private IExpr ParseSymbolLiteral()
{
LookAhead();
if (mHeadToken != TokenType.Identifier)
{
throw new RheaException(
Expected("Identifier"), mLexer.GetSourceInfo()
);
}
IExpr expr = new ExprConst(
ValueSymbol.Intern((string)mLexer.Value)
);
LookAhead();
return expr;
}
private IExpr ParseInt()
{
IExpr expr = new ExprConst(new ValueInt((int)mLexer.Value));
LookAhead();
return expr;
}
private IExpr ParseString()
{
IExpr expr = new ExprConst(new ValueString((string)mLexer.Value));
LookAhead();
return expr;
}
private IExpr ParseAtom()
{
IExpr expr;
switch (mHeadToken)
{
case TokenType.Int:
expr = ParseInt();
break;
case TokenType.String:
expr = ParseString();
break;
case TokenType.Identifier:
expr = ParseVariableReference();
break;
case TokenType.Colon:
expr = ParseSymbolLiteral();
break;
case TokenType.Hat:
expr = ParseLambdaExpression();
if (mHeadToken == TokenType.End)
{
LookAhead();
}
break;
case TokenType.LeftParen:
expr = ParseParenthesizedExpression();
break;
case TokenType.True:
expr = new ExprConst(ValueTrue.Instance);
LookAhead();
break;
case TokenType.False:
expr = new ExprConst(ValueFalse.Instance);
LookAhead();
break;
case TokenType.Nil:
expr = new ExprConst(ValueNil.Instance);
LookAhead();
break;
default:
throw new RheaException(Unexpected(), mLexer.GetSourceInfo());
}
return expr;
}
