added a basic heap inspection utility to the debugger and modified the impl of the buffer object

build.sh

@@ -73,6 +73,7 @@ gcc tests/src/test-objects.c -o build/test-objects $FLAGS -Lbuild/ -lnoja-object
 
 gcc src/main.c \
 	src/debug.c \
+	src/heap_reconst.c \
 	temp/o_builtins.o \
 	temp/o_net_builtins.o \
 	temp/utils/hash.o \

samples/makegarbage.noja

@@ -10,7 +10,7 @@ while i < n:
 		i = i + 1;
 
 		fun printPercent()
-			print('\r', 100.0 * i / n, '% ');
+			print(100.0 * i / n, '%\n');
 	
 		printPercent();
 	}

src/debug.c

@@ -7,6 +7,7 @@
 #include <ctype.h>
 #include "debug.h"
 #include "utils/defs.h"
+#include "heap_reconst.h"
 
 #define ANSI_COLOR_RED     "\x1b[31m"
 #define ANSI_COLOR_GREEN   "\x1b[32m"
@@ -269,6 +270,7 @@ _Bool Debug_Callback(Runtime *runtime, void *userp)
 						"continue .......... Run until a breakpoint or the end of the code is reached\n"
 						"breakpoint ........ Add a breakpoint\n"
 						"stack ............. Show the contents of the stack\n"
+						"heap .............. Show the contents of the heap\n"
 						"disassembly ....... Show the current file's bytecode\n");
 						}
 					else if(!strcmp(argv[1], "help"))
@@ -363,6 +365,17 @@ _Bool Debug_Callback(Runtime *runtime, void *userp)
 								" Description | Show the contents of the stack.\n"
 								"\n");
 						}
+					else if(!strcmp(argv[1], "heap"))
+						{
+							fprintf(stderr, 
+								"\n"
+								"     Command | heap\n"
+								"             | \n"
+								"       Usage | > heap\n"
+								"             | \n"
+								" Description | Show the contents of the heap.\n"
+								"\n");
+						}
 					else
 						{
 							fprintf(stdout, "Unknown command \"%s\".\n", argv[1]);
@@ -483,6 +496,59 @@ _Bool Debug_Callback(Runtime *runtime, void *userp)
 							fprintf(stderr, "\n");
 						}
 				}
+			else if(!strcmp(argv[0], "heap"))
+				{
+					ReconstructedHeap *rh = reconstruct_heap(runtime);
+
+					if(rh == NULL)
+						{
+							fprintf(stderr, "Something went wrong.\n");
+						}
+					else
+						{
+							if(rh->count == 0)
+								{
+									printf("The heap is empty.\n");
+								}
+							else 
+								{
+									_Bool in_pool = 0;
+								
+									for(int i = 0; i < rh->count; i += 1)
+										{
+											MemoryChunk *chunk = rh->chunks + i;
+
+											if(in_pool == 0 && chunk->in_pool == 1)
+												{
+													printf("-- Pool start --\n");
+													in_pool = 1;
+												}
+											else if(in_pool == 1 && chunk->in_pool == 0)
+												{
+													printf("-- Pool end --\n");
+													in_pool = 0;
+												}
+
+											if(chunk->parent == NULL)
+												printf("%d bytes at %p (%s)\n", 
+													chunk->size, 
+													chunk->addr, 
+													Object_GetName(chunk->addr));
+											else
+												printf("%d bytes at %p, extension of %p (%s)\n", 
+													chunk->size, 
+													chunk->addr, 
+													chunk->parent, 
+													Object_GetName(chunk->parent));
+										}
+
+									if(in_pool)
+										printf("-- Pool end --\n");
+								}
+
+							free(rh);
+						}
+				}
 			else if(!strcmp(argv[0], "quit"))
 				{
 					return 0;

