Abort semantics added.

Signed-off-by: tamasmeszaros <meszaros.q@gmail.com>

xs/src/libnest2d/libnest2d/libnest2d.hpp

@@ -640,6 +640,7 @@ public:
 
 // The progress function will be called with the number of placed items
 using ProgressFunction = std::function<void(unsigned)>;
+using StopCondition = std::function<bool(void)>;
 
 /**
  * A wrapper interface (trait) class for any selections strategy provider.
@@ -674,6 +675,8 @@ public:
      */
     void progressIndicator(ProgressFunction fn) { impl_.progressIndicator(fn); }
 
+    void stopCondition(StopCondition cond) { impl_.stopCondition(cond); }
+
     /**
      * \brief A method to start the calculation on the input sequence.
      *
@@ -864,6 +867,11 @@ public:
         selector_.progressIndicator(func); return *this;
     }
 
+    /// Set a predicate to tell when to abort nesting.
+    inline Nester& stopCondition(StopCondition fn) {
+        selector_.stopCondition(fn); return *this;
+    }
+
     inline PackGroup lastResult() {
         PackGroup ret;
         for(size_t i = 0; i < selector_.binCount(); i++) {

xs/src/libnest2d/libnest2d/selections/djd_heuristic.hpp

@@ -551,7 +551,7 @@ public:
         // Safety test: try to pack each item into an empty bin. If it fails
         // then it should be removed from the not_packed list
         { auto it = store_.begin();
-            while (it != store_.end()) {
+            while (it != store_.end() && !this->stopcond_()) {
                 Placer p(bin); p.configure(pconfig);
                 if(!p.pack(*it, rem(it, store_))) {
                     it = store_.erase(it);
@@ -592,9 +592,11 @@ public:
 
         bool do_pairs = config_.try_pairs;
         bool do_triplets = config_.try_triplets;
+        StopCondition stopcond = this->stopcond_;
 
         // The DJD heuristic algorithm itself:
         auto packjob = [INITIAL_FILL_AREA, bin_area, w, do_triplets, do_pairs,
+                        stopcond,
                         &tryOneByOne,
                         &tryGroupsOfTwo,
                         &tryGroupsOfThree,
@@ -606,12 +608,12 @@ public:
             double waste = .0;
             bool lasttry = false;
 
-            while(!not_packed.empty()) {
+            while(!not_packed.empty() && !stopcond()) {
 
                 {// Fill the bin up to INITIAL_FILL_PROPORTION of its capacity
                     auto it = not_packed.begin();
 
-                    while(it != not_packed.end() &&
+                    while(it != not_packed.end() && !stopcond() &&
                           filled_area < INITIAL_FILL_AREA)
                     {
                         if(placer.pack(*it, rem(it, not_packed))) {
@@ -623,14 +625,14 @@ public:
                     }
                 }
 
-                // try pieses one by one
+                // try pieces one by one
                 while(tryOneByOne(placer, not_packed, waste, free_area,
                                   filled_area)) {
                     waste = 0; lasttry = false;
                     makeProgress(placer, idx, 1);
                 }
 
-                // try groups of 2 pieses
+                // try groups of 2 pieces
                 while(do_pairs &&
                       tryGroupsOfTwo(placer, not_packed, waste, free_area,
                                      filled_area)) {
@@ -638,7 +640,7 @@ public:
                     makeProgress(placer, idx, 2);
                 }
 
-                // try groups of 3 pieses
+                // try groups of 3 pieces
                 while(do_triplets &&
                       tryGroupsOfThree(placer, not_packed, waste, free_area,
                                        filled_area)) {

xs/src/libnest2d/libnest2d/selections/filler.hpp

@@ -60,7 +60,7 @@ public:
         placer.configure(pconfig);
 
         auto it = store_.begin();
-        while(it != store_.end()) {
+        while(it != store_.end() && !this->stopcond_()) {
             if(!placer.pack(*it, {std::next(it), store_.end()}))  {
                 if(packed_bins_.back().empty()) ++it;
                 placer.clearItems();

xs/src/libnest2d/libnest2d/selections/firstfit.hpp

@@ -56,10 +56,12 @@ public:
             this->progress_(static_cast<unsigned>(--total));
         };
 
+        auto& cancelled = this->stopcond_;
+
         // Safety test: try to pack each item into an empty bin. If it fails
         // then it should be removed from the list
         { auto it = store_.begin();
-            while (it != store_.end()) {
+            while (it != store_.end() && !cancelled()) {
                 Placer p(bin); p.configure(pconfig);
                 if(!p.pack(*it)) {
                     it = store_.erase(it);
@@ -67,13 +69,14 @@ public:
             }
         }
 
+
         auto it = store_.begin();
 
-        while(it != store_.end()) {
+        while(it != store_.end() && !cancelled()) {
             bool was_packed = false;
             size_t j = 0;
-            while(!was_packed) {
-                for(; j < placers.size() && !was_packed; j++) {
+            while(!was_packed && !cancelled()) {
+                for(; j < placers.size() && !was_packed && !cancelled(); j++) {
                     if((was_packed = placers[j].pack(*it, rem(it, store_) )))
                             makeProgress(placers[j], j);
                 }

xs/src/libnest2d/libnest2d/selections/selection_boilerplate.hpp

@@ -2,6 +2,7 @@
 #define SELECTION_BOILERPLATE_HPP
 
 #include "../libnest2d.hpp"
+#include <atomic>
 
 namespace libnest2d { namespace selections {
 
@@ -25,14 +26,15 @@ public:
         return packed_bins_[binIndex];
     }
 
-    inline void progressIndicator(ProgressFunction fn) {
-        progress_ = fn;
-    }
+    inline void progressIndicator(ProgressFunction fn) { progress_ = fn; }
+
+    inline void stopCondition(StopCondition cond) { stopcond_ = cond; }
 
 protected:
 
     PackGroup packed_bins_;
     ProgressFunction progress_ = [](unsigned){};
+    StopCondition stopcond_ = [](){ return false; };
 };
 
 }