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  16         <h1>eVaf Tutorial</h1>
  17
  18         <h2>06 - Storage Module</h2>
  19
  20         <p>In this section we start implementing the Storage module. The storage module stores non-sensitive data required to re-generate
  21         passwords. We use a simple SQLITE database in this module, but nothing prevents us replacing it with a more complex storage
  22         module in the future.</p>
  23
  24         <h3>iStorage interface</h3>
  25
  26         <p>Once again, we start by defining the interface for the module and create the file <tt>istorage.h</tt> in the
  27         <tt>src/apps/PswGen/Storage</tt> directory:</p>
  28
  29         <pre class="hl"><span class="hl com">/**</span>
  30 <span class="hl com"> * &#64;file PswGen/Storage/istorage.h</span>
  31 <span class="hl com"> */</span>
  32
  33 <span class="hl ppc">#ifndef __PSWGEN_STORAGE_ISTORAGE_H</span>
  34 <span class="hl ppc">#  define __PSWGEN_STORAGE_ISTORAGE_H</span>
  35 <span class="hl ppc">#endif</span> <span class="hl slc">// istorage.h</span></pre>
  36
  37         <p>Include Qt header files for <tt>QObject</tt> and <tt>QString</tt> as they are almost always needed. In additon, we are going to
  38         include headers for <tt>QSharedData</tt> and <tt>QExplicitlySharedDataPointer</tt>. We need a container for the data that
  39         we store and making it shared data object with the benefit of automatic reference counting and memory management makes sense.</p>
  40
  41         <pre class="hl"><span class="hl ppc">#include &lt;QObject&gt;</span>
  42 <span class="hl ppc">#include &lt;QString&gt;</span>
  43 <span class="hl ppc">#include &lt;QSharedData&gt;</span>
  44 <span class="hl ppc">#include &lt;QExplicitlySharedDataPointer&gt;</span></pre>
  45
  46         <p>Use the <tt>eVaf::PswGen</tt> namespace:</p>
  47
  48         <pre class="hl"><span class="hl kwa">namespace</span> eVaf <span class="hl opt">{</span>
  49 <span class="hl kwa">namespace</span> PswGen <span class="hl opt">{</span>
  50
  51 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen</span>
  52 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf</span></pre>
  53
  54         <p>The container class for stored data has the following attributes:</p>
  55         <ul>
  56             <li>Name -- Name of the generated password</li>
  57             <li>Length -- Length of the password</li>
  58             <li>Options -- Additional parameters for the password generator</li>
  59         </ul>
  60
  61         <p>The container class belongs to the Storage module and we use the <tt>eVaf::PswGen::Storage</tt> namespace for it:</p>
  62
  63         <pre class="hl"><span class="hl kwa">namespace</span> Storage <span class="hl opt">{</span>
  64
  65 <span class="hl kwc">class</span> Data <span class="hl opt">:</span> <span class="hl kwc">public</span> QSharedData
  66 <span class="hl opt">{</span>
  67 <span class="hl kwc">private</span><span class="hl opt">:</span>
  68
  69     <span class="hl kwb">bool</span> mModified<span class="hl opt">;</span>
  70     QString mName<span class="hl opt">;</span>
  71     <span class="hl kwb">int</span> mLength<span class="hl opt">;</span>
  72     uint mFlags<span class="hl opt">;</span>
  73
  74 <span class="hl opt">};</span>
  75
  76 <span class="hl opt">}</span> <span class="hl slc">// eVaf::PswGen::Storage</span></pre>
  77
  78         <p>The extra attribute - <tt>mModified</tt> - is used to detect unsaved modifications in the data object.</p>
  79
  80         <p>Add constructors for the shared data class. Creating a data object without name makes no sense and we include the
  81         name attribute in all our constructors:</p>
  82
  83         <pre class="hl"><span class="hl kwc">public</span><span class="hl opt">:</span>
  84
  85     <span class="hl kwd">Data</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span>
  86         <span class="hl opt">:</span> <span class="hl kwd">QSharedData</span><span class="hl opt">()</span>
  87         <span class="hl opt">,</span> <span class="hl kwd">mModified</span><span class="hl opt">(</span><span class="hl kwa">false</span><span class="hl opt">)</span>
  88         <span class="hl opt">,</span> <span class="hl kwd">mName</span><span class="hl opt">(</span>name<span class="hl opt">)</span>
  89         <span class="hl opt">,</span> <span class="hl kwd">mLength</span><span class="hl opt">(</span><span class="hl num">0</span><span class="hl opt">)</span>
  90         <span class="hl opt">,</span> <span class="hl kwd">mFlags</span><span class="hl opt">(</span><span class="hl num">0</span><span class="hl opt">)</span>
  91     <span class="hl opt">{}</span>
  92
