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      <h1 class="title">std/strscans</h1>
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  <li><a class="reference" id="startswith-vs-full-match_toc" href="#startswith-vs-full-match">Startswith vs full match</a></li>
<li><a class="reference" id="user-definable-matchers_toc" href="#user-definable-matchers">User definable matchers</a></li>
<li><a class="reference" id="the-scanp-macro_toc" href="#the-scanp-macro">The scanp macro</a></li>
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  <a class="reference reference-toplevel" href="#6" id="56">Imports</a>
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      <ul class="simple nested-toc-section">scanf
  <li><a class="reference" href="#scanf.m%2Cstring%2Cstatic%5Bstring%5D%2Cvarargs%5Btyped%5D" title="scanf(input: string; pattern: static[string]; results: varargs[typed]): bool">scanf(input: string; pattern: static[string]; results: varargs[typed]): bool</a></li>

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<ul class="simple nested-toc-section">scanp
  <li><a class="reference" href="#scanp.m%2Ctyped%2Ctyped%2Cvarargs%5Buntyped%5D" title="scanp(input, idx: typed; pattern: varargs[untyped]): bool">scanp(input, idx: typed; pattern: varargs[untyped]): bool</a></li>

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<ul class="simple nested-toc-section">scanTuple
  <li><a class="reference" href="#scanTuple.m%2Cuntyped%2Cstatic%5Bstring%5D%2Cvarargs%5Buntyped%5D" title="scanTuple(input: untyped; pattern: static[string];
          matcherTypes: varargs[untyped]): untyped">scanTuple(input: untyped; pattern: static[string];
          matcherTypes: varargs[untyped]): untyped</a></li>

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      <ul class="simple nested-toc-section">atom
  <li><a class="reference" href="#atom.t%2Cstring%2Cint%2Cchar" title="atom(input: string; idx: int; c: char): bool">atom(input: string; idx: int; c: char): bool</a></li>
<li><a class="reference" href="#atom.t%2Cstring%2Cint%2Cset%5Bchar%5D" title="atom(input: string; idx: int; s: set[char]): bool">atom(input: string; idx: int; s: set[char]): bool</a></li>

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<ul class="simple nested-toc-section">hasNxt
  <li><a class="reference" href="#hasNxt.t%2Cstring%2Cint" title="hasNxt(input: string; idx: int): bool">hasNxt(input: string; idx: int): bool</a></li>

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<ul class="simple nested-toc-section">nxt
  <li><a class="reference" href="#nxt.t%2Cstring%2Cint%2Cint" title="nxt(input: string; idx: int; step: int = 1)">nxt(input: string; idx: int; step: int = 1)</a></li>

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<ul class="simple nested-toc-section">success
  <li><a class="reference" href="#success.t%2Cint" title="success(x: int): bool">success(x: int): bool</a></li>

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  <div class="nine columns" id="content">
    <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L1" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
<a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L1" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;

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    <p class="module-desc"><p>This module contains a <span id="scanf_1">scanf</span> macro that can be used for extracting substrings from an input string. This is often easier than regular expressions. Some examples as an appetizer:</p>
<p><pre class="listing"><span class="Comment"># check if input string matches a triple of integers:</span>
<span class="Keyword">const</span> <span class="Identifier">input</span> <span class="Operator">=</span> <span class="StringLit">&quot;(1,2,4)&quot;</span>
<span class="Keyword">var</span> <span class="Identifier">x</span><span class="Punctuation">,</span> <span class="Identifier">y</span><span class="Punctuation">,</span> <span class="Identifier">z</span><span class="Punctuation">:</span> <span class="Identifier">int</span>
<span class="Keyword">if</span> <span class="Identifier">scanf</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">,</span> <span class="StringLit">&quot;($i,$i,$i)&quot;</span><span class="Punctuation">,</span> <span class="Identifier">x</span><span class="Punctuation">,</span> <span class="Identifier">y</span><span class="Punctuation">,</span> <span class="Identifier">z</span><span class="Punctuation">)</span><span class="Punctuation">:</span>
  <span class="Identifier">echo</span> <span class="StringLit">&quot;matches and x is &quot;</span><span class="Punctuation">,</span> <span class="Identifier">x</span><span class="Punctuation">,</span> <span class="StringLit">&quot; y is &quot;</span><span class="Punctuation">,</span> <span class="Identifier">y</span><span class="Punctuation">,</span> <span class="StringLit">&quot; z is &quot;</span><span class="Punctuation">,</span> <span class="Identifier">z</span>

