Clean implementation of Parser/pgen and fix some style issues (GH-12156)
diff --git a/Parser/pgen/grammar.py b/Parser/pgen/grammar.py
index bd405e6..05a37d6 100644
--- a/Parser/pgen/grammar.py
+++ b/Parser/pgen/grammar.py
@@ -1,19 +1,8 @@
import collections
+
class Grammar:
- """Pgen parsing tables conversion class.
-
- Once initialized, this class supplies the grammar tables for the
- parsing engine implemented by parse.py. The parsing engine
- accesses the instance variables directly. The class here does not
- provide initialization of the tables; several subclasses exist to
- do this (see the conv and pgen modules).
-
- The load() method reads the tables from a pickle file, which is
- much faster than the other ways offered by subclasses. The pickle
- file is written by calling dump() (after loading the grammar
- tables using a subclass). The report() method prints a readable
- representation of the tables to stdout, for debugging.
+ """Pgen parsing tables class.
The instance variables are as follows:
@@ -36,8 +25,7 @@
dfas -- a dict mapping symbol numbers to (DFA, first)
pairs, where DFA is an item from the states list
above, and first is a set of tokens that can
- begin this grammar rule (represented by a dict
- whose values are always 1).
+ begin this grammar rule.
labels -- a list of (x, y) pairs where x is either a token
number or a symbol number, and y is either None
@@ -92,14 +80,12 @@
"static label labels[{n_labels}] = {{\n".format(n_labels=len(self.labels))
)
for label, name in self.labels:
- if name is None:
- writer(" {{{label}, 0}},\n".format(label=label))
- else:
- writer(
- ' {{{label}, "{label_name}"}},\n'.format(
- label=label, label_name=name
- )
+ label_name = '"{}"'.format(name) if name is not None else 0
+ writer(
+ ' {{{label}, {label_name}}},\n'.format(
+ label=label, label_name=label_name
)
+ )
writer("};\n")
def print_dfas(self, writer):
@@ -114,10 +100,9 @@
+ "0, {n_states}, states_{dfa_index},\n".format(
n_states=len(dfa), dfa_index=dfaindex
)
+ + ' "'
)
- writer(' "')
- k = [name for label, name in self.labels if label in first_sets]
bitset = bytearray((len(self.labels) >> 3) + 1)
for token in first_sets:
bitset[token >> 3] |= 1 << (token & 7)