blepping
2481e7263b
Improve sequence operator in expressions Documentation improvements Turn down eval debug spam a bit Add ternary operator Support static eval for constants in some more operator types
266 lines
8.0 KiB
Python
266 lines
8.0 KiB
Python
import re
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import operator
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from .parser import Parser, ParserSpec, ParseError
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from .types import (
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Empty,
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ExpBase,
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ExpOp,
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ExpBinOp,
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ExpSym,
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ExpStatements,
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ExpFunAp,
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ExpTuple,
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ExpDict,
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ExpKV,
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)
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COMMA_PRECEDENCE = 2
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class Expression:
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EXPR_RE = re.compile(
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r"""
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\s*
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(
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\d+ # Numeric literal
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(?: \. \d* )? # Floating point
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(?: e [+-] \d+)? # Scientific notation
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| (?: \*\* | // ) # Doubled operators
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| [<>]=? # Relative comparison
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| [!=]= # Equality
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| (?: \|\| | && ) # Logic
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| [-+*/|!(),] # Operators
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| :> # Key value binop
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| := # Assignment
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| ; # Sequencing
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| [?:] # Ternary
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| \[ | ] # Index
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| \.\.\. # Index ellipsis
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| '[\w.]+ # Symbol
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| `?[a-z][\w.]*`? # Function/variable names
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)
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\s*
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""",
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re.I | re.S | re.X | re.A,
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)
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def __init__(self, toks):
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if isinstance(toks, str):
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toks = tuple(self.tokenize(toks))
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self.expr = Parser(ExprParserSpec(), iter(toks)).go()
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def __repr__(self):
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return f"<Expr{self.expr!r}>"
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def __call__(self, *args, **kwargs):
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return self.eval(*args, **kwargs)
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def eval(self, handlers, *args, **kwargs):
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if self.expr != ExpOp("default"):
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print("\nEVAL", self.expr)
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if not isinstance(self.expr, ExpBase):
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return self.expr
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return self.expr.eval(handlers, *args, **kwargs)
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def __len__(self):
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return len(self.expr)
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def pretty_string(self, depth=0):
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sval = (
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repr(self.expr)
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if not isinstance(self.expr, ExpBase)
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else self.expr.pretty_string(depth=depth + 1)
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)
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pad = " " * (depth + 1) * 2
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return f"<Expr:\n{pad}{sval}\n{pad[:-2]}>"
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FIXUP = {"true": True, "false": False, "...": Ellipsis, "none": None}
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@classmethod
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def fixup_token(cls, t):
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if t == "":
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return t
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t = t.lower()
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val = cls.FIXUP.get(t, Empty)
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if val is not Empty:
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return val
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if t[0] == "`":
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return ExpBinOp(t.strip("`"))
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if t[0] == "'":
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return ExpSym(t[1:])
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if (len(t) > 1 and t[0] == "-" and t[1].isdigit()) or t[0].isdigit():
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return float(t) if "." in t else int(t)
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return ExpOp(t)
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@classmethod
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def tokenize(cls, s):
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yield from (cls.fixup_token(m.group(1)) for m in cls.EXPR_RE.finditer(s))
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CONST_OP_HANDLERS = {
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"+": operator.add,
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"-": operator.sub,
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"*": operator.mul,
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"/": operator.truediv,
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"//": operator.floordiv,
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"**": operator.pow,
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"%": operator.mod,
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"add": operator.add,
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"sub": operator.sub,
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"mul": operator.mul,
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"div": operator.truediv,
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"idiv": operator.floordiv,
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"pow": operator.pow,
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"mod": operator.mod,
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"neg": operator.neg,
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">": operator.gt,
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"<": operator.lt,
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">=": operator.ge,
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"<=": operator.le,
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"!=": operator.ne,
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"==": operator.eq,
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}
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def is_const_value(val):
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return val in (None, True, False) or isinstance(val, (int, float, ExpSym))
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def make_funap(op, args=(), kwargs=None):
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if kwargs is None:
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kwargs = ExpDict()
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argc = len(args)
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if argc > 2 or len(kwargs) or not all(is_const_value(v) for v in args):
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return ExpFunAp(op, args, kwargs)
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if argc == 1 and op in "-+":
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return -args[0] if op == "-" else args[0]
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h = CONST_OP_HANDLERS.get(op)
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if h is None:
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return ExpFunAp(op, args, kwargs)