<span class="Comment"># check if input string matches an ISO date followed by an identifier followed</span>
<span class="Comment"># by whitespace and a floating point number:</span>
<span class="Keyword">var</span> <span class="Identifier">year</span><span class="Punctuation">,</span> <span class="Identifier">month</span><span class="Punctuation">,</span> <span class="Identifier">day</span><span class="Punctuation">:</span> <span class="Identifier">int</span>
<span class="Keyword">var</span> <span class="Identifier">identifier</span><span class="Punctuation">:</span> <span class="Identifier">string</span>
<span class="Keyword">var</span> <span class="Identifier">myfloat</span><span class="Punctuation">:</span> <span class="Identifier">float</span>
<span class="Keyword">if</span> <span class="Identifier">scanf</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">,</span> <span class="StringLit">&quot;$i-$i-$i $w$s$f&quot;</span><span class="Punctuation">,</span> <span class="Identifier">year</span><span class="Punctuation">,</span> <span class="Identifier">month</span><span class="Punctuation">,</span> <span class="Identifier">day</span><span class="Punctuation">,</span> <span class="Identifier">identifier</span><span class="Punctuation">,</span> <span class="Identifier">myfloat</span><span class="Punctuation">)</span><span class="Punctuation">:</span>
  <span class="Identifier">echo</span> <span class="StringLit">&quot;yes, we have a match!&quot;</span></pre></p>
<p>As can be seen from the examples, strings are matched verbatim except for substrings starting with <tt class="docutils literal"><span class="pre">$</span></tt>. These constructions are available:</p>
<table border="1" class="docutils"><tr><td><tt class="docutils literal"><span class="pre">$b</span></tt></td><td>Matches a binary integer. This uses <tt class="docutils literal"><span class="pre">parseutils.parseBin</span></tt>.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$o</span></tt></td><td>Matches an octal integer. This uses <tt class="docutils literal"><span class="pre">parseutils.parseOct</span></tt>.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$i</span></tt></td><td>Matches a decimal integer. This uses <tt class="docutils literal"><span class="pre">parseutils.parseInt</span></tt>.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$h</span></tt></td><td>Matches a hex integer. This uses <tt class="docutils literal"><span class="pre">parseutils.parseHex</span></tt>.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$f</span></tt></td><td>Matches a floating-point number. Uses <tt class="docutils literal"><span class="pre">parseFloat</span></tt>.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$w</span></tt></td><td>Matches an ASCII identifier: <tt class="docutils literal"><span class="pre">[A-Za-z_][A-Za-z_0-9]*</span></tt>.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$c</span></tt></td><td>Matches a single ASCII character.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$s</span></tt></td><td>Skips optional whitespace.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$$</span></tt></td><td>Matches a single dollar sign.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$.</span></tt></td><td>Matches if the end of the input string has been reached.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$*</span></tt></td><td>Matches until the token following the <tt class="docutils literal"><span class="pre">$*</span></tt> was found. The match is allowed to be of 0 length.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$+</span></tt></td><td>Matches until the token following the <tt class="docutils literal"><span class="pre">$+</span></tt> was found. The match must consist of at least one char.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">${foo}</span></tt></td><td>User defined matcher. Uses the proc <tt class="docutils literal"><span class="pre">foo</span></tt> to perform the match. See below for more details.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$[foo]</span></tt></td><td>Call user defined proc <tt class="docutils literal"><span class="pre">foo</span></tt> to <strong>skip</strong> some optional parts in the input string. See below for more details.</td></tr>
</table><p>Even though <tt class="docutils literal"><span class="pre">$*</span></tt> and <tt class="docutils literal"><span class="pre">$+</span></tt> look similar to the regular expressions <tt class="docutils literal"><span class="pre">.*</span></tt> and <tt class="docutils literal"><span class="pre">.+</span></tt>, they work quite differently. There is no non-deterministic state machine involved and the matches are non-greedy. <tt class="docutils literal"><span class="pre">[$*]</span></tt> matches <tt class="docutils literal"><span class="pre">[xyz]</span></tt> via <tt class="docutils literal"><span class="pre">parseutils.parseUntil</span></tt>.</p>
<p>Furthermore no backtracking is performed, if parsing fails after a value has already been bound to a matched subexpression this value is not restored to its original value. This rarely causes problems in practice and if it does for you, it's easy enough to bind to a temporary variable first.</p>

<h1><a class="toc-backref" id="startswith-vs-full-match" href="#startswith-vs-full-match">Startswith vs full match</a></h1><p><tt class="docutils literal"><span class="pre">scanf</span></tt> returns true if the input string <strong>starts with</strong> the specified pattern. If instead it should only return true if there is also nothing left in the input, append <tt class="docutils literal"><span class="pre">$.</span></tt> to your pattern.</p>