src/heap_reconst.c

@@ -0,0 +1,240 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include "heap_reconst.h"
+
+typedef struct {
+	Object *parent;
+	void   *addr;
+	int     size;
+} Extension;
+
+typedef struct {
+	Object   **objs;
+	Extension *exts;
+	int ext_size, ext_used;
+	int obj_size, obj_used;
+} ReconstructionState;
+
+static _Bool append_ext(ReconstructionState *state, Extension ext)
+{
+	if(state->exts == NULL)
+		{
+			int n = 8;
+			
+			state->exts = malloc(n * sizeof(Extension));
+
+			if(state->exts == NULL)
+				return 0;
+
+			state->ext_size = n;
+			state->ext_used = 0;
+		}
+	else if(state->ext_size == state->ext_used)
+		{
+			int factor = 2;
+			
+			Extension *temp = realloc(state->exts, factor * state->ext_size * sizeof(Extension));
+		
+			if(temp == NULL)
+				return 0;
+
+			state->exts = temp;
+			state->ext_size *= factor;
+		}
+
+	state->exts[state->ext_used++] = ext;
+	return 1;
+}
+
+static _Bool contains_ext(ReconstructionState *state, void *addr)
+{
+	for(int i = 0; i < state->ext_used; i += 1)
+		if(state->exts[i].addr == addr)
+			return 1;
+	return 0;
+}
+
+static void exension_walker(void **addr, unsigned int size, void *userp)
+{
+	ReconstructionState *state = userp;
+
+	if(contains_ext(state, *addr))
+		return;
+
+	if(!append_ext(state, (Extension) { .addr = *addr, .size = size, .parent = NULL }))
+		{
+			assert(0);
+		}
+}
+
+static _Bool append_obj(ReconstructionState *state, Object *obj)
+{
+	if(state->objs == NULL)
+		{
+			int n = 8;
+			
+			state->objs = malloc(n * sizeof(Object*));
+
+			if(state->objs == NULL)
+				return 0;
+
+			state->obj_size = n;
+			state->obj_used = 0;
+		}
+	else if(state->obj_size == state->obj_used)
+		{
+			int factor = 2;
+			
+			Object **temp = realloc(state->objs, factor * state->obj_size * sizeof(Extension));
+		
+			if(temp == NULL)
+				return 0;
+
+			state->objs = temp;
+			state->obj_size *= factor;
+		}
+
+	state->objs[state->obj_used++] = obj;
+	return 1;
+}
+
+static _Bool contains_obj(ReconstructionState *state, Object *obj)
+{
+	for(int i = 0; i < state->obj_used; i += 1)
+		if(state->objs[i] == obj)
+			return 1;
+	return 0;
+}
+
+static void object_walker(Object **referer, void *userp)
+{
+	ReconstructionState *state = userp;
+	Object *obj = *referer;
+
+	if(obj == NULL)
+		return;
+
+	if(!contains_obj(state, obj))
+		{
+			// Object wasn't already encountered.
+			// Store it at index `left`.
+
+			if(!append_obj(state, obj))
+				{
+					assert(0);
+				}
+
+			// Walk over its extensions.
+			{
+				Object_WalkExtensions(obj, exension_walker, userp);
+
+				if(state->ext_used > 0)
+					{
+						int i = state->ext_used-1;
+						while(i >= 0 && state->exts[i].parent == NULL)
+							{
+								state->exts[i].parent = obj;
+								i -= 1;
+							}
+					}
+			}
+
+			// Walk over its children.
+			Object_WalkReferences(obj, object_walker, state);
+		}
+	else
+		{
+			// Object was already encountered and
+			// it's pointer is stored at index `index`.
+		}
+}
+
+static int chunk_order(const void *p1, const void *p2)
+{
+	const MemoryChunk 
+		*c1 = p1, 
+		*c2 = p2;
+
+	intptr_t l = (intptr_t) c1->addr;
+	intptr_t r = (intptr_t) c2->addr;
+
+	return (l > r) - (l < r);
+}
+
+ReconstructedHeap *reconstruct_heap(Runtime *runtime)
+{
+	ReconstructionState state;
+	state.exts = NULL;
+	state.ext_used = 0;
+	state.ext_size = 0;
+	state.objs = NULL;
+	state.obj_used = 0;
+	state.obj_size = 0;
+
+	Object *builtins = Runtime_GetBuiltins(runtime);
+	if(builtins != NULL)
+		{
+			object_walker(&builtins, &state);
+			Object_WalkReferences(builtins, object_walker, &state);
+		}
+
+	CallStackScanner *scanner = CallStackScanner_New(runtime);
+	assert(scanner != NULL);
+
+	Object *locals, *closure;
+	while(CallStackScanner_Next(&scanner, &locals, &closure, NULL, NULL))
+		{
+			if(locals != NULL)
+				{
+					object_walker(&locals, &state);
+					Object_WalkReferences(locals,  object_walker, &state);
+				}
+
+			if(closure != NULL)
+				{
+					object_walker(&closure, &state);
+					Object_WalkReferences(closure, object_walker, &state);
+				}
+		}
+
+	ReconstructedHeap *recheap = malloc(sizeof(ReconstructedHeap) + (state.obj_used + state.ext_used) * sizeof(MemoryChunk));
+	if(recheap == NULL)
+		{
+			free(state.objs);
+			free(state.exts);
+			return NULL;
+		}
+
+	recheap->count = state.obj_used + state.ext_used;
+
+	Heap        *heap      = Runtime_GetHeap(runtime);
+	char        *heap_addr = Heap_GetPointer(heap);
+	unsigned int heap_size = Heap_GetSize(heap);
+
+	for(int i = 0; i < state.obj_used; i += 1)
+		{
+			recheap->chunks[i] = (MemoryChunk) {
+				.in_pool = (heap_addr <= (char*) state.objs[i] && (char*) state.objs[i] < heap_addr + heap_size),
+				.parent = NULL,
+				.addr = state.objs[i],
+				.size = state.objs[i]->type->size,
+			};
+		}
+
+	for(int i = 0; i < state.ext_used; i += 1)
+		{
+			recheap->chunks[state.obj_used + i] = (MemoryChunk) {
+				.in_pool = (heap_addr <= (char*) state.exts[i].addr && (char*) state.exts[i].addr < heap_addr + heap_size),
+				.parent = state.exts[i].parent,
+				.addr   = state.exts[i].addr,
+				.size   = state.exts[i].size,
+			};
+		}
+
+	qsort(recheap->chunks, recheap->count, sizeof(MemoryChunk), chunk_order);
+
+	free(state.objs);
+	free(state.exts);
+	return recheap;
+}

