func (pp *__arg_parserparser) _parse_alt(first _arg_parser) _arg_parser {
switch pp.ch { //make sure next is kosher
case _alt, _cseq, _eot, _eoi, _star, _plus, _maybe:
gelo.SyntaxError("Illegal prefix:", pp.spec[pp.pos])
}
head := &_alt_parser{first, nil}
tail := head
for {
if p := pp._parse1(true); p != nil {
tail.next = &_alt_parser{p, nil}
tail = tail.next
} else { //_eoi
return head
}
switch pp.ch {
default:
gelo.SyntaxError("Unexpected token",
string(pp.spec), string(pp.spec[pp.pos-1]))
case _alt:
pp._next()
switch pp.ch { //make sure next is kosher
case _alt, _cseq, _eot, _star, _plus, _maybe:
gelo.SyntaxError("Illegal prefix:", pp.spec[pp.pos-1])
case _eoi:
gelo.SyntaxError("Input ends after |")
}
case _cseq, _eot:
return head
}
pp._next()
}
panic("parse alt in impossible state") //Issue 65
}
func (pp *__arg_parserparser) _parse1(inalt bool) _arg_parser {
var p _arg_parser
for ; pp.ch == _eot; pp._next() {
} //spin past whitespace
switch pp.ch { //parse prefix
default:
gelo.SyntaxError("Unexpected token", string(pp.spec[pp.pos]))
case _eoi:
return nil
case _lit:
pp._next()
str := pp._parse_string()
if len(str) == 0 {
gelo.SyntaxError("No literal after '")
}
pp.s[str] = true
p = _lit_parser(str)
case _char:
//len >= 1, no need for check like above
p = _var_parser(pp._parse_string())
case _oseq:
p = pp._parse_seq(false)
}
switch pp.ch {
default:
gelo.SyntaxError("Unexpected token", string(pp.spec[pp.pos]))
case _star, _plus, _maybe:
switch pp.ch {
case _star:
p = &_star_parser{p}
case _plus:
p = &_plus_parser{p}
case _maybe:
p = &_maybe_parser{p}
}
pp._next()
switch pp.ch {
case _char, _oseq, _star, _plus, _maybe, _lit:
gelo.SyntaxError("Unexpected token after postfix operator")
}
case _alt:
if !inalt {
pp._next()
p = pp._parse_alt(p)
}
case _eot, _eoi, _cseq: //nothing more to do
}
return p
}
func SyntaxError(vm *gelo.VM, args *gelo.List, ac uint) gelo.Word {
if ac == 0 {
gelo.ArgumentError(vm, "SyntaxError", "error-msg+", "")
}
//TODO should get a line-no, etc to allow creation of good error message
gelo.SyntaxError(args)
panic("Issue 65")
}
func (pp *__arg_parserparser) _next() {
pp.pos++
if pp.ch == _eoi || pp.pos >= len(pp.spec) {
pp.ch = _eoi
return
}
ch := pp.spec[pp.pos]
if int(ch) < 32 {
gelo.SyntaxError("Illegal character in argument parser specification")
}
switch ch {
case '\\':
pp._next() //This is severly broken, what was I thinking?
if pp.ch == _eoi {
gelo.SyntaxError("Attempted to escape end of input")
}
if pp.ch != _char {
pp.ch = _char
}
case ' ':
pp.ch = _eot
case '\'':
pp.ch = _lit
case '*':
pp.ch = _star
case '+':
pp.ch = _plus
case '?':
pp.ch = _maybe
case '|':
pp.ch = _alt
case '[':
pp.ch = _oseq
case ']':
pp.ch = _cseq
default:
pp.ch = _char
}
if pp.ch == _char {
pp.buf.WriteByte(ch)
}
}
func ReCon(vm *gelo.VM, args *gelo.List, ac uint) gelo.Word {
if ac != 1 {
gelo.ArgumentError(vm, "Re", "specification", args)
}
spec := vm.API.LiteralOrElse(args.Value)
rex, err := regexp.Compile(string(spec))
if err != nil {
gelo.SyntaxError(vm, err.Error())
}
return &Regexp{rex}
}
func (pp *__arg_parserparser) _parse_seq(top bool) *_seq_parser {
var p _arg_parser
var head, tail *_seq_parser
for {
pp._next()
if p = pp._parse1(false); p != nil {
if head != nil {
tail.next = &_seq_parser{p, nil}
tail = tail.next
} else {
head = &_seq_parser{p, nil}
tail = head
}
}
switch pp.ch {
case _cseq:
if top {
gelo.SyntaxError("] before [ in argument specification")
}
if head == nil {
gelo.SyntaxError("Empty argument specification")
}
pp._next() //step over ]
return head //postfix handled in _parse1
case _eoi:
if !top {
gelo.SyntaxError("[ without ] in argument specification")
}
if head == nil {
gelo.SyntaxError("[] empty sequence in argument specification")
}
return head
}
}
panic("argument parser parser in impossible state") //Issue 65
}
func Case_of(vm *gelo.VM, args *gelo.List, ac uint) gelo.Word {
Args := _cases_parser(vm, args)
key := Args["value"]
arguments := gelo.AsList(key)
cases, ok := vm.API.PartialEval(vm.API.QuoteOrElse(Args["cases"]))
if !ok || cases.Next == nil && cases.Value == nil {
gelo.SyntaxError(vm, "Expected:", _cases_parser,
"{[value+ => resultant\n]+ [otherwise result]?} Got:", args)
}
//Give val a name, specified by var, in clauses of the cases block
//XXX This disallows us from making tail calls
if name, there := Args["var"]; there {
if d, there := vm.Ns.DepthOf(name); there && d == 0 {
defer vm.Ns.Set(0, name, vm.Ns.LookupOrElse(name))
} else {
defer vm.Ns.Del(name)
}
vm.Ns.Set(0, name, key)
}
//run val through cmd before comparing
if cmd, there := Args["cmd"]; there {
key = vm.API.InvokeCmdOrElse(cmd, arguments)
}
//Parse lines
for ; cases != nil; cases = cases.Next {
//if last line, see if it's the otherwise clause
if cases.Next == nil {
item := cases.Value.(*gelo.List)
s, ok := item.Value.(gelo.Symbol)
if ok && gelo.StrEqualsSym("otherwise", s) {
if item.Next == nil || item.Next.Next != nil {
_cases_synerr()
}
return _case_eval(vm, item.Next.Value, arguments)
}
}
item := cases.Value.(*gelo.List)
//line is too short
if item.Next == nil || item.Next.Next == nil {
_cases_synerr()
}
//Parse a single line
list := extensions.ListBuilder()
var resultant gelo.Word
for ; item != nil; item = item.Next {
if item.Next == nil { //ultimate cell
resultant = item.Value
} else if item.Next.Next == nil { //penultimate cell
s, ok := item.Value.(gelo.Symbol)
if ok && gelo.StrEqualsSym("=>", s) {
continue
}
_cases_synerr()
} else {
list.Push(item.Value)
}
}
//see if key matches any of the items we found on this line
for head := list.List(); head != nil; head = head.Next {
if key.Equals(head.Value) {
return _case_eval(vm, resultant, arguments)
}
}
}
return gelo.Null //no match, no otherwise
}
func _cases_synerr() {
gelo.SyntaxError("Patterns needs to be:",
"\"value+ => resultant\", where value may be a command")
}