feat: implement objects and classes

.gdbinit

@@ -2,4 +2,17 @@ skip peek
 skip consume
 skip next
 skip is
+skip fzl_mknode
+skip fzl_mktoken
+skip fzl_symt_put
+skip fzl_symt_get
+skip add_const
+skip push_op
+skip push_word
+skip fzl_mkenv
+skip fzl_freeenv
+skip fzl_env_lookup
+skip fzl_env_contains
+skip fzl_env_storevalue
+skip fzl_env_writevalue
 

CMakeLists.txt

@@ -18,6 +18,7 @@ add_executable(fzc
 	src/compiler/utils/fzl_symtable.c
 	src/compiler/utils/fzl_linked.c
 	src/compiler/utils/fzl_options.c
+	src/compiler/utils/fzl_ctable.c
 	src/compiler/main.c)
 
 # Virtual machine

README.md

@@ -18,6 +18,8 @@ At the moment, the language has the following capabilities:
   - `str` - strings
   - `bool` - boolean
 - Assignments
+- Functions
+- Classes and objects
 
 Working examples of code can be found in `exl/` directory.
 

README.ru.md

@@ -9,7 +9,7 @@
 На данный момент язык имеет:
 
 - Встроенную функцию `printline` для вывода аргумента в stdout
-- Строковый и числовой литералы
+- Строковый, булев и числовой литералы
 - Арифметические операции: сложение, вычитание, умножение, деление, модуло, возведение в степень
 - Декларация переменных со следующими типами:
   - `uint`, `int` - целые числа размером с машинное слово
@@ -18,6 +18,8 @@
   - `str` - строки
   - `bool` - булевы
 - Присваивание
+- Функции
+- Классы и объекты
 
 Примеры кода лежат в директории `exl/`.
 

exl/class.fzs

@@ -10,9 +10,6 @@ class Point
   }
 }
 
-// NOTE: WHY THE FUCK THIS FUCKING COMPILER REQUIRES ';' AFTER '='?!
-//         |
-//         v
 Point obj = new Point;
 obj.x = 1;
 obj.y = 2;
@@ -21,6 +18,9 @@ printline("Current X,Y:");
 printline(obj.x);
 printline(obj.y);
 
+// NOTE: WHY THE FUCK THIS FUCKING COMPILER REQUIRES ';' AFTER '='?!
+//      |
+//      v
 obj.move(9, 8);
 printline("X,Y after move:");
 printline(obj.x);

exl/fn.fzs

@@ -1,4 +1,4 @@
-int fib(int n)
+fn fib(int n) int
 {
   if (n <= 1)
     return n;
@@ -6,7 +6,7 @@ int fib(int n)
   return fib(n - 1) + fib(n - 2);
 }
 
-uint sum(uint a, uint b)
+fn sum(uint a, uint b) uint
 {
   return a + b;
 }

include/common/fzl_opcodes.h

@@ -21,6 +21,10 @@ typedef enum
   FZL_OPCODE_CALL = 0xF30001, // Call function
   FZL_OPCODE_RET  = 0xF30002, // Return from function
 
+  FZL_OPCODE_ALLOC_OBJECT = 0xFA0001, // Allocate N slots
+  FZL_OPCODE_GET_FIELD    = 0xFA0002, // Get field N of an object at dstack
+  FZL_OPCODE_SET_FIELD    = 0xFA0003, // Set field N of an object at dstack
+
   FZL_OPCODE_ADD = 0xA00001, // Sum two numbers in dstack
   FZL_OPCODE_SUB = 0xA00002, // Subract two numbers in dstack
   FZL_OPCODE_MUL = 0xA00003, // Multiply two numbers in dstack

include/common/fzl_types.h

@@ -4,6 +4,7 @@
 typedef enum
 {
   FZL_TYPE_NULL,
+  FZL_TYPE_OBJECT,
 
   FZL_TYPE_STRING,
   FZL_TYPE_CHAR,

include/common/fzl_value.h

@@ -13,6 +13,8 @@ typedef struct
 
   union
   {
+    void *obj;
+
     struct
     {
       const char *value;

include/compiler/fzl_parser.h

@@ -17,6 +17,7 @@ typedef enum
   FZL_NODETYPE_RETURN,
   FZL_NODETYPE_CLASS,
   FZL_NODETYPE_FIELD,
+  FZL_NODETYPE_CONSTRUCT,
 
   FZL_NODETYPE_ADD,
   FZL_NODETYPE_SUB,
@@ -133,6 +134,12 @@ typedef struct fzl_node
       struct fzl_node *parent;
       struct fzl_node *field;
     } memb;
+
+    // Object construct
+    struct
+    {
+      struct fzl_node *name;
+    } construct;
   };
 } fzl_node_t;
 

include/compiler/fzl_walker.h

@@ -5,10 +5,20 @@
 #include <common/fzl_types.h>
 #include <compiler/fzl_parser.h>
 #include <compiler/utils/fzl_const_pool.h>
+#include <compiler/utils/fzl_ctable.h>
 #include <compiler/utils/fzl_symtable.h>
 #include <stdbool.h>
 #include <stddef.h>
 
+// Type of context
+typedef enum
+{
+  FZL_WALK_CTX_TYPE_GLOBAL,
+  FZL_WALK_CTX_TYPE_FN,
+  FZL_WALK_CTX_TYPE_CLASS,
+  FZL_WALK_CTX_TYPE_ASSIGN
+} fzl_walk_ctx_type_t;
+
 // Internal walk function result
 typedef struct
 {
@@ -16,11 +26,16 @@ typedef struct
 
   char *error_msg;
   bool error;
+
+  char *classname;
 } fzl_walk_res_t;
 
