changed query processing to only translate global predicates

pom.xml

@@ -7,6 +7,7 @@
     <version>0.3.5-SNAPSHOT</version>
 
 
+
     <name>GDL - Graph Definition Language</name>
     <description>ANTLR Grammar for the definition of extended property graphs.</description>
     <url>http://github.com/s1ck/gdl.git</url>

src/main/java/org/s1ck/gdl/GDLHandler.java

@@ -199,6 +199,11 @@ public static class Builder {
      */
     private boolean useDefaultEdgeLabel = true;
 
+    /**
+     * Flag to indicate if the query should be postprocessed, i.e. reduced to simple comparisons.
+     */
+    private boolean processQuery = true;
+
     /**
      * Strategy for handling parser errors.
      */
@@ -308,6 +313,17 @@ public Builder setErrorStrategy(ANTLRErrorStrategy errorStrategy) {
       return this;
     }
 
+    /**
+     * Sets the processQuery parameter for the {@link GDLLoader}.
+     *
+     * @param processQuery processQuery flag (true iff query should be postprocessed)
+     * @return builder
+     */
+    public Builder setProcessQuery(boolean processQuery){
+      this.processQuery = processQuery;
+      return this;
+    }
+
     /**
      * Initialize GDL Handler from given ASCII String.
      *
@@ -367,7 +383,7 @@ private GDLHandler build(ANTLRInputStream antlrInputStream) {
       parser.setErrorHandler(errorStrategy);
 
       GDLLoader loader = new GDLLoader(graphLabel, vertexLabel, edgeLabel,
-        useDefaultGraphLabel, useDefaultVertexLabel, useDefaultEdgeLabel);
+        useDefaultGraphLabel, useDefaultVertexLabel, useDefaultEdgeLabel, processQuery);
       new ParseTreeWalker().walk(loader, parser.database());
       return new GDLHandler(loader);
     }

src/main/java/org/s1ck/gdl/GDLLoader.java

@@ -352,6 +352,15 @@ public void exitQuery(GDLParser.QueryContext ctx) {
     if(processPredicates) {
       postprocessPredicates();
     }
+    ArrayList<String> vars = new ArrayList<>();
+    vars.addAll(userEdgeCache.keySet());
+    vars.addAll(userVertexCache.keySet());
+    vars.addAll(autoEdgeCache.keySet());
+    vars.addAll(autoVertexCache.keySet());
+    vars.remove(TimeSelector.GLOBAL_SELECTOR);
+    if(predicates!=null) {
+      predicates = predicates.replaceGlobalByLocal(vars);
+    }
     for(Vertex v : vertices) {
       addPredicates(Predicate.fromGraphElement(v, getDefaultVertexLabel()));
     }

src/main/java/org/s1ck/gdl/model/comparables/ComparableExpression.java

@@ -17,12 +17,22 @@
 package org.s1ck.gdl.model.comparables;
 
 import org.s1ck.gdl.model.comparables.time.TimeSelector;
+import org.s1ck.gdl.model.predicates.Predicate;
 
 import java.io.Serializable;
+import java.util.List;
+import java.util.Set;
 
 public interface ComparableExpression extends Serializable{
+  /**
+   * Returns the variables of the expression
+   * @return variable
+   */
+  public Set<String> getVariables();
+
   /**
    * Returns the variable of the expression
+   * Same functionality is given by {@code getVariables}, kept for downward compatibility
    * @return variable
    */
   public String getVariable();
@@ -40,4 +50,15 @@ public interface ComparableExpression extends Serializable{
    */
   boolean isGlobal();
 
+  /**
+   * Replaces global time selectors like __global.val_from by their equivalent expressions
+   * over all local variables.
+   * E.g., {@code __global.val_from} would be replaced by {@code MAX(v1.val_from,...,
+   * vn.val_from)} for variables {@code v1,...,vn}.
+   * @param variables all query variables
+   * @return comparable with global selector replaced by their local variable equivalent
+   * expressions. If comparable is not a global time selector, identity function.
+   */
+  ComparableExpression replaceGlobalByLocal(List<String> variables);
+
 }

src/main/java/org/s1ck/gdl/model/comparables/ElementSelector.java

@@ -18,6 +18,11 @@
 
 import org.s1ck.gdl.model.comparables.time.TimeSelector;
 