  93     <span class="hl kwd">Data</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> <span class="hl kwb">int</span> l<span class="hl opt">,</span> uint f <span class="hl opt">=</span> <span class="hl num">0</span><span class="hl opt">)</span>
  94         <span class="hl opt">:</span> <span class="hl kwd">QSharedData</span><span class="hl opt">()</span>
  95         <span class="hl opt">,</span> <span class="hl kwd">mModified</span><span class="hl opt">(</span><span class="hl kwa">false</span><span class="hl opt">)</span>
  96         <span class="hl opt">,</span> <span class="hl kwd">mName</span><span class="hl opt">(</span>name<span class="hl opt">)</span>
  97         <span class="hl opt">,</span> <span class="hl kwd">mLength</span><span class="hl opt">(</span>l<span class="hl opt">)</span>
  98         <span class="hl opt">,</span> <span class="hl kwd">mFlags</span><span class="hl opt">(</span>f<span class="hl opt">)</span>
  99     <span class="hl opt">{}</span></pre>
 100
 101     <p>Fianlly, we add getter and setter methods:</p>
 102
 103     <pre class="hl">
 104     QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> <span class="hl kwd">name</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mName<span class="hl opt">; }</span>
 105
 106     <span class="hl kwb">int</span> <span class="hl kwd">length</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mLength<span class="hl opt">; }</span>
 107     <span class="hl kwb">void</span> <span class="hl kwd">setLength</span><span class="hl opt">(</span><span class="hl kwb">int</span> value<span class="hl opt">)</span>
 108     <span class="hl opt">{</span>
 109         <span class="hl kwa">if</span> <span class="hl opt">(</span>mLength <span class="hl opt">!=</span> value<span class="hl opt">) {</span>
 110             mLength <span class="hl opt">=</span> value<span class="hl opt">;</span>
 111             mModified <span class="hl opt">=</span> <span class="hl kwa">true</span><span class="hl opt">;</span>
 112         <span class="hl opt">}</span>
 113     <span class="hl opt">}</span>
 114
 115     uint <span class="hl kwd">flags</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mFlags<span class="hl opt">; }</span>
 116     <span class="hl kwb">void</span> <span class="hl kwd">setFlags</span><span class="hl opt">(</span>uint value<span class="hl opt">)</span>
 117     <span class="hl opt">{</span>
 118         <span class="hl kwa">if</span> <span class="hl opt">(</span>mFlags <span class="hl opt">!=</span> value<span class="hl opt">) {</span>
 119             mFlags <span class="hl opt">=</span> value<span class="hl opt">;</span>
 120             mModified <span class="hl opt">=</span> <span class="hl kwa">true</span><span class="hl opt">;</span>
 121         <span class="hl opt">}</span>
 122     <span class="hl opt">}</span>
 123
 124     <span class="hl kwb">bool</span> <span class="hl kwd">modified</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mModified<span class="hl opt">; }</span>
 125
 126     <span class="hl kwb">void</span> <span class="hl kwd">reset</span><span class="hl opt">() {</span> mModified <span class="hl opt">=</span> <span class="hl kwa">false</span><span class="hl opt">; }</span></pre>
 127
 128     <p>The <tt>reset()</tt> method resets the <tt>modified</tt> attribute.</p>
 129
 130     <p>Continue with the <tt>iStorage</tt> interface:</tt>
 131
 132     <pre class="hl"><span class="hl kwb">struct</span> iStorage
 133 <span class="hl opt">{</span>
 134
 135 <span class="hl opt">};</span></pre>
 136
 137     <p>According to the specification, we need functions to store and query data:</p>
 138
 139     <pre class="hl">
 140     <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">save</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> data<span class="hl opt">) =</span> <span class="hl num">0</span><span class="hl opt">;</span>
 141
 142     <span class="hl kwc">virtual</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> <span class="hl kwd">query</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span> <span class="hl kwb">const</span> <span class="hl opt">=</span> <span class="hl num">0</span><span class="hl opt">;</span></pre>
 143
 144     <p>The <tt>query()</tt> method returns an explicitly shared shared data pointer, which has the following advantages:</p>
 145     <ul>
 146         <li>The same data object is shared between multiple modules and if a module changes attributes in the data object, these
 147         changes are immediately seen by any other modules;</li>
 148         <li>No need to worry about ownership -- the shared data object is deleted when the last module stops using it;</li>
 149         <li>The <tt>query()</tt> method can return an empty shared data pointer to indicate that no data objects with the
 150         given name exist.</tt>
 151     </ul>
 152
