CODEWITHSUNDEEP
sqlmavenantlrtranslate
user2144555
user2144555

Reputation: 1313

Generate SQL statements using ANTLR

I'm starting to study ANTLR. The aim is to 'translate' Strings into SQL statements.

One simple example of what I want to do:

If I receive the String "name = A and age = B" --- ANTLR ---> "select * from USERS where name = 'A' and age = 'B'"

I've been reading some information about ANTLR, and following some examples, but those just convert the input stream of characters (source file) into a AST. But how can I use ANTLR to translate the input message, and use the translated output?

Can you give me some highlights or tell me where can I found some information about that?

I'm using the Eclipse IDE and Maven ANTLR Plugin.

Upvotes: 0

Views: 1348

Answers (1)

Terence Parr
Terence Parr

Reputation: 5962

ANTLR is just a parser generator. You can insert actions into the grammar that collect information or directly print output. The most common mechanism is to allow ANTLR to create an intermediate presentation in the form of an AST or, with ANTLR 4, a parse tree. From there, you build a tree walker to either build an internal model or directly generate output. From the internal model, which represent constructs in your output language, you can then generate the output. I typically use StringTemplate for generating structured text.

When the input and output are very similar and, more importantly, the order of output is very similar, you can get away with syntax directed translation: i.e. actions directly in the grammar or actions applied directly to a parse tree.

When the order of output is very different, you have to build some form of intermediate representation. Imagine simply reading in a bunch of integers and printing them back out in reverse order. You can do that by simply printing out the numbers as you see them. This is all explained in my [shameless plug] book, Language Implementation Patterns: Create Your Own Domain-Specific and General Programming Languages http://amzn.com/B00A376HGG

Upvotes: 1

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