
+ gen.not_peek_test(gen.non_ignored_tokens(), self.follow))
+ gen.write(indent+INDENT, "raise runtime.SyntaxError(pos=self._scanner.get_pos(), context=_context, msg='Need one of ' + ', '.join(%s))\n" %
+ repr(self.first))
+
generated by cgit (git 2.34.1) at 2025-04-28 19:35:05 -0400