 153     <p>The drawback is that if a module needs a local copy of the data object, it has to use the <tt>QExplicitlySharedDataPointer::detach()</tt> method to create a deep copy of the data object.</p>
 154
 155     <p>The specification also mentions partial matches where entering "fa" would offer "facebook.com" if it exists. This could be done by
 156     using the <tt>QCompleter</tt> class that provides auto completion in Qt widgets like <tt>QLineEdit</tt> and <tt>QComboBox</tt>. The
 157     <tt>QCompleter<tt> class needs a <tt>QAbstractItemModel</tt> for the auto completion word list and we can provide it
 158     from our <tt>Storage</tt> module:</tt>
 159
 160     <pre class="hl">
 161     <span class="hl kwc">virtual</span> QAbstractItemModel <span class="hl opt">*</span> <span class="hl kwd">autoCompletionModel</span><span class="hl opt">() =</span> <span class="hl num">0</span><span class="hl opt">;</span></pre>
 162
 163     <p><tt>QAbstractItemModel</tt> is not known at this moment and we need to add a forward class declaration to the beginning of the
 164     <tt>istorage.h</tt> file:</p>
 165
 166     <pre class="hl">
 167     <span class="hl kwc">class</span> QAbstractItemModel<span class="hl opt">;</span></pre>
 168
 169     <p>At the the end of the <tt>istorage.h</tt> file, we declare the <tt>iStorage</tt> interface:</p>
 170
 171     <pre class="hl"><span class="hl kwd">Q_DECLARE_INTERFACE</span><span class="hl opt">(</span>eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>iStorage<span class="hl opt">,</span> <span class="hl str">&quot;eVaf.PswGen.iStorage/1.0&quot;</span><span class="hl opt">)</span></pre>
 172
 173     <p>This is the complete <tt>istorage.h</tt> file:</p>
 174
 175     <pre class="hl"><span class="hl com">/**</span>
 176 <span class="hl com"> * &#64;file PswGen/Storage/istorage.h</span>
 177 <span class="hl com"> */</span>
 178
 179 <span class="hl ppc">#ifndef __PSWGEN_STORAGE_ISTORAGE_H</span>
 180 <span class="hl ppc">#  define __PSWGEN_STORAGE_ISTORAGE_H</span>
 181
 182 <span class="hl ppc">#include &lt;QObject&gt;</span>
 183 <span class="hl ppc">#include &lt;QString&gt;</span>
 184 <span class="hl ppc">#include &lt;QSharedData&gt;</span>
 185 <span class="hl ppc">#include &lt;QExplicitlySharedDataPointer&gt;</span>
 186
 187 <span class="hl kwc">class</span> QAbstractItemModel<span class="hl opt">;</span>
 188
 189 <span class="hl kwa">namespace</span> eVaf <span class="hl opt">{</span>
 190 <span class="hl kwa">namespace</span> PswGen <span class="hl opt">{</span>
 191
 192 <span class="hl kwa">namespace</span> Storage <span class="hl opt">{</span>
 193
 194 <span class="hl com">/// Data stored for every password.</span>
 195 <span class="hl kwc">class</span> Data <span class="hl opt">:</span> <span class="hl kwc">public</span> QSharedData
 196 <span class="hl opt">{</span>
 197 <span class="hl kwc">public</span><span class="hl opt">:</span>
 198
 199     <span class="hl kwd">Data</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span>
 200         <span class="hl opt">:</span> <span class="hl kwd">QSharedData</span><span class="hl opt">()</span>
 201         <span class="hl opt">,</span> <span class="hl kwd">mModified</span><span class="hl opt">(</span><span class="hl kwa">false</span><span class="hl opt">)</span>
 202         <span class="hl opt">,</span> <span class="hl kwd">mName</span><span class="hl opt">(</span>name<span class="hl opt">)</span>
 203         <span class="hl opt">,</span> <span class="hl kwd">mLength</span><span class="hl opt">(</span><span class="hl num">0</span><span class="hl opt">)</span>
 204         <span class="hl opt">,</span> <span class="hl kwd">mFlags</span><span class="hl opt">(</span><span class="hl num">0</span><span class="hl opt">)</span>
 205     <span class="hl opt">{}</span>
 206
 207     <span class="hl kwd">Data</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> <span class="hl kwb">int</span> l<span class="hl opt">,</span> uint f <span class="hl opt">=</span> <span class="hl num">0</span><span class="hl opt">)</span>
 208         <span class="hl opt">:</span> <span class="hl kwd">QSharedData</span><span class="hl opt">()</span>
 209         <span class="hl opt">,</span> <span class="hl kwd">mModified</span><span class="hl opt">(</span><span class="hl kwa">false</span><span class="hl opt">)</span>
 210         <span class="hl opt">,</span> <span class="hl kwd">mName</span><span class="hl opt">(</span>name<span class="hl opt">)</span>
 211         <span class="hl opt">,</span> <span class="hl kwd">mLength</span><span class="hl opt">(</span>l<span class="hl opt">)</span>
 212         <span class="hl opt">,</span> <span class="hl kwd">mFlags</span><span class="hl opt">(</span>f<span class="hl opt">)</span>
 213     <span class="hl opt">{}</span>