src/heap_reconst.h

@@ -0,0 +1,15 @@
+#include "runtime/runtime.h"
+
+typedef struct {
+	_Bool in_pool;
+	Object *parent;
+	void *addr;
+	int   size;
+} MemoryChunk;
+
+typedef struct {
+	int        count;
+	MemoryChunk chunks[];
+} ReconstructedHeap;
+
+ReconstructedHeap *reconstruct_heap(Runtime *runtime);

src/objects/heap.c

@@ -20,6 +20,7 @@ typedef struct {
 } PendingDestruct;
 
 struct xHeap {
+	int objcount;
 	int   size;
 	int   used;
 	int   total;
@@ -30,7 +31,7 @@ struct xHeap {
 
 	_Bool collecting;
 	_Bool collection_failed;
-	int moved_with_destructors;
+	int movedcount;
 	void *old_body;
 	int   old_used;
 	int   old_total;
@@ -48,6 +49,7 @@ Heap *Heap_New(int size)
 	if(heap == NULL)
 		return NULL;
 
+	heap->objcount = 0;
 	heap->total = 0;
 	heap->size = size;
 	heap->used = 0;
@@ -105,6 +107,21 @@ void Heap_Free(Heap *heap)
 	free(heap);
 }
 
+void *Heap_GetPointer(Heap *heap)
+{
+	return heap->body;
+}
+
+unsigned int Heap_GetSize(Heap *heap)
+{
+	return heap->size;
+}
+
+unsigned int Heap_GetObjectCount(Heap *heap)
+{
+	return heap->objcount;
+}
+
 float Heap_GetUsagePercentage(Heap *heap)
 {
 	return 100.0 * heap->total / heap->size;
@@ -176,6 +193,8 @@ void *Heap_Malloc(Heap *heap, TypeObject *type, Error *err)
 	if(requires_destruct)
 		heap->pend[heap->pend_used++] = (PendingDestruct) { .object = obj, .destructor = obj->type->free };
 
+	heap->objcount += 1;
+
 	return (Object*) addr;
 }
 
@@ -246,7 +265,7 @@ _Bool Heap_StartCollection(Heap *heap, Error *error)
 	heap->oflow = NULL;
 	heap->collecting = 1;
 	heap->collection_failed = 0;
-	heap->moved_with_destructors = 0;
+	heap->movedcount = 0;
 	heap->error = error;
 	return 1;
 }
@@ -311,6 +330,7 @@ _Bool Heap_StopCollection(Heap *heap)
 	free(heap->old_body);
 
 	heap->collecting = 0;
+	heap->objcount = heap->movedcount;
 	return 1;
 }
 
@@ -397,8 +417,7 @@ void Heap_CollectReference(Object **referer, void *userp)
 						((MovedObject*) old_location)->new_location = new_location;
 					}
 