 // Function context descriptor
-typedef struct
+typedef struct fzl_walk_ctx
 {
+  fzl_walk_ctx_type_t type;
+  struct fzl_walk_ctx *parent;
+
   fzl_node_t *fn;
   size_t initial_env_lvl;
 } fzl_walk_ctx_t;
@@ -39,6 +54,9 @@ typedef struct
   size_t sym_top;
 
   fzl_walk_ctx_t *ctx;
+
+  fzl_ctable_t *classes[64];
+  size_t classes_count;
 } fzl_walker_t;
 
 // Allocate new walker

include/compiler/utils/fzl_ctable.h

@@ -0,0 +1,30 @@
+#ifndef FZL_CTABLE_H
+#define FZL_CTABLE_H
+
+#include <common/fzl_types.h>
+#include <stddef.h>
+
+// Class field descriptor
+typedef struct
+{
+  char *name;
+  size_t slot_index;
+  fzl_type_t type;
+} fzl_ctable_field_t;
+
+// Class table descriptor
+typedef struct
+{
+  char *name;
+  fzl_ctable_field_t *fields;
+  size_t fields_count;
+  size_t fields_remainder;
+} fzl_ctable_t;
+
+// Allocate class table
+fzl_ctable_t *fzl_mkctable(char *name);
+
+// Free class table
+void fzl_freectable(fzl_ctable_t *ct);
+
+#endif // FZL_CTABLE_H

include/compiler/utils/fzl_symtable.h

@@ -10,7 +10,8 @@ typedef enum
 {
   FZL_SYMTABLE_RESULT_OK,
   FZL_SYMTABLE_RESULT_ERR,
-  FZL_SYMTABLE_RESULT_EXISTS
+  FZL_SYMTABLE_RESULT_EXISTS,
+  FZL_SYMTABLE_RESULT_NOT_OBJECT
 } fzl_symtable_res_t;
 
 // Symbols table entry descriptor
@@ -19,6 +20,8 @@ typedef struct
   char *name;
   fzl_type_t type;
   size_t ip;
+
+  char *classname;
 } fzl_sym_t;
 
 // Symbols table descriptor
@@ -37,6 +40,10 @@ fzl_symtable_t *fzl_mksymt();
 fzl_symtable_res_t fzl_symt_put(fzl_symtable_t *symt, char *name,
                                 fzl_type_t type, uint64_t ip);
 
+// Assign class name to object type
+fzl_symtable_res_t fzl_symt_setobjclass(fzl_symtable_t *symt, char *name,
+                                        char *classname);
+
 // Get entry from specified symtable
 bool fzl_symt_get(fzl_symtable_t *symt, char *name, fzl_sym_t *res);
 

include/vm/fzl_vm.h

@@ -6,6 +6,7 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <vm/fzl_vm_env.h>
+#include <vm/fzl_vm_object.h>
 
 // VM descriptor
 typedef struct
@@ -29,6 +30,9 @@ typedef struct
   // Environment stack
   fzl_vm_env_t *estack[256];
   size_t etop;
+
+  fzl_vm_object_t *objects[256];
+  size_t objects_count;
 } fzl_vm_t;
 
 // Allocate FZL VM

include/vm/fzl_vm_object.h

@@ -0,0 +1,14 @@
+#ifndef FZL_VM_OBJECT_H
+#define FZL_VM_OBJECT_H
+
+#include <common/fzl_value.h>
+#include <stddef.h>
+
+// Object descriptor
+typedef struct
+{
+  fzl_value_t *values;
+  size_t values_count;
+} fzl_vm_object_t;
+
+#endif // FZL_VM_OBJECT_H

src/compiler/fzl_debug.c

@@ -32,6 +32,27 @@ void print_node(fzl_node_t *node, int level)
 
   switch (node->type)
   {
+    case FZL_NODETYPE_CONSTRUCT:
+      printf("%s Construct class '%s':\n", levelbuf,
+             (char *)node->construct.name->token->value);
+      break;
+
+    case FZL_NODETYPE_CLASS:
+      printf("%s Class '%s':\n", levelbuf, (char *)node->token->value);
+      printf("-%s Fields:\n", levelbuf);
+      for (size_t i = 0; i < node->class.fields_count; i++)
+        print_node(node->class.fields[i], level + 2);
+      printf("-%s Methods:\n", levelbuf);
+      for (size_t i = 0; i < node->class.methods_count; i++)
+        print_node(node->class.methods[i], level + 2);
+      break;
+
+    case FZL_NODETYPE_FIELD:
+      printf("%s Field '%s' access:\n", levelbuf,
+             (char *)node->memb.field->token->value);
+      print_node(node->memb.parent, level + 1);
+      break;
+
     case FZL_NODETYPE_DECLARATION:
       printf("%s Declare variable with type %d:\n", levelbuf,
              node->var.type->type);
@@ -112,6 +133,8 @@ void print_node(fzl_node_t *node, int level)
         print_node(node->ret.value, level + 1);
       break;
 
+    case FZL_NODETYPE_AND:
+    case FZL_NODETYPE_OR:
     case FZL_NODETYPE_EQUAL:
     case FZL_NODETYPE_NEQUAL:
     case FZL_NODETYPE_LESS:

src/compiler/fzl_parser.c

@@ -72,8 +72,9 @@ static fzl_token_t *next(fzl_parser_t *parser)
 // Consume token at cursor and move to the next
 static fzl_token_t *consume(fzl_parser_t *parser)
 {
-  if (!parser || !parser->cursor)
+  if (!parser || !parser->cursor || !parser->cursor->token)
     return NULL;
+
   fzl_token_t *tok = parser->cursor->token;
   parser->cursor   = parser->cursor->next;
   return tok;
@@ -222,71 +223,75 @@ fzl_node_t *parse_postfix(fzl_parser_t *parser)
     return NULL;
   }
 
