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<span class="doccomment">/// An error while defining which columns to display in the output table.</span>

<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>

<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">enum</span> <span class="ident">ColumnError</span> {

<span class="doccomment">/// If a column appears more than once in the `--output` argument.</span>

<span class="ident">MultipleColumns</span>(<span class="ident">String</span>),

}

<span class="doccomment">///</span>

<span class="doccomment">/// # Errors</span>

<span class="doccomment">///</span>

<span class="doccomment">/// This function returns an error if a column is specified more</span>

<span class="doccomment">/// than once in the command-line argument.</span>

<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">from_matches</span>(<span class="ident">matches</span>: <span class="kw-2">&amp;</span><span class="ident">ArgMatches</span>) -&gt; <span class="prelude-ty">Result</span><span class="op">&lt;</span><span class="ident">Vec</span><span class="op">&lt;</span><span class="self">Self</span><span class="op">&gt;</span>, <span class="ident">ColumnError</span><span class="op">&gt;</span> {

(<span class="bool-val">false</span>, <span class="bool-val">false</span>, <span class="bool-val">false</span>) =&gt; <span class="prelude-val">Ok</span>(<span class="macro">vec!</span>[

]),

<span class="comment">// Unwrapping should not panic because in this arm of</span>

<span class="comment">// the `match` statement, we know that `OPT_OUTPUT`</span>

<span class="comment">// is non-empty.</span>

<span class="kw">let</span> <span class="ident">names</span> <span class="op">=</span> <span class="ident">matches</span>.<span class="ident">values_of</span>(<span class="ident">OPT_OUTPUT</span>).<span class="ident">unwrap</span>();

<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">seen</span>: <span class="ident">Vec</span><span class="op">&lt;</span><span class="kw-2">&amp;</span><span class="ident">str</span><span class="op">&gt;</span> <span class="op">=</span> <span class="macro">vec!</span>[];

<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">columns</span> <span class="op">=</span> <span class="macro">vec!</span>[];

<span class="kw">for</span> <span class="ident">name</span> <span class="kw">in</span> <span class="ident">names</span> {

<span class="kw">if</span> <span class="ident">seen</span>.<span class="ident">contains</span>(<span class="kw-2">&amp;</span><span class="ident">name</span>) {

<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">ColumnError::MultipleColumns</span>(<span class="ident">name</span>.<span class="ident">to_string</span>()));

}

<span class="ident">seen</span>.<span class="ident">push</span>(<span class="ident">name</span>);

<span class="comment">// Unwrapping here should not panic because the</span>

<span class="comment">// command-line argument parsing library should be</span>

<span class="comment">// responsible for ensuring each comma-separated</span>

<span class="comment">// string is a valid column label.</span>

<span class="kw">let</span> <span class="ident">column</span> <span class="op">=</span> <span class="ident"><span class="self">Self</span>::parse</span>(<span class="ident">name</span>).<span class="ident">unwrap</span>();

<span class="ident">columns</span>.<span class="ident">push</span>(<span class="ident">column</span>);

}

<span class="prelude-val">Ok</span>(<span class="ident">columns</span>)

(<span class="bool-val">false</span>, <span class="bool-val">true</span>, <span class="bool-val">false</span>) =&gt; <span class="prelude-val">Ok</span>(<span class="macro">vec!</span>[

]),

(<span class="bool-val">true</span>, <span class="bool-val">false</span>, <span class="bool-val">false</span>) =&gt; <span class="prelude-val">Ok</span>(<span class="macro">vec!</span>[

]),

(<span class="bool-val">true</span>, <span class="bool-val">true</span>, <span class="bool-val">false</span>) =&gt; <span class="prelude-val">Ok</span>(<span class="macro">vec!</span>[

]),