feat: implement functions

include/common/fzl_opcodes.h

@@ -18,6 +18,9 @@ typedef enum
   FZL_OPCODE_JMP = 0xF20001, // Jump to specified IP address
   FZL_OPCODE_JZ  = 0xF20002, // Jump if top value in dstack is zero
 
+  FZL_OPCODE_CALL = 0xF30001, // Call function
+  FZL_OPCODE_RET  = 0xF30002, // Return from function
+
   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/compiler/fzl_parser.h

@@ -1,6 +1,7 @@
 #ifndef FZL_PARSER_H
 #define FZL_PARSER_H
 
+#include "common/fzl_types.h"
 #include <compiler/fzl_reader.h>
 #include <compiler/fzl_token.h>
 #include <stddef.h>
@@ -13,6 +14,8 @@ typedef enum
   FZL_NODETYPE_LITERAL,
   FZL_NODETYPE_IDENTIFIER,
   FZL_NODETYPE_CONDITIONAL,
+  FZL_NODETYPE_FUNCTION,
+  FZL_NODETYPE_RETURN,
 
   FZL_NODETYPE_ADD,
   FZL_NODETYPE_SUB,
@@ -93,6 +96,23 @@ typedef struct fzl_node
       struct fzl_node *true_block;
       struct fzl_node *else_block;
     } cond;
+
+    // Function declaration
+    struct
+    {
+      struct fzl_node **args;
+      size_t args_count;
+
+      struct fzl_node *body;
+      fzl_token_t *name;
+      fzl_token_t *type;
+    } fn;
+
+    // Return value
+    struct
+    {
+      struct fzl_node *value;
+    } ret;
   };
 } fzl_node_t;
 

include/compiler/fzl_token.h

@@ -8,6 +8,8 @@
 // Token type
 typedef enum
 {
+  FZL_TOKTYPE_RETURN, // return
+
   FZL_TOKTYPE_IF,   // if
   FZL_TOKTYPE_ELSE, // else
 

include/compiler/fzl_walker.h

@@ -18,6 +18,13 @@ typedef struct
   bool error;
 } fzl_walk_res_t;
 
+// Function context descriptor
+typedef struct
+{
+  fzl_node_t *fn;
+  size_t initial_env_lvl;
+} fzl_walk_ctx_t;
+
 // Walker descriptor
 typedef struct
 {
@@ -30,6 +37,8 @@ typedef struct
 
   fzl_symtable_t *syms[64];
   size_t sym_top;
+
+  fzl_walk_ctx_t *ctx;
 } fzl_walker_t;
 
 // Allocate new walker

include/compiler/utils/fzl_symtable.h

@@ -4,6 +4,7 @@
 #include <common/fzl_types.h>
 #include <stdbool.h>
 #include <stddef.h>
+#include <stdint.h>
 
 typedef enum
 {
@@ -17,6 +18,7 @@ typedef struct
 {
   char *name;
   fzl_type_t type;
+  size_t ip;
 } fzl_sym_t;
 
 // Symbols table descriptor
@@ -33,7 +35,7 @@ fzl_symtable_t *fzl_mksymt();
 
 // Put new entry into symtable
 fzl_symtable_res_t fzl_symt_put(fzl_symtable_t *symt, char *name,
-                                fzl_type_t type);
+                                fzl_type_t type, uint64_t ip);
 
 // Get entry from specified symtable
 bool fzl_symt_get(fzl_symtable_t *symt, char *name, fzl_sym_t *res);

include/vm/fzl_vm_env.h

@@ -33,7 +33,7 @@ typedef struct
 fzl_vm_env_t *fzl_mkenv();
 
 // Try get value by name
-fzl_value_t fzl_env_lookup(fzl_vm_env_t *env, char *name);
+bool fzl_env_lookup(fzl_vm_env_t *env, char *name, fzl_value_t *res);
 
 // Check name in env table
 bool fzl_env_contains(fzl_vm_env_t *env, char *name);