FEATURE: add a conatins operator

Adds the `in` operator that checks for fields in tuples and
elements in a list.

Fixes: #12

docsite/site/content/reference/grammar.md

@@ -52,6 +52,7 @@ mod_keyword: "mod" ;
 out_keyword: "out" ;
 assert_keyword: "assert" ;
 null_keyword: "NULL" ;
+in_keyword: "in" ;
 escaped: "\", VISIBLE_CHAR ;
 str: quot, { escaped | UTF8_CHAR }, quot ;
 ```
@@ -142,8 +143,8 @@ non_operator_expr: literal
 ```
 sum_op: plus | minus ;
 product_op: start | slash ;
-compare_op: equalequal | gtequal | ltequal | gt | lt ;
-binary_op: sum_op | product_op | dot | compare_op;
+compare_op: equalequal | gtequal | ltequal | gt | lt | in_keyword ;
+binary_op: sum_op | product_op | dot | compare_op ;
 binary_expr: non_operator_expr, binary_op, expr ;
 ```
 

integration_tests/comparisons_test.ucg

@@ -87,4 +87,28 @@ assert |(1+1) == (1+1);|;
 let want = "foo";
 assert |
     select want, 1, { foo=2, } == 2;
+|;
+
+// Contains comparison operators.
+assert |
+    "foo" in {
+        foo = "bar",
+    };
+|;
+assert |
+    foo in {
+        foo = "bar",
+    };
+|;
+assert |
+    "foo" in ["foo", "bar"];
+|;
+assert |
+    "foo" in ["bar", "foo", "bar"];
+|;
+assert |
+    { foo = 1 } in ["foo", { foo = 1 }];
+|;
+assert |
+    true in [ "foo" in {foo = 1}, false ];
 |;

src/ast/mod.rs

@@ -495,6 +495,7 @@ pub enum BinaryExprType {
     NotEqual,
     GTEqual,
     LTEqual,
+    IN,
     // Selector operator
     DOT,
 }
@@ -512,6 +513,7 @@ impl BinaryExprType {
             BinaryExprType::LTEqual => 1,
             BinaryExprType::GT => 1,
             BinaryExprType::LT => 1,
+            BinaryExprType::IN => 1,
             // Sum operators are next least tightly bound
             BinaryExprType::Add => 2,
             BinaryExprType::Sub => 2,

src/build/mod.rs

@@ -729,8 +729,58 @@ impl<'a> FileBuilder<'a> {
         }
     }
 
+    fn do_element_check(
+        &mut self,
+        left: &Expression,
+        right: &Expression,
+        scope: &Scope,
+    ) -> Result<Rc<Val>, Box<Error>> {
+        // First we evaluate our right hand side so we have a something to search
+        // inside for our left hand expression.
+        let right_pos = right.pos().clone();
+        let right = self.eval_expr(right, scope)?;
+        // presence checks are only valid for tuples and lists.
+        if !(right.is_tuple() || right.is_list()) {
+            return Err(Box::new(error::BuildError::new(
+                format!(
+                    "Invalid righthand type for in operator {}",
+                    right.type_name()
+                ),
+                error::ErrorType::TypeFail,
+                right_pos,
+            )));
+        }
+        if let &Val::List(ref els) = right.as_ref() {
+            let left_pos = left.pos().clone();
+            let left = self.eval_expr(left, scope)?;
+            for val in els.iter() {
+                if let Ok(b) = self.do_deep_equal(&left_pos, left.clone(), val.clone()) {
+                    if let &Val::Boolean(b) = b.as_ref() {
+                        if b {
+                            // We found a match
+                            return Ok(Rc::new(Val::Boolean(true)));
+                        }
+                    }
+                }
+            }
+            // We didn't find a match anywhere so return false.
+            return Ok(Rc::new(Val::Boolean(false)));
+        } else {
+            // Handle our tuple case since this isn't a list.
+            let mut child_scope = scope.spawn_child();
+            child_scope.set_curr_val(right.clone());
+            // Search for the field in our tuple or list.
+            let maybe_val = self.do_dot_lookup(left, &child_scope);
+            // Return the result of the search.
+            return Ok(Rc::new(Val::Boolean(maybe_val.is_ok())));
+        }
+    }
+
     fn eval_binary(&mut self, def: &BinaryOpDef, scope: &Scope) -> Result<Rc<Val>, Box<Error>> {
         let kind = &def.kind;
+        if let &BinaryExprType::IN = kind {
+            return self.do_element_check(&def.left, &def.right, scope);
+        };
         let left = self.eval_expr(&def.left, scope)?;
         let mut child_scope = scope.spawn_child();
         child_scope.set_curr_val(left.clone());
@@ -756,8 +806,7 @@ impl<'a> FileBuilder<'a> {
             &BinaryExprType::GTEqual => self.do_gtequal(&def.pos, left, right),
             &BinaryExprType::LTEqual => self.do_ltequal(&def.pos, left, right),
             &BinaryExprType::NotEqual => self.do_not_deep_equal(&def.pos, left, right),
-            // TODO Handle the whole selector lookup logic here.
-            &BinaryExprType::DOT => panic!("Unraeachable"),
+            &BinaryExprType::IN | &BinaryExprType::DOT => panic!("Unreachable"),
         }
     }
 

src/parse/precedence.rs

@@ -171,7 +171,8 @@ make_fn!(
         do_each!(_ => punct!("<="), (Element::Op(BinaryExprType::LTEqual))),
         do_each!(_ => punct!(">="), (Element::Op(BinaryExprType::GTEqual))),
         do_each!(_ => punct!("<"),  (Element::Op(BinaryExprType::LT))),
-        do_each!(_ => punct!(">"),  (Element::Op(BinaryExprType::GT)))
+        do_each!(_ => punct!(">"),  (Element::Op(BinaryExprType::GT))),
+        do_each!(_ => word!("in"),  (Element::Op(BinaryExprType::IN)))
     )
 );
 
@@ -191,7 +192,8 @@ fn parse_compare_operator(i: SliceIter<Element>) -> Result<SliceIter<Element>, B
             | &BinaryExprType::LT
             | &BinaryExprType::LTEqual
             | &BinaryExprType::NotEqual
-            | &BinaryExprType::Equal => {
+            | &BinaryExprType::Equal
+            | &BinaryExprType::IN => {
                 return Result::Complete(i_.clone(), op.clone());
             }
             _other => {

src/tokenizer/mod.rs

@@ -264,6 +264,10 @@ make_fn!(selecttok<OffsetStrIter, Token>,
        do_text_token_tok!(TokenType::BAREWORD, "select", WS)
 );
 
+make_fn!(intok<OffsetStrIter, Token>,
+       do_text_token_tok!(TokenType::BAREWORD, "in", WS)
+);
+
 make_fn!(macrotok<OffsetStrIter, Token>,
        do_text_token_tok!(TokenType::BAREWORD, "macro", WS)
 );
@@ -385,6 +389,7 @@ fn token<'a>(input: OffsetStrIter<'a>) -> Result<OffsetStrIter<'a>, Token> {
         leftsquarebracket,
         rightsquarebracket,
         booleantok,
+        intok,
         lettok,
         outtok,
         selecttok,