/*
* Method: FindNextToken
*
* Find the next token. Return 'true' if one was found. False, otherwise.
*/
internal override bool FindNextToken()
{
int startPosition = _reader.Position;
// VB docs claim whitespace is Unicode category Zs. However,
// this category does not contain tabs. Assuming a less restrictive
// definition for whitespace...
if (_reader.SinkWhiteSpace())
{
while (_reader.SinkWhiteSpace())
{
}
// Now, we need to check for the line continuation character.
if (_reader.SinkLineContinuationCharacter()) // Line continuation is '_'
{
// Save the current position because we may need to come back here.
int savePosition = _reader.Position - 1;
// Skip all whitespace after the '_'
while (_reader.SinkWhiteSpace())
{
}
// Now, skip all the newlines.
// Need at least one newline for this to count as line continuation.
int count = 0;
while (_reader.SinkNewLine())
{
++count;
}
if (count > 0)
{
current = new VisualBasicTokenizer.LineContinuationToken();
return true;
}
// Otherwise, fall back to plain old whitespace.
_reader.Position = savePosition;
}
current = new WhitespaceToken();
return true;
}
// Line terminators are separate from whitespace and are significant.
else if (_reader.SinkNewLine())
{
// We want one token per line terminator.
current = new VisualBasicTokenizer.LineTerminatorToken();
return true;
}
// Check for a comment--either those that start with ' or rem.
else if (_reader.SinkLineCommentStart())
{
// Skip to the first EOL.
_reader.SinkToEndOfLine();
current = new CommentToken();
return true;
}
// Identifier or keyword?
else if
(
// VB allows escaping of identifiers by surrounding them with []
// In other words,
// Date is a keyword but,
// [Date] is an identifier.
_reader.CurrentCharacter == '[' ||
_reader.MatchNextIdentifierStart()
)
{
bool escapedIdentifier = false;
if (_reader.CurrentCharacter == '[')
{
escapedIdentifier = true;
_reader.SinkCharacter();
// Now, the next character must be an identifier start.
if (!_reader.SinkIdentifierStart())
{
current = new ExpectedIdentifierToken();
return true;
}
}
// Sink the rest of the identifier.
while (_reader.SinkIdentifierPart())
{
}
// If this was an escaped identifier the we need to get the terminating ']'.
if (escapedIdentifier)
{
if (!_reader.Sink("]"))
{
current = new ExpectedIdentifierToken();
return true;
}
}
else
{
// Escaped identifiers are not allowed to have trailing type character.
_reader.SinkTypeCharacter(); // Type character is optional.
}
// An identifier that is only a '_' is illegal because it is
// ambiguous with line continuation
string identifierOrKeyword = _reader.GetCurrentMatchedString(startPosition);
if (identifierOrKeyword == "_" || identifierOrKeyword == "[_]" || identifierOrKeyword == "[]")
{
current = new ExpectedIdentifierToken();
return true;
}
// Make an upper-case version in order to check whether this may be a keyword.
string upper = identifierOrKeyword.ToUpper(CultureInfo.InvariantCulture);
switch (upper)
{
default:
if (Array.IndexOf(s_keywordList, upper) >= 0)
{
current = new KeywordToken();
return true;
}
// Create the token.
current = new IdentifierToken();
// Trim off the [] if this is an escaped identifier.
if (escapedIdentifier)
{
current.InnerText = identifierOrKeyword.Substring(1, identifierOrKeyword.Length - 2);
}
return true;
case "FALSE":
case "TRUE":
current = new BooleanLiteralToken();
return true;
}
}
// Is it a hex integer?
else if (_reader.SinkHexIntegerPrefix())
{
if (!_reader.SinkMultipleHexDigits())
{
current = new ExpectedValidHexDigitToken();
return true;
}
// Sink a suffix if there is one.
