wip: working on analyzer

- Feat: add `nest_ctx` and `fin_ctx` fns for working with context and
environment
- Feat: add block analyzer
- Feat: add conditional statement analyzer

src/compiler/fzl_analyzer.c

@@ -67,7 +67,11 @@ void fzl_analyze(fzl_analyzer_t *analyzer)
   if (!analyzer)
     return;
 
-  analyzer->symbols[analyzer->symbols_top++] = fzl_mksymt();
+  if (an_nest_ctx(analyzer, FZL_AN_CTX_TYPE_UNNECESSARY) == NULL)
+  {
+    an_push_error(analyzer, NULL, "failed to make global context");
+    return;
+  }
 
   fzl_node_t *current = analyzer->root;
   while (current != NULL)
@@ -79,14 +83,7 @@ void fzl_analyze(fzl_analyzer_t *analyzer)
     current = current->next;
   }
 
-  if (analyzer->symbols_top < 0)
-  {
-    an_push_error(analyzer, NULL,
-                  "undefined error (early finish of global environment)");
-    return;
-  }
-
-  fzl_freesymt(analyzer->symbols[--analyzer->symbols_top]);
+  an_fin_ctx(analyzer);
 }
 
 void fzl_freeanalyzer(fzl_analyzer_t *analyzer)