-  if (is(parser, FZL_TOKTYPE_LPAREN))
+  if (is(parser, FZL_TOKTYPE_LPAREN) || is(parser, FZL_TOKTYPE_DOT))
   {
-    while (is(parser, FZL_TOKTYPE_LPAREN))
+    while (is(parser, FZL_TOKTYPE_LPAREN) || is(parser, FZL_TOKTYPE_DOT))
     {
-      consume(parser);
+      fzl_token_t *post = consume(parser);
 
-      size_t args_capacity = 2;
-      size_t args_count    = 0;
-      fzl_node_t **args    = malloc(args_capacity * sizeof(fzl_node_t *));
-
-      while (!is(parser, FZL_TOKTYPE_RPAREN))
+      if (post->type == FZL_TOKTYPE_LPAREN)
       {
-        fzl_node_t *arg = parse_expression(parser);
-        if (!arg)
+        size_t args_capacity = 2;
+        size_t args_count    = 0;
+        fzl_node_t **args    = malloc(args_capacity * sizeof(fzl_node_t *));
+
+        while (!is(parser, FZL_TOKTYPE_RPAREN))
+        {
+          fzl_node_t *arg = parse_expression(parser);
+          if (!arg)
+          {
+            free(args);
+            return NULL;
+          }
+
+          if (args_capacity <= args_count)
+          {
+            args_capacity *= 2;
+            args = realloc(args, args_capacity * sizeof(fzl_node_t));
+          }
+
+          args[args_count] = arg;
+          args_count++;
+
+          if (is(parser, FZL_TOKTYPE_COMMA))
+            consume(parser);
+        }
+
+        fzl_token_t *rparen = consume(parser);
+        if (!rparen || rparen->type != FZL_TOKTYPE_RPAREN)
         {
           free(args);
+          snprintf(plast_err, sizeof(plast_err),
+                   "'%s': expected ')' after argument list at %ld:%ld",
+                   peek(parser)->filename, peek(parser)->ln, peek(parser)->cn);
           return NULL;
         }
 
-        if (args_capacity <= args_count)
+        fzl_node_t *node      = fzl_mknode(FZL_NODETYPE_CALL, left->token);
+        node->call.callee     = left;
+        node->call.args       = args;
+        node->call.args_count = args_count;
+
+        left = node;
+      }
+      else if (post->type == FZL_TOKTYPE_DOT)
+      {
+        if (!is(parser, FZL_TOKTYPE_NAME))
         {
-          args_capacity *= 2;
-          args = realloc(args, args_capacity * sizeof(fzl_node_t));
+          snprintf(plast_err, sizeof(plast_err),
+                   "'%s': expected name after '.' at %ld:%ld",
+                   last_known_tok->filename, last_known_tok->ln,
+                   last_known_tok->cn);
+          return NULL;
         }
 
-        args[args_count] = arg;
-        args_count++;
+        fzl_token_t *name = consume(parser);
+        fzl_node_t *node  = fzl_mknode(FZL_NODETYPE_FIELD, name);
+        node->memb.parent = left;
+        node->memb.field  = fzl_mknode(FZL_NODETYPE_IDENTIFIER, name);
 
-        if (is(parser, FZL_TOKTYPE_COMMA))
-          consume(parser);
+        left = node;
       }
-
-      fzl_token_t *rparen = consume(parser);
-      if (!rparen || rparen->type != FZL_TOKTYPE_RPAREN)
-      {
-        free(args);
-        snprintf(plast_err, sizeof(plast_err),
-                 "'%s': expected ')' after argument list at %ld:%ld",
-                 peek(parser)->filename, peek(parser)->ln, peek(parser)->cn);
-        return NULL;
-      }
-
-      fzl_node_t *node      = fzl_mknode(FZL_NODETYPE_CALL, left->token);
-      node->call.callee     = left;
-      node->call.args       = args;
-      node->call.args_count = args_count;
-
-      left = node;
-    }
-  }
-  else if (is(parser, FZL_TOKTYPE_DOT))
-  {
-    while (is(parser, FZL_TOKTYPE_DOT))
-    {
-      consume(parser);
-
-      fzl_node_t *right = parse_primary(parser);
-      if (!right)
-        return NULL;
-
-      fzl_node_t *node  = fzl_mknode(FZL_NODETYPE_FIELD, right->token);
-      node->memb.parent = left;
-      node->memb.field  = right;
-
-      left = node;
     }
   }
 
@@ -567,10 +572,33 @@ fzl_node_t *parse_or(fzl_parser_t *parser)
   return left;
 }
 
+// Object construct parsing
+fzl_node_t *parse_new(fzl_parser_t *parser)
+{
+  if (!is(parser, FZL_TOKTYPE_NEW))
+    return parse_or(parser);
+
+  fzl_token_t *new    = consume(parser);
+  fzl_node_t *objname = parse_or(parser);
+  if (objname->type != FZL_NODETYPE_IDENTIFIER &&
+      objname->type != FZL_NODETYPE_FIELD)
+  {
+    snprintf(plast_err, sizeof(plast_err),
+             "'%s': expect class name after 'new' keyword at %ld:%ld",
+             last_known_tok->filename, last_known_tok->ln, last_known_tok->cn);
+    return NULL;
+  }
+
+  fzl_node_t *node     = fzl_mknode(FZL_NODETYPE_CONSTRUCT, new);
+  node->construct.name = objname;
+
+  return node;
+}
+
 // Assignments parsing
 fzl_node_t *parse_assignment(fzl_parser_t *parser)
 {
-  fzl_node_t *left = parse_or(parser);
+  fzl_node_t *left = parse_new(parser);
   if (!left)
     return NULL;
 
