Re-implement Combinations iter's .[count|bool]-only

Fixes #1330
rakudo · Dec 22, 2017 · 5eed2b0 · 5eed2b0
1 parent 1f99aa1
commit 5eed2b0
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Showing 4 changed files with 27 additions and 15 deletions.
diff --git a/src/core/Rakudo/Iterator.pm b/src/core/Rakudo/Iterator.pm
@@ -716,6 +716,7 @@ class Rakudo::Iterator {
               $n < 1 || $n < $k || $k < 0,            # must be HLL comparisons
               Rakudo::Iterator.Empty,                 # nothing to return
               class :: does Iterator {
+                  has int $!pulled-count = 0;
                   has int $!n;
                   has int $!k;
                   has int $!b;
@@ -759,24 +760,27 @@ class Rakudo::Iterator {
                         ),
                         nqp::if(
                           nqp::iseq_i($index,$k),
-                          nqp::if(
-                            $!b,
-                            nqp::clone($!combination),
-                            nqp::p6bindattrinvres(
-                              nqp::create(List),List,'$!reified',
-                              nqp::clone($!combination)
+                          nqp::stmts(
+                            ($!pulled-count = nqp::add_i($!pulled-count,1)),
+                            nqp::if(
+                              $!b,
+                              nqp::clone($!combination),
+                              nqp::p6bindattrinvres(
+                                nqp::create(List),List,'$!reified',
+                                nqp::clone($!combination)
+                              )
                             )
                           ),
                           IterationEnd
                         )
                       )
                   }
-                # XXX TODO: both methods need to account for the number of
-                #           items that were already pulled
-                #   method count-only {
-                #       ([*] ($!n ... 0) Z/ 1 .. min($!n - $!k, $!k)).Int
-                #   }
-                #   method bool-only(--> True) { }
+
+                  method count-only(--> Int) {
+                      (([*] ($!n ... 0) Z/ 1 .. min($!n - $!k, $!k)).Int)
+                      - $!pulled-count
+                  }
+                  method bool-only(--> Bool) { nqp::p6bool(self.count-only) }
               }.new($n,$k,$b)
             )
           )

diff --git a/t/08-performance/01-iterators.t b/t/08-performance/01-iterators.t
@@ -0,0 +1,8 @@
+use Test;
+
+plan 2;
+
+is-deeply  +combinations(100, 70), 29372339821610944823963760,
+  'combinations() iterator implements efficient .count-only';
+is-deeply ?+combinations(100, 70), True,
+  'combinations() iterator implements efficient .bool-only';
diff --git a/tools/build/Makefile-JVM.in b/tools/build/Makefile-JVM.in
@@ -178,7 +178,7 @@ j-test    : j-coretest
 j-fulltest: j-coretest j-stresstest
 
 j-coretest: j-all
-	$(J_HARNESS5) t/01-sanity t/02-rakudo t/03-jvm t/04-nativecall t/05-messages t/06-telemetry t/07-pod-to-text
+	$(J_HARNESS5) t/01-sanity t/02-rakudo t/03-jvm t/04-nativecall t/05-messages t/06-telemetry t/07-pod-to-text t/08-performance
 
 # Run the spectests that we know work.
 j-spectest: j-testable t/spectest.data

diff --git a/tools/build/Makefile-Moar.in b/tools/build/Makefile-Moar.in
@@ -231,7 +231,7 @@ m-quicktest: m-quicktest$(HARNESS_TYPE)
 m-stresstest: m-stresstest$(HARNESS_TYPE)
 
 m-coretest5: m-all
-	$(M_HARNESS5) t/01-sanity t/02-rakudo t/04-nativecall t/05-messages t/06-telemetry t/07-pod-to-text
+	$(M_HARNESS5) t/01-sanity t/02-rakudo t/04-nativecall t/05-messages t/06-telemetry t/07-pod-to-text t/08-performance
 
 # Run the spectests that we know work.
 m-spectest5: m-testable t/spectest.data
@@ -248,7 +248,7 @@ m-stresstest5: m-testable t/spectest.data
 
 
 m-coretest6: m-all
-	$(M_HARNESS6) t/01-sanity t/02-rakudo t/04-nativecall t/05-messages t/06-telemetry t/07-pod-to-text
+	$(M_HARNESS6) t/01-sanity t/02-rakudo t/04-nativecall t/05-messages t/06-telemetry t/07-pod-to-text t/08-performance
 
 # Run the spectests that we know work.
 m-spectest6: m-testable t/spectest.data