private static void MatchToken(TokenType tokenType, string content, TokenStream tokenStream)
{
CheckEnd(tokenStream);
if (tokenStream.Current.Type == tokenType && tokenStream.Current.Content == content)
{
tokenStream.Next();
}
else
{
throw new ParserException(String.Format(
"Expected '{0}' at position {1}.", content, tokenStream.Current.Start));
}
}
private static AstNode LeftAssocCombiner(
string[] operators,
ParseFunction termParser,
TokenStream tokenStream)
{
AstNode leftTerm = termParser(tokenStream);
while (tokenStream.HasMoreTokens && OneOf(tokenStream.Current.Content, operators))
{
AstNode tokenNode = new AstNode(AstNodeType.Identifier, tokenStream.Current);
tokenStream.Next();
AstNode rightTerm = termParser(tokenStream);
leftTerm = new AstNode(
AstNodeType.BinaryExpression,
new AstNode[] { tokenNode, leftTerm, rightTerm });
}
return leftTerm;
}
private static AstNode ParseArgumentList(TokenStream tokenStream)
{
CheckEnd(tokenStream);
List<AstNode> arguments = new List<AstNode>();
bool finish = tokenStream.Current.Type == TokenType.CloseParen;
while (!finish)
{
if (tokenStream.Current.Type == TokenType.Identifier)
{
arguments.Add(new AstNode(AstNodeType.Identifier, tokenStream.Current));
}
else
{
throw new ParserException(string.Format("Expected an identifier at {0}.", tokenStream.Current.Start));
}
tokenStream.Next();
CheckEnd(tokenStream);
if (tokenStream.Current.Type == TokenType.CloseParen)
{
finish = true;
}
else
{
MatchToken(TokenType.Comma, ",", tokenStream);
}
}
return new AstNode(AstNodeType.ArgumentList, arguments);
}
private static AstNode ParseExprUnary(TokenStream tokenStream)
{
CheckEnd(tokenStream);
AstNode result;
if (tokenStream.Current.Type == TokenType.OpenParen)
{
result = ParseParenExpression(tokenStream);
}
else if (tokenStream.Current.Type == TokenType.Minus
|| tokenStream.Current.Type == TokenType.LogicalNot)
{
AstNode tokenNode = new AstNode(AstNodeType.Identifier, tokenStream.Current);
tokenStream.Next();
AstNode negatedExpression = ParseExprUnary(tokenStream);
result = new AstNode(AstNodeType.UnaryExpression, new AstNode[] { tokenNode, negatedExpression });
}
else if (tokenStream.Current.Type == TokenType.Identifier)
{
AstNode tokenNode = new AstNode(AstNodeType.Identifier, tokenStream.Current);
tokenStream.Next();
if (tokenStream.HasMoreTokens && tokenStream.Current.Type == TokenType.OpenParen)
{
result = ParseFunctionCallExpression(tokenNode, tokenStream);
}
else
{
result = tokenNode;
}
}
else if (tokenStream.Current.Type == TokenType.Number)
{
result = new AstNode(AstNodeType.Number, tokenStream.Current);
tokenStream.Next();
}
else
{
throw new ParserException(String.Format(
"Expecting an unary expression at {0}.",
tokenStream.Current.Start));
}
while (tokenStream.HasMoreTokens && tokenStream.Current.Type == TokenType.OpenParen)
{
result = ParseFunctionCallExpression(result, tokenStream);
}
return result;
}
private static AstNode ParseAssignmentOrFunctionCallStatement(TokenStream tokenStream)
{
CheckEnd(tokenStream);
AstNode tokenNode = new AstNode(AstNodeType.Identifier, tokenStream.Current);
tokenStream.Next();
CheckEnd(tokenStream);
if (tokenStream.Current.Type == TokenType.Equal)
{
return ParseAssignmentStatement(tokenNode, tokenStream);
}
else if (tokenStream.Current.Type == TokenType.OpenParen)
{
AstNode result = ParseFunctionCallExpression(tokenNode, tokenStream);
MatchToken(TokenType.Semicolon, ";", tokenStream);
return result;
}
else
{
throw new ParserException(String.Format(
"Expected an assignment or function call at {0}.", tokenNode.Token.Start));
}
}