ANTLR FAQ

Does ANTLR knows about a specific language?
No. It recognizes the language using the provided grammar*.
ANTLR can generate a recognizer which will get a particular sentence or phrase as an input and apply the grammatical structure defined in grammar files for those input symbols.

These recognizers can be implemented using different language targets such as C# or Java.

What do you mean by grammar?
Using the grammar, we can tell ANTR how a particular language looks like, so that ANTLR can identify that. Grammar describes a syntax of a language.
Grammar will consist of set of language rules*. Grammar notation used is BNF*.

What is a rule?
A rule represents a phrase or sentence of the language.
Each rule may consist of one of more alternatives sub rules. Rules are invoked in a recursive manner.

Example for BNF notation?
Postal address ::= Name Route City Country
Name ::= First name Middle name? Last name
Route ::= Route name part*

What is a token file?
Token file can be considered as vocabulary for the grammar of specific language.

What is a target language?
Target language is a computer language which ANTLR can generate the recognizer from.

What are actions?
Actions are code blocks written in target language. Actions can refer tokens, rules or character reference using element labels. (x = T where x - label name, T - token)