unifastregetgen.cc

00001 /* -*- Mode: C++ -*-
00002  * Worldvisions Weaver Software:
00003  *   Copyright (C) 2002-2005 Net Integration Technologies, Inc.
00004  * 
00005  * A lightweight but slightly dangerous version of UniCacheGen.
00006  */
00007 #include <wvassert.h>
00008 
00009 #include "unifastregetgen.h"
00010 #include "uniconftree.h"
00011 #include "wvmoniker.h"
00012 
00013 // if 'obj' is non-NULL and is a UniConfGen, wrap that; otherwise wrap the
00014 // given moniker.
00015 static IUniConfGen *creator(WvStringParm s)
00016 {
00017     return new UniFastRegetGen(wvcreate<IUniConfGen>(s));
00018 }
00019 
00020 static WvMoniker<IUniConfGen> reg("fast-reget", creator);
00021 
00022 
00023 UniFastRegetGen::UniFastRegetGen(IUniConfGen *_inner) :
00024     UniFilterGen(_inner),
00025     tree(NULL)
00026 {
00027     tree = new UniConfValueTree(NULL, "/", UniFilterGen::get("/"));
00028 }
00029 
00030 
00031 UniFastRegetGen::~UniFastRegetGen()
00032 {
00033     if (tree)
00034     {
00035         delete tree;
00036         tree = NULL;
00037     }
00038 }
00039 
00040 
00041 void UniFastRegetGen::gencallback(const UniConfKey &key, WvStringParm value)
00042 {
00043     if (tree == NULL)
00044         return; // initialising
00045 
00046     UniConfValueTree *t = tree->find(key);
00047     if (t) // never previously retrieved; don't cache it
00048         t->setvalue(value);
00049     UniFilterGen::gencallback(key, value);
00050 }
00051 
00052 
00053 WvString UniFastRegetGen::get(const UniConfKey &key)
00054 {
00055     if (!tree)
00056     {
00057         wvassert(tree, "key: '%s'", key);
00058         abort();
00059     }
00060 
00061     UniConfValueTree *t = tree->find(key);
00062     if (!t)
00063     {
00064         get(key.removelast()); // guaranteed to create parent node
00065         t = tree->find(key.removelast());
00066         assert(t);
00067         
00068         WvString value;
00069         if (!t->value().isnull()) // if parent is null, child guaranteed null
00070             value = UniFilterGen::get(key);
00071         new UniConfValueTree(t, key.last(), value);
00072         return value;
00073     }
00074     else
00075         return t->value();
00076 }
00077 
00078 
00079 bool UniFastRegetGen::exists(const UniConfKey &key)
00080 {
00081     // even if inner generator has a more efficient version of exists(),
00082     // do it this way so we can cache the result.
00083     return !!get(key);
00084 }
00085 
00086 
00087 bool UniFastRegetGen::haschildren(const UniConfKey &key)
00088 {
00089     if (!tree)
00090     {
00091         wvassert(tree, "key: '%s'", key);
00092         abort();
00093     }
00094 
00095     // if we already know the node is null, we can short circuit this one
00096     UniConfValueTree *t = tree->find(key);
00097     if (t && t->value().isnull())
00098         return false; // definitely no children
00099     return UniFilterGen::haschildren(key);
00100 }

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