From 64d0100d7a46ca06544b080dcee3e45d72e3df3d Mon Sep 17 00:00:00 2001
From: Pietro Gagliardi <pietro10@mac.com>
Date: Mon, 23 Feb 2015 23:10:38 -0500
Subject: [PATCH] Started rewrite #3. The first file up for bat is an ID system
 for safer C/Go interop.

---
 ids.go | 61 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 ids.go

diff --git a/ids.go b/ids.go
new file mode 100644
index 00000000..66dd587c
--- /dev/null
+++ b/ids.go
@@ -0,0 +1,61 @@
+// 23 february 2015
+
+package ui
+
+// Go pointers cannot be passed to C safely.
+// The Go runtime will move them around, tripping C up.
+// However, C pointers don't have this problem.
+// Solution: use the C pointer to get the Go object needed!
+
+import (
+	"fmt"
+	"sync"
+)
+
+var (
+	ids		map[uintptr]interface{}
+	idsLock	sync.Mutex
+)
+
+func getGoObject(cptr uintptr) interface{} {
+	idsLock.Lock()
+	defer idsLock.Unlock()
+
+	if i, ok := ids[cptr]; ok {
+		return i
+	}
+	panic(fmt.Errorf("[BUG in package ui; report to andlabs immediately] C pointer %p not associated with Go object in package ui", cptr))
+}
+
+func associateGoObject(cptr uintptr, goobj interface{}) {
+	idsLock.Lock()
+	defer idsLock.Unlock()
+
+	if i, ok := ids[cptr]; ok {
+		panic(fmt.Errorf("[BUG in package ui; report to andlabs immediately] C pointer %p already associated with Go object of type %T but we want to associate it with Go object of type %T", cptr, i, goobj))
+	}
+	ids[cptr] = goobj
+}
+
+func disassociateGoObject(cptr uintptr) {
+	idsLock.Lock()
+	defer idsLock.Unlock()
+
+	if _, ok := ids[cptr]; !ok {
+		panic(fmt.Errorf("[BUG in package ui; report to andlabs immediately] C pointer %p not associated with any Go object but we want to disassociate it", cptr))
+	}
+	delete(ids, cptr)
+}
+
+func idsHandler(req *request) bool {
+	switch req.id {
+	case reqObjectDestroyed:
+		disassociateGoObject(req.ptr)
+		return true
+	}
+	return false
+}
+
+func init() {
+	interopHandlers = append(interopHandlers, idsHandler)
+}