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
 /**
  * Used to compare elements (by id)
  */
@@ -37,15 +42,23 @@ public ElementSelector(String variable) {
     this.variable = variable;
   }
 
-  /**
-   * Returns the variable which references the element
-   * @return variable name
-   */
+  @Override
+  public Set<String> getVariables() {
+    HashSet<String> var = new HashSet<>();
+    var.add(variable);
+    return var;
+  }
+
   @Override
   public String getVariable() {
     return this.variable;
   }
 
+  @Override
+  public ComparableExpression replaceGlobalByLocal(List<String> variables) {
+    return this;
+  }
+
   @Override
   public boolean containsSelectorType(TimeSelector.TimeField type){
     return false;

src/main/java/org/s1ck/gdl/model/comparables/Literal.java

@@ -18,6 +18,11 @@
 
 import org.s1ck.gdl.model.comparables.time.TimeSelector;
 
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
 /**
  * Represents a literal like String, Integer, ...
  */
@@ -41,10 +46,17 @@ public Object getValue() {
     return value;
   }
 
-  /**
-   * Returns null since this does not reference a variable
-   * @return null
-   */
+
+  @Override
+  public Set<String> getVariables() {
+    return new HashSet<String>();
+  }
+
+  @Override
+  public ComparableExpression replaceGlobalByLocal(List<String> variables) {
+    return this;
+  }
+
   @Override
   public String getVariable() {
     return null;

src/main/java/org/s1ck/gdl/model/comparables/PropertySelector.java

@@ -18,6 +18,11 @@
 
 import org.s1ck.gdl.model.comparables.time.TimeSelector;
 
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
 /**
  * Selects a property of a variable
  */
@@ -47,10 +52,13 @@ public String getPropertyName() {
     return propertyName;
   }
 
-  /**
-   * Returns the variable which references the element
-   * @return variable name
-   */
+  @Override
+  public Set<String> getVariables() {
+    HashSet<String> var = new HashSet<>();
+    var.add(variable);
+    return var;
+  }
+
   @Override
   public String getVariable() {
     return this.variable;
@@ -66,6 +74,11 @@ public boolean isGlobal(){
     return false;
   }
 
+  @Override
+  public ComparableExpression replaceGlobalByLocal(List<String> variables) {
+    return this;
+  }
+
   @Override
   public String toString() {
     return variable + "." + propertyName;

src/main/java/org/s1ck/gdl/model/comparables/time/MaxTimePoint.java

@@ -1,5 +1,6 @@
 package org.s1ck.gdl.model.comparables.time;
 
+import org.s1ck.gdl.model.comparables.ComparableExpression;
 import org.s1ck.gdl.model.predicates.Predicate;
 import org.s1ck.gdl.model.predicates.booleans.And;
 import org.s1ck.gdl.model.predicates.booleans.Not;
@@ -8,6 +9,7 @@
 import org.s1ck.gdl.utils.Comparator;
 
 import java.util.ArrayList;
+import java.util.List;
 
 /**
  * Represents a MAX(p1,...,pn) term, where p1...pn are TimePoints
@@ -70,6 +72,11 @@ public long getUpperBound(){
         return res;
     }
 
+    @Override
+    public String getVariable() {
+        return null;
+    }
+
     @Override
     public boolean containsSelectorType(TimeSelector.TimeField type){
         for(TimePoint p: args){
@@ -186,6 +193,15 @@ protected Predicate unfoldLTE(TimePoint arg){
         return disjGt;
     }
 
+    @Override
+    public ComparableExpression replaceGlobalByLocal(List<String> variables) {
+        TimePoint[] newArgs = new TimePoint[args.size()];
+        for(int i=0; i<args.size(); i++){
+            newArgs[i] = (TimePoint) args.get(i).replaceGlobalByLocal(variables);
+        }
+        return new MaxTimePoint(newArgs);
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;

src/main/java/org/s1ck/gdl/model/comparables/time/MinTimePoint.java

@@ -1,5 +1,6 @@
 package org.s1ck.gdl.model.comparables.time;
 