-					if(type->free != NULL)
-						heap->moved_with_destructors += 1;
+					heap->movedcount += 1;
 				}
 
 			// Collect the reference to the type.

src/objects/o_buffer.c

@@ -1,35 +1,57 @@
+#include <stdlib.h>
 #include <assert.h>
 #include <string.h>
 #include "../utils/defs.h"
 #include "objects.h"
 
 typedef struct {
-	int           size,
-	              refs;
-	unsigned char data[];
-} BufferBody;
-
-typedef struct {
-	Object      base;
-	BufferBody *body;
-	int offset, length;
+	Object         base;
+	int            size;
+	unsigned char *body;
 } BufferObject;
 
-static Object *select(Object *self, Object *key, Heap *heap, Error *err);
-static _Bool   insert(Object *self, Object *key, Object *val, Heap *heap, Error *err);
-static int     count(Object *self);
-static void	   print(Object *obj, FILE *fp);
+typedef struct {
+	Object        base;
+	BufferObject *sliced;
+	int           offset, 
+	              length;
+} BufferSliceObject;
+
+static Object *buffer_select(Object *self, Object *key, Heap *heap, Error *err);
+static _Bool   buffer_insert(Object *self, Object *key, Object *val, Heap *heap, Error *err);
+static int     buffer_count(Object *self);
+static void	   buffer_print(Object *obj, FILE *fp);
+static _Bool   buffer_free(Object *self, Error *error);
+
+static Object *slice_select(Object *self, Object *key, Heap *heap, Error *err);
+static _Bool   slice_insert(Object *self, Object *key, Object *val, Heap *heap, Error *err);
+static int     slice_count(Object *self);
+static void	   slice_print(Object *obj, FILE *fp);
+
 
 static TypeObject t_buffer = {
 	.base = (Object) { .type = &t_type, .flags = Object_STATIC },
 	.name = "buffer",
 	.size = sizeof (BufferObject),
-	.select = select,
-	.insert = insert,
-	.count = count,
-	.print = print,
+	.select = buffer_select,
+	.insert = buffer_insert,
+	.count = buffer_count,
+	.print = buffer_print,
+	.free  = buffer_free,
 };
 
+static TypeObject t_buffer_slice = {
+	.base = (Object) { .type = &t_type, .flags = Object_STATIC },
+	.name = "buffer slice",
+	.size = sizeof (BufferSliceObject),
+	.select = slice_select,
+	.insert = slice_insert,
+	.count = slice_count,
+	.print = slice_print,
+};
+
+#define THRESHOLD 128
+
 Object *Object_NewBuffer(int size, Heap *heap, Error *error)
 {
 	assert(size >= 0);
@@ -42,73 +64,147 @@ Object *Object_NewBuffer(int size, Heap *heap, Error *error)
 		if(obj == NULL)
 			return NULL;
 
-		obj->offset = 0;
-		obj->length = size;
-		obj->body = Heap_RawMalloc(heap, sizeof(BufferBody) + sizeof(unsigned char) * size, error);
+		unsigned char *body;
 
-		if(obj->body == NULL)
-			return NULL;
+		if(size > THRESHOLD)
+			{
+				body = malloc(sizeof(unsigned char) * size);
 
-		obj->body->size = size;
-		obj->body->refs = 1;
-		memset(obj->body->data, 0, size);
+				if(body == NULL)
+					{
+						Error_Report(error, 1, "No memory");
+						return NULL;
+					}
+			}
+		else
+			{
+				body = Heap_RawMalloc(heap, sizeof(unsigned char) * size, error);
+				
+				if(body == NULL)
+					return NULL;
+			}
+
+		obj->size = size;
+		obj->body = body;
+		memset(obj->body, 0, size);
 	}
 
 	return (Object*) obj;
 }
 
+static _Bool buffer_free(Object *self, Error *error)
+{
+	(void) error;
+
+	BufferObject *buffer = (BufferObject*) self;
+	
+	if(buffer->size > THRESHOLD)
+		free(buffer->body);
+	return 1;
+}
+
 Object *Object_SliceBuffer(Object *buffer, int offset, int length, Heap *heap, Error *error)
 {
-	if(buffer->type != &t_buffer)
+	if(buffer->type != &t_buffer && buffer->type != &t_buffer_slice)
 		{
-			Error_Report(error, 0, "Not a buffer");
+			Error_Report(error, 0, "Not a buffer or a buffer slice");
 			return NULL;
 		}
 
