def recurse(p: Parser) -> Union[DiagramItem, str, None]:
# Transform parsers are just ignored
if isinstance(p, _Transform):
return recurse(p.children[0])
elif isinstance(p, Opt):
# Opt parsers are straightforwardly wrapped into an Optional
return Optional(recurse(p.parser))
elif isinstance(p, _Extract):
# Extract is ignored
return recurse(p.parser)
# For list parsers, we create a sequence with the right separator
# and sub-parser.
elif isinstance(p, List):
sep = recurse(p.sep) if p.sep else None
child = recurse(p.parser)
if p.empty_valid:
return ZeroOrMore(child, repeat=sep)
else:
return OneOrMore(child, repeat=sep)
# For defers, we just return the rule name
elif isinstance(p, Defer):
return p.rule_name
# For tokens, we return either the quoted original string, or the DSL
# name.
elif isinstance(p, _Token):
if p._original_string:
return repr(p._original_string)
else:
return p.val.dsl_name
children = []
for c in p.children:
res = recurse(c)
if res is not None:
children.append(res)
if isinstance(p, Or):
if len(children) == 0:
return None
children = sorted(children, key=lambda c: isinstance(c, Skip))
return Choice(0, *children)
elif isinstance(p, _Row):
if len(children) == 0:
return Skip()
return Sequence(*children)
else:
return None
def expr(self, children):
if len(children) == 3:
base, mi, ma = children
if int(mi.value) == 0:
if int(ma.value) == 1:
return Optional(base)
return ZeroOrMore(base, Comment(f'{mi.value}..{ma.value}'))
else:
return OneOrMore(base, Comment(f'{mi.value}..{ma.value}'))
base, op = children
if op.type != 'OP':
return OneOrMore(base, Comment(f'{op.value} times'))
if op.value == '+':
return OneOrMore(base)
elif op.value == '*':
return ZeroOrMore(base)
elif op.value == '?':
return Optional(base)
else:
raise ValueError(f"Unsupported Operator {op!r}")
import sys
from railroad import Diagram, Choice, OneOrMore
d = Diagram("A",
Choice(0, "B", "C"),
OneOrMore("D"))
with open('diagram.html', 'w') as f:
d.writeSvg(f.write)
def token():
return OneOrMore(Choice(0, alphanum(), tspecials()))
def isdn_subaddress():
return Sequence(";isub=", OneOrMore(NonTerminal("uric")))
def pvalue():
return OneOrMore(NonTerminal("paramchar"))
def pname():
return OneOrMore(Choice(0, alphanum(), "-"))
def extension():
return Sequence(";ext=", OneOrMore(NonTerminal("phonedigit")))
def segment_nz():
return OneOrMore(Choice(0, *pchar()))
def ipvfuture():
return [
"v",
OneOrMore(NonTerminal("HEXDIG")), ".",
OneOrMore(Choice(0, unreserved(), sub_delims(), ":"))
]