<h1><a class="toc-backref" id="user-definable-matchers" href="#user-definable-matchers">User definable matchers</a></h1><p>One very nice advantage over regular expressions is that <tt class="docutils literal"><span class="pre">scanf</span></tt> is extensible with ordinary Nim procs. The proc is either enclosed in <tt class="docutils literal"><span class="pre">${}</span></tt> or in <tt class="docutils literal"><span class="pre">$[]</span></tt>. <tt class="docutils literal"><span class="pre">${}</span></tt> matches and binds the result to a variable (that was passed to the <tt class="docutils literal"><span class="pre">scanf</span></tt> macro) while <tt class="docutils literal"><span class="pre">$[]</span></tt> merely matches optional tokens without any result binding.</p>
<p>In this example, we define a helper proc <tt class="docutils literal"><span class="pre">someSep</span></tt> that skips some separators which we then use in our scanf pattern to help us in the matching process:</p>
<p><pre class="listing"><span class="Keyword">proc</span> <span class="Identifier">someSep</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">:</span> <span class="Identifier">string</span><span class="Punctuation">;</span> <span class="Identifier">start</span><span class="Punctuation">:</span> <span class="Identifier">int</span><span class="Punctuation">;</span> <span class="Identifier">seps</span><span class="Punctuation">:</span> <span class="Identifier">set</span><span class="Punctuation">[</span><span class="Identifier">char</span><span class="Punctuation">]</span> <span class="Operator">=</span> <span class="Punctuation">{</span><span class="Punctuation">'</span><span class="Punctuation">:</span><span class="Punctuation">'</span><span class="Punctuation">,</span><span class="Punctuation">'</span><span class="Operator">-</span><span class="CharLit">','</span><span class="Operator">.</span><span class="CharLit">'}): int =</span>
  <span class="Comment"># Note: The parameters and return value must match to what ``scanf`` requires</span>
  <span class="Identifier">result</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
  <span class="Keyword">while</span> <span class="Identifier">start</span><span class="Operator">+</span><span class="Identifier">result</span> <span class="Operator">&lt;</span> <span class="Identifier">input</span><span class="Operator">.</span><span class="Identifier">len</span> <span class="Keyword">and</span> <span class="Identifier">input</span><span class="Punctuation">[</span><span class="Identifier">start</span><span class="Operator">+</span><span class="Identifier">result</span><span class="Punctuation">]</span> <span class="Keyword">in</span> <span class="Identifier">seps</span><span class="Punctuation">:</span> <span class="Identifier">inc</span> <span class="Identifier">result</span>

<span class="Keyword">if</span> <span class="Identifier">scanf</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">,</span> <span class="StringLit">&quot;$w$[someSep]$w&quot;</span><span class="Punctuation">,</span> <span class="Identifier">key</span><span class="Punctuation">,</span> <span class="Identifier">value</span><span class="Punctuation">)</span><span class="Punctuation">:</span>
  <span class="Operator">...</span></pre></p>
<p>It is also possible to pass arguments to a user definable matcher:</p>
<p><pre class="listing"><span class="Keyword">proc</span> <span class="Identifier">ndigits</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">:</span> <span class="Identifier">string</span><span class="Punctuation">;</span> <span class="Identifier">intVal</span><span class="Punctuation">:</span> <span class="Keyword">var</span> <span class="Identifier">int</span><span class="Punctuation">;</span> <span class="Identifier">start</span><span class="Punctuation">:</span> <span class="Identifier">int</span><span class="Punctuation">;</span> <span class="Identifier">n</span><span class="Punctuation">:</span> <span class="Identifier">int</span><span class="Punctuation">)</span><span class="Punctuation">:</span> <span class="Identifier">int</span> <span class="Operator">=</span>
  <span class="Comment"># matches exactly ``n`` digits. Matchers need to return 0 if nothing</span>
  <span class="Comment"># matched or otherwise the number of processed chars.</span>
  <span class="Keyword">var</span> <span class="Identifier">x</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
  <span class="Keyword">var</span> <span class="Identifier">i</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
  <span class="Keyword">while</span> <span class="Identifier">i</span> <span class="Operator">&lt;</span> <span class="Identifier">n</span> <span class="Keyword">and</span> <span class="Identifier">i</span><span class="Operator">+</span><span class="Identifier">start</span> <span class="Operator">&lt;</span> <span class="Identifier">input</span><span class="Operator">.</span><span class="Identifier">len</span> <span class="Keyword">and</span> <span class="Identifier">input</span><span class="Punctuation">[</span><span class="Identifier">i</span><span class="Operator">+</span><span class="Identifier">start</span><span class="Punctuation">]</span> <span class="Keyword">in</span> <span class="Punctuation">{</span><span class="Punctuation">'</span><span class="DecNumber">0'</span><span class="Operator">..</span><span class="CharLit">'9'</span><span class="Punctuation">}</span><span class="Punctuation">:</span>
    <span class="Identifier">x</span> <span class="Operator">=</span> <span class="Identifier">x</span> <span class="Operator">*</span> <span class="DecNumber">10</span> <span class="Operator">+</span> <span class="Identifier">input</span><span class="Punctuation">[</span><span class="Identifier">i</span><span class="Operator">+</span><span class="Identifier">start</span><span class="Punctuation">]</span><span class="Operator">.</span><span class="Identifier">ord</span> <span class="Operator">-</span> <span class="CharLit">'0'</span><span class="Operator">.</span><span class="Identifier">ord</span>
    <span class="Identifier">inc</span> <span class="Identifier">i</span>
  <span class="Comment"># only overwrite if we had a match</span>
  <span class="Keyword">if</span> <span class="Identifier">i</span> <span class="Operator">==</span> <span class="Identifier">n</span><span class="Punctuation">:</span>
    <span class="Identifier">result</span> <span class="Operator">=</span> <span class="Identifier">n</span>
    <span class="Identifier">intVal</span> <span class="Operator">=</span> <span class="Identifier">x</span>

