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<div class="section" id="module-lib.safe">
<h1>safe<a class="headerlink" href="#module-lib.safe" title="Permalink to this headline">¶</a></h1>
<dl class="exception">
<dt id="lib.safe.UnsafeError">
<em class="property">
exception </em><tt class="descclassname">lib.safe.</tt><tt class="descname">UnsafeError</tt><a class="headerlink" href="#lib.safe.UnsafeError" title="Permalink to this definition">¶</a></dt>
<dd>Bases: <tt class="xref docutils literal"><span class="pre">exceptions.Exception</span></tt></dd></dl>
<dl class="function">
<dt id="lib.safe.assert_safe">
<tt class="descclassname">lib.safe.</tt><tt class="descname">assert_safe</tt><big>(</big><em>expr</em>, <em>_globals=None</em>, <em>_locals=None</em>, <em>validate=None</em><big>)</big><a class="headerlink" href="#lib.safe.assert_safe" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="function">
<dt id="lib.safe.assert_safe_expr">
<tt class="descclassname">lib.safe.</tt><tt class="descname">assert_safe_expr</tt><big>(</big><em>meta_expr</em>, <em>_globals=None</em>, <em>_locals=None</em>, <em>validate=None</em>, <em>preprocess=<function <lambda> at 0x26a9398></em><big>)</big><a class="headerlink" href="#lib.safe.assert_safe_expr" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="function">
<dt id="lib.safe.compile_expr">
<tt class="descclassname">lib.safe.</tt><tt class="descname">compile_expr</tt><big>(</big><em>meta_expr</em>, <em>_globals=None</em>, <em>_locals=None</em>, <em>validate=None</em>, <em>preprocess=<function <lambda> at 0x26a92a8></em>, <em>safe=True</em><big>)</big><a class="headerlink" href="#lib.safe.compile_expr" title="Permalink to this definition">¶</a></dt>
<dd><p>If safe is a list, a restricted evaluation will be executed.
Otherwise if safe is None, a unrestriced eval will be executed.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><em>meta_expr</em> (string) – meta-expression with <subexpressions></li>
<li><em>_globals</em> (dict) – globals</li>
<li><em>_locals</em> (dict) – locals</li>
<li><em>safe</em> (list or None) – safe names which will be accepted by the compiler</li>
<li><em>preprocess</em> (callable) – preprocess expression (e.g. for ## formatting)</li>
</ul>
</td>
</tr>
</tbody>
</table>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">compile_expr</span><span class="p">(</span><span class="s">'<1+1>_<abs(2-3)>'</span><span class="p">,</span> <span class="n">safe</span><span class="o">=</span><span class="bp">False</span><span class="p">)</span>
<span class="go">u'2_1'</span>
<span class="gp">>>> </span><span class="n">compile_expr</span><span class="p">(</span><span class="s">'<###(index+1)>'</span><span class="p">,</span> <span class="n">_locals</span><span class="o">=</span><span class="p">{</span><span class="s">'index'</span><span class="p">:</span><span class="mf">1</span><span class="p">},</span>
<span class="gp">... </span> <span class="n">preprocess</span><span class="o">=</span><span class="n">format_expr</span><span class="p">,</span> <span class="n">safe</span><span class="o">=</span><span class="bp">False</span><span class="p">)</span>
<span class="go">u'002'</span>
</pre></div>
</div>
</dd></dl>
<dl class="function">
<dt id="lib.safe.eval_restricted">
<tt class="descclassname">lib.safe.</tt><tt class="descname">eval_restricted</tt><big>(</big><em>s</em>, <em>_globals=None</em>, <em>_locals=None</em>, <em>allowed=</em><span class="optional">[</span>, <em>'abs'</em>, <em>'int'</em>, <em>'min'</em>, <em>'max'</em>, <em>'pow'</em>, <em>'sum'</em>, <em>'True'</em>, <em>'False'</em>, <em>'denominator'</em>, <em>'numerator'</em>, <em>'chr'</em>, <em>'lower'</em>, <em>'str'</em>, <em>'title'</em>, <em>'upper'</em>, <em>'day'</em>, <em>'hour'</em>, <em>'microsecond'</em>, <em>'minute'</em>, <em>'month'</em>, <em>'monthname'</em>, <em>'second'</em>, <em>'weekday'</em>, <em>'weekdayname'</em>, <em>'year'</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#lib.safe.eval_restricted" title="Permalink to this definition">¶</a></dt>
<dd><p>Evaluate an expression while allowing a restricted set of names.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Parameter:</th><td class="field-body"><em>allowed</em> (list of string) – allowed names</td>
</tr>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">result</td>
</tr>
</tbody>
</table>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">eval_restricted</span><span class="p">(</span><span class="s">'max(a, a+b)'</span><span class="p">,</span> <span class="n">_globals</span><span class="o">=</span><span class="p">{</span><span class="s">'a'</span><span class="p">:</span><span class="mf">0</span><span class="p">,</span> <span class="s">'b'</span><span class="p">:</span><span class="mf">2</span><span class="p">},</span>
<span class="gp">... </span><span class="n">_locals</span><span class="o">=</span><span class="p">{</span><span class="s">'a'</span><span class="p">:</span><span class="mf">1</span><span class="p">},</span> <span class="n">allowed</span><span class="o">=</span><span class="p">[</span><span class="s">'max'</span><span class="p">])</span>
