mirror of https://github.com/python/cpython
239 lines
8.3 KiB
Python
239 lines
8.3 KiB
Python
import token
|
|
from typing import Any, Dict, Optional, IO, Text, Tuple
|
|
|
|
from pegen.grammar import (
|
|
Cut,
|
|
GrammarVisitor,
|
|
NameLeaf,
|
|
StringLeaf,
|
|
Rhs,
|
|
NamedItem,
|
|
Lookahead,
|
|
PositiveLookahead,
|
|
NegativeLookahead,
|
|
Opt,
|
|
Repeat0,
|
|
Repeat1,
|
|
Gather,
|
|
Group,
|
|
Rule,
|
|
Alt,
|
|
)
|
|
from pegen import grammar
|
|
from pegen.parser_generator import ParserGenerator
|
|
|
|
MODULE_PREFIX = """\
|
|
#!/usr/bin/env python3.8
|
|
# @generated by pegen from {filename}
|
|
|
|
import ast
|
|
from typing import Optional, Any
|
|
|
|
from pegen.parser import memoize, memoize_left_rec, logger, Parser
|
|
|
|
"""
|
|
MODULE_SUFFIX = """
|
|
|
|
if __name__ == '__main__':
|
|
from pegen.parser import simple_parser_main
|
|
simple_parser_main(GeneratedParser)
|
|
"""
|
|
|
|
|
|
class PythonCallMakerVisitor(GrammarVisitor):
|
|
def __init__(self, parser_generator: ParserGenerator):
|
|
self.gen = parser_generator
|
|
self.cache: Dict[Any, Any] = {}
|
|
|
|
def visit_NameLeaf(self, node: NameLeaf) -> Tuple[Optional[str], str]:
|
|
name = node.value
|
|
if name in ("NAME", "NUMBER", "STRING", "OP"):
|
|
name = name.lower()
|
|
return name, f"self.{name}()"
|
|
if name in ("NEWLINE", "DEDENT", "INDENT", "ENDMARKER", "ASYNC", "AWAIT"):
|
|
return name.lower(), f"self.expect({name!r})"
|
|
return name, f"self.{name}()"
|
|
|
|
def visit_StringLeaf(self, node: StringLeaf) -> Tuple[str, str]:
|
|
return "literal", f"self.expect({node.value})"
|
|
|
|
def visit_Rhs(self, node: Rhs) -> Tuple[Optional[str], str]:
|
|
if node in self.cache:
|
|
return self.cache[node]
|
|
if len(node.alts) == 1 and len(node.alts[0].items) == 1:
|
|
self.cache[node] = self.visit(node.alts[0].items[0])
|
|
else:
|
|
name = self.gen.name_node(node)
|
|
self.cache[node] = name, f"self.{name}()"
|
|
return self.cache[node]
|
|
|
|
def visit_NamedItem(self, node: NamedItem) -> Tuple[Optional[str], str]:
|
|
name, call = self.visit(node.item)
|
|
if node.name:
|
|
name = node.name
|
|
return name, call
|
|
|
|
def lookahead_call_helper(self, node: Lookahead) -> Tuple[str, str]:
|
|
name, call = self.visit(node.node)
|
|
head, tail = call.split("(", 1)
|
|
assert tail[-1] == ")"
|
|
tail = tail[:-1]
|
|
return head, tail
|
|
|
|
def visit_PositiveLookahead(self, node: PositiveLookahead) -> Tuple[None, str]:
|
|
head, tail = self.lookahead_call_helper(node)
|
|
return None, f"self.positive_lookahead({head}, {tail})"
|
|
|
|
def visit_NegativeLookahead(self, node: NegativeLookahead) -> Tuple[None, str]:
|
|
head, tail = self.lookahead_call_helper(node)
|
|
return None, f"self.negative_lookahead({head}, {tail})"
|
|
|
|
def visit_Opt(self, node: Opt) -> Tuple[str, str]:
|
|
name, call = self.visit(node.node)
|
|
# Note trailing comma (the call may already have one comma
|
|
# at the end, for example when rules have both repeat0 and optional
|
|
# markers, e.g: [rule*])
|
|
if call.endswith(","):
|
|
return "opt", call
|
|
else:
|
|
return "opt", f"{call},"
|
|
|
|
def visit_Repeat0(self, node: Repeat0) -> Tuple[str, str]:
|
|
if node in self.cache:
|
|
return self.cache[node]
|
|
name = self.gen.name_loop(node.node, False)
|
|
self.cache[node] = name, f"self.{name}()," # Also a trailing comma!
|
|
return self.cache[node]
|
|
|
|
def visit_Repeat1(self, node: Repeat1) -> Tuple[str, str]:
|
|
if node in self.cache:
|
|
return self.cache[node]
|
|
name = self.gen.name_loop(node.node, True)
|
|
self.cache[node] = name, f"self.{name}()" # But no trailing comma here!