+import org.s1ck.gdl.model.comparables.ComparableExpression;
 import org.s1ck.gdl.model.predicates.Predicate;
 import org.s1ck.gdl.model.predicates.booleans.And;
 import org.s1ck.gdl.model.predicates.booleans.Not;
@@ -8,6 +9,7 @@
 import org.s1ck.gdl.utils.Comparator;
 
 import java.util.ArrayList;
+import java.util.List;
 
 /**
  * Represents a MAX(p1,...,pn) term, where p1...pn are TimePoints
@@ -67,6 +69,11 @@ public long getUpperBound(){
         return res;
     }
 
+    @Override
+    public String getVariable() {
+        return null;
+    }
+
     @Override
     public boolean containsSelectorType(TimeSelector.TimeField type){
         for(TimePoint p: args){
@@ -223,5 +230,14 @@ public boolean isGlobal(){
         return false;
     }
 
+    @Override
+    public ComparableExpression replaceGlobalByLocal(List<String> variables) {
+        TimePoint[] newArgs = new TimePoint[args.size()];
+        for(int i=0; i<args.size(); i++){
+            newArgs[i] = (TimePoint) args.get(i).replaceGlobalByLocal(variables);
+        }
+        return new MinTimePoint(newArgs);
+    }
+
 
 }

src/main/java/org/s1ck/gdl/model/comparables/time/PlusTimePoint.java

@@ -10,6 +10,7 @@
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Set;
 
 import static org.s1ck.gdl.model.comparables.time.TimeSelector.GLOBAL_SELECTOR;
 import static org.s1ck.gdl.utils.Comparator.*;
@@ -41,10 +42,15 @@ public PlusTimePoint(TimePoint timePoint, TimeConstant constant){
     }
 
     @Override
-    public ArrayList<String> getVariables() {
+    public Set<String> getVariables() {
         return timePoint.getVariables();
     }
 
+    @Override
+    public String getVariable() {
+        return timePoint.getVariable();
+    }
+
     @Override
     public long evaluate(){
         long tp = timePoint.evaluate();
@@ -293,4 +299,9 @@ private Predicate forAllVariables(Comparator comp, ComparableExpression rhs, Lis
     public boolean isGlobal(){
         return timePoint.isGlobal();
     }
+
+    @Override
+    public ComparableExpression replaceGlobalByLocal(List<String> variables) {
+        return new PlusTimePoint((TimePoint)timePoint.replaceGlobalByLocal(variables), constant);
+    }
 }

src/main/java/org/s1ck/gdl/model/comparables/time/TimeLiteral.java

@@ -6,7 +6,9 @@
 
 import java.time.*;
 import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
 
 import org.s1ck.gdl.utils.Comparator;
 
@@ -124,8 +126,13 @@ public int getSecond(){
 
 
     @Override
-    public ArrayList<String> getVariables(){
-        return new ArrayList<>();
+    public Set<String> getVariables(){
+        return new HashSet<>();
+    }
+
+    @Override
+    public String getVariable() {
+        return null;
     }
 
     @Override
@@ -182,4 +189,9 @@ public Predicate unfoldGlobal(Comparator comp, ComparableExpression rhs, List<St
     public boolean isGlobal(){
         return false;
     }
+
+    @Override
+    public ComparableExpression replaceGlobalByLocal(List<String> variables) {
+        return this;
+    }
 }

src/main/java/org/s1ck/gdl/model/comparables/time/TimePoint.java

@@ -17,22 +17,6 @@ public abstract class TimePoint implements ComparableExpression {
      */
     public static final long UNDEFINED = -1L;
 
-    /**
-     * Returns null, no variable involved in a timestamp by default
-     * Not often used in implementations, as typically more than one variable can be involved
-     * @return null
-     */
-    @Override
-    public String getVariable() {
-        return null;
-    }
-
-    /**
-     * all variables involved in the expression
-     * @return ArrayList of variable names (potentially empty)
-     */
-    public abstract ArrayList<String> getVariables();
-
     /**
      * calculates the value of the timestamp (UNIX epoch long), if possible.
      * E.g., a timestamp like v.VAL_FROM can not be assigned a unique long value