moved main.go to bin and updated build files accordingly

hak-inst.go

@@ -0,0 +1,67 @@
+package hak
+
+/*
+#include <hak.h>
+*/
+import "C"
+import "sync"
+import "weak"
+
+type Instance struct {
+	c *C.hak_t // c object
+	g weak.Pointer[Hak] // go object as a weak pointer
+}
+
+type InstanceTable struct {
+	mtx        sync.Mutex
+	insts      []Instance
+	free_slots []int
+}
+
+var inst_table InstanceTable
+
+func (itab *InstanceTable) add_instance(c *C.hak_t, g *Hak) int {
+	itab.mtx.Lock()
+	defer itab.mtx.Unlock()
+
+	var n int = len(itab.free_slots)
+
+	if n <= 0 { // no free slots
+		itab.insts = append(itab.insts, Instance{c: c, g: weak.Make(g)})
+		return len(itab.insts) - 1
+	} else {
+		var slot int
+		n--
+		slot = itab.free_slots[n]
+		itab.free_slots = itab.free_slots[:n]
+		itab.insts[slot].c = c
+		return slot
+	}
+}
+
+func (itab *InstanceTable) delete_instance(slot int) Instance {
+	var h Instance
+	var n int
+
+	itab.mtx.Lock()
+	defer itab.mtx.Unlock()
+
+	h = itab.insts[slot]
+	itab.insts[slot].c = nil
+	itab.insts[slot].g = weak.Make((*Hak)(nil))
+
+	n = len(itab.insts)
+	if slot == n-1 {
+		itab.insts = itab.insts[:n-1]
+	} else {
+		itab.free_slots = append(itab.free_slots, slot)
+	}
+
+	return h
+}
+
+func (itab *InstanceTable) slot_to_instance(slot int) Instance {
+	itab.mtx.Lock()
+	defer itab.mtx.Unlock()
+	return itab.insts[slot]
+}