Add trace support.

trace.go

+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package sqlite provides access to the SQLite library, version 3.
+package sqlite
+
+/*
+#include <sqlite3.h>
+#include <stdlib.h>
+
+extern void goXTrace(void *pArg, const char *t);
+
+static void goSqlite3Trace(sqlite3 *db, void *pArg) {
+	sqlite3_trace(db, goXTrace, pArg);
+}
+*/
+import "C"
+
+import (
+	"unsafe"
+)
+
+type SqliteTrace func(d interface{}, t string)
+
+type sqliteTrace struct {
+	f SqliteTrace
+	d interface{}
+}
+
+//export goXTrace
+func goXTrace(pArg unsafe.Pointer, t *C.char) {
+	arg := (*sqliteTrace)(pArg)
+	arg.f(arg.d, C.GoString(t))
+}
+
+func (c *Conn) Trace(f SqliteTrace, arg interface{}) {
+	pArg := unsafe.Pointer(&sqliteTrace{f, arg})
+	C.goSqlite3Trace(c.db, pArg)
+}