 214
 215     <span class="hl slc">/// Name of the password</span>
 216     QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> <span class="hl kwd">name</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mName<span class="hl opt">; }</span>
 217
 218     <span class="hl slc">/// Length of the generated password</span>
 219     <span class="hl kwb">int</span> <span class="hl kwd">length</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mLength<span class="hl opt">; }</span>
 220     <span class="hl kwb">void</span> <span class="hl kwd">setLength</span><span class="hl opt">(</span><span class="hl kwb">int</span> value<span class="hl opt">)</span>
 221     <span class="hl opt">{</span>
 222         <span class="hl kwa">if</span> <span class="hl opt">(</span>mLength <span class="hl opt">!=</span> value<span class="hl opt">) {</span>
 223             mLength <span class="hl opt">=</span> value<span class="hl opt">;</span>
 224             mModified <span class="hl opt">=</span> <span class="hl kwa">true</span><span class="hl opt">;</span>
 225         <span class="hl opt">}</span>
 226     <span class="hl opt">}</span>
 227
 228     <span class="hl slc">/// Optional flags for the password generator</span>
 229     uint <span class="hl kwd">flags</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mFlags<span class="hl opt">; }</span>
 230     <span class="hl kwb">void</span> <span class="hl kwd">setFlags</span><span class="hl opt">(</span>uint value<span class="hl opt">)</span>
 231     <span class="hl opt">{</span>
 232         <span class="hl kwa">if</span> <span class="hl opt">(</span>mFlags <span class="hl opt">!=</span> value<span class="hl opt">) {</span>
 233             mFlags <span class="hl opt">=</span> value<span class="hl opt">;</span>
 234             mModified <span class="hl opt">=</span> <span class="hl kwa">true</span><span class="hl opt">;</span>
 235         <span class="hl opt">}</span>
 236     <span class="hl opt">}</span>
 237
 238     <span class="hl slc">/// Flag indicating that some fields are modified</span>
 239     <span class="hl kwb">bool</span> <span class="hl kwd">modified</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mModified<span class="hl opt">; }</span>
 240
 241     <span class="hl slc">/// Resets the modified flag</span>
 242     <span class="hl kwb">void</span> <span class="hl kwd">reset</span><span class="hl opt">() {</span> mModified <span class="hl opt">=</span> <span class="hl kwa">false</span><span class="hl opt">; }</span>
 243
 244 <span class="hl kwc">private</span><span class="hl opt">:</span>
 245
 246     <span class="hl kwb">bool</span> mModified<span class="hl opt">;</span>
 247     QString mName<span class="hl opt">;</span>
 248     <span class="hl kwb">int</span> mLength<span class="hl opt">;</span>
 249     uint mFlags<span class="hl opt">;</span>
 250
 251 <span class="hl opt">};</span>
 252
 253 <span class="hl opt">}</span> <span class="hl slc">// eVaf::PswGen::Storage</span>
 254
 255 <span class="hl com">/// Password storage interface.</span>
 256 <span class="hl kwb">struct</span> iStorage
 257 <span class="hl opt">{</span>
 258
 259     <span class="hl com">/// Saves the data record</span>
 260     <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">save</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> data<span class="hl opt">) =</span> <span class="hl num">0</span><span class="hl opt">;</span>
 261
 262     <span class="hl com">/// Returns a data record by the name</span>
 263     <span class="hl kwc">virtual</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> <span class="hl kwd">query</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span> <span class="hl kwb">const</span> <span class="hl opt">=</span> <span class="hl num">0</span><span class="hl opt">;</span>
 264
 265     <span class="hl com">/// Returns an item model with the names of all the stored passwords</span>
 266     <span class="hl kwc">virtual</span> QAbstractItemModel <span class="hl opt">*</span> <span class="hl kwd">autoCompletionModel</span><span class="hl opt">() =</span> <span class="hl num">0</span><span class="hl opt">;</span>
 267
 268 <span class="hl opt">};</span>
 269
 270 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen</span>
 271 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf</span>
 272
 273 <span class="hl kwd">Q_DECLARE_INTERFACE</span><span class="hl opt">(</span>eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>iStorage<span class="hl opt">,</span> <span class="hl str">&quot;eVaf.PswGen.iStorage/1.0&quot;</span><span class="hl opt">)</span>
 274
 275 <span class="hl ppc">#endif</span> <span class="hl slc">// istorage.h</span><span class="hl ppc"></span></pre>
 276
