Replace Constraint(s) with a more generic Expression API.

Expression API allows better evaluation of queries (eg. `field1 = field2`) previously impossible with Constraints. Also definition of new functions
doesn't require changing Visitor API.

This is work in progress.

criteria/README.md

@@ -1,4 +1,6 @@
-This module generates Criteria classes based on immutable model.
+This module generates Criteria classes based on immutable model. 
+
+The functionality is work in progress and API is not stable yet (use at your own risk).
 
 Generated classes allow type-safe query building which can be evaluated on destination data-source.
 

criteria/src/org/immutables/criteria/constraints/BooleanCriteria.java

@@ -23,16 +23,16 @@
  */
 public class BooleanCriteria<C extends DocumentCriteria<C, T>, T> extends ObjectCriteria<Boolean, C, T> {
 
-  public BooleanCriteria(String name, Constraints.Constraint constraint, CriteriaCreator<C, T> creator) {
-    super(name, constraint, creator);
+  public BooleanCriteria(Expression<T> expression, CriteriaCreator<C, T> creator) {
+    super(expression, creator);
   }
 
   public C isTrue() {
-    return creator.create(constraint.equal(name, false, Boolean.TRUE));
+    return creator.create(Expressions.<T>call(Operators.EQUAL, expression, Expressions.literal(Boolean.TRUE)));
   }
 
   public C isFalse() {
-    return creator.create(constraint.equal(name, false, Boolean.FALSE));
+    return creator.create(Expressions.<T>call(Operators.EQUAL, expression, Expressions.literal(Boolean.FALSE)));
   }
 
 }

criteria/src/org/immutables/criteria/constraints/Call.java

@@ -0,0 +1,24 @@
+package org.immutables.criteria.constraints;
+
+import java.util.List;
+
+/**
+ * An expression formed by a call to an operator (eg. {@link Operators#EQUAL}) with zero or more arguments.
+ */
+public interface Call<T> extends Expression<T> {
+
+
+  /**
+   * Get the arguments of this operation
+   *
+   * @return arguments
+   */
+  List<Expression<?>> getOperands();
+
+  /**
+   * Get the operator symbol for this operation
+   *
+   * @return operator
+   */
+  Operator getOperator();
+}

criteria/src/org/immutables/criteria/constraints/ComparableCriteria.java

@@ -16,7 +16,6 @@
 package org.immutables.criteria.constraints;
 
 
-import com.google.common.collect.Range;
 import org.immutables.criteria.DocumentCriteria;
 
 /**
@@ -25,52 +24,38 @@
 public class ComparableCriteria<V extends Comparable<V>, C extends DocumentCriteria<C, T>, T>
         extends ObjectCriteria<V, C, T> {
 
-  public ComparableCriteria(String name, Constraints.Constraint constraint, CriteriaCreator<C, T> creator) {
-    super(name, constraint, creator);
+  public ComparableCriteria(Expression<T> expression, CriteriaCreator<C, T> creator) {
+    super(expression, creator);
   }
 
-  /**
-   * Checks that attribute is in {@code range}.
-   */
-  public C isIn(Range<V> range) {
-    return creator.create(constraint.range(name, false, range));
-  }
-
-  /**
-   * Checks that attribute is <i>not</i> in {@code range}.
-   */
-  public C isNotIn(Range<V> range) {
-    return creator.create(constraint.range(name, true, range));
-  }
-
-  /**
+  /**]
    * Checks that attribute is less than (but not equal to) {@code upper}.
    * <p>Use {@link #isAtMost(Comparable)} for less <i>or equal</i> comparison</p>
    */
   public C isLessThan(V upper) {
-    return isIn(Range.lessThan(upper));
+    return creator.create(Expressions.<T>call(Operators.LESS_THAN, expression, Expressions.literal(upper)));
   }
 
   /**
    * Checks that attribute is greater than (but not equal to)  {@code lower}.
    * <p>Use {@link #isAtLeast(Comparable)} for greater <i>or equal</i> comparison</p>
    */
   public C isGreaterThan(V lower) {
-    return isIn(Range.greaterThan(lower));
+    return creator.create(Expressions.<T>call(Operators.GREATER_THAN, expression, Expressions.literal(lower)));
   }
 
   /**
    * Checks that attribute is less than or equal to {@code upperInclusive}.
    */
   public C isAtMost(V upperInclusive) {
-    return isIn(Range.atMost(upperInclusive));
+    return creator.create(Expressions.<T>call(Operators.LESS_THAN_OR_EQUAL, expression, Expressions.literal(upperInclusive)));
   }
 
   /**
    * Checks that attribute is greater or equal to {@code lowerInclusive}.
    */
   public C isAtLeast(V lowerInclusive) {
-    return isIn(Range.atLeast(lowerInclusive));
+    return creator.create(Expressions.<T>call(Operators.GREATER_THAN_OR_EQUAL, expression, Expressions.literal(lowerInclusive)));
   }
 
 }

criteria/src/org/immutables/criteria/constraints/CriteriaCreator.java

@@ -18,10 +18,10 @@
 import org.immutables.criteria.DocumentCriteria;
 
 /**
- * Creates document criteria from a constraint.
+ * Creates document criteria from existing expression.
  */
 public interface CriteriaCreator<C extends DocumentCriteria<C, T>, T> {
 
-  C create(Constraints.Constraint constraint);
+  C create(Expression<T> expression);
 
 }