Add new module-system features for existing functions (#720)

CHANGELOG.md

@@ -1,3 +1,10 @@
+## 1.22.0
+
+### Dart API
+
+* Add a `Value.realNull` getter, which returns Dart's `null` if the value is
+  Sass's null.
+
 ## 1.21.0
 
 ### Dart API

lib/src/async_environment.dart

@@ -403,7 +403,13 @@ class AsyncEnvironment {
   bool variableExists(String name) => getVariable(name) != null;
 
   /// Returns whether a global variable named [name] exists.
-  bool globalVariableExists(String name) {
+  ///
+  /// Throws a [SassScriptException] if there is no module named [namespace], or
+  /// if multiple global modules expose functions named [name].
+  bool globalVariableExists(String name, {String namespace}) {
+    if (namespace != null) {
+      return _getModule(namespace).variables.containsKey(name);
+    }
     if (_variables.first.containsKey(name)) return true;
     return _getVariableFromGlobalModule(name) != null;
   }
@@ -536,7 +542,11 @@ class AsyncEnvironment {
   }
 
   /// Returns whether a function named [name] exists.
-  bool functionExists(String name) => getFunction(name) != null;
+  ///
+  /// Throws a [SassScriptException] if there is no module named [namespace], or
+  /// if multiple global modules expose functions named [name].
+  bool functionExists(String name, {String namespace}) =>
+      getFunction(name, namespace: namespace) != null;
 
   /// Sets the variable named [name] to [value] in the current scope.
   void setFunction(AsyncCallable callable) {
@@ -581,7 +591,11 @@ class AsyncEnvironment {
   }
 
   /// Returns whether a mixin named [name] exists.
-  bool mixinExists(String name) => getMixin(name) != null;
+  ///
+  /// Throws a [SassScriptException] if there is no module named [namespace], or
+  /// if multiple global modules expose functions named [name].
+  bool mixinExists(String name, {String namespace}) =>
+      getMixin(name, namespace: namespace) != null;
 
   /// Sets the variable named [name] to [value] in the current scope.
   void setMixin(AsyncCallable callable) {

lib/src/environment.dart

@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_environment.dart.
 // See tool/grind/synchronize.dart for details.
 //
-// Checksum: c1515ac728ab32d953e902e2608f1cc97411e57d
+// Checksum: 9037d898096d2eb998be8f01a65739ee34bec024
 //
 // ignore_for_file: unused_import
 
@@ -408,7 +408,13 @@ class Environment {
   bool variableExists(String name) => getVariable(name) != null;
 
   /// Returns whether a global variable named [name] exists.
-  bool globalVariableExists(String name) {
+  ///
+  /// Throws a [SassScriptException] if there is no module named [namespace], or
+  /// if multiple global modules expose functions named [name].
+  bool globalVariableExists(String name, {String namespace}) {
+    if (namespace != null) {
+      return _getModule(namespace).variables.containsKey(name);
+    }
     if (_variables.first.containsKey(name)) return true;
     return _getVariableFromGlobalModule(name) != null;
   }
@@ -541,7 +547,11 @@ class Environment {
   }
 
   /// Returns whether a function named [name] exists.
-  bool functionExists(String name) => getFunction(name) != null;
+  ///
+  /// Throws a [SassScriptException] if there is no module named [namespace], or
+  /// if multiple global modules expose functions named [name].
+  bool functionExists(String name, {String namespace}) =>
+      getFunction(name, namespace: namespace) != null;
 
   /// Sets the variable named [name] to [value] in the current scope.
   void setFunction(Callable callable) {
@@ -586,7 +596,11 @@ class Environment {
   }
 
   /// Returns whether a mixin named [name] exists.
-  bool mixinExists(String name) => getMixin(name) != null;
+  ///
+  /// Throws a [SassScriptException] if there is no module named [namespace], or
+  /// if multiple global modules expose functions named [name].
+  bool mixinExists(String name, {String namespace}) =>
+      getMixin(name, namespace: namespace) != null;
 
