uniconf/unifastregetgen.cc

   1 /* -*- Mode: C++ -*-
   2  * Worldvisions Weaver Software:
   3  *   Copyright (C) 2002-2005 Net Integration Technologies, Inc.
   4  *
   5  * A lightweight but slightly dangerous version of UniCacheGen.
   6  */
   7 #include <wvassert.h>
   8
   9 #include "unifastregetgen.h"
  10 #include "uniconftree.h"
  11 #include "wvmoniker.h"
  12
  13 // if 'obj' is non-NULL and is a UniConfGen, wrap that; otherwise wrap the
  14 // given moniker.
  15 static IUniConfGen *creator(WvStringParm s, IObject *_obj)
  16 {
  17     return new UniFastRegetGen(wvcreate<IUniConfGen>(s, _obj));
  18 }
  19
  20 static WvMoniker<IUniConfGen> reg("fast-reget", creator);
  21
  22
  23 UniFastRegetGen::UniFastRegetGen(IUniConfGen *_inner) :
  24     UniFilterGen(_inner),
  25     tree(NULL)
  26 {
  27     tree = new UniConfValueTree(NULL, "/", UniFilterGen::get("/"));
  28 }
  29
  30
  31 UniFastRegetGen::~UniFastRegetGen()
  32 {
  33     if (tree)
  34     {
  35         delete tree;
  36         tree = NULL;
  37     }
  38 }
  39
  40
  41 void UniFastRegetGen::gencallback(const UniConfKey &key, WvStringParm value)
  42 {
  43     if (tree == NULL)
  44         return; // initialising
  45
  46     UniConfValueTree *t = tree->find(key);
  47     if (t) // never previously retrieved; don't cache it
  48         t->setvalue(value);
  49     UniFilterGen::gencallback(key, value);
  50 }
  51
  52
  53 WvString UniFastRegetGen::get(const UniConfKey &key)
  54 {
  55     if (!tree)
  56     {
  57         wvassert(tree, "key: '%s'", key);
  58         abort();
  59     }
  60
  61     // Keys with trailing slashes can't have values set on them
  62     if (key.hastrailingslash())
  63         return WvString::null;
  64
  65     UniConfValueTree *t = tree->find(key);
  66     if (!t)
  67     {
  68         UniConfKey parentkey(key.removelast());
  69         get(parentkey); // guaranteed to create parent node
  70         t = tree->find(parentkey);
  71         assert(t);
  72
  73         WvString value;
  74         if (!t->value().isnull()) // if parent is null, child guaranteed null
  75             value = UniFilterGen::get(key);
  76         new UniConfValueTree(t, key.last(), value);
  77         return value;
  78     }
  79     else
  80         return t->value();
  81 }
  82
  83
  84 bool UniFastRegetGen::exists(const UniConfKey &key)
  85 {
  86     // even if inner generator has a more efficient version of exists(),
  87     // do it this way so we can cache the result.
  88     return !get(key).isnull();
  89 }
  90
  91
  92 bool UniFastRegetGen::haschildren(const UniConfKey &key)
  93 {
  94     if (!tree)
  95     {
  96         wvassert(tree, "key: '%s'", key);
  97         abort();
  98     }
  99
 100     // if we already know the node is null, we can short circuit this one
 101     UniConfValueTree *t = tree->find(key);
 102     if (t && t->value().isnull())
 103         return false; // definitely no children
 104     return UniFilterGen::haschildren(key);
 105 }