@@ -1090,6 +1118,15 @@ void fzl_freeast(fzl_node_t *root)
           fzl_freenode(root->class.methods[i]);
       free(root->class.methods);
     }
+    else if (root->type == FZL_NODETYPE_CONSTRUCT)
+    {
+      fzl_freenode(root->construct.name);
+    }
+    else if (root->type == FZL_NODETYPE_FIELD)
+    {
+      fzl_freenode(root->memb.field);
+      fzl_freenode(root->memb.parent);
+    }
 
     root = root->next;
     free(root);

src/compiler/fzl_walker.c

@@ -5,6 +5,7 @@
 #include <compiler/fzl_token.h>
 #include <compiler/fzl_walker.h>
 #include <compiler/utils/fzl_const_pool.h>
+#include <compiler/utils/fzl_ctable.h>
 #include <compiler/utils/fzl_symtable.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -52,7 +53,9 @@ fzl_walker_t *fzl_mkwalker(fzl_node_t *root)
     return NULL;
   }
 
-  walker->ctx = NULL;
+  walker->ctx           = NULL;
+  walker->classes_count = 0;
+  memset(walker->classes, 0, sizeof(walker->classes));
 
   return walker;
 }
@@ -103,6 +106,36 @@ static bool is_compatible(fzl_type_t t1, fzl_type_t t2)
   return t1 >= FZL_TYPE_INT8 && t2 >= FZL_TYPE_INT8;
 }
 
+// Add one layer of ctx
+fzl_walk_ctx_t *nest_ctx(fzl_walker_t *walker, fzl_walk_ctx_type_t type)
+{
+  if (!walker)
+    return NULL;
+
+  fzl_walk_ctx_t *newctx = malloc(sizeof(fzl_walk_ctx_t));
+  if (!newctx)
+    return NULL;
+
+  newctx->type   = type;
+  newctx->parent = walker->ctx;
+  walker->ctx    = newctx;
+
+  return walker->ctx;
+}
+
+// Go outside current ctx and then clean it
+fzl_walk_ctx_t *fin_ctx(fzl_walker_t *walker)
+{
+  if (!walker)
+    return NULL;
+
+  fzl_walk_ctx_t *curr = walker->ctx;
+  walker->ctx          = walker->ctx->parent;
+
+  free(curr);
+  return walker->ctx;
+}
+
 // Add const to consts table
 size_t add_const(fzl_walker_t *walker, fzl_const_t c)
 {
@@ -154,6 +187,178 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
   {
     switch (node->type)
     {
+      case FZL_NODETYPE_CLASS:
+      {
+        fzl_walk_ctx_t *newctx = nest_ctx(walker, FZL_WALK_CTX_TYPE_CLASS);
+        if (!newctx)
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to nest context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        newctx->fn              = node;
+        newctx->initial_env_lvl = walker->sym_top;
+
+        walker->classes[walker->classes_count] =
+            fzl_mkctable(node->class.name->value);
+        fzl_ctable_t *class = walker->classes[walker->classes_count++];
+        class->name         = node->class.name->value;
+
+        for (size_t i = 0; i < node->class.fields_count; i++)
+        {
+          if (class->fields_remainder <= class->fields_count)
+          {
+            class->fields_remainder *= 2;
+            class->fields =
+                realloc(class->fields,
+                        class->fields_remainder * sizeof(fzl_ctable_field_t));
+          }
+
+          class->fields[class->fields_count] = (fzl_ctable_field_t){
+              .name       = node->class.fields[i]->var.identifier->token->value,
+              .type       = tok_to_type(node->class.fields[i]->var.type),
+              .slot_index = class->fields_count++};
+        }
+
+        for (size_t i = 0; i < node->class.methods_count; i++)
+        {
+          fzl_node_t *fn = node->class.methods[i];
+
+          size_t classname_len = strlen(class->name);
+          size_t fnname_len    = strlen(fn->fn.name->value);
+          char *method_name    = malloc(classname_len + fnname_len + 2);
+
+          strcpy(method_name, class->name);
+          method_name[classname_len] = '_';
+          strcpy((method_name + classname_len + 1), fn->fn.name->value);
+          method_name[classname_len + fnname_len + 1] = 0;
+
+          fn->fn.name->value   = method_name;
+          fzl_walk_res_t fnres = walk(walker, fn);
+          if (fnres.error)
+            return fnres;
+        }
+
+        if (!fin_ctx(walker))
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to clean context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        current_res = (fzl_walk_res_t){.type = FZL_TYPE_NULL, .error = false};
+        break;
+      }
+
+      case FZL_NODETYPE_CONSTRUCT:
+      {
+        fzl_node_t *classname = node->construct.name;
+        fzl_ctable_t *ct      = NULL;
+        for (size_t i = 0; i < walker->classes_count; i++)
+        {
+          if (strcmp((char *)classname->token->value,
+                     walker->classes[i]->name) == 0)
+          {
+            ct = walker->classes[i];
+            break;
+          }
+        }
+        if (!ct)
+        {
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "'%s': class '%s' not found (at %ld:%ld)",
+                   classname->token->filename, (char *)classname->token->value,
+                   classname->token->ln, classname->token->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        push_op(walker, FZL_OPCODE_ALLOC_OBJECT);
+        push_word(walker, ct->fields_count);
+
+        current_res = (fzl_walk_res_t){
+            .type = FZL_TYPE_OBJECT, .error = false, .classname = ct->name};
+        break;
+      }
+
+      case FZL_NODETYPE_FIELD:
+      {
+        fzl_sym_t sym;
+        bool exists = false;
+        for (ssize_t i = walker->sym_top - 1; i >= 0; i--)
+          if ((exists = fzl_symt_get(walker->syms[i],
+                                     node->memb.parent->token->value, &sym)))
+            break;
+
+        if (!exists)
+        {
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "'%s': cannot find symbol '%s' at %ld:%ld",
+                   node->token->filename, (char *)node->token->value,
+                   node->token->ln, node->token->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        if (!sym.classname)
+        {
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "'%s': '%s' is not an object (at %ld:%ld)",
+                   node->token->filename, sym.name, node->token->ln,
+                   node->token->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        fzl_ctable_t *ct = NULL;
+        for (size_t i = 0; i < walker->classes_count; i++)
+        {
+          if (strcmp(sym.classname, walker->classes[i]->name) == 0)
+          {
+            ct = walker->classes[i];
+            break;
+          }
+        }
+
+        fzl_token_t *tok = node->memb.parent->token;
+        if (!ct)
+        {
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "'%s': access to unknown class '%s' at %ld:%ld",
+                   tok->filename, (char *)tok->value, tok->ln, tok->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        fzl_token_t *ftok = node->memb.field->token;
+        fzl_ctable_field_t ctf;
+        bool field_exists = false;
+        for (size_t i = 0; i < ct->fields_count; i++)
+        {
+          if (strcmp(ftok->value, ct->fields[i].name) == 0)
+          {
+            field_exists = true;
+            ctf          = ct->fields[i];
+            break;
+          }
+        }
+
+        if (!field_exists)
+        {
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "'%s': cannot find field '%s' in class '%s' at %ld:%ld",
+                   ftok->filename, (char *)ftok->value, (char *)tok->value,
+                   ftok->ln, ftok->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        fzl_walk_res_t parent_res = walk(walker, node->memb.parent);
+        if (parent_res.error)
+          return parent_res;
+
+        push_op(walker, FZL_OPCODE_GET_FIELD);
+        push_word(walker, ctf.slot_index);
+
+        current_res = (fzl_walk_res_t){
+            .type = ctf.type, .error = false, .classname = sym.classname};
+        break;
+      }
+
       case FZL_NODETYPE_FUNCTION:
       {
         push_op(walker, FZL_OPCODE_JMP);
@@ -183,9 +388,17 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         // NOTE: add sym_top limit check
         size_t lvl                      = walker->sym_top;
         walker->syms[walker->sym_top++] = fzl_mksymt();
-        walker->ctx                     = malloc(sizeof(fzl_walk_ctx_t));
-        walker->ctx->fn                 = node;
-        walker->ctx->initial_env_lvl    = lvl;
+
+        fzl_walk_ctx_t *newctx = nest_ctx(walker, FZL_WALK_CTX_TYPE_FN);
+        if (!newctx)
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to nest context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
+        newctx->type            = FZL_WALK_CTX_TYPE_FN;
+        newctx->fn              = node;
+        newctx->initial_env_lvl = lvl;
 
