Merge pull request #238 from ThakeeNathees/register-builtin

Register builtin function implementation

src/core/public.c

@@ -177,6 +177,30 @@ void pkSetUserData(PKVM* vm, void* user_data) {
   vm->config.user_data = user_data;
 }
 
+void pkRegisterBuiltinFn(PKVM* vm, const char* name, pkNativeFn fn,
+                         int arity, const char* docstring) {
+  ASSERT(vm->builtins_count < BUILTIN_FN_CAPACITY,
+        "Maximum builtin function limit reached, To increase the limit set "
+        "BUILTIN_FN_CAPACITY and recompile.");
+
+  // TODO: if the functions are sorted, we can do a binary search, but builtin
+  // functions are not searched at runtime, just looked up using it's index
+  // O(1) However it'll decrease the compile time.
+  for (int i = 0; i < vm->builtins_count; i++) {
+    Closure* bfn = vm->builtins_funcs[i];
+    ASSERT(strcmp(bfn->fn->name, name) != 0,
+           "Overriding existing function not supported yet.");
+  }
+
+  Function* fptr = newFunction(vm, name, (int) strlen(name), NULL,
+                               true, docstring, NULL);
+  vmPushTempRef(vm, &fptr->_super); // fptr.
+  fptr->native = fn;
+  fptr->arity = arity;
+  vm->builtins_funcs[vm->builtins_count++] = newClosure(vm, fptr);
+  vmPopTempRef(vm); // fptr.
+}
+
 PkHandle* pkNewModule(PKVM* vm, const char* name) {
   CHECK_ARG_NULL(name);
   Module* module = newModuleInternal(vm, name);
@@ -260,14 +284,8 @@ void pkClassAddMethod(PKVM* vm, PkHandle* cls,
   vmPopTempRef(vm); // fn.
   vmPushTempRef(vm, &method->_super); // method.
   {
-    if (strcmp(name, CTOR_NAME) == 0) {
-      class_->ctor = method;
-
-    } else {
-      vmPushTempRef(vm, &method->_super); // method.
     pkClosureBufferWrite(&class_->methods, vm, method);
-      vmPopTempRef(vm); // method.
-    }
+    if (!strcmp(name, CTOR_NAME)) class_->ctor = method;
   }
   vmPopTempRef(vm); // method.
 }
@@ -670,7 +688,7 @@ bool pkIsSlotInstanceOf(PKVM* vm, int inst, int cls, bool* val) {
 void pkReserveSlots(PKVM* vm, int count) {
   if (vm->fiber == NULL) vm->fiber = newFiber(vm, NULL);
   int needed = (int)(vm->fiber->ret - vm->fiber->stack) + count;
-  vmEnsureStackSize(vm, needed);
+  vmEnsureStackSize(vm, vm->fiber, needed);
 }
 
 int pkGetSlotsCount(PKVM* vm) {

src/core/vm.c

@@ -231,6 +231,8 @@ bool vmPrepareFiber(PKVM* vm, Fiber* fiber, int argc, Var* argv) {
 
   ASSERT(fiber->stack != NULL && fiber->sp == fiber->stack + 1, OOPS);
   ASSERT(fiber->ret == fiber->stack, OOPS);
+
+  vmEnsureStackSize(vm, fiber, (int) (fiber->sp - fiber->stack) + argc);
   ASSERT((fiber->stack + fiber->stack_size) - fiber->sp >= argc, OOPS);
 
   // Pass the function arguments.
@@ -454,14 +456,13 @@ Var vmImportModule(PKVM* vm, String* from, String* path) {
   return VAR_OBJ(module);
 }
 
-void vmEnsureStackSize(PKVM* vm, int size) {
+void vmEnsureStackSize(PKVM* vm, Fiber* fiber, int size) {
 
   if (size >= (MAX_STACK_SIZE / sizeof(Var))) {
     VM_SET_ERROR(vm, newString(vm, "Maximum stack limit reached."));
     return;
   }
 
