xo-alloc2: DX1CollectorIterator infra [WIP]

src/alloc2/DX1CollectorIterator.cpp

@@ -0,0 +1,88 @@
+/** @file DX1CollectorIterator.cpp
+ *
+ *  @author Roland Conybeare, Dec 2025
+ **/
+
+#include "gc/DX1CollectorIterator.hpp"
+#include "gc/DX1Collector.hpp"
+#include <xo/indentlog/scope.hpp>
+#include <xo/indentlog/print/tag.hpp>
+
+namespace xo {
+    namespace mm {
+        DX1CollectorIterator::DX1CollectorIterator(const DX1Collector * gc,
+                                                   generation gen_ix,
+                                                   generation gen_hi,
+                                                   DArenaIterator arena_ix,
+                                                   DArenaIterator arena_hi) : gc_{gc},
+                                                                              gen_ix_{gen_ix},
+                                                                              gen_hi_{gen_hi},
+                                                                              arena_ix_{arena_ix},
+                                                                              arena_hi_{arena_hi}
+        {
+            this->normalize();
+        }
+
+        void
+        DX1CollectorIterator::normalize() noexcept
+        {
+            /* normalize: find lowest generation with non-empty to-space */
+
+            for (; gen_ix_ < gen_hi_; ++gen_ix_) {
+                const DArena * arena
+                    = gc_->get_space(role::to_space(), gen_ix_);
+
+                arena_ix_ = arena->begin();
+                arena_hi_ = arena->end();
+
+                if (arena_ix_ != arena_hi_) {
+                    // normalization achieved!
+                    break;
+                }
+            }
+        }
+
+        AllocInfo
+        DX1CollectorIterator::deref() const noexcept
+        {
+            return arena_ix_.deref();
+        }
+
+        cmpresult
+        DX1CollectorIterator::compare(const DX1CollectorIterator & other_ix) const noexcept
+        {
+            scope log(XO_DEBUG(true),
+                      xtag("is_valid", is_valid()),
+                      xtag("other_ix.is_valid", other_ix.is_valid()) );
+
+            if (is_invalid() || (gc_ != other_ix.gc_)) {
+                log && log("incomparable!");
+                return cmpresult::incomparable();
+            }
+
+            if (gen_ix_ != other_ix.gen_ix_) {
+                log && log(xtag("gen", gen_ix_), xtag("other.gen", other_ix.gen_ix_));
+
+                /* same collector, different arenas -> compare based on gen# */
+
+                return cmpresult::from_cmp(gen_ix_, other_ix.gen_ix_);
+            }
+
+            /* both iterators refer to the same arena,
+             * so can compare their arena iterators directly
+             */
+            return arena_ix_.compare(other_ix.arena_ix_);
+        }
+
+        void
+        DX1CollectorIterator::next() noexcept
+        {
+            if (arena_ix_ != arena_hi_) {
+                ++arena_ix_;
+                this->normalize();
+            }
+        }
+    } /*namespace mm*/
+} /*namespace xo*/
+
+/* end DX1CollectorIterator.cpp */