1 files changed, 113 insertions, 0 deletions
diff --git a/gc.cpp b/gc.cpp
new file mode 100644
index 0000000..13dfb3c
--- /dev/null
+++ b/gc.cpp
@@ -0,0 +1,113 @@
+#include "gc.h"
+#include "exc.h"
+#include "consts.h"
+
+#if defined(GC_DEBUG) || defined (GC_INFO)
+#include <cstdio>
+typedef unsigned long long ull;
+#endif
+
+static EvalObj *gcq[GC_QUEUE_SIZE];
+
+GarbageCollector::GarbageCollector() {
+    mapping.clear();
+    pend_cnt = 0;
+    pending_list = NULL;
+}
+
+GarbageCollector::PendingEntry::PendingEntry(
+        EvalObj *_obj, PendingEntry *_next) : obj(_obj), next(_next) {}
+
+
+void GarbageCollector::expose(EvalObj *ptr) {
+    bool flag = mapping.count(ptr);
+    if (flag)
+    {
+#ifdef GC_DEBUG
+        fprintf(stderr, "GC: 0x%llx exposed. count = %lu \"%s\"\n", 
+            (ull)ptr, mapping[ptr] - 1, ptr->ext_repr().c_str());
+#endif
+        if (!--mapping[ptr])
+        {
+#ifdef GC_DEBUG
+            fprintf(stderr, "GC: 0x%llx pending. \n", (ull)ptr);
+#endif
+            pending_list = new PendingEntry(ptr, pending_list);
+        } 
+    }
+}
+
+void GarbageCollector::force() {
+    EvalObj **l = gcq, **r = l;
+    for (PendingEntry *p = pending_list, *np; p; p = np)
+    {
+        np = p->next;
+        if (mapping[p->obj] == 0)
+            *r++ = p->obj;
+        delete p;
+    }   // fetch the pending pointers in the list
+    // clear the list
+    pending_list = NULL; 
+/*    for (EvalObj2Int::iterator it = mapping.begin(); 
+            it != mapping.end(); it++)
+        if (it->second == 0) *r++ = it->first;*/
+
+#ifdef GC_INFO
+    fprintf(stderr, "%ld\n", mapping.size());
+    size_t cnt = 0;
+#endif
+#ifdef GC_DEBUG
+    fprintf(stderr, 
+            "================================\n"
+            "GC: Forcing the clear process...\n");
+#endif
+    for (; l != r; l++)
+    {
+#ifdef GC_DEBUG
+        fprintf(stderr, "GC: !!! destroying space 0x%llx. \n", (ull)*l);
+#endif
+#ifdef GC_INFO
+        cnt++;
+#endif
+        delete *l;
+        mapping.erase(*l);
+        // maybe it's a complex structure, 
+        // so that more pointers are reported
+        for (PendingEntry *p = pending_list, *np; p; p = np)
+        {
+            np = p->next;
+            *r++ = p->obj;
+            if (r == gcq + GC_QUEUE_SIZE)
+                throw NormalError(RUN_ERR_GC_OVERFLOW);
+            delete p;
+        }   
+        pending_list = NULL;
+    }
+#ifdef GC_INFO
+    fprintf(stderr, "GC: Forced clear, %lu objects are freed, "
+            "%lu remains\n"
+            "=============================\n", cnt, mapping.size());
+        
+#endif
+#ifdef GC_DEBUG
+/*    for (EvalObj2Int::iterator it = mapping.begin();
+            it != mapping.end(); it++)
+        fprintf(stderr, "%llx => %s\n", (ull)it->first, it->first->ext_repr().c_str());
+        */
+#endif
+}
+
+EvalObj *GarbageCollector::attach(EvalObj *ptr) {
+    if (!ptr) return NULL;   // NULL pointer
+    bool flag = mapping.count(ptr);
+    if (flag) mapping[ptr]++;
+    else mapping[ptr] = 1;
+#ifdef GC_DEBUG
+    fprintf(stderr, "GC: 0x%llx attached. count = %lu \"%s\"\n", 
+            (ull)ptr, mapping[ptr], ptr->ext_repr().c_str());
+#endif
+    if (mapping.size() > GC_QUEUE_SIZE >> 1)
+        force();
+    return ptr; // passing through
+}
+