-	BufferObject *original = (BufferObject*) buffer;
-	BufferObject *slice = (BufferObject*) Heap_Malloc(heap, &t_buffer, error);
+	BufferSliceObject *slice = (BufferSliceObject*) Heap_Malloc(heap, &t_buffer_slice, error);
 
-	if(offset < 0 || offset >= original->length)
+	if(slice == NULL)
+		return NULL;
+
+	if(buffer->type == &t_buffer)
 		{
-			Error_Report(error, 0, "offset out of range");
-			return NULL;
+			BufferObject *original = (BufferObject*) buffer;
+
+			if(offset < 0 || offset >= original->size)
+				{
+					Error_Report(error, 0, "offset out of range");
+					return NULL;
+				}
+
+			if(length < 0 || length >= original->size)
+				{
+					Error_Report(error, 0, "length out of range");
+					return NULL;
+				}
+
+			if(offset + length > original->size)
+				{
+					Error_Report(error, 0, "slice out of range");
+					return NULL;
+				}
+
+			slice->sliced = original;
+			slice->offset = offset;
+			slice->length = length;
+		}
+	else
+		{
+			assert(buffer->type == &t_buffer_slice);
+
+			BufferSliceObject *original = (BufferSliceObject*) buffer;
+
+			if(offset < 0 || offset >= original->length)
+				{
+					Error_Report(error, 0, "offset out of range");
+					return NULL;
+				}
+
+			if(length < 0 || length >= original->length)
+				{
+					Error_Report(error, 0, "length out of range");
+					return NULL;
+				}
+
+			if(offset + length > original->length)
+				{
+					Error_Report(error, 0, "slice out of range");
+					return NULL;
+				}
+
+			slice->sliced = original->sliced;
+			slice->offset = original->offset + offset;
+			slice->length = length;
 		}
 
-	if(length < 0 || length >= original->length)
-		{
-			Error_Report(error, 0, "length out of range");
-			return NULL;
-		}
-
-	if(offset + length > original->length)
-		{
-			Error_Report(error, 0, "slice out of range");
-			return NULL;
-		}
-
-	slice->offset = original->offset + offset;
-	slice->length = length;
-	slice->body = original->body;
-	slice->body->refs += 1;
 	return (Object*) slice;
 }
 
 void *Object_GetBufferAddrAndSize(Object *obj, int *size, Error *error)
 {
-	if(obj->type != &t_buffer)
+	if(obj->type != &t_buffer && obj->type != &t_buffer_slice)
 		{
-			Error_Report(error, 0, "Not a buffer");
+			Error_Report(error, 0, "Not a buffer or a buffer slice");
 			return NULL;
 		}
 
-	BufferObject *buf = (BufferObject*) obj;
+	if(obj->type == &t_buffer)
+		{
+			BufferObject *buffer = (BufferObject*) obj;
+		
+			if(size)
+				*size = buffer->size;
 
-	if(size)
-		*size = buf->length;
-	return buf->body->data + buf->offset;
+			return buffer->body;
+		}
+	else
+		{
+			assert(obj->type == &t_buffer_slice);
+
+			BufferSliceObject *slice = (BufferSliceObject*) obj;
+
+			if(size)
+				*size = slice->length;
+
+			return slice->sliced->body + slice->offset;
+		}
 }
 
-static Object *select(Object *self, Object *key, Heap *heap, Error *error)
+static Object *buffer_select(Object *self, Object *key, Heap *heap, Error *error)
 {
 	assert(self != NULL);
 	assert(self->type == &t_buffer);
@@ -127,18 +223,48 @@ static Object *select(Object *self, Object *key, Heap *heap, Error *error)
 
 	BufferObject *buffer = (BufferObject*) self;
 
-	if(idx < 0 || idx >= buffer->length)
+	if(idx < 0 || idx >= buffer->size)
 		{
 			Error_Report(error, 0, "Out of range index");
 			return NULL;
 		}
 
