// (1 2 '(3)) => (1 2 3)
func ExpandApplyArgs(args []value.Value) value.Value {
prev := value.NewPairValue(nil, nil)
curr := value.NewPairValue(nil, nil)
front := prev
expectlist := false
for i, arg := range args {
switch arg.(type) {
case *value.PairValue:
prev.Second = arg.(*value.PairValue)
for {
if _, ok := arg.(*value.PairValue); ok {
arg = arg.(*value.PairValue).Second
} else if _, ok := arg.(*value.EmptyPairValue); ok {
break
} else {
panic(fmt.Sprint("apply: expected list, given: ", arg))
}
}
expectlist = false
if i != len(args)-1 {
panic(fmt.Sprint("apply: expected list, given: ", arg))
}
case *value.EmptyPairValue:
expectlist = false
if i != len(args)-1 {
panic(fmt.Sprint("apply: expected list, given: ", arg))
}
default:
expectlist = true
curr.First = arg
prev.Second = curr
prev = curr
curr = value.NewPairValue(nil, nil)
}
}
if expectlist {
panic(fmt.Sprint("apply: expected list, given: ", args[len(args)-1]))
}
return front.Second
}
func (self *Pair) Eval(env *scope.Scope) value.Value {
var first value.Value
var second value.Value
if self.Second == NilPair {
second = value.NilPairValue
} else {
switch self.Second.(type) {
case *Name:
second = value.NewSymbol(self.Second.(*Name).Identifier)
default:
second = self.Second.Eval(env)
}
}
if name, ok := self.First.(*Name); ok {
// treat Name as Symbol
first = value.NewSymbol(name.Identifier)
} else if _, ok := self.First.(*UnquoteBase); ok {
// our parser garantees unquote-splicing only appears in quasiquote
// and unquote-splicing will be evaluated to a list
first = self.First.Eval(env)
// () empty list must be handled
if first == value.NilPairValue {
return second
}
// seek for the last element
var last value.Value = first
for {
switch last.(type) {
case *value.PairValue:
pair := last.(*value.PairValue)
if pair.Second == value.NilPairValue {
pair.Second = second
return first
}
last = pair.Second
default:
if second == value.NilPairValue {
return first
} else {
// `(,@(cdr '(1 . 2) 3))
panic(fmt.Sprintf("unquote-splicing: expected list?, given: %s", first))
}
}
}
} else {
first = self.First.Eval(env)
}
return value.NewPairValue(first, second)
}
func (self *Cons) Apply(args []value.Value) value.Value {
checkargsnumber(args, 2)
return value.NewPairValue(args[0], args[1])
}