// expr ::= term { <op> term }
// op := "<" | ">" | "<=" | ">=" | "==" | "~=" | "&&" | "||" | ...... (see lang desc)
private SyntaxNode ParseExprNode()
{
var Left = ParseTermNode();
if (Left == null)
{
return(null);
}
while (!TokenStream_.IsEnd())
{
var Tok = TokenStream_.Peek();
switch (Tok.Type)
{
case TokenType.Operator:
TokenStream_.Take();
var Right = ParseTermNode();
if (Right == null)
{
return(null);
}
Left = new SyntaxBinaryExpressionNode(Tok, Left, Right);
break;
default:
return(Left);
}
}
return(Left);
}
public LiteValue Visit(SyntaxBinaryExpressionNode Node, LiteEnv Env)
{
var ValLeft = Node.GetLeft().Accept(this, Env);
var ValRight = Node.GetRight().Accept(this, Env);
var Op = Node.GetOperator().Code;
switch (Op)
{
case "<":
return(ValLeft < ValRight ? LiteValue.True : LiteValue.False);
case "<=":
return(ValLeft <= ValRight ? LiteValue.True : LiteValue.False);
case ">":
return(ValLeft > ValRight ? LiteValue.True : LiteValue.False);
case ">=":
return(ValLeft >= ValRight ? LiteValue.True : LiteValue.False);
case "==":
return(ValLeft == ValRight ? LiteValue.True : LiteValue.False);
case "~=":
return(ValLeft != ValRight ? LiteValue.True : LiteValue.False);
case "+":
return(ValLeft + ValRight);
case "-":
return(ValLeft - ValRight);
case "*":
return(ValLeft * ValRight);
case "/":
return(ValLeft / ValRight);
case "%":
return(ValLeft % ValRight);
default:
Logger.DError($"unknown op : {Op}");
return(LiteValue.Error);
}
}
// factor ::= assignment | dot | call | primary { <'*' | '/' | '%' > primary }
// call ::= args
// dot ::= "." ident
private SyntaxNode ParseFactorNode()
{
var Left = ParsePrimaryNode();
if (Left == null)
{
return(null);
}
while (!TokenStream_.IsEnd())
{
var Tok = TokenStream_.Peek();
switch (Tok.Type)
{
case TokenType.Operator:
switch (Tok.Code)
{
case "*":
case "/":
case "%":
TokenStream_.Take();
var Right = ParsePrimaryNode();
if (Right == null)
{
return(null);
}
Left = new SyntaxBinaryExpressionNode(Tok, Left, Right);
break;
case "=":
TokenStream_.Take();
var Val = ParseExprNode();
if (Val == null)
{
return(null);
}
Left = new SyntaxAssignmentExpressionNode(Tok, Left, Val);
break;
default:
return(Left);
}
break;
case TokenType.Delimiter:
switch (Tok.Code)
{
case ".":
TokenStream_.Take();
if (Left.GetType() != SyntaxNodeType.Identifier)
{
ExitCode_ = new ExitFailedCode(". must use for class ident");
return(null);
}
if (!TokenStream_.TakeExpect(TokenType.Identifier, out Token CallIdent))
{
ExitCode_ = new ExitUnexpectedSymbolCode(CallIdent);
return(null);
}
Left = new SyntaxDotClassExpressionNode(Left as SyntaxIdentifierNode, new SyntaxIdentifierNode(CallIdent));
break;
case "(":
var ArgsNode = ParseArgumentListNode();
if (ArgsNode == null)
{
return(null);
}
Left = new SyntaxCallFunctionExpressionNode(Left, ArgsNode);
break;
case "[":
var IndexNode = ParseIndexNode();
if (IndexNode == null)
{
return(null);
}
Left = new SyntaxIndexElementsExpressionNode(Left, IndexNode);
break;
default:
return(Left);
}
break;
default:
return(Left);
}
}
return(Left);
}
