# IMP-Logics

IMP-logics is the implementation of:

- the metamodel of a **Datalog schema** extended with negation and built-in literals.
  That is, it implements the Datalog concepts of term, atom, literal, derivation rule, etc.
In addition, the schema also includes logic constraints written in the form of logic denials.
- the metamodel of **dependencies** (e.g. tuple-generating dependencies), which is useful for implementing a *
  *Datalog+/- schema**.
  That is, it implements the concepts of TGDs and EGDs.

E.g., with this library you can parse the following (datalog) logic schema:

```
% This rule says that d is a DeptWithEmploye if there is one employee e, working in d with a salary greather than 1000
DeptWithEmploye(d) :- Emp(e, d, s), s > 1000

% This other rule is a logic denial stating that there cannot be Dept d that is not a DeptWithEmploye
:- Dept(d), not(DeptWithEmploye(d))
```

This library is not a datalog interpreter. Hence, it does not implement the notion of fact, or the process to run a
query.

## What is this library good for?

IMP-logics can be used to parse, transform, or analyze a datalog (dependency) schema, that is, the normal clauses (
dependencies) that conforms a
datalog (datalog+/-) program.

For instance, you can parse a datalog schema, and check whether it is safe.

```
LogicSchema logicSchema = new LogicSchemaWithoutIDsParser().parse(schemaString);
logicSchema.isSafe();
```

Or you can traverse their derivation rules, logc constraints, or predicates:

```
LogicSchema logicSchema = new LogicSchemaWithoutIDsParser().parse(schemaString);

for(DerivationRule rule: logicSchema.getAllDerivationRules){
   ...
}

for(LogicConstraint constraint: logicSchema.getAllLogicConstraints){
   ...
}

for(Predicate predicate: logicSchema.getAllPredicates){
   ...
}
```

You can see more examples in docs\USERS_GUIDE.md file.

## Build

### Building with ANTLR4

To compile the project for the first time, or whenever we change the grammar files, we need to execute
the `mvn generate-sources` phase.
Indeed, this phase creates the ANTLR4 autogenerated classes to visit the grammar. Hence, we recommend compiling the
project with maven.

## Authorship

This library is implemented by the IMP research group (https://imp.upc.edu/en), and the innovation
lab group inLab-FIB (https://inlab.fib.upc.edu/en/), both from Universitat Politècnica de Catalunya - BarcelonaTech
(https://www.upc.edu/en)