public static Node.Expression Parse()
{
Node.Expression n;
if (IsLookahead(1, Tokens.Keyword, Lexemes.If))
{
Match(Tokens.Keyword, Lexemes.If);
Node.Expression test = Parser.Expression.Parse();
Match(Tokens.Keyword, Lexemes.Then);
Node.Expression expIf = Parser.Expression.Parse();
if (IsLookahead(1, Tokens.Keyword, Lexemes.Else))
{
Match(Tokens.Keyword, Lexemes.Else);
Node.Expression expElse = Parser.Expression.Parse();
n = new Node.IfThenElse
{
Test = test,
If = expIf,
Else = expElse
};
}
else
{
n = new Node.IfThen
{
Test = test,
If = expIf
}
};
}
else if (IsLookahead(1, Tokens.Keyword, Lexemes.While))
{
Match(Tokens.Keyword, Lexemes.While);
Node.Expression test = Parser.Expression.Parse();
Match(Tokens.Keyword, Lexemes.Loop);
Node.Expression exp = Parser.Expression.Parse();
n = new Node.WhileLoop
{
Test = test,
Loop = exp
};
}
else if (IsLookahead(1, Tokens.Keyword, Lexemes.Loop))
{
Match(Tokens.Keyword, Lexemes.Loop);
Node.Expression exp = Parser.Expression.Parse();
Match(Tokens.Keyword, Lexemes.While);
Node.Expression test = Parser.Expression.Parse();
n = new Node.LoopWhile
{
Test = test,
Loop = exp
};
}
else if (IsLookahead(1, Tokens.Keyword, Lexemes.Do))
{
Match(Tokens.Keyword, Lexemes.Do);
n = new Node.Do
{
E = Parser.Expression.Parse()
};
}
else if (IsLookahead(1, Tokens.Keyword, Lexemes.Async))
{
Match(Tokens.Keyword, Lexemes.Async);
n = new Node.Async
{
E = Parser.Expression.Parse()
};
}
else if (IsLookahead(1, Tokens.Identifier) ||
IsLookahead(1, Tokens.Number) ||
IsLookahead(1, Tokens.Keyword, Lexemes.Function) ||
IsLookahead(1, Tokens.Operator, Lexemes.BrackOpen) ||
IsLookahead(1, Tokens.Operator, Lexemes.BraceOpen) ||
IsLookahead(1, Tokens.Keyword, Lexemes.Undefined))
{
n = new Node.Structured
{
V = Parser.Value.Parse(),
C = Parser.Continuation.Parse()
};
}
else
{
throw new Exceptions.Parser.UnexpectedLookahead("Parse(Expression)", Lexer.Lookahead(1), 1);
}
return(n);
}