   /// Sets the variable named [name] to [value] in the current scope.
   void setMixin(Callable callable) {

lib/src/value.dart

@@ -62,6 +62,10 @@ abstract class Value implements ext.Value {
   /// these arguments are passed in.
   bool get isVar => false;
 
+  /// Returns Dart's `null` value if this is [sassNull], and returns [this]
+  /// otherwise.
+  Value get realNull => this;
+
   const Value();
 
   /// Calls the appropriate visit method on [visitor].

lib/src/value/external/value.dart

@@ -61,6 +61,10 @@ abstract class Value {
   /// and all other values count as single-value lists.
   List<Value> get asList;
 
+  /// Returns Dart's `null` value if this is [sassNull], and returns [this]
+  /// otherwise.
+  Value get realNull;
+
   /// Converts [sassIndex] into a Dart-style index into the list returned by
   /// [asList].
   ///

lib/src/value/null.dart

@@ -16,6 +16,8 @@ class SassNull extends Value {
 
   bool get isBlank => true;
 
+  Value get realNull => null;
+
   const SassNull._();
 
   T accept<T>(ValueVisitor<T> visitor) => visitor.visitNull(this);

lib/src/visitor/async_evaluate.dart

@@ -253,9 +253,12 @@ class _EvaluateVisitor
     var metaFunctions = [
       // These functions are defined in the context of the evaluator because
       // they need access to the [_environment] or other local state.
-      BuiltInCallable("global-variable-exists", r"$name", (arguments) {
+      BuiltInCallable("global-variable-exists", r"$name, $module: null",
+          (arguments) {
         var variable = arguments[0].assertString("name");
-        return SassBoolean(_environment.globalVariableExists(variable.text));
+        var module = arguments[1].realNull?.assertString("module");
+        return SassBoolean(_environment.globalVariableExists(variable.text,
+            namespace: module?.text));
       }),
 
       BuiltInCallable("variable-exists", r"$name", (arguments) {
@@ -263,15 +266,19 @@ class _EvaluateVisitor
         return SassBoolean(_environment.variableExists(variable.text));
       }),
 
-      BuiltInCallable("function-exists", r"$name", (arguments) {
+      BuiltInCallable("function-exists", r"$name, $module: null", (arguments) {
         var variable = arguments[0].assertString("name");
-        return SassBoolean(_environment.functionExists(variable.text) ||
+        var module = arguments[1].realNull?.assertString("module");
+        return SassBoolean(_environment.functionExists(variable.text,
+                namespace: module?.text) ||
             _builtInFunctions.containsKey(variable.text));
       }),
 
-      BuiltInCallable("mixin-exists", r"$name", (arguments) {
+      BuiltInCallable("mixin-exists", r"$name, $module: null", (arguments) {
         var variable = arguments[0].assertString("name");
-        return SassBoolean(_environment.mixinExists(variable.text));
+        var module = arguments[1].realNull?.assertString("module");
+        return SassBoolean(
+            _environment.mixinExists(variable.text, namespace: module?.text));
       }),
 
       BuiltInCallable("content-exists", "", (arguments) {
@@ -282,16 +289,23 @@ class _EvaluateVisitor
         return SassBoolean(_environment.content != null);
       }),
 
-      BuiltInCallable("get-function", r"$name, $css: false", (arguments) {
+      BuiltInCallable("get-function", r"$name, $css: false, $module: null",
+          (arguments) {
         var name = arguments[0].assertString("name");
         var css = arguments[1].isTruthy;
+        var module = arguments[2].realNull?.assertString("module");
+
+        if (css && module != null) {
+          throw r"$css and $module may not both be passed at once.";
+        }
 
         var callable = css
             ? PlainCssCallable(name.text)
-            : _addExceptionSpan(_callableNode, () => _getFunction(name.text));
+            : _addExceptionSpan(_callableNode,
+                () => _getFunction(name.text, namespace: module?.text));
         if (callable != null) return SassFunction(callable);
 
