Simple ChemicalTerms evaluator

/*
* Evaluate Chemical Terms expression
* 
* For API example see  
* https://www.chemaxon.com/jchem/doc/dev/java/api/chemaxon/jep/Evaluator.html
*
* Usage:
* 1. Edit the name of the Structure field
* 2. Set your ChemTerms expression
* 3. Run button script
*
* @author David Pech <dpech@chemaxon.com>
*/
import com.im.df.api.*
import chemaxon.struc.Molecule
import chemaxon.jep.*
import chemaxon.jep.context.MolContext
init = { widget ->
}
destroy = { widget ->
}
evaluate = { widget ->
    def ety = dataTree.rootVertex.entity // assumes you have reference to the data tree
    def edp = ety.schema.dataProvider.getEntityDataProvider(ety)
    def molFld = ety.fields.items.find { it.name == 'Structure' } // find the structure field
    def rs = ety.schema.dataProvider.getDefaultResultSet(dataTree, false, DFEnvironmentRO.DEV_NULL) // find the ResultSet
    def rootVS = rs.getVertexState(dataTree.rootVertex) // obtain the VertexState

    List ids = rootVS.getSelectedRowsIds() // get the selected IDs
    if (ids.size == 1) {
        Map rows = rootVS.getData(ids, DFEnvironmentRO.DEV_NULL) // get the data
        Map row = rows[ids[0]] // get the first and only row
        MarvinStructure mol = row[molFld.id] // Get the Structure. Its a com.im.df.api.chem.MarvinStructure instance
        Molecule cxnMol = mol.getNative() // obtain the chemaxon.struc.Molecule instance

        // create Evaluator and create
        // ChemJEP and compile ChemTerms expression
        Evaluator evaluator = new Evaluator()
        ChemJEP chemJEP = evaluator.compile("logP()")

        // create context and parse current molecule
        MolContext context = new MolContext()
        context.setMolecule(cxnMol)
        // evaluate and print out the result from context
        result = chemJEP.evaluate(context)
        println result

    } else {
        println "bad selection"
    }
}
on_change = { widget, button ->

}