         push_op(walker, FZL_OPCODE_MK_ENVTABLE);
 
@@ -205,18 +418,25 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         // near future
 
         push_op(walker, FZL_OPCODE_RM_ENVTABLE);
+        push_op(walker, FZL_OPCODE_RET);
         walker->ops[skip_ip] = walker->op_count;
 
-        walker->ctx = NULL; // NOTE: think about nested function defs (not now)
+        if (!fin_ctx(walker))
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to clean context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
         for (ssize_t i = walker->sym_top - 1; i >= lvl; i--)
           fzl_freesymt(walker->syms[--walker->sym_top]);
 
+        current_res = (fzl_walk_res_t){.type = fntype, .error = false};
         break;
       }
 
       case FZL_NODETYPE_RETURN:
       {
-        if (!walker->ctx)
+        if (!walker->ctx || walker->ctx->type != FZL_WALK_CTX_TYPE_FN)
         {
           snprintf(
               wlast_err, sizeof(wlast_err),
@@ -415,7 +635,8 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         push_word(walker, n);
         push_op(walker, FZL_OPCODE_LOOKUP_ENV);
 
-        current_res = (fzl_walk_res_t){.type = sym.type, .error = false};
+        current_res = (fzl_walk_res_t){
+            .type = sym.type, .error = false, .classname = sym.classname};
         break;
       }
 
@@ -434,18 +655,18 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         break;
 
       case FZL_NODETYPE_CALL:
-        if (node->call.args_count > 0)
-        {
-          for (size_t i = 0; i < node->call.args_count; i++)
-          {
-            fzl_walk_res_t res = walk(walker, node->call.args[i]);
-            if (res.error)
-              return res;
-          }
-        }
-
         if (strcmp(node->token->value, "printline") == 0)
         {
+          if (node->call.args_count > 0)
+          {
+            for (size_t i = 0; i < node->call.args_count; i++)
+            {
+              fzl_walk_res_t res = walk(walker, node->call.args[i]);
+              if (res.error)
+                return res;
+            }
+          }
+
           push_op(walker, FZL_OPCODE_CALL_BUILTIN);
           push_word(walker, FZL_BUILTIN_PRINTLINE);
           if (node->call.args_count < 1)
@@ -459,32 +680,138 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         }
         else
         {
-          fzl_sym_t res;
-          bool found = false;
-          for (ssize_t i = walker->sym_top - 1; i >= 0; i--)
-            if ((found =
-                     fzl_symt_get(walker->syms[i], node->token->value, &res)))
-              break;
-
-          if (!found)
+          if (node->call.callee->type == FZL_NODETYPE_IDENTIFIER)
           {
-            snprintf(wlast_err, sizeof(wlast_err),
-                     "call to unknown function '%s'",
-                     (char *)node->token->value);
-            return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
-          }
+            if (node->call.args_count > 0)
+            {
+              for (size_t i = 0; i < node->call.args_count; i++)
+              {
+                fzl_walk_res_t res = walk(walker, node->call.args[i]);
+                if (res.error)
+                  return res;
+              }
+            }
 
