Make for $@arr { } iterate only once

my @arr = 1, 2; for @arr {} will iterate twice for $@arr {} will iterate once @arr.map: {} will iterate twice $@arr.map: {} will iterate twice
rakudo · Aug 29, 2015 · 7aee0ac · 7aee0ac
1 parent 2a58180
commit 7aee0ac
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Showing 2 changed files with 26 additions and 10 deletions.
diff --git a/src/Perl6/Actions.nqp b/src/Perl6/Actions.nqp
@@ -1231,18 +1231,34 @@ Compilation unit '$file' contained the following violations:
 
     method statement_control:sym<for>($/) {
         my $xblock := $<xblock>.ast;
-        my $past := QAST::Op.new(
+        my $for-list-name := QAST::Node.unique('for-list');
+        my $iscont := QAST::Op.new(:op('iscont'), QAST::Var.new( :name($for-list-name), :scope('local') ));
+        $iscont.named('item');
+        my $call := QAST::Op.new(
             :op<callmethod>, :name<map>, :node($/),
-            $xblock[0],
-            block_closure($xblock[1])
+            QAST::Var.new( :name($for-list-name), :scope('local') ),
+            block_closure($xblock[1]),
+            $iscont,
         );
         if $*LABEL {
-            $past.push(QAST::WVal.new( :value($*W.find_symbol([$*LABEL])), :named('label') ));
+            $call.push(QAST::WVal.new( :value($*W.find_symbol([$*LABEL])), :named('label') ));
         }
-        $past := QAST::Want.new(
-            QAST::Op.new( :op<callmethod>, :name<eager>, $past ),
-            'v', QAST::Op.new( :op<callmethod>, :name<sink>, $past ));
-        my $sinkee := $past[0];
+        my $bind := QAST::Op.new(
+            :op('bind'),
+            QAST::Var.new( :name($for-list-name), :scope('local'), :decl('var') ),
+            $xblock[0],
+        );
+        my $past := QAST::Want.new(
+            QAST::Stmts.new(
+                $bind,
+                QAST::Op.new( :op<callmethod>, :name<eager>, $call )
+            ),
+            'v', QAST::Stmts.new(
+                $bind,
+                QAST::Op.new( :op<callmethod>, :name<sink>, $call )
+            ),
+        );
+        my $sinkee := $past[0][1];
         $past.annotate('statement_level', -> { $sinkee.name('sink') });
         make $past;
     }

diff --git a/src/core/Any-iterable-methods.pm b/src/core/Any-iterable-methods.pm
@@ -19,8 +19,8 @@ augment class Any {
 
     proto method map(|) { * }
 
-    multi method map(\SELF: &block, :$label) {
-        sequential-map(as-iterable(SELF).iterator, &block, :$label);
+    multi method map(\SELF: &block, :$label, :$item) {
+        sequential-map(as-iterable($item ?? (SELF,) !! SELF).iterator, &block, :$label);
     }
 
     multi method map(HyperIterable:D: &block, :$label) {