_reader.SinkIntegerSuffix();
current = new HexIntegerLiteralToken();
return true;
}
// Is it an octal integer?
else if (_reader.SinkOctalIntegerPrefix())
{
if (!_reader.SinkMultipleOctalDigits())
{
current = new VisualBasicTokenizer.ExpectedValidOctalDigitToken();
return true;
}
// Sink a suffix if there is one.
_reader.SinkIntegerSuffix();
current = new VisualBasicTokenizer.OctalIntegerLiteralToken();
return true;
}
// Is it a decimal integer?
else if (_reader.SinkMultipleDecimalDigits())
{
// Sink a suffix if there is one.
_reader.SinkDecimalIntegerSuffix();
current = new DecimalIntegerLiteralToken();
return true;
}
// Preprocessor line
else if (_reader.CurrentCharacter == '#')
{
if (_reader.SinkIgnoreCase("#if"))
{
current = new OpenConditionalDirectiveToken();
}
else if (_reader.SinkIgnoreCase("#end if"))
{
current = new CloseConditionalDirectiveToken();
}
else
{
current = new PreprocessorToken();
}
_reader.SinkToEndOfLine();
return true;
}
// Is it a separator?
else if (_reader.SinkSeparatorCharacter())
{
current = new VisualBasicTokenizer.SeparatorToken();
return true;
}
// Is it an operator?
else if (_reader.SinkOperator())
{
current = new OperatorToken();
return true;
}
// A string?
else if (_reader.Sink("\""))
{
do
{
// Inside a verbatim string "" is treated as a special character
while (_reader.Sink("\"\""))
{
}
}
while (!_reader.EndOfLines && _reader.SinkCharacter() != '\"');
// Can't end a file inside a string
if (_reader.EndOfLines)
{
current = new EndOfFileInsideStringToken();
return true;
}
current = new StringLiteralToken();
return true;
}
// We didn't recognize the token, so this is a syntax error.
_reader.SinkCharacter();
current = new UnrecognizedToken();
return true;
}
/*
* Method: FindNextToken
*
* Find the next token. Return 'true' if one was found. False, otherwise.
*/
override internal bool FindNextToken()
{
int startPosition = _reader.Position;
// VB docs claim whitespace is Unicode category Zs. However,
// this category does not contain tabs. Assuming a less restrictive
// definition for whitespace...
if (_reader.SinkWhiteSpace())
{
while (_reader.SinkWhiteSpace())
{
}
// Now, we need to check for the line continuation character.
if (_reader.SinkLineContinuationCharacter()) // Line continuation is '_'
{
// Save the current position because we may need to come back here.
int savePosition = _reader.Position - 1;
// Skip all whitespace after the '_'
while (_reader.SinkWhiteSpace())
{
}
// Now, skip all the newlines.
// Need at least one newline for this to count as line continuation.
int count = 0;
while (_reader.SinkNewLine())
{
++count;
}
if (count > 0)
{
current = new VisualBasicTokenizer.LineContinuationToken();
return(true);
}
// Otherwise, fall back to plain old whitespace.
_reader.Position = savePosition;
}
current = new WhitespaceToken();
return(true);
}
// Line terminators are separate from whitespace and are significant.
else if (_reader.SinkNewLine())
{
// We want one token per line terminator.
current = new VisualBasicTokenizer.LineTerminatorToken();
return(true);
}
// Check for a comment--either those that start with ' or rem.
else if (_reader.SinkLineCommentStart())
{
// Skip to the first EOL.
_reader.SinkToEndOfLine();
current = new CommentToken();
return(true);
}
// Identifier or keyword?
else if
(
// VB allows escaping of identifiers by surrounding them with []
// In other words,
// Date is a keyword but,
// [Date] is an identifier.