-          if (!res.ip)
+            fzl_sym_t res;
+            bool found = false;
+            for (ssize_t i = walker->sym_top - 1; i >= 0; i--)
+              if ((found =
+                       fzl_symt_get(walker->syms[i], node->token->value, &res)))
+                break;
+
+            if (!found)
+            {
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "call to unknown function '%s'",
+                       (char *)node->token->value);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            }
+
+            if (!res.ip)
+            {
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "cannot jump to address 0x0");
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            }
+
+            push_op(walker, FZL_OPCODE_CALL);
+            push_word(walker, res.ip);
+
+            current_res = (fzl_walk_res_t){.type = res.type, .error = false};
+          }
+          else if (node->call.callee->type == FZL_NODETYPE_FIELD)
           {
-            snprintf(wlast_err, sizeof(wlast_err),
-                     "cannot jump to address 0x0");
-            return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            fzl_node_t *parent_node = node->call.callee->memb.parent;
+
+            fzl_sym_t res;
+            bool found = false;
+            for (ssize_t i = walker->sym_top - 1; i >= 0; i--)
+              if ((found = fzl_symt_get(walker->syms[i],
+                                        parent_node->token->value, &res)))
+                break;
+
+            if (!found)
+            {
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "'%s': access to unknown object '%s' at %ld:%ld",
+                       node->token->filename, (char *)parent_node->token->value,
+                       node->token->ln, node->token->cn);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            }
+
+            if (res.type != FZL_TYPE_OBJECT || !res.classname)
+            {
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "'%s': name '%s' is not an object (at %ld:%ld)",
+                       parent_node->token->filename,
+                       (char *)parent_node->token->value,
+                       parent_node->token->ln, parent_node->token->cn);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            }
+
+            found = false;
+            for (size_t i = 0; i < walker->classes_count; i++)
+            {
+              if (strcmp(walker->classes[i]->name, res.classname) == 0)
+              {
+                found = true;
+                break;
+              }
+            }
+
+            if (!found)
+            {
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "'%s': class '%s' not found at %ld:%ld",
+                       node->token->filename, res.classname, node->token->ln,
+                       node->token->cn);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            }
+
+            char *classname  = res.classname;
+            size_t classlen  = strlen(res.classname);
+            size_t fnlen     = strlen(node->call.callee->token->value);
+            char *methodname = malloc(classlen + fnlen + 2);
+            strcpy(methodname, res.classname);
+            strcpy((methodname + classlen + 1),
+                   node->call.callee->token->value);
+            methodname[classlen]             = '_';
+            methodname[classlen + fnlen + 1] = 0;
+
+            found = false;
+            for (ssize_t i = walker->sym_top - 1; i >= 0; i--)
+              if ((found = fzl_symt_get(walker->syms[i], methodname, &res)))
+                break;
+
+            if (!found)
+            {
+              snprintf(wlast_err, sizeof(wlast_err),
+                       "'%s': class '%s' has no method '%s' at %ld:%ld",
+                       node->token->filename, classname,
+                       (char *)node->call.callee->token->value, node->token->ln,
+                       node->token->cn);
+              return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+            }
+
+            fzl_walk_res_t parent = walk(walker, parent_node);
+            if (parent.error)
+              return parent;
+
+            if (node->call.args_count > 0)
+            {
+              for (size_t i = 0; i < node->call.args_count; i++)
+              {
+                fzl_walk_res_t res = walk(walker, node->call.args[i]);
+                if (res.error)
+                  return res;
+              }
+            }
+
+            push_op(walker, FZL_OPCODE_CALL);
+            push_word(walker, res.ip);
+
+            current_res = (fzl_walk_res_t){.type = res.type, .error = false};
           }
-
-          push_op(walker, FZL_OPCODE_CALL);
-          push_word(walker, res.ip);
-
-          current_res = (fzl_walk_res_t){.type = res.type, .error = false};
         }
         break;
 
@@ -604,9 +931,33 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
 
       case FZL_NODETYPE_DECLARATION:
       {
+        fzl_ctable_t *ct = NULL;
+        for (size_t i = 0; i < walker->classes_count; i++)
+        {
+          if (strcmp(node->var.type->value, walker->classes[i]->name) == 0)
+          {
+            ct = walker->classes[i];
+            break;
+          }
+        }
+
         fzl_symtable_res_t res = fzl_symt_put(
             walker->syms[walker->sym_top - 1],
-            node->var.identifier->token->value, tok_to_type(node->var.type), 0);
+            node->var.identifier->token->value,
+            ct != NULL ? FZL_TYPE_OBJECT : tok_to_type(node->var.type), 0);
+
+        if (ct)
+          fzl_symt_setobjclass(walker->syms[walker->sym_top - 1],
+                               node->var.identifier->token->value, ct->name);
+
+        if (res != FZL_SYMTABLE_RESULT_OK)
+        {
+          fzl_token_t *tok = node->var.identifier->token;
+          snprintf(wlast_err, sizeof(wlast_err),
+                   "'%s': cannot store '%s' at %ld:%ld", tok->filename,
+                   (char *)tok->value, tok->ln, tok->cn);
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
 
         fzl_token_t *id_tok = node->var.identifier->token;
         size_t const_n      = add_const(
@@ -631,11 +982,20 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
         if (rres.error)
           return rres;
 