<span class="go">3</span>
<span class="gp">>>> </span><span class="k">try</span><span class="p">:</span>
<span class="gp">... </span> <span class="n">eval_restricted</span><span class="p">(</span><span class="s">'a+b+c'</span><span class="p">,</span> <span class="n">_globals</span><span class="o">=</span><span class="p">{</span><span class="s">'a'</span><span class="p">:</span><span class="mf">0</span><span class="p">,</span> <span class="s">'b'</span><span class="p">:</span><span class="mf">2</span><span class="p">},</span> <span class="n">_locals</span><span class="o">=</span><span class="p">{</span><span class="s">'a'</span><span class="p">:</span><span class="mf">1</span><span class="p">})</span>
<span class="gp">... </span><span class="k">except</span> <span class="n">UnsafeError</span><span class="p">,</span> <span class="n">error</span><span class="p">:</span>
<span class="gp">... </span> <span class="k">print</span><span class="p">(</span><span class="n">error</span><span class="p">)</span>
<span class="go">The following name(s) are invalid: c</span>
</pre></div>
</div>
</dd></dl>
<dl class="function">
<dt id="lib.safe.eval_safe">
<tt class="descclassname">lib.safe.</tt><tt class="descname">eval_safe</tt><big>(</big><em>expr</em>, <em>_globals=None</em>, <em>_locals=None</em>, <em>validate=None</em><big>)</big><a class="headerlink" href="#lib.safe.eval_safe" title="Permalink to this definition">¶</a></dt>
<dd><p>Safely evaluate an expression. It will raise a <tt class="docutils literal"><span class="pre">ValueError</span></tt> if
non validated names are used.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Parameter:</th><td class="field-body"><em>expr</em> (string) – expression</td>
</tr>
<tr class="field"><th class="field-name">Returns:</th><td class="field-body">result</td>
</tr>
</tbody>
</table>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">eval_safe</span><span class="p">(</span><span class="s">'1+1'</span><span class="p">)</span>
<span class="go">2</span>
<span class="gp">>>> </span><span class="k">try</span><span class="p">:</span>
<span class="gp">... </span> <span class="n">eval_safe</span><span class="p">(</span><span class="s">'"lowercase".upper()'</span><span class="p">)</span>
<span class="gp">... </span><span class="k">except</span> <span class="n">UnsafeError</span><span class="p">,</span> <span class="n">error</span><span class="p">:</span>
<span class="gp">... </span> <span class="k">print</span><span class="p">(</span><span class="n">error</span><span class="p">)</span>
<span class="go">The following name(s) are invalid: upper</span>
</pre></div>
</div>
</dd></dl>
<dl class="function">
<dt id="lib.safe.extend_vars">
<tt class="descclassname">lib.safe.</tt><tt class="descname">extend_vars</tt><big>(</big><em>vars</em>, <em>s</em><big>)</big><a class="headerlink" href="#lib.safe.extend_vars" title="Permalink to this definition">¶</a></dt>
<dd><p>Extend <tt class="docutils literal"><span class="pre">vars</span></tt> with new unique variables from <tt class="docutils literal"><span class="pre">s</span></tt>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Parameters:</th><td class="field-body"><ul class="first last simple">
<li><em>vars</em> (list of string) – collection of previous variables</li>
<li><em>s</em> (string) – multiple expressions</li>
</ul>
</td>
</tr>
</tbody>
</table>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="nb">vars</span> <span class="o">=</span> <span class="p">[</span><span class="s">'a1'</span><span class="p">]</span>
<span class="gp">>>> </span><span class="n">extend_vars</span><span class="p">(</span><span class="nb">vars</span><span class="p">,</span> <span class="s">'<a1>_<foo>_<world>_<###index>'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="nb">vars</span>
<span class="go">['a1', 'foo', 'world', 'index']</span>
</pre></div>
</div>
</dd></dl>
<dl class="function">
<dt id="lib.safe.format_expr">
<tt class="descclassname">lib.safe.</tt><tt class="descname">format_expr</tt><big>(</big><em>s</em><big>)</big><a class="headerlink" href="#lib.safe.format_expr" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns an expression with <tt class="docutils literal"><span class="pre">####</span></tt> in a pure python expression
which can be evaluated.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Parameter:</th><td class="field-body"><em>s</em> (expression) – expression</td>
</tr>
</tbody>
</table>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">f</span> <span class="o">=</span> <span class="n">format_expr</span><span class="p">(</span><span class="s">'###(5+1)'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">f</span>
<span class="go">'"%03d"%(5+1)'</span>
<span class="gp">>>> </span><span class="nb">eval</span><span class="p">(</span><span class="n">f</span><span class="p">)</span>
<span class="go">'006'</span>
</pre></div>
</div>
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