|
|
return self.cache[node]
|
|
|
|
def visit_Gather(self, node: Gather) -> Tuple[str, str]:
|
|
if node in self.cache:
|
|
return self.cache[node]
|
|
name = self.gen.name_gather(node)
|
|
self.cache[node] = name, f"self.{name}()" # No trailing comma here either!
|
|
return self.cache[node]
|
|
|
|
def visit_Group(self, node: Group) -> Tuple[Optional[str], str]:
|
|
return self.visit(node.rhs)
|
|
|
|
def visit_Cut(self, node: Cut) -> Tuple[str, str]:
|
|
return "cut", "True"
|
|
|
|
|
|
class PythonParserGenerator(ParserGenerator, GrammarVisitor):
|
|
def __init__(
|
|
self,
|
|
grammar: grammar.Grammar,
|
|
file: Optional[IO[Text]],
|
|
tokens: Dict[int, str] = token.tok_name,
|
|
):
|
|
super().__init__(grammar, tokens, file)
|
|
self.callmakervisitor = PythonCallMakerVisitor(self)
|
|
|
|
def generate(self, filename: str) -> None:
|
|
header = self.grammar.metas.get("header", MODULE_PREFIX)
|
|
if header is not None:
|
|
self.print(header.rstrip("\n").format(filename=filename))
|
|
subheader = self.grammar.metas.get("subheader", "")
|
|
if subheader:
|
|
self.print(subheader.format(filename=filename))
|
|
self.print("class GeneratedParser(Parser):")
|
|
while self.todo:
|
|
for rulename, rule in list(self.todo.items()):
|
|
del self.todo[rulename]
|
|
self.print()
|
|
with self.indent():
|
|
self.visit(rule)
|
|
trailer = self.grammar.metas.get("trailer", MODULE_SUFFIX)
|
|
if trailer is not None:
|
|
self.print(trailer.rstrip("\n"))
|
|
|
|
def visit_Rule(self, node: Rule) -> None:
|
|
is_loop = node.is_loop()
|
|
is_gather = node.is_gather()
|
|
rhs = node.flatten()
|
|
if node.left_recursive:
|
|
if node.leader:
|
|
self.print("@memoize_left_rec")
|
|
else:
|
|
# Non-leader rules in a cycle are not memoized,
|
|
# but they must still be logged.
|
|
self.print("@logger")
|
|
else:
|
|
self.print("@memoize")
|
|
node_type = node.type or "Any"
|
|
self.print(f"def {node.name}(self) -> Optional[{node_type}]:")
|
|
with self.indent():
|
|
self.print(f"# {node.name}: {rhs}")
|
|
if node.nullable:
|
|
self.print(f"# nullable={node.nullable}")
|
|
self.print("mark = self.mark()")
|
|
if is_loop:
|
|
self.print("children = []")
|
|
self.visit(rhs, is_loop=is_loop, is_gather=is_gather)
|
|
if is_loop:
|
|
self.print("return children")
|
|
else:
|
|
self.print("return None")
|
|
|
|
def visit_NamedItem(self, node: NamedItem) -> None:
|
|
name, call = self.callmakervisitor.visit(node.item)
|
|
if node.name:
|
|
name = node.name
|
|
if not name:
|
|
self.print(call)
|
|
else:
|
|
if name != "cut":
|
|
name = self.dedupe(name)
|
|
self.print(f"({name} := {call})")
|
|
|
|
def visit_Rhs(self, node: Rhs, is_loop: bool = False, is_gather: bool = False) -> None:
|
|
if is_loop:
|
|
assert len(node.alts) == 1
|
|
for alt in node.alts:
|
|
self.visit(alt, is_loop=is_loop, is_gather=is_gather)
|
|
|
|
def visit_Alt(self, node: Alt, is_loop: bool, is_gather: bool) -> None:
|
|
with self.local_variable_context():
|
|
self.print("cut = False") # TODO: Only if needed.
|
|
if is_loop:
|
|
self.print("while (")
|
|
else:
|
|
self.print("if (")
|
|
with self.indent():
|
|
first = True
|
|
for item in node.items:
|
|
if first:
|
|
first = False
|
|
else:
|
|
self.print("and")
|
|
self.visit(item)
|
|
if is_gather:
|
|
self.print("is not None")
|
|
|
|
self.print("):")
|
|
with self.indent():
|
|
action = node.action
|
|
if not action:
|
|
if is_gather:
|
|
assert len(self.local_variable_names) == 2
|
|
action = (
|
|
f"[{self.local_variable_names[0]}] + {self.local_variable_names[1]}"
|
|
)
|
|
else:
|
|
action = f"[{', '.join(self.local_variable_names)}]"
|
|
if is_loop:
|
|
self.print(f"children.append({action})")
|
|
self.print(f"mark = self.mark()")
|
|
else:
|
|
self.print(f"return {action}")
|
|
self.print("self.reset(mark)")
|
|
# Skip remaining alternatives if a cut was reached.
|
|
self.print("if cut: return None") # TODO: Only if needed.
|