Allow module reimporting. Pull module from VM if already imported for…

… main path

docs/docs/standard-lib/importlib.md

@@ -23,11 +23,12 @@ To make use of the Importlib module an import is required.
 import Importlib;
 ```
 
-### Importlib.include(String) -> Module
+### Importlib.include(String, Bool: reload -> Optional) -> Module
 
-This allows you to dynamically import a module. 
+This allows you to dynamically import a module. It also allows you to reload a module that was previously imported.
 
 Note: The path is relative to the file include() is called in.
+Note: Reloading an already imported module will mutate all references to the previously imported module.
 
 ```js
 // someFile.du

src/optionals/importlib.c

@@ -1,16 +1,27 @@
 #include "importlib.h"
 
 Value includeNative(DictuVM *vm, int argCount, Value *args) {
-    if (argCount != 1) {
-        runtimeError(vm, "include() takes 1 argument (%d given)", argCount);
+    if (argCount != 1 && argCount != 2) {
+        runtimeError(vm, "include() takes 1 or 2 arguments (%d given)", argCount);
         return EMPTY_VAL;
     }
 
     if (!IS_STRING(args[0])) {
-        runtimeError(vm, "include() argument must be a string");
+        runtimeError(vm, "include() first argument must be a string");
         return EMPTY_VAL;
     }
 
+    bool reload = false;
+
+    if (argCount == 2) {
+        if (!IS_BOOL(args[1])) {
+            runtimeError(vm, "include() second argument must be a boolean");
+            return EMPTY_VAL;
+        }
+
+        reload = AS_BOOL(args[1]);
+    }
+
     CallFrame *frame = &vm->frames[vm->frameCount - 1];
     char path[PATH_MAX];
 
@@ -19,7 +30,12 @@ Value includeNative(DictuVM *vm, int argCount, Value *args) {
         return EMPTY_VAL;
     }
 
+    Value moduleVal;
     ObjString *pathObj = copyString(vm, path, strlen(path));
+    if (!reload && tableGet(&vm->modules, pathObj, &moduleVal)) {
+        return moduleVal;
+    }
+
     push(vm, OBJ_VAL(pathObj));
     ObjModule *module = newModule(vm, pathObj);
     pop(vm);

tests/importlib/include.du

@@ -20,6 +20,23 @@ class TestImportLibInclude < UnitTest {
         this.assertType(Level1.Level2.Level3, 'module');
         this.assertEquals(Level1.Level2.Level3.list, [1, 2, 3]);
     }
+
+    testImportLibIncludeReload() {
+        // reset test file
+        with('tests/importlib/data/test.du', 'w') {
+            file.write('var test = 10;');
+        }
+
+        const TestModule = Importlib.include('data/test.du');
+        this.assertEquals(TestModule.test, 10);
+
+        with('tests/importlib/data/test.du', 'w') {
+            file.write('var test = 100;');
+        }
+
+        const TestModuleReimport = Importlib.include('data/test.du', true);
+        this.assertEquals(TestModuleReimport.test, 100);
+    }
 }
 
 TestImportLibInclude().run();