html/082persist.cc.html


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<span class="Comment">//: Dead simple persistence.</span>
<span class="Comment">//:   'restore' - reads string from a file</span>
<span class="Comment">//:   'save' - writes string to a file</span>

<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
RESTORE<span class="Delimiter">,</span>
<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
Recipe_ordinal[<span class="Constant">&quot;restore&quot;</span>] = RESTORE<span class="Delimiter">;</span>
<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
case RESTORE: <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>!scalar<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span>
    raise &lt;&lt; <span class="Constant">&quot;restore: illegal operand &quot;</span> &lt;&lt; current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
  products<span class="Delimiter">.</span>resize<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">);</span>
  products<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>push_back<span class="Delimiter">(</span>new_string<span class="Delimiter">(</span>slurp<span class="Delimiter">(</span><span class="Constant">&quot;lesson/&quot;</span>+current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>name<span class="Delimiter">)));</span>
  <span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>

<span class="Delimiter">:(code)</span>
string slurp<span class="Delimiter">(</span>const string&amp; filename<span class="Delimiter">)</span> <span class="Delimiter">{</span>
<span class="CommentedCode">//?   cerr &lt;&lt; filename &lt;&lt; '\n'; //? 1</span>
  ostringstream result<span class="Delimiter">;</span>
  ifstream fin<span class="Delimiter">(</span>filename<span class="Delimiter">.</span>c_str<span class="Delimiter">());</span>
  fin<span class="Delimiter">.</span>peek<span class="Delimiter">();</span>
  if <span class="Delimiter">(</span>!fin<span class="Delimiter">)</span> <span class="Identifier">return</span> result<span class="Delimiter">.</span>str<span class="Delimiter">();</span>  <span class="Comment">// don't bother checking errno</span>
  const int N = <span class="Constant">1024</span><span class="Delimiter">;</span>
  char buf[N]<span class="Delimiter">;</span>
  while <span class="Delimiter">(</span>!fin<span class="Delimiter">.</span>eof<span class="Delimiter">())</span> <span class="Delimiter">{</span>
    bzero<span class="Delimiter">(</span>buf<span class="Delimiter">,</span> N<span class="Delimiter">);</span>
    fin<span class="Delimiter">.</span>read<span class="Delimiter">(</span>buf<span class="Delimiter">,</span> N-<span class="Constant">1</span><span class="Delimiter">);</span>  <span class="Comment">// leave at least one null</span>
    result &lt;&lt; buf<span class="Delimiter">;</span>
  <span class="Delimiter">}</span>
  fin<span class="Delimiter">.</span>close<span class="Delimiter">();</span>
<span class="CommentedCode">//?   cerr &lt;&lt; &quot;=&gt; &quot; &lt;&lt; result.str(); //? 1</span>
  <span class="Identifier">return</span> result<span class="Delimiter">.</span>str<span class="Delimiter">();</span>
<span class="Delimiter">}</span>

<span class="Delimiter">:(before &quot;End Primitive Recipe Declarations&quot;)</span>
SAVE<span class="Delimiter">,</span>
<span class="Delimiter">:(before &quot;End Primitive Recipe Numbers&quot;)</span>
Recipe_ordinal[<span class="Constant">&quot;save&quot;</span>] = SAVE<span class="Delimiter">;</span>
<span class="Delimiter">:(before &quot;End Primitive Recipe Implementations&quot;)</span>
case SAVE: <span class="Delimiter">{</span>
  if <span class="Delimiter">(</span>!scalar<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span>
    raise &lt;&lt; <span class="Constant">&quot;save: illegal operand 0 &quot;</span> &lt;&lt; current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
  string filename = current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>name<span class="Delimiter">;</span>
  if <span class="Delimiter">(</span>!is_literal<span class="Delimiter">(</span>current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">)))</span> <span class="Delimiter">{</span>
    ostringstream tmp<span class="Delimiter">;</span>
    tmp &lt;&lt; ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">);</span>
    filename = tmp<span class="Delimiter">.</span>str<span class="Delimiter">();</span>
  <span class="Delimiter">}</span>
  ofstream fout<span class="Delimiter">((</span><span class="Constant">&quot;lesson/&quot;</span>+filename<span class="Delimiter">).</span>c_str<span class="Delimiter">());</span>
  if <span class="Delimiter">(</span>!scalar<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">)))</span>
    raise &lt;&lt; <span class="Constant">&quot;save: illegal operand 1 &quot;</span> &lt;&lt; current_instruction<span class="Delimiter">().</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>to_string<span class="Delimiter">()</span> &lt;&lt; <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
  string contents = to_string<span class="Delimiter">(</span>ingredients<span class="Delimiter">.</span>at<span class="Delimiter">(</span><span class="Constant">1</span><span class="Delimiter">).</span>at<span class="Delimiter">(</span><span class="Constant">0</span><span class="Delimiter">));</span>
  fout &lt;&lt; contents<span class="Delimiter">;</span>
  fout<span class="Delimiter">.</span>close<span class="Delimiter">();</span>
  if <span class="Delimiter">(</span>!exists<span class="Delimiter">(</span><span class="Constant">&quot;lesson/.git&quot;</span><span class="Delimiter">))</span> <span class="Identifier">break</span><span class="Delimiter">;</span>
  <span class="Comment">// bug in git: git diff -q messes up --exit-code</span>
  int status = system<span class="Delimiter">(</span><span class="Constant">&quot;cd lesson; git add .; git diff HEAD --exit-code &gt;/dev/null || git commit -a -m . &gt;/dev/null&quot;</span><span class="Delimiter">);</span>
  if <span class="Delimiter">(</span>status != <span class="Constant">0</span><span class="Delimiter">)</span>
    raise &lt;&lt; <span class="Constant">&quot;error in commit: contents &quot;</span> &lt;&lt; contents &lt;&lt; <span class="cSpecial">'\n'</span><span class="Delimiter">;</span>
  <span class="Identifier">break</span><span class="Delimiter">;</span>
<span class="Delimiter">}</span>

<span class="Delimiter">:(code)</span>
bool exists<span class="Delimiter">(</span>const string&amp; filename<span class="Delimiter">)</span> <span class="Delimiter">{</span>
  struct stat dummy<span class="Delimiter">;</span>
  <span class="Identifier">return</span> <span class="Constant">0</span> == stat<span class="Delimiter">(</span>filename<span class="Delimiter">.</span>c_str<span class="Delimiter">(),</span> &amp;dummy<span class="Delimiter">);</span>
<span class="Delimiter">}</span>

<span class="Delimiter">:(before &quot;End Includes&quot;)</span>
<span class="PreProc">#include</span><span class="Constant">&lt;sys/stat.h&gt;</span>
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