Fix comparisons with empty and blank (#305)

Fluid.Tests/ParserTests.cs

@@ -590,7 +590,30 @@ public Task EmptyShouldEqualToNil(string source, string expected)
         {
             return CheckAsync(source, expected, t => t.SetValue("e", "").SetValue("f", "hello"));
         }
+
+        [Theory]
+        [InlineData("zero == empty", "false")]
+        [InlineData("empty == zero", "false")]
+        [InlineData("zero == blank", "false")]
+        [InlineData("blank == zero", "false")]
+
+        [InlineData("one == empty", "false")]
+        [InlineData("empty == one", "false")]
+        [InlineData("one == blank", "false")]
+        [InlineData("blank == one", "false")]
+        public Task EmptyShouldNotEqualNumbers(string source, string expected)
+        {
+            return CheckAsync(source, expected, t => t.SetValue("zero", 0).SetValue("one", 1));
+        }
 
+        [Theory]
+        [InlineData("blank == false", "true")]
+        [InlineData("empty == false", "false")]
+        public Task BlankShouldComparesToFalse(string source, string expected)
+        {
+            return CheckAsync(source, expected, t => t.SetValue("zero", 0).SetValue("one", 1));
+        }
+
         [Fact]
         public void CycleShouldHandleNumbers()
         {

Fluid/Values/ArrayValue.cs

@@ -55,7 +55,11 @@ public override bool Equals(FluidValue other)
                     }
                 }
             }
-
+            else if (other.Type == FluidValues.Empty)
+            {
+                return _value.Length == 0;
+            }
+
             return false;
         }
 

Fluid/Values/BlankValue.cs

@@ -27,6 +27,7 @@ public override bool Equals(FluidValue other)
 
         public override bool ToBooleanValue()
         {
+            // The only values that are falsy in Liquid are nil and false
             return true;
         }
 

Fluid/Values/BooleanValue.cs

@@ -28,6 +28,9 @@ public static BooleanValue Create(bool value)
 
         public override bool Equals(FluidValue other)
         {
+            // blank == false -> true
+            if (other.Type == FluidValues.Blank) return _value == false;
+
             return _value == other.ToBooleanValue();
         }
 

Fluid/Values/DictionaryValue.cs

@@ -46,6 +46,10 @@ public override bool Equals(FluidValue other)
                     }
                 }
             }
+            else if (other.Type == FluidValues.Empty)
+            {
+                return _value.Count == 0;
+            }
 
             return false;
         }

Fluid/Values/EmptyValue.cs

@@ -18,6 +18,7 @@ public override bool Equals(FluidValue other)
         {
             if (other.Type == FluidValues.String && other.ToStringValue() == "") return true;
             if (other.Type == FluidValues.Array && other.ToNumberValue() == 0) return true;
+            if (other.Type == FluidValues.Dictionary &&other.ToNumberValue() == 0) return true;
             if (other == BlankValue.Instance) return true;
             if (other == EmptyValue.Instance) return true;
             if (other == NilValue.Instance) return false;

Fluid/Values/NumberValue.cs

@@ -35,6 +35,12 @@ private NumberValue(decimal value)
 
         public override bool Equals(FluidValue other)
         {
+            // Delegating other types 
+            if (other == BlankValue.Instance || other == NilValue.Instance || other == EmptyValue.Instance)
+            {
+                return false;
+            }
+
             return _value == other.ToNumberValue();
         }
 

Fluid/Values/StringValue.cs

@@ -82,9 +82,13 @@ internal static StringValue Create(in TextSpan span)
         public override bool Equals(FluidValue other)
         {
             if (other.Type == FluidValues.String) return _value == other.ToStringValue();
-            if (other == BlankValue.Instance) return String.IsNullOrWhiteSpace(ToStringValue());
-            if (other == EmptyValue.Instance) return ToStringValue().Length == 0;
-
+
+            // Delegating other types 
+            if (other == BlankValue.Instance || other == NilValue.Instance || other == EmptyValue.Instance)
+            {
+                return other.Equals(this);
+            }
+
             return false;
         }