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from tokens import *
from std import STD
def peek(inp):
if len(inp) == 0:
return None
return inp[0]
def evaluate_expression(expr):
if not expr.symbol.name in STD:
raise Exception(f"no such symbol: {expr.symbol.name}")
this_func = STD[expr.symbol.name]
# try to match the signature
in_sig = expr.in_sig()
if in_sig in this_func:
ret = this_func[expr.in_sig()].impl(*(expr.args))
return ret
# evaluate inner expressions, if possible/necessary
for idx, arg in enumerate(expr.args):
if arg.type_ == NebType.EXPR:
expr.args[idx] = evaluate_expression(arg)
return evaluate_expression(expr)
raise Exception(f"'{expr.symbol.name}' called with unknown signature: '{expr.in_sig()}'")
def evaluate(items, pop):
nxt = peek(items)
if nxt is None:
return pop
elif isinstance(nxt, NebLiteral):
return evaluate(items[1:], nxt)
elif isinstance(nxt, NebSymbol):
if not nxt.name in STD:
raise Exception(f"no such symbol: '{nxt.name}'")
this_func = STD[nxt.name]
return evaluate(items[1:], this_func[list(this_func.keys())[0]].impl) # TODO show all
elif isinstance(nxt, NebExpression):
return evaluate(items[1:], evaluate_expression(nxt))
else:
raise Exception("expected a literal or an expression")
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