compiler.n3

	
@prefix math: <http://www.w3.org/2000/10/swap/math#>.
@prefix string: <http://www.w3.org/2000/10/swap/string#>.
@prefix graph: <http://www.w3.org/2000/10/swap/graph#>.
@prefix log: <http://www.w3.org/2000/10/swap/log#>.
@prefix : <http://example.org/ns#>.

## Compiler

# Search for forward rules
# ... For each triple check if the predicate is available as a backward rule
# ... If this is the case, then create a getter triple for the subject/object
{
    ?F => ?G .
    ?F log:includes { ?S ?P ?O } .
    # Do we have a backward rule for this ?P 
    { ?X ?P ?Y } :backward ?H .

    # Create a data name
    ?P log:uri ?Puri .
    ( ?Puri "_data" ) string:concatenation ?Py .
    ?Pdata log:uri ?Py .
} 
=>
{
    # Create a triple .. using a { false log:equalTo true . ?S ?P ?O } => true trick to
    # keep possible variables in ?S ?P ?O available as variables.
    # The (false log:equalTo true) trick is used to stop this rule from firing
    { false log:equalTo true . (?S ?O) ?Pdata true } => true .
} .

# Transform the backward rule into a getter
{
    { ?S ?P ?O } :backward ?G .

    ?P log:uri ?Puri .

    # Create a getter name
    ( ?Puri "_get" ) string:concatenation ?Px .
    ?Pgetter log:uri ?Px .

    # Create a data name
    ( ?Puri "_data" ) string:concatenation ?Py .
    ?Pdata log:uri ?Py .

    # Create a functor name
    ( ?Puri "_funktor" ) string:concatenation ?Pz .
    ?Pfunc log:uri ?Pz .

    # Package the old body into the new head
    (
      { { false log:equalTo true . (?S ?O) ?Pgetter true } => true } 
      ?G
    ) graph:union ?Magic .
}
=>
{
    { ?X ?Pfunc ?Y } => { ?X ?P ?Y }.

    ?Magic => { ?S ?Pfunc ?O  } .

    { 
        { false log:equalTo true . (?X ?Y) ?Pdata true . } => true .
    } 
    => 
    { 
        { false log:equalTo true . (?X ?Y) ?Pgetter true . } => true .
    } .
}.