<span class="Comment"># match an ISO date extracting year, month, day at the same time.</span>
<span class="Comment"># Also ensure the input ends after the ISO date:</span>
<span class="Keyword">var</span> <span class="Identifier">year</span><span class="Punctuation">,</span> <span class="Identifier">month</span><span class="Punctuation">,</span> <span class="Identifier">day</span><span class="Punctuation">:</span> <span class="Identifier">int</span>
<span class="Keyword">if</span> <span class="Identifier">scanf</span><span class="Punctuation">(</span><span class="StringLit">&quot;2013-01-03&quot;</span><span class="Punctuation">,</span> <span class="StringLit">&quot;${ndigits(4)}-${ndigits(2)}-${ndigits(2)}$.&quot;</span><span class="Punctuation">,</span> <span class="Identifier">year</span><span class="Punctuation">,</span> <span class="Identifier">month</span><span class="Punctuation">,</span> <span class="Identifier">day</span><span class="Punctuation">)</span><span class="Punctuation">:</span>
  <span class="Operator">...</span></pre></p>

<h1><a class="toc-backref" id="the-scanp-macro" href="#the-scanp-macro">The scanp macro</a></h1><p>This module also implements a <tt class="docutils literal"><span class="pre">scanp</span></tt> macro, which syntax somewhat resembles an EBNF or PEG grammar, except that it uses Nim's expression syntax and so has to use prefix instead of postfix operators.</p>
<table border="1" class="docutils"><tr><td><tt class="docutils literal"><span class="pre">(E)</span></tt></td><td>Grouping</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">*E</span></tt></td><td>Zero or more</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">+E</span></tt></td><td>One or more</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">?E</span></tt></td><td>Zero or One</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">E{n,m}</span></tt></td><td>From <tt class="docutils literal"><span class="pre">n</span></tt> up to <tt class="docutils literal"><span class="pre">m</span></tt> times <tt class="docutils literal"><span class="pre">E</span></tt></td></tr>
<tr><td><tt class="docutils literal"><span class="pre">~E</span></tt></td><td>Not predicate</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">a ^* b</span></tt></td><td>Shortcut for <tt class="docutils literal"><span class="pre">?(a *(b a))</span></tt>. Usually used for separators.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">a ^+ b</span></tt></td><td>Shortcut for <tt class="docutils literal"><span class="pre">?(a +(b a))</span></tt>. Usually used for separators.</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">'a'</span></tt></td><td>Matches a single character</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">{'a'..'b'}</span></tt></td><td>Matches a character set</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">&quot;s&quot;</span></tt></td><td>Matches a string</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">E -&gt; a</span></tt></td><td>Bind matching to some action</td></tr>
<tr><td><tt class="docutils literal"><span class="pre">$_</span></tt></td><td>Access the currently matched character</td></tr>
</table><p>Note that unordered or ordered choice operators (<tt class="docutils literal"><span class="pre">/</span></tt>, <tt class="docutils literal"><span class="pre">|</span></tt>) are not implemented.</p>
<p>Simple example that parses the <tt class="docutils literal"><span class="pre">/etc/passwd</span></tt> file line by line:</p>
<p><pre class="listing"><span class="Keyword">const</span>
  <span class="Identifier">etc_passwd</span> <span class="Operator">=</span> <span class="LongStringLit">&quot;&quot;&quot;root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/bin/sh
bin:x:2:2:bin:/bin:/bin/sh
sys:x:3:3:sys:/dev:/bin/sh
nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
messagebus:x:103:107::/var/run/dbus:/bin/false
&quot;&quot;&quot;</span>

