ANTLR - Embedding Java code, evaluate before or after?

I开发者_StackOverflow社区'm writing a simple scripting language on top of Java/JVM, where you can also embed Java code using the {} brackets. The problem is, how do I parse this in the grammar? I have two options:

1. Allow everything to be in it, such as: [a-z|a-Z|0-9|_|$], and go on
2. Get an extra java grammar and use that grammar to parse that small code (is it actually possible and efficient?)

Since option 2] is basically a double-check since when evaluating java code it's also being checked. Now my last question is -- is way that can dynamically execute java code also with objects which have been created at runtime?

Thanks,

William van Doorn

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1] Allow everything to be in it, such as: [a-z|a-Z|0-9|_|$], and go on

You can't just do that: you'll have to account for opening and closing brackets.

2] Get an extra java grammar and use that grammar to parse that small code (is it actually possible and efficient?)

Yes that's possible. But I suggest you first get something working, and then worry about efficiency (is that really an issue here?).

... is way that can dynamically execute java code also with objects which have been created at runtime?

Yes, since Java 6, there's a way to compile source files dynamically. See the JavaCompiler API.

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I propose enclose your Java code inside characters like '`' which are not used in Java code and barely present in literals.

JavaCode: '' ( EscapeSequence | ~('\\'|'') )* '`' ;

Use java.g provided by antlr examples to get definition of EscapeSequence ,...

The only catch is that you need to ask programmers to use code of this character ('`') if it is required to be as an literal.