-  Fiber* fiber = vm->fiber;
   if (fiber->stack_size >= size) return;
 
   int new_size = utilPowerOf2Ceil(size);
@@ -524,7 +525,7 @@ static inline void pushCallFrame(PKVM* vm, const Closure* closure) {
   // Grow the stack if needed.
   int current_stack_slots = (int)(vm->fiber->sp - vm->fiber->stack) + 1;
   int needed = closure->fn->fn->stack_size + current_stack_slots;
-  vmEnsureStackSize(vm, needed);
+  vmEnsureStackSize(vm, vm->fiber, needed);
 
   CallFrame* frame = vm->fiber->frames + vm->fiber->frame_count++;
   frame->rbp = vm->fiber->ret;
@@ -567,7 +568,7 @@ static inline void reuseCallFrame(PKVM* vm, const Closure* closure) {
   // Grow the stack if needed (least probably).
   int needed = (closure->fn->fn->stack_size +
                 (int)(vm->fiber->sp - vm->fiber->stack));
-  vmEnsureStackSize(vm, needed);
+  vmEnsureStackSize(vm, vm->fiber, needed);
 }
 
 // Capture the [local] into an upvalue and return it. If the upvalue already

src/core/vm.h

@@ -147,7 +147,7 @@ PkHandle* vmNewHandle(PKVM* vm, Var value);
 
 // If the stack size is less than [size], the stack will grow to keep more
 // values on it.
-void vmEnsureStackSize(PKVM* vm, int size);
+void vmEnsureStackSize(PKVM* vm, Fiber* fiber, int size);
 
 // Trigger garbage collection. This is an implementation of mark and sweep
 // garbage collection (https://en.wikipedia.org/wiki/Tracing_garbage_collection).

src/include/pocketlang.h

@@ -212,6 +212,12 @@ PK_PUBLIC void pkSetUserData(PKVM* vm, void* user_data);
 // Returns the associated user data.
 PK_PUBLIC void* pkGetUserData(const PKVM* vm);
 
+// Register a new builtin function with the given [name]. [docstring] could be
+// NULL or will always valid pointer since PKVM doesn't allocate a string for
+// docstrings.
+PK_PUBLIC void pkRegisterBuiltinFn(PKVM* vm, const char* name, pkNativeFn fn,
+                                   int arity, const char* docstring);
+
 // Invoke pocketlang's allocator directly.  This function should be called 
 // when the host application want to send strings to the PKVM that are claimed
 // by the VM once the caller returned it. For other uses you **should** call

src/libs/std_io.c

@@ -402,12 +402,32 @@ DEF(_fileTell, "") {
   pkSetSlotNumber(vm, 0, (double) ftell(file->fp));
 }
 
+// open(path, mode='r') is equal to:
+//
+// from io import File
+// return File().open(path, mode)
+DEF(_open, NULL /* == _fileOpen */) {
+
+  // slots[1] = path
+  // slots[2] = mode
+  int argc = pkGetArgc(vm);
+  if (!pkCheckArgcRange(vm, argc, 1, 2)) return;
+  if (argc == 1) pkSetSlotString(vm, 2, "r");
+
+  if (!pkImportModule(vm, "io", 0)) return;           // slots[0] = io
+  if (!pkGetAttribute(vm, 0, "File", 0)) return;      // slots[0] = File
+  if (!pkNewInstance(vm, 0, 0, 0, 0)) return;         // slots[0] = File()
+  if (!pkCallMethod(vm, 0, "open", 2, 1, -1)) return; // slots[0] = opened file
+}
+
 /*****************************************************************************/
 /* MODULE REGISTER                                                           */
 /*****************************************************************************/
 
 void registerModuleIO(PKVM* vm) {
 
+  pkRegisterBuiltinFn(vm, "open", _open, -1, DOCSTRING(_fileOpen));
+
   PkHandle* io = pkNewModule(vm, "io");
 
   pkReserveSlots(vm, 2);