add predefined rules

[furesoft]

like add a statement to make predefined rules available. for example:

` use std;

struct = "struct", IDENTIFIER, "{", "}"; `

when IDENTIFIER it predefines.

examples:

Idenifier String Number

[ed-cooper]

Whilst I can see the potential utility of this feature, I have a few issues with this feature which leave me inclined to close the issue:

• Slight variations in keywords between different languages (e.g. different capitalisation standards) mean that this is likely impractical for most users.
• There is not a sufficient user base to either create rule sets or take advantage of them.
• The addition of this breaks all existing EBNF specifications.
• The purpose for a tool like this is to give someone complete flexibility over how a language is defined, rather than simply creating clones of existing languages, and features like this break that principal.