feat: implement AST walker

include/common/fzl_builtins.h

@@ -0,0 +1,9 @@
+#ifndef FZL_BUILTINS_H
+#define FZL_BUILTINS_H
+
+typedef enum
+{
+  FZL_BUILTIN_PRINTLINE // Print message in arg with newline at end
+} fzl_builtin_t;
+
+#endif // FZL_BUILTINS_H

include/common/fzl_opcodes.h

@@ -0,0 +1,12 @@
+#ifndef FZL_OPCODES_H
+#define FZL_OPCODES_H
+
+// Available opcodes
+typedef enum
+{
+  FZL_OPCODE_LOADCONST,   // Load const into T (temp) reg
+  FZL_OPCODE_PUSHARG,     // Push argument from T into args stack
+  FZL_OPCODE_CALL_BUILTIN // Call builtin function
+} fzl_opcode_t;
+
+#endif // FZL_OPCODES_H

include/compiler/fzl_walker.h

@@ -0,0 +1,34 @@
+#ifndef FZL_WALKER_H
+#define FZL_WALKER_H
+
+#include <common/fzl_opcodes.h>
+#include <compiler/fzl_parser.h>
+#include <compiler/utils/fzl_const_pool.h>
+#include <stddef.h>
+
+// Walker descriptor
+typedef struct
+{
+  fzl_node_t *root;
+  fzl_const_hash_pool_t *consts;
+
+  uint64_t *ops;
+  size_t op_count;
+  size_t op_remainder;
+} fzl_walker_t;
+
+// Allocate new walker
+fzl_walker_t *fzl_mkwalker(fzl_node_t *root);
+
+// Walk throught the entire AST and build:
+// 1. Constants table
+// 2. Operations
+int fzl_walk(fzl_walker_t *walker);
+
+// Get last error message
+char *fzl_walker_geterror();
+
+// Free walker
+void fzl_freewalker(fzl_walker_t *walker);
+
+#endif // FZL_WALKER_H

include/compiler/utils/fzl_const_pool.h

@@ -0,0 +1,64 @@
+#ifndef FZL_CONST_SET_H
+#define FZL_CONST_SET_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+// Constant types
+typedef enum
+{
+  FZL_CONSTTYPE_STRING
+} fzl_consttype_t;
+
+// Constant descriptor
+typedef struct
+{
+  fzl_consttype_t type;
+
+  union
+  {
+    struct
+    {
+      const char *chars;
+      size_t length;
+    } string;
+  } as;
+} fzl_const_t;
+
+typedef struct
+{
+  size_t pool_index;
+} fzl_const_hash_slot_t;
+
+// Constant pool descriptor
+typedef struct
+{
+  fzl_const_t *array;
+  size_t size;
+  size_t capacity;
+
+  fzl_const_hash_slot_t *slots;
+  size_t slots_count;
+  size_t slots_capacity;
+} fzl_const_hash_pool_t;
+
+// Compare two constants for equality
+bool fzl_consts_equal(fzl_const_t a, fzl_const_t b);
+
+// Get hash of specified constant
+static uint32_t fzl_hash_const(fzl_const_t c);
+
+// Allocate constants hash pool
+fzl_const_hash_pool_t *fzl_mkconstpool();
+
+// Resize the hash table
+static void fzl_consts_pool_resize_hash(fzl_const_hash_pool_t *pool);
+
+// Push constant. Returns unique index
+size_t fzl_consts_pool_add(fzl_const_hash_pool_t *pool, fzl_const_t c);
+
+// Free constants hash pool
+void fzl_consts_pool_free(fzl_const_hash_pool_t *pool);
+
+#endif // FZL_CONST_SET_H