From c90bc89522bd0ba39ac0786dd43f19a8502c4224 Mon Sep 17 00:00:00 2001
From: stefan <mail@s-holst.de>
Date: Wed, 24 Jun 2026 22:42:10 +0900
Subject: [PATCH] construct input connected to output on passthrough connection

---
 src/kyupy/bench.py | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/kyupy/bench.py b/src/kyupy/bench.py
index 63cb8b4..d8fe98f 100644
--- a/src/kyupy/bench.py
+++ b/src/kyupy/bench.py
@@ -14,7 +14,7 @@ Since simulators only support at most four-input-gates, gates with more than fou
 from lark import Lark, Transformer
 
 from .circuit import Circuit, Node, Line
-from . import readtext, batchrange
+from . import readtext, batchrange, log
 
 def treeify(l, max_degree=4):
     if len(l) <= max_degree: return l
@@ -26,12 +26,32 @@ class BenchTransformer(Transformer):
     def __init__(self, name):
         super().__init__()
         self.c = Circuit(name)
+        self.inputs = set()
+        self.outputs = set()
 
     def start(self, _): return self.c
 
     def parameters(self, args): return [self.c.get_or_add_fork(str(name)) for name in args if name is not None]
 
-    def interface(self, args): self.c.io_nodes.extend(args[0])
+    def input(self, args):
+        for input in args[0]:
+            if input in self.outputs:
+                new_input = self.c.get_or_add_fork(input.name + '~i')
+                Line(self.c, new_input, input)
+                log.warn(f'input-output passthrough, renaming input: {input.name} -> {new_input.name}')
+                input = new_input
+            self.inputs.add(input)
+            self.c.io_nodes.append(input)
+
+    def output(self, args):
+        for output in args[0]:
+            if output in self.inputs:
+                new_output = self.c.get_or_add_fork(output.name + '~o')
+                Line(self.c, output, new_output)
+                log.warn(f'input-output passthrough, renaming output: {output.name} -> {new_output.name}')
+                output = new_output
+            self.outputs.add(output)
+            self.c.io_nodes.append(output)
 
     def _cell_tree_inner(self, name, kind, inner_kind, drivers):
         cell = Node(self.c, name, f'{kind}{len(drivers)}')
@@ -69,8 +89,8 @@ class BenchTransformer(Transformer):
 GRAMMAR = r"""
     start: (statement)*
     statement: input | output | assignment
-    input: ("INPUT" | "input") parameters -> interface
-    output: ("OUTPUT" | "output") parameters -> interface
+    input: ("INPUT" | "input") parameters
+    output: ("OUTPUT" | "output") parameters
     assignment: NAME "=" NAME parameters
     parameters: "(" [ NAME ( "," NAME )* ] ")"
     NAME: /[-_a-z0-9]+/i