Author: Carl Friedrich Bolz-Tereick <cfb...@gmx.de>
Branch: pyparser-improvements
Changeset: r93973:dde9199be301
Date: 2018-03-12 14:48 +0100
http://bitbucket.org/pypy/pypy/changeset/dde9199be301/
Log: use a chained stack instead of list-of-tuples
diff --git a/pypy/interpreter/pyparser/parser.py
b/pypy/interpreter/pyparser/parser.py
--- a/pypy/interpreter/pyparser/parser.py
+++ b/pypy/interpreter/pyparser/parser.py
@@ -181,12 +181,25 @@
return "ParserError(%s, %r)" % (self.token_type, self.value)
+class StackEntry(object):
+ def __init__(self, next, dfa, state, node):
+ self.next = next
+ self.dfa = dfa
+ self.state = state
+ self.node = node
+
+ def push(self, dfa, state, node):
+ return StackEntry(self, dfa, state, node)
+
+ def pop(self):
+ return self.next
+
+
class Parser(object):
def __init__(self, grammar):
self.grammar = grammar
self.root = None
- self.stack = None
def prepare(self, start=-1):
"""Setup the parser for parsing.
@@ -197,14 +210,14 @@
start = self.grammar.start
self.root = None
current_node = Nonterminal(start, [])
- self.stack = []
- self.stack.append((self.grammar.dfas[start - 256], 0, current_node))
+ self.stack = StackEntry(None, self.grammar.dfas[start - 256], 0,
current_node)
def add_token(self, token_type, value, lineno, column, line):
label_index = self.classify(token_type, value, lineno, column, line)
sym_id = 0 # for the annotator
while True:
- dfa, state_index, node = self.stack[-1]
+ dfa = self.stack.dfa
+ state_index = self.stack.state
states, first = dfa
arcs, is_accepting = states[state_index]
for i, next_state in arcs:
@@ -217,10 +230,12 @@
# the stack.
while state[1] and not state[0]:
self.pop()
- if not self.stack:
+ if self.stack is None:
+ assert self.stack is None
# Parsing is done.
return True
- dfa, state_index, node = self.stack[-1]
+ dfa = self.stack.dfa
+ state_index = self.stack.state
state = dfa[0][state_index]
return False
elif sym_id >= 256:
@@ -235,7 +250,8 @@
# state is accepting, it's invalid input.
if is_accepting:
self.pop()
- if not self.stack:
+ if self.stack is None:
+ assert self.stack is None
raise ParseError("too much input", token_type, value,
lineno, column, line)
else:
@@ -262,26 +278,27 @@
def shift(self, next_state, token_type, value, lineno, column):
"""Shift a non-terminal and prepare for the next state."""
- dfa, state, node = self.stack[-1]
new_node = Terminal(token_type, value, lineno, column)
- node.append_child(new_node)
- self.stack[-1] = (dfa, next_state, node)
+ self.stack.node.append_child(new_node)
+ self.stack.state = next_state
def push(self, next_dfa, next_state, node_type, lineno, column):
"""Push a terminal and adjust the current state."""
- dfa, state, node = self.stack[-1]
new_node = Nonterminal(node_type, [])
- self.stack[-1] = (dfa, next_state, node)
- self.stack.append((next_dfa, 0, new_node))
+
+ self.stack.state = next_state
+ self.stack = self.stack.push(next_dfa, 0, new_node)
def pop(self):
"""Pop an entry off the stack and make its node a child of the last."""
- dfa, state, node = self.stack.pop()
+ top = self.stack
+ self.stack = top.pop()
+ node = top.node
if self.stack:
# we are now done with node, so we can store it more efficiently if
# it has just one child
if node.num_children() == 1:
node = Nonterminal1(node.type, node.get_child(0))
- self.stack[-1][2].append_child(node)
+ self.stack.node.append_child(node)
else:
self.root = node
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