def push(self, typ, opaque, newdfa, newstate):
# type: (int, Token, dfa_t, int) -> None
"""Push a nonterminal. (Internal)"""
top = self.stack[-1]
newnode = PNode(typ, opaque, [])
self.stack[-1].state = newstate
self.stack.append(_StackItem(newdfa, 0, newnode))
def shift(self, typ, opaque, newstate):
# type: (int, Token, int) -> None
"""Shift a token. (Internal)"""
top = self.stack[-1]
newnode = PNode(typ, opaque, None)
top.node.children.append(newnode)
self.stack[-1].state = newstate
def setup(self, start):
# type: (int) -> None
"""Prepare for parsing.
This *must* be called before starting to parse.
The optional argument is an alternative start symbol; it
defaults to the grammar's start symbol.
You can use a Parser instance to parse any number of programs;
each time you call setup() the parser is reset to an initial
state determined by the (implicit or explicit) start symbol.
"""
newnode = PNode(start, None, [])
# Each stack entry is a tuple: (dfa, state, node).
self.stack = [_StackItem(self.grammar.dfas[start], 0, newnode)]
self.rootnode = None # type: Optional[PNode]