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Extract visitors from the grammar nodes and call makers in the peg generator #28172

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Merged
pablogsal merged 1 commit into from
Sep 5, 2021
Merged

Extract visitors from the grammar nodes and call makers in the peg generator #28172

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16 changes: 8 additions & 8 deletions Lib/test/test_peg_generator/test_pegen.py
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
from pegen.grammar import GrammarVisitor, GrammarError, Grammar
from pegen.grammar_visualizer import ASTGrammarPrinter
from pegen.parser import Parser
from pegen.parser_generator import compute_nullables, compute_left_recursives
from pegen.python_generator import PythonParserGenerator


Expand Down Expand Up @@ -502,23 +503,22 @@ def test_nullable(self) -> None:
sign: ['-' | '+']
"""
grammar: Grammar = parse_string(grammar_source, GrammarParser)
out = io.StringIO()
genr = PythonParserGenerator(grammar, out)
rules = grammar.rules
self.assertFalse(rules["start"].nullable) # Not None!
self.assertTrue(rules["sign"].nullable)
nullables = compute_nullables(rules)
self.assertNotIn(rules["start"], nullables) # Not None!
self.assertIn(rules["sign"], nullables)

def test_advanced_left_recursive(self) -> None:
grammar_source = """
start: NUMBER | sign start
sign: ['-']
"""
grammar: Grammar = parse_string(grammar_source, GrammarParser)
out = io.StringIO()
genr = PythonParserGenerator(grammar, out)
rules = grammar.rules
self.assertFalse(rules["start"].nullable) # Not None!
self.assertTrue(rules["sign"].nullable)
nullables = compute_nullables(rules)
compute_left_recursives(rules)
self.assertNotIn(rules["start"], nullables) # Not None!
self.assertIn(rules["sign"], nullables)
self.assertTrue(rules["start"].left_recursive)
self.assertFalse(rules["sign"].left_recursive)

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