Fix show for expressions (parentheses); allow parentheses in input

2 files changed, 11 insertions, 2 deletions

diff --git a/Logic.icl b/Logic.icl
index 97d8df5..c678248 100644
--- a/Logic.icl
+++ b/Logic.icl
@@ -117,7 +117,16 @@ where
     show opt (B b)              = show opt b
     show opt (Atom a)           = show opt a
     show opt (App1 op e)        = show opt op +++ show opt e
-    show opt (App2 e1 op e2)    = show opt e1 +++ " " +++ show opt op +++ " " +++ show opt e2
+    show opt (App2 e1 op e2)    = if needs_l "(" "" +++ 
+                                    show opt e1 +++ 
+                                    if needs_l ")" "" +++
+                                    " " +++ show opt op +++ " " +++ 
+                                    if needs_r "(" "" +++
+                                    show opt e2 +++
+                                    if needs_r ")" ""
+    where
+        needs_l = needs_parentheses_left (App2 e1 op e2)
+        needs_r = needs_parentheses_right (App2 e1 op e2)
 
 instance == Op1
 where
diff --git a/request.php b/request.php
index 2866ada..9dfb4bc 100644
--- a/request.php
+++ b/request.php
@@ -36,7 +36,7 @@ if ($expressions == [])
     die('Not enough expressions requested');
 
 foreach ($expressions as $k => $e)
-    if (preg_match('/[^a-zA-Z\|\&~\-><01 ]/', $e))
+    if (preg_match('/[^a-zA-Z\|\&~\-><01 \(\)]/', $e))
         die('Forbidden character in expression ' . $e);
 
 $expressions = array_map('escapeshellarg', $expressions);