private static List <AssertionError> AssertReturnStatementSyntax(StatementParseResultBuilderState currentState)
{
var nextToken = currentState.Tokens.Skip(currentState.Position + Skip.Return).Take(1).FirstOrDefault();
var errors = new List <AssertionError>();
if (nextToken == default(Token) || nextToken.Kind == SyntaxKind.Semicolon || nextToken.Kind == SyntaxKind.EOF)
{
return(errors);
}
var info = new ErrorInfo
{
Kind = ErrorKind.InvalidToken,
Position = currentState.Position + Skip.Return,
Source = ErrorSource.Parser,
Tokens = currentState.Tokens
};
if (!IsExpressionToken(nextToken))
{
info.Code = ErrorCode.InvalidReturnExpression;
info.Kind = ErrorKind.InvalidToken;
errors.Add(Error.Create(info));
}
return(errors);
}
public StatementParseResultBuilder(StatementParseResult currentState)
{
internalState = new StatementParseResultBuilderState
{
Errors = currentState.Errors,
Position = currentState.Position,
Tokens = currentState.Tokens
};
}
private static bool IsIfElseExpression(StatementParseResultBuilderState currentState, int position)
{
var nextToken = currentState.Tokens.Skip(position + Skip.Brace).Take(1).FirstOrDefault();
if (nextToken != null && nextToken.Kind == SyntaxKind.Else)
{
return(true);
}
return(false);
}
internal static List <AssertionError> Syntax(StatementParseResultBuilderState currentState)
{
switch (currentState.Kind)
{
case NodeKind.Let:
return(AssertLetStatementSyntax(currentState));
case NodeKind.Return:
return(AssertReturnStatementSyntax(currentState));
default:
return(new List <AssertionError>());
}
}
private int DetermineTokenRangeInternal(StatementParseResultBuilderState state)
{
var noOfLeftBraces = 0;
var noOfRightBraces = 0;
var position = state.Position;
var ignoreSemicolon = false;
while (position < state.Tokens.Count)
{
var currentToken = state.Tokens.Skip(position).Take(1).FirstOrDefault();
// Enable parsing of simple expressions, eg. '1 + 1' without semicolon
if (currentToken.Kind == SyntaxKind.EOF)
{
return(position);
}
// Top-level semicolons, eg. let a = 42;<< or if (true) { 1; };<<
else if (currentToken.Kind == SyntaxKind.Semicolon && !ignoreSemicolon && noOfLeftBraces == noOfRightBraces)
{
return(position + Include.Semicolon - state.Position);
}
// Brace after consequence body in If-Else expression, eg. if (true) { 1 }<< else...
if (currentToken.Kind == SyntaxKind.RightBrace && IsIfElseExpression(state, position))
{
noOfRightBraces++;
position++;
}
// Inside the block, ie. { ...<< }
else if (currentToken.Kind == SyntaxKind.RightBrace && noOfLeftBraces != noOfRightBraces)
{
ignoreSemicolon = false;
noOfRightBraces++;
position++;
}
// Block opening, eg. {<< ... }. We ignore semicolons inside blocks
else if (currentToken.Kind == SyntaxKind.LeftBrace)
{
ignoreSemicolon = true;
noOfLeftBraces++;
position++;
}
// Everything else
else
{
position++;
}
}
return(-1);
}
private static List <AssertionError> AssertLetStatementSyntax(StatementParseResultBuilderState currentState)
{
var identifierToken = currentState.Tokens
.Skip(currentState.Position + Skip.Let)
.Take(1)
.FirstOrDefault();
var assignToken = currentState.Tokens
.Skip(currentState.Position + Skip.Let + Skip.Identifier)
.Take(1)
.FirstOrDefault();
var expressionToken = currentState.Tokens
.Skip(currentState.Position + Skip.Let + Skip.Identifier + Skip.Assign)
.Take(1)
.FirstOrDefault();
var errors = new List <AssertionError>();
var info = new ErrorInfo
{
Kind = ErrorKind.UnexpectedToken,
Position = currentState.Position + Skip.Let,
Source = ErrorSource.Parser,
Tokens = currentState.Tokens
};
if (identifierToken == default(Token) || identifierToken.Kind == SyntaxKind.EOF)
{
info.Code = ErrorCode.MissingLetIdentifierToken;
info.Kind = ErrorKind.MissingToken;
errors.Add(Error.Create(info));
return(errors);
}
if (assignToken == default(Token) || assignToken.Kind == SyntaxKind.EOF)
{
info.Code = ErrorCode.MissingLetAssignToken;
info.Kind = ErrorKind.MissingToken;
info.Position = currentState.Position + Skip.Let + Skip.Identifier;
errors.Add(Error.Create(info));
return(errors);
}
if (identifierToken.Kind != SyntaxKind.Identifier)
{
info.Code = ErrorCode.InvalidLetIdentifierToken;
info.Kind = ErrorKind.InvalidToken;
errors.Add(Error.Create(info));
}
if (assignToken.Kind != SyntaxKind.Assign)
{
info.Code = ErrorCode.InvalidLetAssignToken;
info.Kind = ErrorKind.InvalidToken;
info.Position = info.Position + Skip.Identifier;
errors.Add(Error.Create(info));
}
if (expressionToken == default(Token) || expressionToken.Kind == SyntaxKind.EOF)
{
info.Code = ErrorCode.MissingExpressionToken;
info.Kind = ErrorKind.MissingToken;
info.Position = currentState.Position + Skip.Let + Skip.Identifier + Skip.Assign;
errors.Add(Error.Create(info));
return(errors);
}
if (!IsExpressionToken(expressionToken))
{
info.Code = ErrorCode.InvalidLetExpression;
info.Kind = ErrorKind.InvalidToken;
info.Position = currentState.Position + Skip.Let + Skip.Identifier + Skip.Assign;
errors.Add(Error.Create(info));
}
return(errors);
}