From 06d6b434de57771d7d67d455883eaaa123e9846d Mon Sep 17 00:00:00 2001
From: John Lorentzson <john_lorentzson@yahoo.com>
Date: Wed, 9 Jul 2025 16:06:56 +0200
Subject: [PATCH] Remove unused "NEXT" slots from syntax tree nodes (and
 related code)

---
 wip-duuqnd/user-side-compiler/high-level.lisp | 29 +------------------
 wip-duuqnd/user-side-compiler/parser.lisp     | 27 ++---------------
 2 files changed, 4 insertions(+), 52 deletions(-)

diff --git a/wip-duuqnd/user-side-compiler/high-level.lisp b/wip-duuqnd/user-side-compiler/high-level.lisp
index a794c2c..78b1446 100644
--- a/wip-duuqnd/user-side-compiler/high-level.lisp
+++ b/wip-duuqnd/user-side-compiler/high-level.lisp
@@ -3,17 +3,11 @@
 ;;; Base node
 
 (defclass node ()
-  ((%next :accessor next :accessor normal-next :initform nil
-          :initarg :next)
-   (%source :accessor source :initarg :source :initform nil)
-   (%comment :accessor comment :initarg :comment :initform nil)))
+  ((%source :accessor source :initarg :source :initform nil)))
 
 (defun nodep (obj)
   (typep obj 'node))
 
-(defmethod node-nexts ((node node))
-  (list (normal-next node)))
-
 ;;; Basic nodes
 
 (defclass node-nop (node) ())
@@ -36,9 +30,6 @@
 
 (define-transformation (node (node-expr-grouping node-expr)) node)
 
-(defmethod node-nexts ((node node-expr-grouping))
-  (append (list (expression node)) (call-next-method)))
-
 (defclass node-assignment (node-expr)
   ((%dst-variable :accessor dst-variable :initarg :variable)
    (%value :accessor value :initarg :value)))
@@ -48,11 +39,6 @@
   (setf (operands instance) (list (dst-variable instance)
                                   (value instance))))
 
-(defmethod node-nexts ((node node-assignment))
-  (append (when (nodep (value node))
-            (list (value node)))
-          (call-next-method)))
-
 (defclass node-standard-expr (node-expr) ())
 
 (defmacro define-standard-expr-node (name)
@@ -60,10 +46,6 @@
      (defclass ,name (node-standard-expr) ())
      (define-transformation (node (,name node-expr)) node)))
 
-(defmethod node-nexts ((node node-standard-expr))
-  (append (remove-if-not #'nodep (operands node))
-          (call-next-method)))
-
 (define-standard-expr-node node-expr-plus)
 (define-standard-expr-node node-expr-minus)
 (define-standard-expr-node node-expr-multiply)
@@ -90,12 +72,6 @@
    (%then :accessor then-node :initarg :then)
    (%else :accessor else-node :initarg :else :initform nil)))
 
-(defclass node-branch (node)
-  ((%branch-next :accessor branch-next :initarg :branch-next)))
-
-(defmethod node-nexts ((node node-branch))
-  (list (normal-next node) (branch-next node)))
-
 (defclass node-dotimes (node)
   ((%stop-ref :accessor stop-ref :initarg :stop-ref
               :documentation "A reference giving a value of how many times to run the loop.")
@@ -103,6 +79,3 @@
                  :documentation "A reference to a variable being set to the loop index.")
    (%loopee-node :accessor loopee-node :initarg :loopee-node)))
 
-(defmethod node-nexts ((node node-dotimes))
-  (append (list (loopee-node node))
-          (call-next-method)))
diff --git a/wip-duuqnd/user-side-compiler/parser.lisp b/wip-duuqnd/user-side-compiler/parser.lisp
index 201c206..76fa93b 100644
--- a/wip-duuqnd/user-side-compiler/parser.lisp
+++ b/wip-duuqnd/user-side-compiler/parser.lisp
@@ -228,8 +228,7 @@ comma ',' is required to separate arguments.")))
 (defun wire-up-statements (statements)
   (loop :for statement :in statements
         :for rest := (rest statements) :then (rest rest)
-        :for next := (first rest)
-        :do (setf (normal-next statement) next))
+        :for next := (first rest))
   statements)
 
 (define-syntax-matcher block (statements)
@@ -244,8 +243,7 @@ comma ',' is required to separate arguments.")))
   (setf statements (wire-up-statements (nreverse statements)))
   (make-instance 'node-block
                  :source *syntax-source*
-                 :statements statements
-                 :next (first statements)))
+                 :statements statements))
 
 (defmacro match-syntax-pattern (syntax-list error-messages)
   (append
@@ -287,12 +285,6 @@ comma ',' is required to separate arguments.")))
                  :stop-ref (transform n 'reference)
                  :loopee-node (transform code 'node)))
 
-(defmethod node-nexts ((node node-conditional))
-  (append (list (test-node node) (then-node node))
-          (unless (null (else-node node))
-            (list (else-node node)))
-          (call-next-method)))
-
 (define-syntax-matcher if (test then else)
   (match-syntax-pattern
    ((test expression) :then token-end-of-statement (then block))
@@ -319,17 +311,4 @@ comma ',' is required to separate arguments.")))
   (setf statements (wire-up-statements (nreverse statements)))
   (make-instance 'node-program
                  :source *syntax-source*
-                 :statements statements
-                 :next (first statements)))
-
-;;; Testing jigs
-
-(defmacro do-node-tree ((node start-node) &body body)
-  (let ((stack (gensym))
-        (current (gensym)))
-    `(loop :with ,stack := (list (normal-next ,start-node))
-           :for ,current := (pop ,stack)
-           :until (null ,current)
-           :do (setf ,stack (append (remove nil (node-nexts ,current)) ,stack))
-           :do (let ((,node ,current))
-                 ,@body))))
+                 :statements statements))