<span class="Keyword">proc</span> <span class="Identifier">parsePasswd</span><span class="Punctuation">(</span><span class="Identifier">content</span><span class="Punctuation">:</span> <span class="Identifier">string</span><span class="Punctuation">)</span><span class="Punctuation">:</span> <span class="Identifier">seq</span><span class="Punctuation">[</span><span class="Identifier">string</span><span class="Punctuation">]</span> <span class="Operator">=</span>
  <span class="Identifier">result</span> <span class="Operator">=</span> <span class="Operator">@</span><span class="Punctuation">[</span><span class="Punctuation">]</span>
  <span class="Keyword">var</span> <span class="Identifier">idx</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
  <span class="Keyword">while</span> <span class="Identifier">true</span><span class="Punctuation">:</span>
    <span class="Keyword">var</span> <span class="Identifier">entry</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
    <span class="Keyword">if</span> <span class="Identifier">scanp</span><span class="Punctuation">(</span><span class="Identifier">content</span><span class="Punctuation">,</span> <span class="Identifier">idx</span><span class="Punctuation">,</span> <span class="Operator">+</span><span class="Punctuation">(</span><span class="Operator">~</span><span class="Punctuation">{</span><span class="Punctuation">'</span><span class="Operator">\</span><span class="Identifier">L</span><span class="CharLit">', '</span><span class="Operator">\</span><span class="DecNumber">0'</span><span class="Punctuation">}</span> <span class="Operator">-&gt;</span> <span class="Identifier">entry</span><span class="Operator">.</span><span class="Identifier">add</span><span class="Punctuation">(</span><span class="Operator">$</span><span class="Identifier">_</span><span class="Punctuation">)</span><span class="Punctuation">)</span><span class="Punctuation">,</span> <span class="CharLit">'\L'</span><span class="Punctuation">)</span><span class="Punctuation">:</span>
      <span class="Identifier">result</span><span class="Operator">.</span><span class="Identifier">add</span> <span class="Identifier">entry</span>
    <span class="Keyword">else</span><span class="Punctuation">:</span>
      <span class="Keyword">break</span></pre></p>
<p>The <tt class="docutils literal"><span class="pre">scanp</span></tt> maps the grammar code into Nim code that performs the parsing. The parsing is performed with the help of 3 helper templates that that can be implemented for a custom type.</p>
<p>These templates need to be named <tt class="docutils literal"><span class="pre">atom</span></tt> and <tt class="docutils literal"><span class="pre">nxt</span></tt>. <tt class="docutils literal"><span class="pre">atom</span></tt> should be overloaded to handle both <tt class="docutils literal"><span class="pre"><span class="Identifier">char</span></span></tt> and <tt class="docutils literal"><span class="pre"><span class="Identifier">set</span><span class="Punctuation">[</span><span class="Identifier">char</span><span class="Punctuation">]</span></span></tt>.</p>
<p><pre class="listing"><span class="Keyword">import</span> <span class="Identifier">std</span><span class="Operator">/</span><span class="Identifier">streams</span>

<span class="Keyword">template</span> <span class="Identifier">atom</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">:</span> <span class="Identifier">Stream</span><span class="Punctuation">;</span> <span class="Identifier">idx</span><span class="Punctuation">:</span> <span class="Identifier">int</span><span class="Punctuation">;</span> <span class="Identifier">c</span><span class="Punctuation">:</span> <span class="Identifier">char</span><span class="Punctuation">)</span><span class="Punctuation">:</span> <span class="Identifier">bool</span> <span class="Operator">=</span>
  <span class="Comment">## Used in scanp for the matching of atoms (usually chars).</span>
  <span class="Identifier">peekChar</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">)</span> <span class="Operator">==</span> <span class="Identifier">c</span>

<span class="Keyword">template</span> <span class="Identifier">atom</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">:</span> <span class="Identifier">Stream</span><span class="Punctuation">;</span> <span class="Identifier">idx</span><span class="Punctuation">:</span> <span class="Identifier">int</span><span class="Punctuation">;</span> <span class="Identifier">s</span><span class="Punctuation">:</span> <span class="Identifier">set</span><span class="Punctuation">[</span><span class="Identifier">char</span><span class="Punctuation">]</span><span class="Punctuation">)</span><span class="Punctuation">:</span> <span class="Identifier">bool</span> <span class="Operator">=</span>
  <span class="Identifier">peekChar</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">)</span> <span class="Keyword">in</span> <span class="Identifier">s</span>

<span class="Keyword">template</span> <span class="Identifier">nxt</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">:</span> <span class="Identifier">Stream</span><span class="Punctuation">;</span> <span class="Identifier">idx</span><span class="Punctuation">,</span> <span class="Identifier">step</span><span class="Punctuation">:</span> <span class="Identifier">int</span> <span class="Operator">=</span> <span class="DecNumber">1</span><span class="Punctuation">)</span> <span class="Operator">=</span>
  <span class="Identifier">inc</span><span class="Punctuation">(</span><span class="Identifier">idx</span><span class="Punctuation">,</span> <span class="Identifier">step</span><span class="Punctuation">)</span>
  <span class="Identifier">setPosition</span><span class="Punctuation">(</span><span class="Identifier">input</span><span class="Punctuation">,</span> <span class="Identifier">idx</span><span class="Punctuation">)</span>