 277     <p>We also create the <tt>iStorage</tt> file so that we can use <tt>#include &lt;Storage/iStorage&gt;</tt> in our other modules:</tt>
 278
 279     <pre class="hl"><span class="hl ppc">#include </span><span class="hl pps">&quot;istorage.h&quot;</span></pre>
 280
 281     <h3>Storage module</h3>
 282
 283     <p>The <tt>Storage<tt> module is simple enough to be derived directly from the <tt>Plugins::iPlugin</tt> interface and needs only one
 284     header/source file. In general, I personally prefer short source files and follow the <i>one-class-per-file</i> rule. Only when classes
 285     are very simple and closely related I put the into the same source file.</p>
 286
 287     <p>Create the <tt>module.h</tt> header file in the <tt>src/apps/PswGen/Storage</tt> directory. Include <tt>istorage.h</tt> and
 288     <tt>Plugins/iPlugin</tt> header files. We use the <tt>eVaf::PswGen::Storage</tt> namespace for public classes and
 289     <tt>eVaf::PswGen::Storage::Internal<tt> namespace for private classes.</p>
 290
 291     <pre class="hl"><span class="hl ppc">#ifndef __PSWGEN_STORAGE_MODULE_H</span>
 292 <span class="hl ppc">#  define __PSWGEN_STORAGE_MODULE_H</span>
 293
 294 <span class="hl ppc">#include</span> <span class="hl pps">&quot;istorage.h&quot;</span><span class="hl ppc"></span>
 295 <span class="hl ppc">#include &lt;Plugins/iPlugin&gt;</span>
 296
 297 <span class="hl kwa">namespace</span> eVaf <span class="hl opt">{</span>
 298 <span class="hl kwa">namespace</span> PswGen <span class="hl opt">{</span>
 299
 300 <span class="hl slc">/// Module that stores options for strong passwords</span>
 301 <span class="hl kwa">namespace</span> Storage <span class="hl opt">{</span>
 302
 303 <span class="hl slc">/// Internal implementation of the Storage module</span>
 304 <span class="hl kwa">namespace</span> Internal <span class="hl opt">{</span>
 305
 306 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage::Internal</span>
 307 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage</span>
 308 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen</span>
 309 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf</span>
 310 <span class="hl ppc">#endif</span> <span class="hl slc">// module.h</span><span class="hl ppc"></span></pre>
 311
 312     <p>We use the same name <tt>Module</tt> for the class that implements the module. This class is public and goes to the
 313     <tt>eVaf::PswGen::Storage</tt> namespace:</p>
 314
 315     <pre class="hl"><span class="hl kwc">class</span> Module <span class="hl opt">:</span> <span class="hl kwc">public</span> Plugins<span class="hl opt">::</span>iPlugin
 316 <span class="hl opt">{</span>
 317     Q_OBJECT
 318
 319 <span class="hl kwc">public</span><span class="hl opt">:</span>
 320
 321     <span class="hl kwd">Module</span><span class="hl opt">();</span>
 322
 323     <span class="hl kwc">virtual</span> <span class="hl opt">~</span><span class="hl kwd">Module</span><span class="hl opt">();</span>
 324
 325 <span class="hl opt">};</span></pre>
 326
 327     <p>Implement pure virtual methods in the <tt>iPlugin</tt> interface:</p>
 328
 329     <pre class="hl">
 330     <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">init</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> args<span class="hl opt">);</span>
 331
 332     <span class="hl kwc">virtual</span> <span class="hl kwb">void</span> <span class="hl kwd">done</span><span class="hl opt">();</span>
 333
 334     <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">isReady</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mReady<span class="hl opt">; }</span></pre>
 335
 336     <p>This module needs more complex initialization that the <tt>Generator</tt> module and we use the <tt>mReady</tt> flag to
 337     indicate that the module is fully initialized:</p>
 338
 339     <pre class="hl">
 340 <span class="hl kwc">private</span><span class="hl opt">:</span>
 341
 342     <span class="hl kwb">bool</span> mReady<span class="hl opt">;</span></pre>
 343
 344     <p>The <tt>StorageImpl</tt> class is the internal implementation of the <tt>iStorage</tt> interface:</p>
 345
 346     <pre class="hl">
 347     Internal<span class="hl opt">::</span>StorageImpl <span class="hl opt">*</span> mStorage<span class="hl opt">;</span></pre>
 348
 349     <p>We could declare the <tt>Internal::StorageImpl</tt> class before the <tt>Module</tt> class, but as I like starting with more
 350     generic (public) classes and then go into the details, we add a forward declaration to the beginning of the file:</p>
 351
 352     <pre class="hl">
 353 <span class="hl kwa">namespace</span> Internal <span class="hl opt">{</span>
 354     <span class="hl kwc">class</span> StorageImpl<span class="hl opt">;</span>
 355 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage::Internal</span></pre>
 356