-	unsigned char byte = buffer->body->data[buffer->offset + idx];
+	unsigned char byte = buffer->body[idx];
 
 	return Object_FromInt(byte, heap, error);
 }
 
-static _Bool insert(Object *self, Object *key, Object *val, Heap *heap, Error *error)
+static Object *slice_select(Object *self, Object *key, Heap *heap, Error *error)
+{
+	assert(self != NULL);
+	assert(self->type == &t_buffer_slice);
+	assert(key != NULL);
+	assert(heap != NULL);
+	assert(error != NULL);
+
+	if(!Object_IsInt(key))
+		{
+			Error_Report(error, 0, "Non integer key");
+			return NULL;
+		}
+
+	int idx = Object_ToInt(key, error);
+	assert(error->occurred == 0);
+
+	BufferSliceObject *slice = (BufferSliceObject*) self;
+
+	if(idx < 0 || idx >= slice->length)
+		{
+			Error_Report(error, 0, "Out of range index");
+			return NULL;
+		}
+
+	unsigned char byte = slice->sliced->body[slice->offset + idx];
+
+	return Object_FromInt(byte, heap, error);
+}
+
+static _Bool buffer_insert(Object *self, Object *key, Object *val, Heap *heap, Error *error)
 {
 	assert(error != NULL);
 	assert(key != NULL);
@@ -158,39 +284,95 @@ static _Bool insert(Object *self, Object *key, Object *val, Heap *heap, Error *e
 	int idx = Object_ToInt(key, error);
 	assert(error->occurred == 0);
 
-	if(idx < 0 || idx >= buffer->length)
+	if(idx < 0 || idx >= buffer->size)
 		{
 			Error_Report(error, 0, "Out of range index");
 			return NULL;
 		}
 
-	unsigned char byte = Object_ToInt(val, error);
+	long long int qword = Object_ToInt(val, error);
+
+	if(qword > 255 || qword < 0)
+		{
+			Error_Report(error, 0, "Not in range [0, 255]");
+			return NULL;
+		}
+
+	unsigned char byte = qword & 0xff;
 
 	if(error->occurred == 1)
 		return 0;
 
-	buffer->body->data[buffer->offset + idx] = byte;
+	buffer->body[idx] = byte;
 	return 1;
 }
 
-static int count(Object *self)
+static _Bool slice_insert(Object *self, Object *key, Object *val, Heap *heap, Error *error)
 {
-	BufferObject *buffer = (BufferObject*) self;
+	assert(error != NULL);
+	assert(key != NULL);
+	assert(val != NULL);
+	assert(heap != NULL);
+	assert(self != NULL);
+	assert(self->type == &t_buffer_slice);
 
-	return buffer->length;
+	BufferSliceObject *slice = (BufferSliceObject*) self;
+
+	if(!Object_IsInt(key))
+		{
+			Error_Report(error, 0, "Non integer key");
+			return NULL;
+		}
+
+	int idx = Object_ToInt(key, error);
+	assert(error->occurred == 0);
+
+	if(idx < 0 || idx >= slice->length)
+		{
+			Error_Report(error, 0, "Out of range index");
+			return NULL;
+		}
+
+	long long int qword = Object_ToInt(val, error);
+
+	if(qword > 255 || qword < 0)
+		{
+			Error_Report(error, 0, "Not in range [0, 255]");
+			return NULL;
+		}
+
+	unsigned char byte = qword & 0xff;
+
+	if(error->occurred == 1)
+		return 0;
+
+	slice->sliced->body[slice->offset + idx] = byte;
+	return 1;
 }
 
-static void print(Object *self, FILE *fp)
+static int buffer_count(Object *self)
 {
 	BufferObject *buffer = (BufferObject*) self;
 
+	return buffer->size;
+}
+
+static int slice_count(Object *self)
+{
+	BufferSliceObject *slice = (BufferSliceObject*) self;
+
+	return slice->length;
+}
+
+static void print_bytes(FILE *fp, unsigned char *addr, int size)
+{
 	fprintf(fp, "[");
 
-	for(int i = 0; i < buffer->length; i += 1)
+	for(int i = 0; i < size; i += 1)
 		{
 			unsigned char byte, low, high;
 
-			byte = buffer->body->data[buffer->offset + i];
+			byte = addr[i];
 			low  = byte & 0xf;
 			high = byte >> 4;
 
@@ -204,8 +386,20 @@ static void print(Object *self, FILE *fp)
 
 			fprintf(fp, "%c%c", c1, c2);
 