<span class="Keyword">if</span> <span class="Identifier">scanp</span><span class="Punctuation">(</span><span class="Identifier">content</span><span class="Punctuation">,</span> <span class="Identifier">idx</span><span class="Punctuation">,</span> <span class="Operator">+</span><span class="Punctuation">(</span> <span class="Operator">~</span><span class="Punctuation">{</span><span class="Punctuation">'</span><span class="Operator">\</span><span class="Identifier">L</span><span class="CharLit">', '</span><span class="Operator">\</span><span class="DecNumber">0'</span><span class="Punctuation">}</span> <span class="Operator">-&gt;</span> <span class="Identifier">entry</span><span class="Operator">.</span><span class="Identifier">add</span><span class="Punctuation">(</span><span class="Identifier">peekChar</span><span class="Punctuation">(</span><span class="Operator">$</span><span class="Identifier">input</span><span class="Punctuation">)</span><span class="Punctuation">)</span><span class="Punctuation">)</span><span class="Punctuation">,</span> <span class="CharLit">'\L'</span><span class="Punctuation">)</span><span class="Punctuation">:</span>
  <span class="Identifier">result</span><span class="Operator">.</span><span class="Identifier">add</span> <span class="Identifier">entry</span></pre></p>
<p>Calling ordinary Nim procs inside the macro is possible:</p>
<p><pre class="listing"><span class="Keyword">proc</span> <span class="Identifier">digits</span><span class="Punctuation">(</span><span class="Identifier">s</span><span class="Punctuation">:</span> <span class="Identifier">string</span><span class="Punctuation">;</span> <span class="Identifier">intVal</span><span class="Punctuation">:</span> <span class="Keyword">var</span> <span class="Identifier">int</span><span class="Punctuation">;</span> <span class="Identifier">start</span><span class="Punctuation">:</span> <span class="Identifier">int</span><span class="Punctuation">)</span><span class="Punctuation">:</span> <span class="Identifier">int</span> <span class="Operator">=</span>
  <span class="Keyword">var</span> <span class="Identifier">x</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
  <span class="Keyword">while</span> <span class="Identifier">result</span><span class="Operator">+</span><span class="Identifier">start</span> <span class="Operator">&lt;</span> <span class="Identifier">s</span><span class="Operator">.</span><span class="Identifier">len</span> <span class="Keyword">and</span> <span class="Identifier">s</span><span class="Punctuation">[</span><span class="Identifier">result</span><span class="Operator">+</span><span class="Identifier">start</span><span class="Punctuation">]</span> <span class="Keyword">in</span> <span class="Punctuation">{</span><span class="Punctuation">'</span><span class="DecNumber">0'</span><span class="Operator">..</span><span class="CharLit">'9'</span><span class="Punctuation">}</span> <span class="Keyword">and</span> <span class="Identifier">s</span><span class="Punctuation">[</span><span class="Identifier">result</span><span class="Operator">+</span><span class="Identifier">start</span><span class="Punctuation">]</span> <span class="Operator">!=</span> <span class="CharLit">':'</span><span class="Punctuation">:</span>
    <span class="Identifier">x</span> <span class="Operator">=</span> <span class="Identifier">x</span> <span class="Operator">*</span> <span class="DecNumber">10</span> <span class="Operator">+</span> <span class="Identifier">s</span><span class="Punctuation">[</span><span class="Identifier">result</span><span class="Operator">+</span><span class="Identifier">start</span><span class="Punctuation">]</span><span class="Operator">.</span><span class="Identifier">ord</span> <span class="Operator">-</span> <span class="CharLit">'0'</span><span class="Operator">.</span><span class="Identifier">ord</span>
    <span class="Identifier">inc</span> <span class="Identifier">result</span>
  <span class="Identifier">intVal</span> <span class="Operator">=</span> <span class="Identifier">x</span>

