From b0b24cfd5744b3ee40c2b165f2d15d32b07d3f99 Mon Sep 17 00:00:00 2001
From: Carl Masak <cmasak@gmail.com>
Date: Fri, 25 May 2012 22:45:56 +0200
Subject: [PATCH] [QAST::Block] only create hashes when .symbol sets

When the getter variant of .symbol is used, it now returns an
undefined value, rather than autovivify a hash for it.
---
 src/QAST/Block.nqp | 8 +++++---
 t/qast/qast.t      | 6 ++++++
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/src/QAST/Block.nqp b/src/QAST/Block.nqp
index 8b6c45dfa8..9a69dabc06 100644
--- a/src/QAST/Block.nqp
+++ b/src/QAST/Block.nqp
@@ -27,9 +27,11 @@ class QAST::Block is QAST::Node {
     }
 
     method symbol($name, *%attrs) {
-        %!symbol{$name} := %!symbol{$name} // {};
-        for %attrs {
-            %!symbol{$name}{$_.key} := $_.value;
+        if %attrs {
+            %!symbol{$name} := %!symbol{$name} // {};
+            for %attrs {
+                %!symbol{$name}{$_.key} := $_.value;
+            }
         }
         %!symbol{$name}
     }
diff --git a/t/qast/qast.t b/t/qast/qast.t
index cc9ad5d924..fb2080629c 100644
--- a/t/qast/qast.t
+++ b/t/qast/qast.t
@@ -741,3 +741,9 @@ is_qast(
     my %hash := $block.symbol('slug');
     ok(%hash<food> eq 'cheeseburger', 'QAST::Block.symbol existing attributes don\'t disappear');
 }
+
+{
+    my $block := QAST::Block.new();
+    my $missing := $block.symbol('sabre-toothed tiger');
+    ok(!pir::defined($missing), 'QAST::Block.symbol on a nonexistent key returns an undefined value');
+}