From bbcda663d5b2b2f055de12107e0abab536e5beea Mon Sep 17 00:00:00 2001
From: c
Date: Sat, 23 Mar 2024 10:52:52 -0400
Subject: Doubly-linked the abstract syntax tree.

---
 src/include/doer.h   | 8 ++++----
 src/include/parser.h | 3 +++
 src/include/tree.h   | 5 +++--
 3 files changed, 10 insertions(+), 6 deletions(-)

(limited to 'src/include')

diff --git a/src/include/doer.h b/src/include/doer.h
index 641abed..2bdad56 100644
--- a/src/include/doer.h
+++ b/src/include/doer.h
@@ -63,9 +63,9 @@ static tree_type_t blin_print_args[] = { TREE_TYPE_LSTR };
 // `printl`: print a string, and add a newline.
 void blin_printl(doer_t* doer);
 static tree_type_t blin_printl_args[] = { TREE_TYPE_LSTR };
-// `to_str`: convert any (primitive) type to a string.
-void blin_to_str(doer_t* doer);
-static tree_type_t blin_to_str_args[] = { TREE_TYPE_CALL };
+// `str_cat`: concatenate strings.
+void blin_str_cat(doer_t* doer);
+static tree_type_t blin_str_cat_args[] = { TREE_TYPE_LSTR, TREE_TYPE_LSTR };
 
 void doer_do_block(doer_t* tree);
 void doer_do_expr(doer_t* tree);
@@ -81,7 +81,7 @@ static blinf_t blinfs[] = {
    { blin_die, TREE_TYPE_LINT, NULL, "die" },
    { blin_print, TREE_TYPE_LSTR, blin_print_args, "print" },
    { blin_printl, TREE_TYPE_LSTR, blin_printl_args, "printl" },
-   { blin_to_str, TREE_TYPE_LSTR, blin_to_str_args, "to_str" },
+   { blin_str_cat, TREE_TYPE_LSTR, blin_str_cat_args, "str_cat" },
 };
 
 #endif
diff --git a/src/include/parser.h b/src/include/parser.h
index 6961be8..3891a5c 100644
--- a/src/include/parser.h
+++ b/src/include/parser.h
@@ -27,6 +27,9 @@ typedef struct PARSER {
    
    /* The AST being produced. */
    tree_t* tree;
+
+   /* The current parent tree node. */
+   tree_t* ltree;
 } parser_t;
 
 /* Creates a new parser. */
diff --git a/src/include/tree.h b/src/include/tree.h
index 2a62f26..e1adf85 100644
--- a/src/include/tree.h
+++ b/src/include/tree.h
@@ -19,6 +19,8 @@ typedef enum TREE_TYPE {
 typedef struct TREE {
    tree_type_t type;
 
+   struct TREE* parent;
+
    union TREE_DATA{
       /* Block. */
       struct TREE_DATA_BLOCK {
@@ -77,12 +79,11 @@ typedef struct TREE {
          char* target;
          struct TREE* arg; /* CARG */
       } call;
-
    } data;
 } tree_t;
 
 /* Create a new AST. */
-tree_t* tree_init(tree_type_t type);
+tree_t* tree_init(tree_type_t type, tree_t* parent);
 /* Destroy the AST (if it exists). */
 void tree_destroy(tree_t* tree);
 
-- 
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