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return h(*args)
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class ExprParserSpec(ParserSpec):
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def __init__(self):
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super().__init__()
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self.populate()
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@staticmethod
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def split_funap_args(toks):
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if not isinstance(toks, (list, tuple)):
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return ExpTuple((toks,)), ExpDict()
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return ExpTuple(t for t in toks if not isinstance(t, ExpKV)), ExpDict({
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str(t.k): t.v for t in toks if isinstance(t, ExpKV)
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})
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@staticmethod
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def null_constant(p, token, bp):
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return token
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@staticmethod
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def null_paren(p, token, bp):
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result = p.parse_until(bp) if p.token != ")" else ExpTuple()
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if p.token == ",":
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p.advance()
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p.expect(")")
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return result
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@staticmethod
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def null_prefixop(p, token, bp):
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val = p.parse_until(bp)
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return make_funap(token, ExpTuple((val,)))
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@classmethod
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def left_binop(cls, p, token, left, bp):
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return make_funap(token, *cls.split_funap_args((left, p.parse_until(bp))))
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@staticmethod
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def left_kv(p, token, left, bp):
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if not isinstance(left, (ExpOp, ExpSym)):
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raise ParseError(f"{left!r} is not a valid key")
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return ExpKV(left, p.parse_until(bp))
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@classmethod
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def left_funcall(cls, p, token, left, bp):
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if not isinstance(left, ExpOp):
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raise ParseError(f"{left!r} is not a valid function/variable name")
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args = []
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while p.lexer and p.token != ")":
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args.append(p.parse_until(COMMA_PRECEDENCE))
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if p.token == ",":
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p.advance()
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p.expect(")")
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return make_funap(left, *cls.split_funap_args(args))
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@staticmethod
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def left_comma(p, token, left, bp):
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if p.token == ")":
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return left if isinstance(left, ExpTuple) else ExpTuple((left,))
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r = p.parse_until(bp)
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return ExpTuple((*left, r) if isinstance(left, ExpTuple) else (left, r))
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@staticmethod
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def left_semicolon(p, token, left, bp):
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r = None if p.token in (None, ")", ";") else p.parse_until(0)
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return ExpStatements(
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ExpTuple((*left.statements, r))
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if isinstance(left, ExpStatements)
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else ExpTuple((left, r))
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)
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@staticmethod
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def left_index(p, token, left, bp):
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idx = p.parse_until(0)
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p.expect("]")
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return make_funap("index", ExpTuple((idx, left)))
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@staticmethod
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def left_assign(p, token, left, bp):
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if not isinstance(left, (ExpOp, ExpSym)):
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raise ParseError(f"bad LHS type for assignment operation {type(left)}")
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val = p.parse_until(bp)
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return make_funap("set_var", ExpTuple((ExpSym(left), val)))
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@staticmethod
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def left_ternary(p, token, left, bp):
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true_branch = p.parse_until(0)
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p.expect(":")
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false_branch = p.parse_until(bp)
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return make_funap("if", ExpTuple((left, true_branch, false_branch)))
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@staticmethod
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def get_type(token):
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if isinstance(token, (int, float)):
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return "number"
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if isinstance(token, ExpSym):
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return "sym"
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if isinstance(token, ExpBinOp):
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return "binop"
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if isinstance(token, ExpOp) and token[0].isalpha():
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return "op"
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return token
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def populate(self):
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self.add_left(31, self.left_funcall, ("(",))
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self.add_left(31, self.left_index, ("[",))
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self.add_leftright(29, self.left_binop, ("**",))
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self.add_null(27, self.null_prefixop, ("+", "-", "!"))
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self.add_left(25, self.left_binop, ("*", "/"))
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self.add_left(23, self.left_binop, ("+", "-"))
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self.add_left(22, self.left_binop, ("binop",))
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self.add_left(19, self.left_binop, ("<", ">", "<=", ">="))
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self.add_left(19, self.left_binop, ("==", "!="))
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self.add_left(9, self.left_binop, ("&&",))
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self.add_left(7, self.left_binop, ("||",))
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self.add_left(6, self.left_kv, (":>",))
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self.add_leftright(5, self.left_ternary, ("?",))
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self.add_leftright(4, self.left_assign, (":=",))
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self.add_left(COMMA_PRECEDENCE, self.left_comma, (",",))
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self.add_left(1, self.left_semicolon, (";",))
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self.add_null(0, self.null_paren, ("(",))
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self.add_null(
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-1, self.null_constant, ("number", "op", "sym", Ellipsis, True, False, None)
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)
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self.add_null(-1, ParserSpec.null_error, (")", "]", ":"))
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