arces.unibo.SEPA.commons.SPARQL.BindingsResults.java Source code

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Here is the source code for arces.unibo.SEPA.commons.SPARQL.BindingsResults.java

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/* This class represents the results of a SPARQL 1.1 Query
 * 
 * Author: Luca Roffia (luca.roffia@unibo.it)
    
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
    
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
    
You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/
package arces.unibo.SEPA.commons.SPARQL;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;

/**
 * This class represents the results of a SPARQL 1.1 Query
 * 
 * This conforms with the following:
 * - SPARQL 1.1 Query Results JSON Format https://www.w3.org/TR/2013/REC-sparql11-results-json-20130321/
 * 
 * It uses https://github.com/google/gso as internal representation of the results in JSON format
 * 
 * @author Luca Roffia (luca.roffia@unibo.it)
 * @version 0.1
 */

public class BindingsResults {

    private JsonObject results;

    public BindingsResults(JsonObject results) {
        this.results = results;
    }

    public BindingsResults(Set<String> varSet, List<Bindings> solutions) {
        results = new JsonObject();

        JsonObject vars = new JsonObject();
        JsonArray varArray = new JsonArray();
        if (varSet != null)
            for (String var : varSet) {
                varArray.add(var);
            }
        vars.add("vars", varArray);
        results.add("head", vars);

        JsonArray bindingsArray = new JsonArray();
        if (solutions != null)
            for (Bindings solution : solutions)
                bindingsArray.add(solution.toJson());
        JsonObject bindings = new JsonObject();
        bindings.add("bindings", bindingsArray);
        results.add("results", bindings);
    }

    public BindingsResults(BindingsResults newBindings) {
        results = new JsonObject();

        JsonObject vars = new JsonObject();
        JsonArray varArray = new JsonArray();
        if (newBindings != null)
            for (String var : newBindings.getVariables()) {
                varArray.add(var);
            }
        vars.add("vars", varArray);
        results.add("head", vars);

        JsonArray bindingsArray = new JsonArray();
        if (newBindings != null)
            for (Bindings solution : newBindings.getBindings())
                bindingsArray.add(solution.toJson());
        JsonObject bindings = new JsonObject();
        bindings.add("bindings", bindingsArray);
        results.add("results", bindings);
    }

    public Set<String> getVariables() {
        Set<String> vars = new HashSet<String>();
        JsonArray variables = getVariablesArray();
        if (variables == null)
            return vars;

        for (JsonElement var : variables)
            vars.add(var.getAsString());
        return vars;
    }

    public List<Bindings> getBindings() {
        List<Bindings> list = new ArrayList<Bindings>();
        JsonArray bindings = getBindingsArray();
        if (bindings == null)
            return list;

        for (JsonElement solution : bindings) {
            list.add(new Bindings(solution.getAsJsonObject()));
        }
        return list;
    }

    public JsonObject toJson() {
        return results;
    }

    public String toString() {
        return results.toString();
    }

    public boolean isEmpty() {
        JsonArray bindings = getBindingsArray();
        if (bindings == null)
            return true;

        return (bindings.size() == 0);
    }

    public void add(Bindings binding) {
        if (binding == null)
            return;
        JsonArray bindings = getBindingsArray();
        if (bindings == null)
            return;

        bindings.add(binding.toJson());
    }

    public boolean contains(Bindings solution) {
        if (solution == null)
            return false;
        JsonArray bindings = getBindingsArray();
        if (bindings == null)
            return false;

        return bindings.contains(solution.toJson());
    }

    public void remove(Bindings solution) {
        if (solution == null)
            return;
        JsonArray bindings = getBindingsArray();
        if (bindings == null)
            return;

        bindings.remove(solution.toJson());
    }

    public int size() {
        JsonArray bindings = getBindingsArray();
        if (bindings == null)
            return 0;
        return bindings.size();
    }

    private JsonArray getBindingsArray() {
        JsonElement varArray;
        if (results == null)
            return null;
        if ((varArray = results.get("results")) == null)
            return null;
        if ((varArray = varArray.getAsJsonObject().get("bindings")) == null)
            return null;

        return varArray.getAsJsonArray();
    }

    private JsonArray getVariablesArray() {
        JsonElement varArray;
        if (results == null)
            return null;
        if ((varArray = results.get("head")) == null)
            return null;
        if ((varArray = varArray.getAsJsonObject().get("vars")) == null)
            return null;

        return varArray.getAsJsonArray();
    }
}