CODEWITHSUNDEEP
antlr4
jineff
jineff

Reputation: 482

Simplest way to deal with "import" statement in ANTLR4

I’m using ANTLR4 and I have an "import" statement inside my grammar.

Does ANTLR4 have an option to automatically open and parse input file instead of doing it inside my visitor (creating another parser/lexer and visitor for each "import" declaration) ?

"Pretty" sure that I've already seen it but I can't find it anymore.

Inside my grammar :

importStatement : 'import' ID ';' // Here ? an action (Java code)
                                  // to prepend an AST to my current AST ?

Inside an input files :

Import test;

Upvotes: 0

Views: 1016

Answers (1)

Sam Harwell
Sam Harwell

Reputation: 99939

There is no built-in functionality for this, primarily because every language requiring it has its own set of rules for how it needs to be done. In addition, this can quickly make the parse operation for your whole project go from O(n) to O(n²) (i.e. parsing each file once, to parsing up to the whole project for each file).

If your language allows you to build a correct parse tree prior to resolving the imports (e.g. it doesn't have arbitrary #define statements that can appear in imports), then you should be glad you aren't C/C++ and parse each file independently before resolving the import statements.

Upvotes: 1

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