 357     <p>The declaration of the <tt>StorageImpl</tt> class goes into the <tt>eVaf::PswGen::Storage::Internal</tt> namespace and the class
 358     shall be derived both from <tt>QObject</tt> and <tt>iStorage</tt>. However, since we also need to implement the
 359     <tt>QAbstractItemModel</tt> data model for the <tt>iStorage::autoCompletionModel()</tt> method, we derive it from the
 360     <tt>QAbstractListModel</tt> class instead. We use the <tt>QAbstractListModel</tt> class because it meets our requirements
 361     to return a list of auto completion words.</p>
 362
 363     <pre class="hl">
 364 <span class="hl kwa">namespace</span> Internal <span class="hl opt">{</span>
 365
 366 <span class="hl kwc">class</span> StorageImpl <span class="hl opt">:</span> <span class="hl kwc">public</span> QAbstractListModel<span class="hl opt">,</span> <span class="hl kwc">public</span> iStorage
 367 <span class="hl opt">{</span>
 368     Q_OBJECT
 369     <span class="hl kwd">Q_INTERFACES</span><span class="hl opt">(</span>eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>iStorage<span class="hl opt">)</span>
 370
 371 <span class="hl kwc">public</span><span class="hl opt">:</span>
 372
 373     <span class="hl kwd">StorageImpl</span><span class="hl opt">();</span>
 374
 375     <span class="hl kwc">virtual</span> <span class="hl opt">~</span><span class="hl kwd">StorageImpl</span><span class="hl opt">();</span>
 376
 377 <span class="hl opt">};</span>
 378
 379 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage::Internal</span></pre>
 380
 381     <p>First, we implement pure virtual methods found in the <tt>iStorage</tt> interface:</p>
 382
 383     <pre class="hl">
 384     <span class="hl com">/*</span>
 385         <span class="hl com">iStorage interface</span>
 386     <span class="hl com">*/</span>
 387
 388     <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">save</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> data<span class="hl opt">);</span>
 389
 390     <span class="hl kwc">virtual</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> <span class="hl kwd">query</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span> <span class="hl kwb">const</span><span class="hl opt">;</span>
 391
 392     <span class="hl kwc">virtual</span> QAbstractItemModel <span class="hl opt">*</span> <span class="hl kwd">autoCompletionModel</span><span class="hl opt">() {</span> <span class="hl kwa">return this</span><span class="hl opt">; }</span></pre>
 393
 394     <p>Since the <tt>QAbstractItemModel</tt> data model is implemented by the same class, we can simply return <tt>this</tt> in the
 395     <tt>autoCompletionModel()</tt> model.</p>
 396
 397     <p>The <tt>QAbstractListModel</tt> class also has pure virtual methods that need to be implemented:</p>
 398
 399     <pre class="hl">
 400     <span class="hl com">/*</span>
 401         <span class="hl com">QAbstractListModel methods</span>
 402     <span class="hl com">*/</span>
 403
 404     <span class="hl kwc">virtual</span> <span class="hl kwb">int</span> <span class="hl kwd">rowCount</span><span class="hl opt">(</span>QModelIndex <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> parent<span class="hl opt">)</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mData<span class="hl opt">.</span><span class="hl kwd">count</span><span class="hl opt">(); }</span>
 405
 406     <span class="hl kwc">virtual</span> QVariant <span class="hl kwd">data</span><span class="hl opt">(</span>QModelIndex <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> index<span class="hl opt">,</span> <span class="hl kwb">int</span> role <span class="hl opt">=</span> Qt<span class="hl opt">::</span>DisplayRole<span class="hl opt">)</span> <span class="hl kwb">const</span><span class="hl opt">;</span></pre>
 407
 408     <p><tt>mData</tt> here is a container with all the stored data objects, which we add to the <tt>private</tt> section. We use
 409     a <tt>QMap&lt;QString, QExplicitlySharedDataPointer&lt;Storage::Data&gt; &gt;</tt> for this purpose as it allows fast lookups
 410     by the name string.</p>
 411
 412     <pre class="hl">
 413 <span class="hl kwc">private</span><span class="hl opt">:</span>
 414
 415     QMap<span class="hl opt">&lt;</span>QString<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt; &gt;</span> mData<span class="hl opt">;</span></pre>
 416
 417     <p>Permanent data storage is done using a SQLITE database. We add the database object and a methods to load data from the database. We
 418     also need a method to create database tables if they do not exist yet:</p>
 419
 420     <pre class="hl">
 421     QSqlDatabase mDb<span class="hl opt">;</span>
 422
 423     <span class="hl kwb">bool</span> <span class="hl kwd">createTables</span><span class="hl opt">();</span>
