wip: working on generator

- Feat: add break handler
- Feat: add class handler
- Feat: add format string handler
- Feat: add loop handler

src/compiler/generator/gen_loop.c

@@ -0,0 +1,61 @@
+#include <compiler/fzl_gen.h>
+#include <compiler/internals/gen.h>
+#include <stdbool.h>
+
+// While or for loops
+bool gen_loop(fzl_gen_t *gen, fzl_node_t *node)
+{
+  if (!gen || !node)
+    return false;
+
+  fzl_gen_ctx_t *ctx = gen_ctx(gen, FZL_GEN_CTX_TYPE_LOOP, node);
+  if (!ctx)
+    return false;
+
+  gen_op(gen, FZL_OPCODE_MK_ENVTABLE);
+
+  if (node->loop.init)
+    if (!gen_common(gen, node->loop.init))
+      return false;
+
+  size_t start_ip = gen->ops_count;
+  if (node->loop.cond)
+  {
+    if (!gen_common(gen, node->loop.cond))
+      return false;
+  }
+  else
+  {
+    gen_op(gen, FZL_OPCODE_PUSHNUM);
+    gen_word(gen, 1);
+  }
+
+  gen_op(gen, FZL_OPCODE_JZ);
+  ctx->loop.breaks[ctx->loop.breaks_count++] = gen->ops_count;
+  gen_word(gen, 0);
+
+  if (!gen_common(gen, node->loop.body))
+    return false;
+
+  if (node->loop.step)
+    if (!gen_common(gen, node->loop.step))
+      return false;
+
+  gen_op(gen, FZL_OPCODE_JMP);
+  gen_word(gen, start_ip);
+
+  // backpatch `break`s
+  for (size_t i = 0; i < ctx->loop.breaks_count; i++)
+    gen->ops[ctx->loop.breaks[i]] = gen->ops_count;
+
+  gen_op(gen, FZL_OPCODE_RM_ENVTABLE);
+
+  for (size_t i = gen->syms_top - 1; i > ctx->level; i--)
+    fzl_freesymt(gen->syms[--gen->syms_top]);
+
+  ctx = gen_fin_ctx(gen);
+  if (!ctx)
+    return false;
+
+  return true;
+}