Implement Any.reduce in Perl 6, bacek++, pmichaud++

rakudo · Mar 10, 2009 · 0c893bc · 0c893bc
1 parent d8f59ef
commit 0c893bc
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Showing 2 changed files with 33 additions and 64 deletions.
diff --git a/src/builtins/any-list.pir b/src/builtins/any-list.pir
@@ -296,68 +296,6 @@ Return a List with the keys of the invocant.
     .tailcall self.'pick'($I0)
 .end
 
-=item reduce(...)
-
-=cut
-
-.namespace []
-.sub 'reduce' :multi('Sub')
-    .param pmc expression
-    .param pmc values          :slurpy
-    .tailcall values.'reduce'(expression)
-.end
-
-.namespace ['Any']
-.sub 'reduce' :method :multi(_, 'Sub')
-    .param pmc expression
-    .local pmc retv
-    .local pmc iter
-    .local pmc elem
-    .local pmc args
-    .local int i, arity
-
-    arity = expression.'arity'()
-    if arity < 2 goto error
-
-    iter = self.'iterator'()
-    unless iter goto empty
-    retv = shift iter
-  loop:
-    unless iter goto done
-
-    # Create arguments for closure
-    args = new 'ResizablePMCArray'
-    # Start with 1. First argument is result of previous call
-    i = 1
-
-  args_loop:
-    if i == arity goto invoke
-    unless iter goto elem_undef
-    elem = shift iter
-    goto push_elem
-  elem_undef:
-    elem = 'undef'()
-
-  push_elem:
-    push args, elem
-    inc i
-    goto args_loop
-
-  invoke:
-    retv = expression(retv, args :flat)
-    goto loop
-
-  empty:
-    .tailcall '!FAIL'('Cannot reduce an empty list')
-
-  error:
-    'die'('Cannot reduce() using a unary or nullary function.')
-
-  done:
-    .return(retv)
-.end
-
-
 =item sort()
 
 Sort list.  In this case we copy into an FPA to make use of the

diff --git a/src/setting/Any-list.pm b/src/setting/Any-list.pm
@@ -46,6 +46,33 @@ class Any is also {
             }
         }
     }
+
+    multi method reduce( Code $expression is rw) {
+        my Int $arity = $expression.count;
+        fail('Cannot reduce() using a unary or nullary function.')
+            if $arity < 2;
+
+        my $l := @.list;
+
+        fail('Cannot reduce() empty list') unless +$l;
+
+        my @args;
+        for $l {
+            @args.push($_);
+            if (@args == $arity) {
+                my $res = $expression.(|@args);
+                @args = ($res);
+            }
+        }
+        if @args > 1 {
+            if @args < $expression.arity {
+                warn (@args -1) ~ " trailing item(s) in reduce";
+            } else {
+                return $( $expression.(|@args) );
+            }
+        }
+        return @args[0];
+    }
 }
 
 our List multi grep(Code $test, *@values) {
@@ -56,12 +83,16 @@ our List multi map(Code $expr, *@values) {
     @values.map($expr)
 }
 
+multi min(Code $by, *@values) {
+    @values.min($by);
+}
+
 our List multi pairs(@values, *@indices) {
     @values.pairs(@indices)
 }
 
-multi min(Code $by, *@values) {
-    @values.min($by);
+multi reduce(Code $expression, *@values) {
+    @values.reduce($expression);
 }
 
 # vim: ft=perl6