 424
 425     <span class="hl kwb">bool</span> <span class="hl kwd">loadData</span><span class="hl opt">();</span></pre>
 426
 427     <p>The database object needs names for the connection and for the database, which we can add as constants to the class:</p>
 428
 429     <pre class="hl">
 430     <span class="hl kwb">static char const</span> <span class="hl opt">*</span> <span class="hl kwb">const</span> DbConnectionName<span class="hl opt">;</span>
 431
 432     <span class="hl kwb">static char const</span> <span class="hl opt">*</span> <span class="hl kwb">const</span> DbName<span class="hl opt">;</span></pre>
 433
 434     <p>The database needs to be opened and closed, and the list of data objects populated with data from the database. For this purpose
 435     we add <tt>init()</tt> and <tt>done()</tt> methods to the public section of the class. The <tt>init()</tt> method can return
 436     <tt>false</tt> if the initialization fails.</p>
 437
 438     <pre class="hl">
 439     <span class="hl kwb">bool</span> <span class="hl kwd">init</span><span class="hl opt">();</span>
 440
 441     <span class="hl kwb">void</span> <span class="hl kwd">done</span><span class="hl opt">();</span></pre>
 442
 443     <p>This is the final <tt>module.h</tt> file:</p>
 444
 445 <pre class="hl"><span class="hl com">/**</span>
 446 <span class="hl com"> * &#64;file PswGen/Storage/module.h</span>
 447 <span class="hl com"> */</span>
 448
 449 <span class="hl ppc">#ifndef __PSWGEN_STORAGE_MODULE_H</span>
 450 <span class="hl ppc">#  define __PSWGEN_STORAGE_MODULE_H</span>
 451
 452 <span class="hl ppc">#include</span> <span class="hl pps">&quot;istorage.h&quot;</span><span class="hl ppc"></span>
 453
 454 <span class="hl ppc">#include &lt;Plugins/iPlugin&gt;</span>
 455
 456 <span class="hl ppc">#include &lt;QObject&gt;</span>
 457 <span class="hl ppc">#include &lt;QString&gt;</span>
 458 <span class="hl ppc">#include &lt;QAbstractListModel&gt;</span>
 459 <span class="hl ppc">#include &lt;QMap&gt;</span>
 460 <span class="hl ppc">#include &lt;QtSql/QSqlDatabase&gt;</span>
 461
 462
 463 <span class="hl kwa">namespace</span> eVaf <span class="hl opt">{</span>
 464 <span class="hl kwa">namespace</span> PswGen <span class="hl opt">{</span>
 465
 466 <span class="hl slc">/// Module that stores options for strong passwords</span>
 467 <span class="hl kwa">namespace</span> Storage <span class="hl opt">{</span>
 468
 469 <span class="hl slc">/// Internal implementation of the Storage module</span>
 470 <span class="hl kwa">namespace</span> Internal <span class="hl opt">{</span>
 471     <span class="hl kwc">class</span> StorageImpl<span class="hl opt">;</span>
 472 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage::Internal</span>
 473
 474 <span class="hl com">/// Module implementing the iStorage interface.</span>
 475 <span class="hl kwc">class</span> Module <span class="hl opt">:</span> <span class="hl kwc">public</span> Plugins<span class="hl opt">::</span>iPlugin
 476 <span class="hl opt">{</span>
 477     Q_OBJECT
 478
 479 <span class="hl kwc">public</span><span class="hl opt">:</span>
 480
 481     <span class="hl kwd">Module</span><span class="hl opt">();</span>
 482
 483     <span class="hl kwc">virtual</span> <span class="hl opt">~</span><span class="hl kwd">Module</span><span class="hl opt">();</span>
 484
 485     <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">init</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> args<span class="hl opt">);</span>
 486
 487     <span class="hl kwc">virtual</span> <span class="hl kwb">void</span> <span class="hl kwd">done</span><span class="hl opt">();</span>
 488
 489     <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">isReady</span><span class="hl opt">()</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mReady<span class="hl opt">; }</span>
 490
 491
 492 <span class="hl kwc">private</span><span class="hl opt">:</span> <span class="hl slc">// Members</span>
 493
 494     <span class="hl slc">/// Flag indicating that the module is ready</span>
 495     <span class="hl kwb">bool</span> mReady<span class="hl opt">;</span>
 496
 497     <span class="hl slc">/// iStorage interface instance</span>
 498     Internal<span class="hl opt">::</span>StorageImpl <span class="hl opt">*</span> mStorage<span class="hl opt">;</span>
 499
 500 <span class="hl opt">};</span>
 501
 502 <span class="hl kwa">namespace</span> Internal <span class="hl opt">{</span>
 503
 504 <span class="hl com">/// iStorage interface implementation.</span>
 505 <span class="hl kwc">class</span> StorageImpl <span class="hl opt">:</span> <span class="hl kwc">public</span> QAbstractListModel<span class="hl opt">,</span> <span class="hl kwc">public</span> iStorage
 506 <span class="hl opt">{</span>
 507     Q_OBJECT