<span class="Keyword">proc</span> <span class="Identifier">extractUsers</span><span class="Punctuation">(</span><span class="Identifier">content</span><span class="Punctuation">:</span> <span class="Identifier">string</span><span class="Punctuation">)</span><span class="Punctuation">:</span> <span class="Identifier">seq</span><span class="Punctuation">[</span><span class="Identifier">string</span><span class="Punctuation">]</span> <span class="Operator">=</span>
  <span class="Comment"># Extracts the username and home directory</span>
  <span class="Comment"># of each entry (with UID greater than 1000)</span>
  <span class="Keyword">const</span>
    <span class="Identifier">digits</span> <span class="Operator">=</span> <span class="Punctuation">{</span><span class="Punctuation">'</span><span class="DecNumber">0'</span><span class="Operator">..</span><span class="CharLit">'9'</span><span class="Punctuation">}</span>
  <span class="Identifier">result</span> <span class="Operator">=</span> <span class="Operator">@</span><span class="Punctuation">[</span><span class="Punctuation">]</span>
  <span class="Keyword">var</span> <span class="Identifier">idx</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
  <span class="Keyword">while</span> <span class="Identifier">true</span><span class="Punctuation">:</span>
    <span class="Keyword">var</span> <span class="Identifier">login</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
    <span class="Keyword">var</span> <span class="Identifier">uid</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
    <span class="Keyword">var</span> <span class="Identifier">homedir</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
    <span class="Keyword">if</span> <span class="Identifier">scanp</span><span class="Punctuation">(</span><span class="Identifier">content</span><span class="Punctuation">,</span> <span class="Identifier">idx</span><span class="Punctuation">,</span> <span class="Operator">*</span><span class="Punctuation">(</span><span class="Operator">~</span> <span class="Punctuation">{</span><span class="Punctuation">'</span><span class="Punctuation">:</span><span class="Punctuation">'</span><span class="Punctuation">,</span> <span class="CharLit">'\0'</span><span class="Punctuation">}</span><span class="Punctuation">)</span> <span class="Operator">-&gt;</span> <span class="Identifier">login</span><span class="Operator">.</span><span class="Identifier">add</span><span class="Punctuation">(</span><span class="Operator">$</span><span class="Identifier">_</span><span class="Punctuation">)</span><span class="Punctuation">,</span> <span class="CharLit">':'</span><span class="Punctuation">,</span> <span class="Operator">*</span> <span class="Operator">~</span> <span class="CharLit">':'</span><span class="Punctuation">,</span> <span class="CharLit">':'</span><span class="Punctuation">,</span>
            <span class="Identifier">digits</span><span class="Punctuation">(</span><span class="Operator">$</span><span class="Identifier">input</span><span class="Punctuation">,</span> <span class="Identifier">uid</span><span class="Punctuation">,</span> <span class="Operator">$</span><span class="Identifier">index</span><span class="Punctuation">)</span><span class="Punctuation">,</span> <span class="CharLit">':'</span><span class="Punctuation">,</span> <span class="Operator">*</span><span class="Punctuation">`</span><span class="Identifier">digits</span><span class="Punctuation">`</span><span class="Punctuation">,</span> <span class="CharLit">':'</span><span class="Punctuation">,</span> <span class="Operator">*</span> <span class="Operator">~</span> <span class="CharLit">':'</span><span class="Punctuation">,</span> <span class="CharLit">':'</span><span class="Punctuation">,</span>
            <span class="Operator">*</span><span class="Punctuation">(</span><span class="Punctuation">'</span><span class="Operator">/</span><span class="CharLit">', * ~{'</span><span class="Punctuation">:</span><span class="Punctuation">'</span><span class="Punctuation">,</span> <span class="CharLit">'/'</span><span class="Punctuation">}</span><span class="Punctuation">)</span> <span class="Operator">-&gt;</span> <span class="Identifier">homedir</span><span class="Operator">.</span><span class="Identifier">add</span><span class="Punctuation">(</span><span class="Operator">$</span><span class="Identifier">_</span><span class="Punctuation">)</span><span class="Punctuation">,</span> <span class="CharLit">':'</span><span class="Punctuation">,</span> <span class="Operator">*</span><span class="Punctuation">(</span><span class="Punctuation">'</span><span class="Operator">/</span><span class="CharLit">', * ~{'</span><span class="Operator">\</span><span class="Identifier">L</span><span class="CharLit">', '</span><span class="Operator">/</span><span class="CharLit">'}), '</span><span class="Operator">\</span><span class="Identifier">L</span><span class="CharLit">'):</span>
      <span class="Keyword">if</span> <span class="Identifier">uid</span> <span class="Operator">&gt;=</span> <span class="DecNumber">1000</span><span class="Punctuation">:</span>
        <span class="Identifier">result</span><span class="Operator">.</span><span class="Identifier">add</span> <span class="Identifier">login</span> <span class="Operator">&amp;</span> <span class="StringLit">&quot; &quot;</span> <span class="Operator">&amp;</span> <span class="Identifier">homedir</span>
    <span class="Keyword">else</span><span class="Punctuation">:</span>
      <span class="Keyword">break</span></pre></p>
<p>When used for matching, keep in mind that likewise scanf, no backtracking is performed.</p>
<p><pre class="listing"><span class="Keyword">proc</span> <span class="Identifier">skipUntil</span><span class="Punctuation">(</span><span class="Identifier">s</span><span class="Punctuation">:</span> <span class="Identifier">string</span><span class="Punctuation">;</span> <span class="Identifier">until</span><span class="Punctuation">:</span> <span class="Identifier">string</span><span class="Punctuation">;</span> <span class="Identifier">unless</span> <span class="Operator">=</span> <span class="CharLit">'\0'</span><span class="Punctuation">;</span> <span class="Identifier">start</span><span class="Punctuation">:</span> <span class="Identifier">int</span><span class="Punctuation">)</span><span class="Punctuation">:</span> <span class="Identifier">int</span> <span class="Operator">=</span>
  <span class="Comment"># Skips all characters until the string `until` is found. Returns 0</span>
  <span class="Comment"># if the char `unless` is found first or the end is reached.</span>
  <span class="Keyword">var</span> <span class="Identifier">i</span> <span class="Operator">=</span> <span class="Identifier">start</span>
  <span class="Keyword">var</span> <span class="Identifier">u</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
  <span class="Keyword">while</span> <span class="Identifier">true</span><span class="Punctuation">:</span>
    <span class="Keyword">if</span> <span class="Identifier">i</span> <span class="Operator">&gt;=</span> <span class="Identifier">s</span><span class="Operator">.</span><span class="Identifier">len</span> <span class="Keyword">or</span> <span class="Identifier">s</span><span class="Punctuation">[</span><span class="Identifier">i</span><span class="Punctuation">]</span> <span class="Operator">==</span> <span class="Identifier">unless</span><span class="Punctuation">:</span>
      <span class="Keyword">return</span> <span class="DecNumber">0</span>
    <span class="Keyword">elif</span> <span class="Identifier">s</span><span class="Punctuation">[</span><span class="Identifier">i</span><span class="Punctuation">]</span> <span class="Operator">==</span> <span class="Identifier">until</span><span class="Punctuation">[</span><span class="DecNumber">0</span><span class="Punctuation">]</span><span class="Punctuation">:</span>
      <span class="Identifier">u</span> <span class="Operator">=</span> <span class="DecNumber">1</span>
      <span class="Keyword">while</span> <span class="Identifier">i</span><span class="Operator">+</span><span class="Identifier">u</span> <span class="Operator">&lt;</span> <span class="Identifier">s</span><span class="Operator">.</span><span class="Identifier">len</span> <span class="Keyword">and</span> <span class="Identifier">u</span> <span class="Operator">&lt;</span> <span class="Identifier">until</span><span class="Operator">.</span><span class="Identifier">len</span> <span class="Keyword">and</span> <span class="Identifier">s</span><span class="Punctuation">[</span><span class="Identifier">i</span><span class="Operator">+</span><span class="Identifier">u</span><span class="Punctuation">]</span> <span class="Operator">==</span> <span class="Identifier">until</span><span class="Punctuation">[</span><span class="Identifier">u</span><span class="Punctuation">]</span><span class="Punctuation">:</span>
        <span class="Identifier">inc</span> <span class="Identifier">u</span>
      <span class="Keyword">if</span> <span class="Identifier">u</span> <span class="Operator">&gt;=</span> <span class="Identifier">until</span><span class="Operator">.</span><span class="Identifier">len</span><span class="Punctuation">:</span> <span class="Keyword">break</span>
    <span class="Identifier">inc</span><span class="Punctuation">(</span><span class="Identifier">i</span><span class="Punctuation">)</span>
  <span class="Identifier">result</span> <span class="Operator">=</span> <span class="Identifier">i</span><span class="Operator">+</span><span class="Identifier">u</span><span class="Operator">-</span><span class="Identifier">start</span>

