refactor how default variables are evaluated

src/parse/variable.rs

@@ -39,30 +39,43 @@ impl<'a> Parser<'a> {
         } = self.parse_variable_value()?;
 
         if default {
-            let config_val = self.module_config.get(ident);
-            if self.at_root && !self.flags.in_control_flow() {
-                if !self.global_scope.default_var_exists(ident) {
-                    let value = if let Some(config_val) = config_val {
-                        config_val
-                    } else {
-                        self.parse_value_from_vec(val_toks, true)?.node
-                    };
+            let config_val = self.module_config.get(ident).filter(|v| !v.is_null());
 
-                    self.global_scope.insert_var(ident, value);
-                }
-            } else {
-                let value = if let Some(config_val) = config_val {
-                    config_val
+            let value = if (self.at_root && !self.flags.in_control_flow()) || global {
+                if self.global_scope.default_var_exists(ident) {
+                    return Ok(());
+                } else if let Some(value) = config_val {
+                    value
                 } else {
                     self.parse_value_from_vec(val_toks, true)?.node
-                };
-
-                if global && !self.global_scope.default_var_exists(ident) {
-                    self.global_scope.insert_var(ident, value.clone());
                 }
-                self.scopes.insert_default_var(ident, value);
+            } else if self.at_root && self.flags.in_control_flow() {
+                if self.global_scope.default_var_exists(ident) {
+                    return Ok(());
+                }
+
+                self.parse_value_from_vec(val_toks, true)?.node
+            } else if !self.at_root {
+                if self.scopes.default_var_exists(ident) {
+                    return Ok(());
+                }
+
+                self.parse_value_from_vec(val_toks, true)?.node
+            } else {
+                self.parse_value_from_vec(val_toks, true)?.node
+            };
+
+            if self.at_root && !self.flags.in_control_flow() {
+                self.global_scope.insert_var(ident, value);
+                return Ok(());
             }
 
+            if global {
+                self.global_scope.insert_var(ident, value.clone());
+            }
+
+            self.scopes.insert_var(ident, value);
+
             return Ok(());
         }
 

src/scope.rs

@@ -88,21 +88,13 @@ impl Scope {
         self.merge(other.scope);
     }
 
-    pub fn default_var_exists(&mut self, s: Identifier) -> bool {
+    pub fn default_var_exists(&self, s: Identifier) -> bool {
         if let Some(default_var) = self.get_var_no_err(s) {
             !default_var.is_null()
         } else {
             false
         }
     }
-
-    pub fn insert_default_var(&mut self, s: Identifier, v: Value) -> Option<Value> {
-        if self.default_var_exists(s) {
-            None
-        } else {
-            self.insert_var(s, v)
-        }
-    }
 }
 
 #[derive(Debug, Default)]
@@ -171,12 +163,14 @@ impl Scopes {
         }
     }
 
-    pub fn insert_default_var(&mut self, s: Identifier, v: Value) -> Option<Value> {
-        if let Some(scope) = self.0.last_mut() {
-            scope.insert_default_var(s, v)
-        } else {
-            panic!()
+    pub fn default_var_exists(&self, name: Identifier) -> bool {
+        for scope in self.0.iter().rev() {
+            if scope.default_var_exists(name) {
+                return true;
+            }
         }
+
+        false
     }
 
     pub fn get_var<'a>(

tests/selectors.rs

@@ -682,7 +682,7 @@ test!(
     "null {\n  color: null;\n}\n"
 );
 test!(
-    #[ignore = "we do not yet have a good way of consuming a string without converting \a to a newline"]
+    #[ignore = "we do not yet have a good way of consuming a string without converting \\a to a newline"]
     silent_comment_in_quoted_attribute_value,
     ".foo bar[val=\"//\"] {\n  color: &;\n}\n",
     ".foo bar[val=\"//\"] {\n  color: .foo bar[val=\"//\"];\n}\n"

tests/variables.rs

@@ -182,6 +182,32 @@ test!(
     }",
     "a {\n  color: red;\n}\n"
 );
+test!(
+    default_at_root_inside_control_flow,
+    "$a: initial;
+
+    @if true {
+        $a: outer !default;
+    }
+
+    a {
+        color: $a;
+    }",
+    "a {\n  color: initial;\n}\n"
+);
+test!(
+    default_at_root_inside_control_flow_outer_is_null,
+    "$a: null;
+
+    @if true {
+        $a: outer !default;
+    }
+
+    a {
+        color: $a;
+    }",
+    "a {\n  color: outer;\n}\n"
+);
 // https://github.com/Kixiron/lasso/issues/7
 test!(
     regression_test_for_lasso_0_3_0,