Merge pull request #7762 from jacob-carlborg/objc_class_methods

Add support for Objective-C class/static methods
merged-on-behalf-of: Mike Franklin <JinShil@users.noreply.github.com>

changelog/objc_class_methods.dd

@@ -0,0 +1,45 @@
+Support for calling Objective-C class (static) methods has been added.
+
+Previously to call an Objective-C class method it was necessary to make explicit
+calls to the Objective-C runtime. The following code is an example of the old
+way to call a class method:
+
+---
+extern (C) Class objc_lookUpClass(in char* name);
+
+extern (Objective-C)
+interface Class
+{
+    NSObject alloc() @selector("alloc");
+}
+
+extern (Objective-C)
+interface NSObject
+{
+    NSObject init() @selector("init");
+}
+
+void main()
+{
+    auto cls = objc_lookUpClass("NSObject");
+    auto o = cls.alloc().init();
+}
+---
+
+The above code can now be replaced with the following:
+
+---
+extern (Objective-C)
+interface NSObject
+{
+    static NSObject alloc() @selector("alloc");
+    NSObject init() @selector("init");
+}
+
+void main()
+{
+    auto o = NSObject.alloc().init();
+}
+---
+
+Note the use of the `static` attribute in the method declaration.

src/dmd/aggregate.h

@@ -290,6 +290,7 @@ class ClassDeclaration : public AggregateDeclaration
 
     Abstract isabstract;                // 0: fwdref, 1: is abstract class, 2: not abstract
     Baseok baseok;                      // set the progress of base classes resolving
+    ObjcClassDeclaration objc;          // Data for a class declaration that is needed for the Objective-C integration
     Symbol *cpp_type_info_ptr_sym;      // cached instance of class Id.cpp_type_info_ptr
 
     static ClassDeclaration *create(Loc loc, Identifier *id, BaseClasses *baseclasses, Dsymbols *members, bool inObject);

src/dmd/dclass.d

@@ -27,6 +27,7 @@ import dmd.globals;
 import dmd.id;
 import dmd.identifier;
 import dmd.mtype;
+import dmd.objc;
 import dmd.root.rmem;
 import dmd.target;
 import dmd.visitor;
@@ -244,6 +245,12 @@ extern (C++) class ClassDeclaration : AggregateDeclaration
     /// set the progress of base classes resolving
     Baseok baseok;
 
+    /**
+     * Data for a class declaration that is needed for the Objective-C
+     * integration.
+     */
+    ObjcClassDeclaration objc;
+
     Symbol* cpp_type_info_ptr_sym;      // cached instance of class Id.cpp_type_info_ptr
 
     final extern (D) this(Loc loc, Identifier id, BaseClasses* baseclasses, Dsymbols* members, bool inObject)

src/dmd/dsymbolsem.d

@@ -4800,6 +4800,7 @@ private extern(C++) final class DsymbolSemanticVisitor : Visitor
         if (idec.baseok == Baseok.done)
         {
             idec.baseok = Baseok.semanticdone;
+            objc.setMetaclass(idec);
 
             // initialize vtbl
             if (idec.vtblOffset())

src/dmd/e2ir.d

@@ -5423,6 +5423,11 @@ elem *toElem(Expression e, IRState *irs)
             result = toElemStructLit(sle, irs, TOK.construct, sle.sym, true);
         }
 
+        override void visit(ObjcClassReferenceExp e)
+        {
+            result = objc.toElem(e);
+        }
+
         /*****************************************************/
         /*                   CTFE stuff                      */
         /*****************************************************/

src/dmd/expression.d

@@ -49,6 +49,7 @@ import dmd.identifier;
 import dmd.inline;
 import dmd.mtype;
 import dmd.nspace;
+import dmd.objc;
 import dmd.opover;
 import dmd.optimize;
 import dmd.root.ctfloat;
@@ -97,6 +98,18 @@ L1:
     Type t = e1.type.toBasetype();
     //printf("e1.type = %s, var.type = %s\n", e1.type.toChars(), var.type.toChars());
 
+    if (e1.op == TOK.objcClassReference)
+    {
+        // We already have an Objective-C class reference, just use that as 'this'.
+        return e1;
+    }
+    else if (ad && ad.isClassDeclaration && ad.isClassDeclaration.classKind == ClassKind.objc &&
+             var.isFuncDeclaration && var.isFuncDeclaration.isStatic &&
+             var.isFuncDeclaration.selector)
+    {
+        return new ObjcClassReferenceExp(e1.loc, cast(ClassDeclaration) ad);
+    }
+
     /* If e1 is not the 'this' pointer for ad
      */
     if (ad &&
@@ -7237,3 +7250,26 @@ extern (C++) final class PrettyFuncInitExp : DefaultInitExp
         v.visit(this);
     }
 }
+
+/**
+ * Objective-C class reference expression.
+ *
+ * Used to get the metaclass of an Objective-C class, `NSObject.Class`.
+ */
+extern (C++) final class ObjcClassReferenceExp : Expression
+{
+    ClassDeclaration classDeclaration;
+
+    extern (D) this(Loc loc, ClassDeclaration classDeclaration)
+    {
+        super(loc, TOK.objcClassReference,
+            __traits(classInstanceSize, ObjcClassReferenceExp));
+        this.classDeclaration = classDeclaration;
+        type = objc.getRuntimeMetaclass(classDeclaration).getType();
+    }
+
+    override void accept(Visitor v)
+    {
+        v.visit(this);
+    }
+}

src/dmd/expression.h

@@ -1383,6 +1383,13 @@ struct UnionExp
 
 /****************************************************************/
 
+class ObjcClassReferenceExp : public Expression
+{
+    ClassDeclaration* classDeclaration;
+
+    void accept(Visitor *v) { v->visit(this); }
+};
+
 /* Special values used by the interpreter
  */
 

src/dmd/func.d

@@ -1518,7 +1518,7 @@ extern (C++) class FuncDeclaration : Declaration
     override inout(AggregateDeclaration) isThis() inout
     {
         //printf("+FuncDeclaration::isThis() '%s'\n", toChars());
-        auto ad = (storage_class & STC.static_) ? null : isMember2();
+        auto ad = (storage_class & STC.static_) ? objc.isThis(this) : isMember2();
         //printf("-FuncDeclaration::isThis() %p\n", ad);
         return ad;
     }

src/dmd/id.d

@@ -142,6 +142,8 @@ immutable Msgtable[] msgtable =
     { "xopCmp", "__xopCmp" },
     { "xtoHash", "__xtoHash" },
 
+    { "Class" },
+
     { "LINE", "__LINE__" },
     { "FILE", "__FILE__" },
     { "MODULE", "__MODULE__" },

src/dmd/mtype.d

@@ -7857,7 +7857,15 @@ extern (C++) final class TypeClass : Type
                 e = e.expressionSemantic(sc);
                 return e;
             }
-            if (d.needThis() && sc.intypeof != 1)
+            if (sym.classKind == ClassKind.objc
+                && d.isFuncDeclaration()
+                && d.isFuncDeclaration().isStatic
+                && d.isFuncDeclaration().selector)
+            {
+                auto classRef = new ObjcClassReferenceExp(e.loc, sym);
+                return new DotVarExp(e.loc, classRef, d).expressionSemantic(sc);
+            }
+            else if (d.needThis() && sc.intypeof != 1)
             {
                 /* Rewrite as:
                  *  this.d