_reader.CurrentCharacter == '[' ||
_reader.MatchNextIdentifierStart()
)
{
bool escapedIdentifier = false;
if (_reader.CurrentCharacter == '[')
{
escapedIdentifier = true;
_reader.SinkCharacter();
// Now, the next character must be an identifier start.
if (!_reader.SinkIdentifierStart())
{
current = new ExpectedIdentifierToken();
return(true);
}
}
// Sink the rest of the identifier.
while (_reader.SinkIdentifierPart())
{
}
// If this was an escaped identifier the we need to get the terminating ']'.
if (escapedIdentifier)
{
if (!_reader.Sink("]"))
{
current = new ExpectedIdentifierToken();
return(true);
}
}
else
{
// Escaped identifiers are not allowed to have trailing type character.
_reader.SinkTypeCharacter(); // Type character is optional.
}
// An identifier that is only a '_' is illegal because it is
// ambiguous with line continuation
string identifierOrKeyword = _reader.GetCurrentMatchedString(startPosition);
if (identifierOrKeyword == "_" || identifierOrKeyword == "[_]" || identifierOrKeyword == "[]")
{
current = new ExpectedIdentifierToken();
return(true);
}
// Make an upper-case version in order to check whether this may be a keyword.
string upper = identifierOrKeyword.ToUpperInvariant();
switch (upper)
{
default:
if (Array.IndexOf(s_keywordList, upper) >= 0)
{
current = new KeywordToken();
return(true);
}
// Create the token.
current = new IdentifierToken();
// Trim off the [] if this is an escaped identifier.
if (escapedIdentifier)
{
current.InnerText = identifierOrKeyword.Substring(1, identifierOrKeyword.Length - 2);
}
return(true);
case "FALSE":
case "TRUE":
current = new BooleanLiteralToken();
return(true);
}
}
// Is it a hex integer?
else if (_reader.SinkHexIntegerPrefix())
{
if (!_reader.SinkMultipleHexDigits())
{
current = new ExpectedValidHexDigitToken();
return(true);
}
// Sink a suffix if there is one.
_reader.SinkIntegerSuffix();
current = new HexIntegerLiteralToken();
return(true);
}
// Is it an octal integer?
else if (_reader.SinkOctalIntegerPrefix())
{
if (!_reader.SinkMultipleOctalDigits())
{
current = new VisualBasicTokenizer.ExpectedValidOctalDigitToken();
return(true);
}
// Sink a suffix if there is one.
_reader.SinkIntegerSuffix();
current = new VisualBasicTokenizer.OctalIntegerLiteralToken();
return(true);
}
// Is it a decimal integer?
else if (_reader.SinkMultipleDecimalDigits())
{
// Sink a suffix if there is one.
_reader.SinkDecimalIntegerSuffix();
current = new DecimalIntegerLiteralToken();
return(true);
}
// Preprocessor line
else if (_reader.CurrentCharacter == '#')
{
if (_reader.SinkIgnoreCase("#if"))
{
current = new OpenConditionalDirectiveToken();
}
else if (_reader.SinkIgnoreCase("#end if"))
{
current = new CloseConditionalDirectiveToken();
}
else
{
current = new PreprocessorToken();
}
_reader.SinkToEndOfLine();
return(true);
}
// Is it a separator?
else if (_reader.SinkSeparatorCharacter())
{
current = new VisualBasicTokenizer.SeparatorToken();
return(true);
}
// Is it an operator?
else if (_reader.SinkOperator())
{
current = new OperatorToken();
return(true);
}
// A string?
else if (_reader.Sink("\""))
{
do
{
// Inside a verbatim string "" is treated as a special character
while (_reader.Sink("\"\""))
{
}
}while (!_reader.EndOfLines && _reader.SinkCharacter() != '\"');
// Can't end a file inside a string
if (_reader.EndOfLines)
{
current = new EndOfFileInsideStringToken();
return(true);
}
current = new StringLiteralToken();
return(true);
}
// We didn't recognize the token, so this is a syntax error.
_reader.SinkCharacter();
current = new UnrecognizedToken();
return(true);
}