 508     <span class="hl kwd">Q_INTERFACES</span><span class="hl opt">(</span>eVaf<span class="hl opt">::</span>PswGen<span class="hl opt">::</span>iStorage<span class="hl opt">)</span>
 509
 510 <span class="hl kwc">public</span><span class="hl opt">:</span>
 511
 512     <span class="hl kwd">StorageImpl</span><span class="hl opt">();</span>
 513
 514     <span class="hl kwc">virtual</span> <span class="hl opt">~</span><span class="hl kwd">StorageImpl</span><span class="hl opt">();</span>
 515
 516     <span class="hl kwb">bool</span> <span class="hl kwd">init</span><span class="hl opt">();</span>
 517
 518     <span class="hl kwb">void</span> <span class="hl kwd">done</span><span class="hl opt">();</span>
 519
 520     <span class="hl com">/*</span>
 521         <span class="hl com">iStorage interface</span>
 522     <span class="hl com">*/</span>
 523
 524     <span class="hl kwc">virtual</span> <span class="hl kwb">bool</span> <span class="hl kwd">save</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> data<span class="hl opt">);</span>
 525
 526     <span class="hl kwc">virtual</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt;</span> <span class="hl kwd">query</span><span class="hl opt">(</span>QString <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> name<span class="hl opt">)</span> <span class="hl kwb">const</span><span class="hl opt">;</span>
 527
 528     <span class="hl kwc">virtual</span> QAbstractItemModel <span class="hl opt">*</span> <span class="hl kwd">autoCompletionModel</span><span class="hl opt">() {</span> <span class="hl kwa">return this</span><span class="hl opt">; }</span>
 529
 530     <span class="hl com">/*</span>
 531         <span class="hl com">QAbstractListModel methods</span>
 532     <span class="hl com">*/</span>
 533
 534     <span class="hl kwc">virtual</span> <span class="hl kwb">int</span> <span class="hl kwd">rowCount</span><span class="hl opt">(</span>QModelIndex <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> parent<span class="hl opt">)</span> <span class="hl kwb">const</span> <span class="hl opt">{</span> <span class="hl kwa">return</span> mData<span class="hl opt">.</span><span class="hl kwd">count</span><span class="hl opt">(); }</span>
 535
 536     <span class="hl kwc">virtual</span> QVariant <span class="hl kwd">data</span><span class="hl opt">(</span>QModelIndex <span class="hl kwb">const</span> <span class="hl opt">&amp;</span> index<span class="hl opt">,</span> <span class="hl kwb">int</span> role <span class="hl opt">=</span> Qt<span class="hl opt">::</span>DisplayRole<span class="hl opt">)</span> <span class="hl kwb">const</span><span class="hl opt">;</span>
 537
 538 <span class="hl kwc">private</span><span class="hl opt">:</span> <span class="hl slc">// Members</span>
 539
 540     <span class="hl slc">/// Name of the database connection</span>
 541     <span class="hl kwb">static char const</span> <span class="hl opt">*</span> <span class="hl kwb">const</span> DbConnectionName<span class="hl opt">;</span>
 542
 543     <span class="hl slc">/// Name of the database file without path</span>
 544     <span class="hl kwb">static char const</span> <span class="hl opt">*</span> <span class="hl kwb">const</span> DbName<span class="hl opt">;</span>
 545
 546     <span class="hl slc">/// Database connection</span>
 547     QSqlDatabase mDb<span class="hl opt">;</span>
 548
 549     <span class="hl slc">/// List of name/data pairs</span>
 550     QMap<span class="hl opt">&lt;</span>QString<span class="hl opt">,</span> QExplicitlySharedDataPointer<span class="hl opt">&lt;</span>Storage<span class="hl opt">::</span>Data<span class="hl opt">&gt; &gt;</span> mData<span class="hl opt">;</span>
 551
 552
 553 <span class="hl kwc">private</span><span class="hl opt">:</span> <span class="hl slc">// Methods</span>
 554
 555     <span class="hl com">/// Creates database tables if necessary</span>
 556     <span class="hl kwb">bool</span> <span class="hl kwd">createTables</span><span class="hl opt">();</span>
 557
 558     <span class="hl com">/// Loads data from the database</span>
 559     <span class="hl kwb">bool</span> <span class="hl kwd">loadData</span><span class="hl opt">();</span>
 560
 561 <span class="hl opt">};</span>
 562
 563 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage::Internal</span>
 564 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen::Storage</span>
 565 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf::PswGen</span>
 566 <span class="hl opt">}</span> <span class="hl slc">// namespace eVaf</span>
 567
 568 <span class="hl ppc">#endif</span> <span class="hl slc">// module.h</span><span class="hl ppc"></span></pre>
 569
 570     <p>Continue implementing the <a href="pswgen07.html">Storage Module</a>.</p>
 571
 572     </body>
 573 </html>