-        throw SassScriptException("Function not found: $name");
+        throw "Function not found: $name";
       }),
 
       AsyncBuiltInCallable("call", r"$function, $args...", (arguments) async {

lib/src/visitor/evaluate.dart

@@ -5,7 +5,7 @@
 // DO NOT EDIT. This file was generated from async_evaluate.dart.
 // See tool/grind/synchronize.dart for details.
 //
-// Checksum: 948db9d9efe2ed5572ecc0d2763817a56df88bd6
+// Checksum: f6dcd674164d13633df1359d5a4cfc215f3a3469
 //
 // ignore_for_file: unused_import
 
@@ -261,9 +261,12 @@ class _EvaluateVisitor
     var metaFunctions = [
       // These functions are defined in the context of the evaluator because
       // they need access to the [_environment] or other local state.
-      BuiltInCallable("global-variable-exists", r"$name", (arguments) {
+      BuiltInCallable("global-variable-exists", r"$name, $module: null",
+          (arguments) {
         var variable = arguments[0].assertString("name");
-        return SassBoolean(_environment.globalVariableExists(variable.text));
+        var module = arguments[1].realNull?.assertString("module");
+        return SassBoolean(_environment.globalVariableExists(variable.text,
+            namespace: module?.text));
       }),
 
       BuiltInCallable("variable-exists", r"$name", (arguments) {
@@ -271,15 +274,19 @@ class _EvaluateVisitor
         return SassBoolean(_environment.variableExists(variable.text));
       }),
 
-      BuiltInCallable("function-exists", r"$name", (arguments) {
+      BuiltInCallable("function-exists", r"$name, $module: null", (arguments) {
         var variable = arguments[0].assertString("name");
-        return SassBoolean(_environment.functionExists(variable.text) ||
+        var module = arguments[1].realNull?.assertString("module");
+        return SassBoolean(_environment.functionExists(variable.text,
+                namespace: module?.text) ||
             _builtInFunctions.containsKey(variable.text));
       }),
 
-      BuiltInCallable("mixin-exists", r"$name", (arguments) {
+      BuiltInCallable("mixin-exists", r"$name, $module: null", (arguments) {
         var variable = arguments[0].assertString("name");
-        return SassBoolean(_environment.mixinExists(variable.text));
+        var module = arguments[1].realNull?.assertString("module");
+        return SassBoolean(
+            _environment.mixinExists(variable.text, namespace: module?.text));
       }),
 
       BuiltInCallable("content-exists", "", (arguments) {
@@ -290,16 +297,23 @@ class _EvaluateVisitor
         return SassBoolean(_environment.content != null);
       }),
 
-      BuiltInCallable("get-function", r"$name, $css: false", (arguments) {
+      BuiltInCallable("get-function", r"$name, $css: false, $module: null",
+          (arguments) {
         var name = arguments[0].assertString("name");
         var css = arguments[1].isTruthy;
+        var module = arguments[2].realNull?.assertString("module");
+
+        if (css && module != null) {
+          throw r"$css and $module may not both be passed at once.";
+        }
 
         var callable = css
             ? PlainCssCallable(name.text)
-            : _addExceptionSpan(_callableNode, () => _getFunction(name.text));
+            : _addExceptionSpan(_callableNode,
+                () => _getFunction(name.text, namespace: module?.text));
         if (callable != null) return SassFunction(callable);
 
-        throw SassScriptException("Function not found: $name");
+        throw "Function not found: $name";
       }),
 
       BuiltInCallable("call", r"$function, $args...", (arguments) {

pubspec.yaml

@@ -1,5 +1,5 @@
 name: sass
-version: 1.21.0
+version: 1.22.0-dev
 description: A Sass implementation in Dart.
 author: Dart Team <misc@dartlang.org>
 homepage: https://github.com/sass/dart-sass