Handle == and !=

src/lexer.rs

@@ -46,7 +46,18 @@ impl<'a> Iterator for Lexer<'a> {
             '(' => symbol!(self, OpenParen),
             ')' => symbol!(self, CloseParen),
             '+' => symbol!(self, Plus),
-            '=' => symbol!(self, Equal),
+            '=' => {
+                self.buf.next();
+                self.pos.next_char();
+                match self.buf.peek() {
+                    Some('=') => {
+                        self.buf.next();
+                        self.pos.next_char();
+                        TokenKind::Op(Op::Equal)
+                    }
+                    _ => TokenKind::Symbol(Symbol::Equal)
+                }
+            },
             '?' => symbol!(self, QuestionMark),
             '\\' => symbol!(self, BackSlash),
             '~' => symbol!(self, Tilde),

src/value.rs

@@ -226,7 +226,8 @@ impl Value {
     }
 
     pub fn is_true(&self) -> bool {
-        !(self == &Value::Null || self == &Value::False)
+        let s = self.eval();
+        !(s == Value::Null || s == Value::False)
     }
 
     pub fn unquote(self) -> Self {
@@ -250,11 +251,21 @@ impl Value {
         }
     }
 
+    pub fn bool(b: bool) -> Self {
+        if b {
+            Value::True
+        } else {
+            Value::False
+        }
+    }
+
     pub fn eval(&self) -> Self {
         match self {
             Self::BinaryOp(lhs, op, rhs) => match op {
                 Op::Plus => *lhs.clone() + *rhs.clone(),
                 Op::Minus => *lhs.clone() - *rhs.clone(),
+                Op::Equal => Self::bool(*lhs == *rhs),
+                Op::NotEqual => Self::bool(*lhs != *rhs),
                 _ => Self::BinaryOp(lhs.clone(), *op, rhs.clone()),
             },
             _ => self.clone(),

tests/meta.rs

@@ -8,6 +8,16 @@ test!(
     "a {\n  color: if(true, 1, 2)\n}\n",
     "a {\n  color: 1;\n}\n"
 );
+test!(
+    if_equal,
+    "a {\n  color: if(1 == 1, 1, 2)\n}\n",
+    "a {\n  color: 1;\n}\n"
+);
+test!(
+    if_not_equal,
+    "a {\n  color: if(1 != 1, 1, 2)\n}\n",
+    "a {\n  color: 2;\n}\n"
+);
 test!(
     if_named_args,
     "a {\n  color: if($condition: true, $if-true: 1, $if-false: 2)\n}\n",