+        fzl_walk_ctx_t *newctx = nest_ctx(walker, FZL_WALK_CTX_TYPE_ASSIGN);
+        if (!newctx)
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to nest context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+        }
+
         if (node->binary_op.left->type == FZL_NODETYPE_DECLARATION)
         {
           fzl_walk_res_t lres = walk(walker, node->binary_op.left);
           if (lres.error)
             return lres;
+
+          push_op(walker, FZL_OPCODE_WRITE);
         }
         else if (node->binary_op.left->type == FZL_NODETYPE_IDENTIFIER)
         {
@@ -672,9 +1032,65 @@ fzl_walk_res_t walk(fzl_walker_t *walker, fzl_node_t *node)
                                         node->binary_op.left->token->value_sz});
           push_op(walker, FZL_OPCODE_LOADCONST);
           push_word(walker, const_n);
+          push_op(walker, FZL_OPCODE_WRITE);
+        }
+        else if (node->binary_op.left->type == FZL_NODETYPE_FIELD)
+        {
+          fzl_node_t *field_node = node->binary_op.left;
+          fzl_walk_res_t obj_res = walk(walker, field_node->memb.parent);
+          if (obj_res.error)
+            return obj_res;
+
+          fzl_ctable_t *ct;
+          for (size_t i = 0; i < walker->classes_count; i++)
+          {
+            if (strcmp(obj_res.classname, walker->classes[i]->name) == 0)
+            {
+              ct = walker->classes[i];
+              break;
+            }
+          }
+
+          if (!ct)
+          {
+            snprintf(wlast_err, sizeof(wlast_err),
+                     "'%s': cannot find class '%s' at %ld:%ld",
+                     field_node->token->filename, obj_res.classname,
+                     field_node->token->ln, field_node->token->cn);
+            return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+          }
+
+          fzl_ctable_field_t *ctf;
+          for (size_t i = 0; i < ct->fields_count; i++)
+          {
+            if (strcmp(field_node->memb.field->token->value,
+                       ct->fields[i].name) == 0)
+            {
+              ctf = &ct->fields[i];
+              break;
+            }
+          }
+
+          if (!ctf)
+          {
+            fzl_node_t *fn = field_node->memb.field;
+            snprintf(wlast_err, sizeof(wlast_err),
+                     "'%s': class '%s' has no field '%s' at %ld:%ld",
+                     fn->token->filename, obj_res.classname,
+                     (char *)fn->token->value, fn->token->ln, fn->token->cn);
+            return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
+          }
+
+          push_op(walker, FZL_OPCODE_SET_FIELD);
+          push_word(walker, ctf->slot_index);
+        }
+
+        if (!fin_ctx(walker))
+        {
+          snprintf(wlast_err, sizeof(wlast_err), "failed to clean context");
+          return (fzl_walk_res_t){.error = true, .error_msg = wlast_err};
         }
 
-        push_op(walker, FZL_OPCODE_WRITE);
         current_res = (fzl_walk_res_t){.type = rres.type, .error = false};
         break;
       }
@@ -695,10 +1111,14 @@ int fzl_walk(fzl_walker_t *walker)
     return -1;
   }
 
+  nest_ctx(walker, FZL_WALK_CTX_TYPE_GLOBAL);
+
   push_op(walker, FZL_OPCODE_MK_ENVTABLE);
   fzl_walk_res_t result = walk(walker, walker->root);
   push_op(walker, FZL_OPCODE_RM_ENVTABLE);
 
+  fin_ctx(walker);
+
   if (result.error && !wlast_err[0])
     snprintf(wlast_err, sizeof(wlast_err), "%s", result.error_msg);
 
@@ -722,5 +1142,8 @@ void fzl_freewalker(fzl_walker_t *walker)
   while (walker->sym_top > 0)
     fzl_freesymt(walker->syms[--walker->sym_top]);
 
+  for (size_t i = 0; i < walker->classes_count; i++)
+    fzl_freectable(walker->classes[i]);
+
   free(walker);
 }

src/compiler/utils/fzl_ctable.c

@@ -0,0 +1,29 @@
+#include <compiler/utils/fzl_ctable.h>
+#include <stdlib.h>
+#include <string.h>
+
+fzl_ctable_t *fzl_mkctable(char *name)
+{
+  fzl_ctable_t *ctable = malloc(sizeof(fzl_ctable_t));
+  if (!ctable)
+    return NULL;
+
+  memset(ctable, 0, sizeof(fzl_ctable_t));
+  ctable->name             = name;
+  ctable->fields_remainder = 2;
+  ctable->fields =
+      malloc(ctable->fields_remainder * sizeof(fzl_ctable_field_t));
+
+  return ctable;
+}
+
+void fzl_freectable(fzl_ctable_t *ct)
+{
+  if (!ct)
+    return;
+
+  if (ct->fields)
+    free(ct->fields);
+
+  free(ct);
+}

src/compiler/utils/fzl_symtable.c

@@ -1,3 +1,4 @@
+#include <common/fzl_types.h>
 #include <compiler/utils/fzl_symtable.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -37,10 +38,31 @@ fzl_symtable_res_t fzl_symt_put(fzl_symtable_t *symt, char *name,
   }
 
   symt->symbols[symt->size++] =
-      (fzl_sym_t){.name = name, .type = type, .ip = ip};
+      (fzl_sym_t){.name = name, .type = type, .ip = ip, .classname = NULL};
   return FZL_SYMTABLE_RESULT_OK;
 }
 
+fzl_symtable_res_t fzl_symt_setobjclass(fzl_symtable_t *symt, char *name,
+                                        char *classname)
+{
+  if (!symt)
+    return FZL_SYMTABLE_RESULT_ERR;
+
+  for (size_t i = 0; i < symt->size; i++)
+  {
+    if (strcmp(symt->symbols[i].name, name) == 0)
+    {
+      if (symt->symbols[i].type != FZL_TYPE_OBJECT)
+        return FZL_SYMTABLE_RESULT_NOT_OBJECT;
+
+      symt->symbols[i].classname = classname;
+      return FZL_SYMTABLE_RESULT_OK;
+    }
+  }
+
+  return FZL_SYMTABLE_RESULT_ERR;
+}
+
 bool fzl_symt_get(fzl_symtable_t *symt, char *name, fzl_sym_t *res)
 {
   if (!symt)

src/vm/fzl_vm.c

@@ -1,4 +1,3 @@
-#include "vm/fzl_vm_env.h"
 #include <common/fzl_builtins.h>
 #include <common/fzl_opcodes.h>
 #include <common/fzl_types.h>
@@ -10,6 +9,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <vm/fzl_vm.h>
+#include <vm/fzl_vm_env.h>
+#include <vm/fzl_vm_object.h>
 
 char last_err[256];
 
