def parseRest(exp1,toks):
if toks.null():
return (exp1,toks)
else:
with toks as (b,bs):
if b == neg:
exp2,rest = force( parseAtom(bs) )
return parseRest( Diff_exp(exp1,exp2) ,rest)
elif b == lf:
exp2,rest = force( parseExp(bs) )
return parseRest( Call_exp(exp1,exp2) ,strip(rf,rest) )
else:
return (exp1,toks)
def parseRest(exp1, toks):
if toks.null():
return (exp1, toks)
else:
with toks as (b, bs):
if b == "+":
exp2, rest = force(parseAtom(bs))
return parseRest(["BinOp", exp1, b, exp2], rest)
elif b == '-':
exp2, rest = force(parseAtom(bs))
return parseRest(["BinOp", exp1, b, exp2], rest)
else:
return (exp1, toks)
def read(inp):
output = force( parseExp(Lex(inp)) )
with unpack(output) as (result,rest):
if rest.null():
return result
else:
raise ParseError("not all: {}".format(output))
def parseTypeRest(typ1,toks):
if toks.null():
return (typ1,toks)
else:
with toks as (b,rest):
if b == "->":
typ2,rest2 = force( parseTypeAtom(rest) )
return parseTypeRest( Proc_Type(typ1,typ2) ,rest2)
else:
return (typ1,toks)
def parseTypeAtom(toks):
if toks.null():
raise ParseError("parseTypeError: {} is null".format(toks))
else:
with toks as (typ,rest):
if IsType(typ):
return ToType(typ),rest
elif typ == lf :
typ1 ,rest1 = force( parseType(rest) )
#print typ1
return typ1,strip(rf,rest1)
else:
raise ParseError("parseTypeError: {} ,{}".format(var,rest))
def parseAtom(toks):
with toks as (op, rest):
if op == "if":
exp1, rest1 = force(parseExp(rest))
exp2, rest2 = force(parseExp(strip("then", rest1)))
exp3, rest3 = force(parseExp(strip("else", rest2)))
return ["If", exp1, exp2, exp3], rest3
elif op == "let":
var1, rest1 = force(parseVar(rest))
exp1, rest2 = force(parseExp(strip("=", rest1)))
body, rest3 = force(parseExp(strip("in", rest2)))
return ["Let", var1, exp1, body], rest3
elif IsBool(op):
return ["Bool", ToBool(op)], rest
elif IsNum(op):
return ["Num", int(op)], rest
elif IsId(op):
return ["Id", op], rest
elif op == '(':
exp1, rest1 = force(parseExp(rest))
return exp1, strip(')', rest1)
else:
raise ParseError("parseAtom")
def parseExp(toks):
exp1, rest1 = force(parseAtom(toks))
return parseRest(exp1, rest1)
def read(inp):
return force(parseExp(Lex(inp)))
with toks as (b, bs):
if b == "+":
exp2, rest = force(parseAtom(bs))
return parseRest(["BinOp", exp1, b, exp2], rest)
elif b == '-':
exp2, rest = force(parseAtom(bs))
return parseRest(["BinOp", exp1, b, exp2], rest)
else:
return (exp1, toks)
inp = Lex("""
let b = 3 in
if 6 + b then true else false
""")
print(force(parseExp(inp)))
# if true then a else b
def read(inp):
return force(parseExp(Lex(inp)))
print(
read("""
let a = if true then 233 else 332
in (if (let c = a + a in c + a)
then true - 1
else false + 1)
"""))
def _f(lst):
lst = list(reversed(lst))
return force(f(lst, []))
def parseAtom(toks):
if toks.null():
raise ParseError("toks is null: {}".format(toks))
with toks as (op,rest):
if op == If:
exp1,rest1 = force( parseExp(rest) )
exp2,rest2 = force( parseExp( strip("then",rest1)) )
exp3,rest3 = force( parseExp( strip("else",rest2)) )
return If_exp(exp1,exp2,exp3),rest3
elif op == Let:
var1,rest1 = force( parseVar(rest) )
exp1,rest2 = force( parseExp(strip(Defn,rest1)) )
body,rest3 = force( parseExp(strip(In,rest2)) )
return Let_exp(var1,exp1,body),rest3
elif op == LetRec:
pname,rest1 = force( parseVar(rest) )
pvar,rest2 = force( parseVar(strip(lf,rest1) ) )
var_typ,rest3 = force( parseType( strip(":",rest2) ) )
res_typ,rest4 = force( parseType( strip(":",strip(rf,rest3)) ))
pbody,rest5 = force( parseExp( strip("=",rest4) ) )
lbody,rest6 = force( parseExp(strip(In,rest5)) )
return Letrec_exp(pname,pvar,pbody,lbody,var_typ,res_typ),rest6
elif op == Zero:
exp1,rest1 = force( parseExp( strip("?",rest) ) )
return Zerop_exp(exp1),rest1
elif op == Fn:
var,rest1 = force( parseVar(strip(lf,rest)) )
var_type,rest2 = force( parseType(strip(":",rest1) ) )
body,rest2 = force( parseExp(strip(rf,rest2) ) )
return Proc_exp(var,var_type,body),rest2
elif IsNum(op):
return Const_exp(int(op)),rest
elif IsId(op):
return Var_exp(op),rest
elif op == lf:
exp1,rest1 = force( parseExp(rest) )
#try:
# exp2,rest2 = force(parseExp(rest1) )
# return Call_exp(exp1,exp2),strip(rf,rest2)
#except ParseError:
# return exp1,strip(rf,rest1)
return exp1,strip(rf,rest1)
else:
raise ParseError("parseAtomError: {},{}".format(op,rest))
def parseType(toks):
typ1,rest1 = force( parseTypeAtom(toks) )
return parseTypeRest(typ1,rest1)