Package org.antlr.v4.runtime
Interface TokenSource
- All Known Implementing Classes:
Lexer
,LexerInterpreter
,ListTokenSource
,XPathLexer
public interface TokenSource
A source of tokens must provide a sequence of tokens via
nextToken()
and also must reveal it's source of characters; CommonToken
's text is
computed from a CharStream
; it only store indices into the char
stream.
Errors from the lexer are never passed to the parser. Either you want to keep
going or you do not upon token recognition error. If you do not want to
continue lexing then you do not want to continue parsing. Just throw an
exception not under RecognitionException
and Java will naturally toss
you all the way out of the recognizers. If you want to continue lexing then
you should not throw an exception to the parser--it has already requested a
token. Keep lexing until you get a valid one. Just report errors and keep
going, looking for a valid token.
-
Method Summary
Modifier and TypeMethodDescriptionint
Get the index into the current line for the current position in the input stream.Get theCharStream
from which this token source is currently providing tokens.int
getLine()
Get the line number for the current position in the input stream.Gets the name of the underlying input source.TokenFactory
<?> Gets theTokenFactory
this token source is currently using for creatingToken
objects from the input.Return aToken
object from your input stream (usually aCharStream
).void
setTokenFactory
(TokenFactory<?> factory) Set theTokenFactory
this token source should use for creatingToken
objects from the input.
-
Method Details
-
nextToken
Token nextToken()Return aToken
object from your input stream (usually aCharStream
). Do not fail/return upon lexing error; keep chewing on the characters until you get a good one; errors are not passed through to the parser. -
getLine
int getLine()Get the line number for the current position in the input stream. The first line in the input is line 1.- Returns:
- The line number for the current position in the input stream, or 0 if the current token source does not track line numbers.
-
getCharPositionInLine
int getCharPositionInLine()Get the index into the current line for the current position in the input stream. The first character on a line has position 0.- Returns:
- The line number for the current position in the input stream, or -1 if the current token source does not track character positions.
-
getInputStream
CharStream getInputStream()Get theCharStream
from which this token source is currently providing tokens.- Returns:
- The
CharStream
associated with the current position in the input, ornull
if no input stream is available for the token source.
-
getSourceName
String getSourceName()Gets the name of the underlying input source. This method returns a non-null, non-empty string. If such a name is not known, this method returnsIntStream.UNKNOWN_SOURCE_NAME
. -
setTokenFactory
Set theTokenFactory
this token source should use for creatingToken
objects from the input.- Parameters:
factory
- TheTokenFactory
to use for creating tokens.
-
getTokenFactory
TokenFactory<?> getTokenFactory()Gets theTokenFactory
this token source is currently using for creatingToken
objects from the input.- Returns:
- The
TokenFactory
currently used by this token source.
-