@@ -24,18 +25,20 @@ fzl_vm_t *fzl_mkvm(const char *filepath)
     return NULL;
   }
 
-  vm->consts       = NULL;
-  vm->consts_count = 0;
-  vm->ops          = NULL;
-  vm->ops_count    = 0;
-  vm->ip           = 0;
-  vm->dtop         = 0;
-  vm->ctop         = 0;
-  vm->etop         = 0;
+  vm->consts        = NULL;
+  vm->consts_count  = 0;
+  vm->ops           = NULL;
+  vm->ops_count     = 0;
+  vm->ip            = 0;
+  vm->dtop          = 0;
+  vm->ctop          = 0;
+  vm->etop          = 0;
+  vm->objects_count = 0;
 
   memset(vm->dstack, 0, sizeof(vm->dstack));
   memset(vm->cstack, 0, sizeof(vm->cstack));
   memset(vm->estack, 0, sizeof(vm->estack));
+  memset(vm->objects, 0, sizeof(vm->objects));
 
   FILE *fd = fopen(filepath, "rb");
   if (!fd)
@@ -122,6 +125,84 @@ int fzl_vm_run(fzl_vm_t *vm)
 
     switch (opcode)
     {
+      case FZL_OPCODE_ALLOC_OBJECT:
+      {
+        uint64_t values_count = vm->ops[++vm->ip];
+        fzl_vm_object_t *obj  = malloc(sizeof(fzl_vm_object_t));
+        obj->values           = malloc(values_count * sizeof(fzl_value_t));
+        obj->values_count     = values_count;
+
+        vm->objects[vm->objects_count++] = obj;
+        vm->dstack[vm->dtop++] =
+            (fzl_value_t){.type = FZL_TYPE_OBJECT, .as.obj = obj};
+        break;
+      }
+
+      case FZL_OPCODE_GET_FIELD:
+      {
+        if (vm->dtop < 1)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected value in data stack");
+          return -1;
+        }
+
+        uint64_t field_slot = vm->ops[++vm->ip];
+        fzl_value_t val     = vm->dstack[--vm->dtop];
+        if (val.type != FZL_TYPE_OBJECT)
+        {
+          snprintf(
+              last_err, sizeof(last_err),
+              "runtime error - cannot access field #%lu of non-object type",
+              field_slot);
+          return -1;
+        }
+
+        fzl_vm_object_t *obj = val.as.obj;
+        if (obj->values_count <= field_slot)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - cannot access field #%lu", field_slot);
+          return -1;
+        }
+
+        vm->dstack[vm->dtop++] = obj->values[field_slot];
+        break;
+      }
+
+      case FZL_OPCODE_SET_FIELD:
+      {
+        if (vm->dtop < 2)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - expected two values in data stack");
+          return -1;
+        }
+
+        uint64_t field_slot = vm->ops[++vm->ip];
+        fzl_value_t objval  = vm->dstack[--vm->dtop];
+        fzl_value_t wrval   = vm->dstack[--vm->dtop];
+        if (objval.type != FZL_TYPE_OBJECT)
+        {
+          snprintf(
+              last_err, sizeof(last_err),
+              "runtime error - cannot access field #%lu of non-object type",
+              field_slot);
+          return -1;
+        }
+
+        fzl_vm_object_t *obj = objval.as.obj;
+        if (obj->values_count <= field_slot)
+        {
+          snprintf(last_err, sizeof(last_err),
+                   "runtime error - cannot access field #%lu", field_slot);
+          return -1;
+        }
+
+        obj->values[field_slot] = wrval;
+        break;
+      }
+
       case FZL_OPCODE_CALL:
       {
         uint64_t ip            = vm->ops[++vm->ip];

src/vm/fzl_vm_debug.c

@@ -20,15 +20,27 @@ void fzl_vm_print_ops(fzl_vm_t *vm)
 
     switch (vm->ops[i])
     {
+      case FZL_OPCODE_ALLOC_OBJECT:
+        printf("ALLOC_OBJECT: %lu fields\n", vm->ops[++i]);
+        break;
+
+      case FZL_OPCODE_GET_FIELD:
+        printf("GET_FIELD #%lu\n", vm->ops[++i]);
+        break;
+
+      case FZL_OPCODE_SET_FIELD:
+        printf("SET_FIELD #%lu\n", vm->ops[++i]);
+        break;
+
       case FZL_OPCODE_CALL:
       {
         size_t ip = vm->ops[++i];
-        printf("Call IP: %lu\n", ip);
+        printf("CALL IP: %lu\n", ip);
         break;
       }
 
       case FZL_OPCODE_RET:
-        printf("Return\n");
+        printf("RET\n");
         break;
 
       case FZL_OPCODE_LOADCONST:
@@ -77,7 +89,7 @@ void fzl_vm_print_ops(fzl_vm_t *vm)
       case FZL_OPCODE_DIV:
       case FZL_OPCODE_POW:
       case FZL_OPCODE_MOD:
-        printf("Math opcode\n");
+        printf("MATH\n");
         break;
 
       case FZL_OPCODE_AND:
@@ -129,7 +141,7 @@ void fzl_vm_print_ops(fzl_vm_t *vm)
         break;
 
       default:
-        printf("<Unknown>\n");
+        printf("<UNKNOWN>\n");
     }
   }
 }