private static Atom ParseString(StringIterator Iterator)
{
var stringValue = "";
Iterator.Advance();
while (!Iterator.AtEnd && Iterator.Next != '\"')
{
stringValue += Iterator.Next;
Iterator.Advance();
//Todo: Escape chars.
}
if (Iterator.AtEnd)
{
throw new ParseError("Unexpected end of input in string literal.", Iterator.place);
}
Iterator.Advance();
if (!Iterator.AtEnd && !" \t\n\r)".Contains(Iterator.Next))
{
throw new ParseError("Expected end of token", Iterator.place);
}
return(new StringAtom {
Value = stringValue
});
}
private static void SkipWhitespace(this StringIterator Iterator)
{
while (!Iterator.AtEnd && " \t\r\n".Contains(Iterator.Next))
{
Iterator.Advance();
}
//if (Iterator.AtEnd)
// throw new ParseError("Unexpected end of input", Iterator.place);
}
public static Atom Parse(StringIterator Iterator)
{
var result = ParseAtom(Iterator);
if (!Iterator.AtEnd)
{
throw new ParseError("Did not consume all input", Iterator.place);
}
return(result);
}
private static Atom ParseString(StringIterator Iterator)
{
var stringValue = "";
Iterator.Advance();
while (!Iterator.AtEnd && Iterator.Next != '\"')
{
if (Iterator.Next == '\\') //escape sequence
{
Iterator.Advance();
if (Iterator.AtEnd)
{
throw new ParseError("Unexpected end of input in escape sequence.", Iterator.place);
}
if (Iterator.Next == 'n')
{
stringValue += '\n';
}
else if (Iterator.Next == '\\')
{
stringValue += '\\';
}
else
{
throw new ParseError("Unknown escape sequence.", Iterator.place);
}
}
else
{
stringValue += Iterator.Next;
}
Iterator.Advance();
}
if (Iterator.AtEnd)
{
throw new ParseError("Unexpected end of input in string literal.", Iterator.place);
}
Iterator.Advance();
if (!Iterator.AtEnd && !" \t\n\r.)".Contains(Iterator.Next))
{
throw new ParseError("Expected end of token", Iterator.place);
}
return(new StringAtom {
Value = stringValue
});
}
private static Atom ParseToken(StringIterator Iterator)
{
var tokenValue = "";
while (!Iterator.AtEnd && !" \t\r\n.()".Contains(Iterator.Next))
{
tokenValue += Iterator.Next;
Iterator.Advance();
}
return(new TokenAtom {
Value = tokenValue
});
}
private static Atom ParseAtom(StringIterator Iterator)
{
if (Iterator.AtEnd)
{
return(null);
}
while (Iterator.Next == ';')
{
while (!Iterator.AtEnd && Iterator.Next != '\n')
{
Iterator.Advance();
}
Iterator.SkipWhitespace();
if (Iterator.AtEnd)
{
return(null);
}
}
var modifier = Modifier.None;
Atom result = null;
if (Iterator.Next == '\'')
{
Iterator.Advance();
modifier = Modifier.Quote;
}
else if (Iterator.Next == '$')
{
Iterator.Advance();
modifier = Modifier.Expand;
}
else if (Iterator.Next == ':')
{
Iterator.Advance();
modifier = Modifier.Evaluate;
}
if (Iterator.AtEnd)
{
throw new ParseError("Unexpected end of input", Iterator.place);
}
if (Iterator.Next == '(')
{
Iterator.Advance();
Iterator.SkipWhitespace();
var list = new ListAtom {
Value = new List <Atom>()
};
while (!Iterator.AtEnd && Iterator.Next != ')')
{
list.Value.Add(ParseAtom(Iterator));
Iterator.SkipWhitespace();
}
Iterator.Advance();
result = list;
}
else if (Iterator.Next == '[')
{
if (modifier != Modifier.None)
{
throw new ParseError("Modifiers not allowed on record.", Iterator.place);
}
Iterator.Advance();
Iterator.SkipWhitespace();
var record = new RecordAtom();
while (!Iterator.AtEnd && Iterator.Next != ']')
{
var listItem = ParseAtom(Iterator) as ListAtom;
if (listItem == null)
{
throw new ParseError("Expected list inside record", Iterator.place);
}
if (listItem.Value.Count != 2)
{
throw new ParseError("Malformed record", Iterator.place);
}
var entryName = listItem.Value[0] as TokenAtom;
if (entryName == null)
{
throw new ParseError("Malformed record", Iterator.place);
}
record.Variables.Upsert(entryName.Value, listItem.Value[1]);
}
Iterator.Advance();
record.Literal = true;
result = record;
}
else if ("0123456789-".Contains(Iterator.Next))
{
if (modifier != Modifier.None)
{
throw new ParseError("Modifiers not allowed on literals.", Iterator.place);
}
result = ParseNumber(Iterator);
}
else if (Iterator.Next == '\"')
{
if (modifier != Modifier.None)
{
throw new ParseError("Modifiers not allowed on literals.", Iterator.place);
}
result = ParseString(Iterator);
}
else
{
result = ParseToken(Iterator);
if (result.Type == AtomType.Token && (result as TokenAtom).Value == "nil")
{
result = new NilAtom();
}
}
Iterator.SkipWhitespace();
if (!Iterator.AtEnd && Iterator.Next == '.')
{
Iterator.Advance();
Iterator.SkipWhitespace();
var member = ParseAtom(Iterator);
if (member.Modifier == Modifier.Expand)
{
throw new ParseError("Modifier illegal in this context", Iterator.place);
}
result = TransformMemberAccess(new MemberAtom
{
Lhs = result,
Rhs = member
});
}
result.Modifier = modifier;
return(result);
}
private static Atom ParseNumber(StringIterator Iterator)
{
var numberString = "";
bool decimalFound = false;
bool negate = false;
if (Iterator.Next == '-')
{
negate = true;
Iterator.Advance();
}
if (Iterator.AtEnd || !"0123456789".Contains(Iterator.Next))
{
Iterator.Rewind();
return(ParseToken(Iterator));
}
while (!Iterator.AtEnd && "0123456789".Contains(Iterator.Next))
{
numberString += Iterator.Next;
Iterator.Advance();
}
if (!Iterator.AtEnd && Iterator.Next == '.')
{
decimalFound = true;
numberString += '.';
Iterator.Advance();
while (!Iterator.AtEnd && "0123456789".Contains(Iterator.Next))
{
numberString += Iterator.Next;
Iterator.Advance();
}
}
if (!Iterator.AtEnd && !" \t\n\r.)".Contains(Iterator.Next))
{
throw new ParseError("Expected end of token", Iterator.place);
}
if (decimalFound)
{
var number = Convert.ToSingle(numberString);
if (negate)
{
number = -number;
}
return(new DecimalAtom {
Value = number
});
}
else
{
var number = Convert.ToInt32(numberString);
if (negate)
{
number = -number;
}
return(new IntegerAtom {
Value = number
});
}
}