-			if(i+1 < buffer->length)
+			if(i+1 < size)
 				fprintf(fp, ", ");
 		}
 	fprintf(fp, "]");
+}
+
+static void buffer_print(Object *self, FILE *fp)
+{
+	BufferObject *buffer = (BufferObject*) self;
+	print_bytes(fp, buffer->body, buffer->size);
+}
+
+static void slice_print(Object *self, FILE *fp)
+{
+	BufferSliceObject *slice = (BufferSliceObject*) self;
+	print_bytes(fp, slice->sliced->body + slice->offset, slice->length);
 }

src/objects/objects.c

@@ -364,12 +364,14 @@ _Bool Object_Compare(Object *obj1, Object *obj2, Error *error)
 
 void Object_WalkReferences(Object *parent, void (*callback)(Object **referer, void *userp), void *userp)
 {
+	assert(parent != NULL);
 	if(parent->type->walk != NULL)
 		parent->type->walk(parent, callback, userp);
 }
 
 void Object_WalkExtensions(Object *parent, void (*callback)(void **referer, unsigned int size, void *userp), void *userp)
 {
+	assert(parent != NULL);
 	if(parent->type->walkexts != NULL)
 		parent->type->walkexts(parent, callback, userp);
 }

src/objects/objects.h

@@ -81,6 +81,9 @@ _Bool 	 	 Heap_StartCollection(Heap *heap, Error *error);
 _Bool 	  	 Heap_StopCollection(Heap *heap);
 void  	 	 Heap_CollectReference(Object **referer, void *heap);
 float 		 Heap_GetUsagePercentage(Heap *heap);
+unsigned int Heap_GetObjectCount(Heap *heap);
+void        *Heap_GetPointer(Heap *heap);
+unsigned int Heap_GetSize(Heap *heap);
 
 const TypeObject* Object_GetType(const Object *obj);
 const char*	 Object_GetName(const Object *obj);

src/runtime/runtime.c

@@ -6,8 +6,8 @@
 #define MAX_FRAME_STACK 16
 #define MAX_FRAMES 16
 
-typedef struct Frame Frame;
-struct Frame {
+typedef struct xFrame Frame;
+struct xFrame {
 	Frame  *prev;
 	Object *locals;
 	Object *closure;
@@ -25,6 +25,39 @@ struct xRuntime {
 	Heap  *heap;
 };
 
+CallStackScanner *CallStackScanner_New(Runtime *runtime)
+{
+	return runtime->frame;
+}
+
+_Bool CallStackScanner_Next(CallStackScanner **scanner, Object **locals, Object **closure, Executable **exe, int *index)
+{
+	assert(scanner != NULL);
+
+	if(*scanner == NULL)
+		return 0;
+		
+	{
+		Frame *frame = *scanner;
+
+		if(exe) 
+			*exe = frame->exe;
+		
+		if(index) 
+			*index = frame->index;
+
+		if(locals) 
+			*locals = frame->locals;
+		
+		if(closure) 
+			*closure = frame->closure;
+	}
+
+	(*scanner) = ((Frame*) (*scanner))->prev;
+	return 1;
+}
+
+
 Stack *Runtime_GetStack(Runtime *runtime)
 {
 	return Stack_Copy(runtime->stack, 1);

src/runtime/runtime.h

@@ -7,6 +7,7 @@
 #include "../common/executable.h"
 
 typedef struct xRuntime Runtime;
+typedef void CallStackScanner;
 Runtime*	Runtime_New(int stack_size, int heap_size, void *callback_userp, _Bool (*callback_addr)(Runtime*, void*));
 void 		Runtime_Free(Runtime *runtime);
 _Bool 		Runtime_Pop(Runtime *runtime, Error *error, unsigned int n);
@@ -23,6 +24,10 @@ Snapshot *Snapshot_New(Runtime *runtime);
 void 	  Snapshot_Free(Snapshot *snapshot);
 void 	  Snapshot_Print(Snapshot *snapshot, FILE *fp);
 
+CallStackScanner *CallStackScanner_New(Runtime *runtime);
+_Bool             CallStackScanner_Next(CallStackScanner **scanner, Object **locals, Object **closure, Executable **exe, int *index);
+
+
 Object *run(Runtime *runtime, Error *error, Executable *exe, int index, Object *closure, Object **argv, int argc);
 
 Object*	Object_FromNativeFunction(Runtime *runtime, Object *(*callback)(Runtime*, Object**, unsigned int, Error*), int argc, Heap *heap, Error *error);