QueryExpression rewriter (#820)

* Added Equals/GetHashCode to QueryExpression concrete types
* Added expression rewriter

Author: Bart Koelman

src/JsonApiDotNetCore/Queries/Expressions/CollectionNotEmptyExpression.cs

@@ -24,5 +24,27 @@ public override string ToString()
         {
             return $"{Keywords.Has}({TargetCollection})";
         }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(this, obj))
+            {
+                return true;
+            }
+
+            if (obj is null || GetType() != obj.GetType())
+            {
+                return false;
+            }
+
+            var other = (CollectionNotEmptyExpression) obj;
+
+            return TargetCollection.Equals(other.TargetCollection);
+        }
+
+        public override int GetHashCode()
+        {
+            return TargetCollection.GetHashCode();
+        }
     }
 }

src/JsonApiDotNetCore/Queries/Expressions/ComparisonExpression.cs

@@ -28,5 +28,27 @@ public override string ToString()
         {
             return $"{Operator.ToString().Camelize()}({Left},{Right})";
         }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(this, obj))
+            {
+                return true;
+            }
+
+            if (obj is null || GetType() != obj.GetType())
+            {
+                return false;
+            }
+
+            var other = (ComparisonExpression) obj;
+
+            return Operator == other.Operator && Left.Equals(other.Left) && Right.Equals(other.Right);
+        }
+
+        public override int GetHashCode()
+        {
+            return HashCode.Combine(Operator, Left, Right);
+        }
     }
 }

src/JsonApiDotNetCore/Queries/Expressions/CountExpression.cs

@@ -24,5 +24,27 @@ public override string ToString()
         {
             return $"{Keywords.Count}({TargetCollection})";
         }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(this, obj))
+            {
+                return true;
+            }
+
+            if (obj is null || GetType() != obj.GetType())
+            {
+                return false;
+            }
+
+            var other = (CountExpression) obj;
+
+            return TargetCollection.Equals(other.TargetCollection);
+        }
+
+        public override int GetHashCode()
+        {
+            return TargetCollection.GetHashCode();
+        }
     }
 }

src/JsonApiDotNetCore/Queries/Expressions/EqualsAnyOfExpression.cs

@@ -39,5 +39,35 @@ public override string ToString()
 
             return builder.ToString();
         }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(this, obj))
+            {
+                return true;
+            }
+
+            if (obj is null || GetType() != obj.GetType())
+            {
+                return false;
+            }
+
+            var other = (EqualsAnyOfExpression) obj;
+
+            return TargetAttribute.Equals(other.TargetAttribute) && Constants.SequenceEqual(other.Constants);
+        }
+
+        public override int GetHashCode()
+        {
+            var hashCode = new HashCode();
+            hashCode.Add(TargetAttribute);
+
+            foreach (var constant in Constants)
+            {
+                hashCode.Add(constant);
+            }
+
+            return hashCode.ToHashCode();
+        }
     }
 }

src/JsonApiDotNetCore/Queries/Expressions/IncludeElementExpression.cs

@@ -44,5 +44,35 @@ public override string ToString()
 
             return builder.ToString();
         }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(this, obj))
+            {
+                return true;
+            }
+
+            if (obj is null || GetType() != obj.GetType())
+            {
+                return false;
+            }
+
+            var other = (IncludeElementExpression) obj;
+
+            return Relationship.Equals(other.Relationship) == Children.SequenceEqual(other.Children);
+        }
+
+        public override int GetHashCode()
+        {
+            var hashCode = new HashCode();
+            hashCode.Add(Relationship);
+
+            foreach (var child in Children)
+            {
+                hashCode.Add(child);
+            }
+
+            return hashCode.ToHashCode();
+        }
     }
 }

src/JsonApiDotNetCore/Queries/Expressions/IncludeExpression.cs

@@ -38,5 +38,34 @@ public override string ToString()
             var chains = IncludeChainConverter.GetRelationshipChains(this);
             return string.Join(",", chains.Select(child => child.ToString()));
         }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(this, obj))
+            {
+                return true;
+            }
+
+            if (obj is null || GetType() != obj.GetType())
+            {
+                return false;
+            }
+
+            var other = (IncludeExpression) obj;
+
+            return Elements.SequenceEqual(other.Elements);
+        }
+
+        public override int GetHashCode()
+        {
+            var hashCode = new HashCode();
+
+            foreach (var element in Elements)
+            {
+                hashCode.Add(element);
+            }
+
+            return hashCode.ToHashCode();
+        }
     }
 }

src/JsonApiDotNetCore/Queries/Expressions/LiteralConstantExpression.cs

@@ -24,5 +24,27 @@ public override string ToString()
             string value = Value.Replace("\'", "\'\'");
             return $"'{value}'";
         }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(this, obj))
+            {
+                return true;
+            }
+
+            if (obj is null || GetType() != obj.GetType())
+            {
+                return false;
+            }
+
+            var other = (LiteralConstantExpression) obj;
+
+            return Value == other.Value;
+        }
+
+        public override int GetHashCode()
+        {
+            return Value.GetHashCode();
+        }
     }
 }

src/JsonApiDotNetCore/Queries/Expressions/LogicalExpression.cs

@@ -46,5 +46,35 @@ public override string ToString()
 
             return builder.ToString();
         }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(this, obj))
+            {
+                return true;
+            }
+
+            if (obj is null || GetType() != obj.GetType())
+            {
+                return false;
+            }
+
+            var other = (LogicalExpression) obj;
+
+            return Operator == other.Operator && Terms.SequenceEqual(other.Terms);
+        }
+
+        public override int GetHashCode()
+        {
+            var hashCode = new HashCode();
+            hashCode.Add(Operator);
+
+            foreach (var term in Terms)
+            {
+                hashCode.Add(term);
+            }
+
+            return hashCode.ToHashCode();
+        }
     }
 }

src/JsonApiDotNetCore/Queries/Expressions/MatchTextExpression.cs

@@ -37,5 +37,27 @@ public override string ToString()
 
             return builder.ToString();
         }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(this, obj))
+            {
+                return true;
+            }
+
+            if (obj is null || GetType() != obj.GetType())
+            {
+                return false;
+            }
+
+            var other = (MatchTextExpression) obj;
+
+            return TargetAttribute.Equals(other.TargetAttribute) && TextValue.Equals(other.TextValue) && MatchKind == other.MatchKind;
+        }
+
+        public override int GetHashCode()
+        {
+            return HashCode.Combine(TargetAttribute, TextValue, MatchKind);
+        }
     }
 }

src/JsonApiDotNetCore/Queries/Expressions/NotExpression.cs

@@ -24,5 +24,27 @@ public override string ToString()
         {
             return $"{Keywords.Not}({Child})";
         }
+
+        public override bool Equals(object obj)
+        {
+            if (ReferenceEquals(this, obj))
+            {
+                return true;
+            }
+
+            if (obj is null || GetType() != obj.GetType())
+            {
+                return false;
+            }
+
+            var other = (NotExpression) obj;
+
+            return Child.Equals(other.Child);
+        }
+
+        public override int GetHashCode()
+        {
+            return Child.GetHashCode();
+        }
     }
 }