Support importing multi-mode lexer grammars

[sharwell]

Note that specific semantics for this feature have not yet been established.

[itzg]

Is there a recommended workaround until this feature is implemented? Since hybrid parser/lexer grammars don't allow multiple modes, the only way I can see using a multi-mode lexer is via an import from a parser or hybrid grammar. With 4.3 it almost works -- the most apparent thing missing is the public static final int declaration of the mode(s) within the generated lexer class.

[parrt]

you could fake it by putting in a @lexer::members { ... } action maybe?

[mar9000]

Not, with this addition I get this exception (I'm extending ANTLRv4Lexer).

Exception in thread "main" java.util.EmptyStackException
at org.antlr.v4.runtime.Lexer.popMode(Lexer.java:216)
at org.antlr.v4.runtime.atn.LexerPopModeAction.execute(LexerPopModeAction.java:82)
at org.antlr.v4.runtime.atn.LexerActionExecutor.execute(LexerActionExecutor.java:193)
at org.antlr.v4.runtime.atn.LexerATNSimulator.accept(LexerATNSimulator.java:395)
at org.antlr.v4.runtime.atn.LexerATNSimulator.failOrAccept(LexerATNSimulator.java:328)
at org.antlr.v4.runtime.atn.LexerATNSimulator.execATN(LexerATNSimulator.java:259)
at org.antlr.v4.runtime.atn.LexerATNSimulator.match(LexerATNSimulator.java:143)
at org.antlr.v4.runtime.Lexer.nextToken(Lexer.java:165)

Another difference is that my lexer gets a method NESTED_ARG_ACTION_action() that ANTLR lexer does not have.

[zhaohuiyang]

Could anyone please share an update on this issue?

[parrt]

Hmm..Unfortunately I'm not going to be able to get to this for the next 4.5.1 release

[TheEricWilson]

If the modes are not in the thing being imported, but only in the part doing the import would that work?

[parrt]

Actually, you don't need to import a lexer. Just use it as a separate lexer g4 file, right?

[TheEricWilson]

Yes the wording of several things seems to imply to me that I can not do includes if I have modes in my lexer.

On Jul 21, 2015, at 2:08 PM, Terence Parr notifications@github.com wrote:

Actually, you don't need to import a lexer. Just use it as a separate lexer g4 file, right?

—
Reply to this email directly or view it on GitHub #160 (comment).

[parrt]

Well, it's true, no includes of modes but it's easier to not import the lexer into the parser. just use as separate file. I'll close for now.

[TheEricWilson]

I am trying to import modes into a lexer and not the parser

On Jul 21, 2015, at 2:21 PM, Terence Parr notifications@github.com wrote:

Well, it's true, no includes of modes but it's easier to not import the lexer into the parser. just use as separate file. I'll close for now.

—
Reply to this email directly or view it on GitHub.

[parrt]

ah. ok, reopening.