<span class="Keyword">iterator</span> <span class="Identifier">collectLinks</span><span class="Punctuation">(</span><span class="Identifier">s</span><span class="Punctuation">:</span> <span class="Identifier">string</span><span class="Punctuation">)</span><span class="Punctuation">:</span> <span class="Identifier">string</span> <span class="Operator">=</span>
  <span class="Keyword">const</span> <span class="Identifier">quote</span> <span class="Operator">=</span> <span class="Punctuation">{</span><span class="Punctuation">'</span><span class="Operator">\</span><span class="CharLit">''</span><span class="Punctuation">,</span> <span class="CharLit">'&quot;'</span><span class="Punctuation">}</span>
  <span class="Keyword">var</span> <span class="Identifier">idx</span><span class="Punctuation">,</span> <span class="Identifier">old</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
  <span class="Keyword">var</span> <span class="Identifier">res</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
  <span class="Keyword">while</span> <span class="Identifier">idx</span> <span class="Operator">&lt;</span> <span class="Identifier">s</span><span class="Operator">.</span><span class="Identifier">len</span><span class="Punctuation">:</span>
    <span class="Identifier">old</span> <span class="Operator">=</span> <span class="Identifier">idx</span>
    <span class="Keyword">if</span> <span class="Identifier">scanp</span><span class="Punctuation">(</span><span class="Identifier">s</span><span class="Punctuation">,</span> <span class="Identifier">idx</span><span class="Punctuation">,</span> <span class="StringLit">&quot;&lt;a&quot;</span><span class="Punctuation">,</span> <span class="Identifier">skipUntil</span><span class="Punctuation">(</span><span class="Operator">$</span><span class="Identifier">input</span><span class="Punctuation">,</span> <span class="StringLit">&quot;href=&quot;</span><span class="Punctuation">,</span> <span class="CharLit">'&gt;'</span><span class="Punctuation">,</span> <span class="Operator">$</span><span class="Identifier">index</span><span class="Punctuation">)</span><span class="Punctuation">,</span>
            <span class="Punctuation">`</span><span class="Identifier">quote</span><span class="Punctuation">`</span><span class="Punctuation">,</span> <span class="Operator">*</span><span class="Punctuation">(</span> <span class="Operator">~</span><span class="Punctuation">`</span><span class="Identifier">quote</span><span class="Punctuation">`</span><span class="Punctuation">)</span> <span class="Operator">-&gt;</span> <span class="Identifier">res</span><span class="Operator">.</span><span class="Identifier">add</span><span class="Punctuation">(</span><span class="Operator">$</span><span class="Identifier">_</span><span class="Punctuation">)</span><span class="Punctuation">)</span><span class="Punctuation">:</span>
      <span class="Keyword">yield</span> <span class="Identifier">res</span>
      <span class="Identifier">res</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
    <span class="Identifier">idx</span> <span class="Operator">=</span> <span class="Identifier">old</span> <span class="Operator">+</span> <span class="DecNumber">1</span>

<span class="Keyword">for</span> <span class="Identifier">r</span> <span class="Keyword">in</span> <span class="Identifier">collectLinks</span><span class="Punctuation">(</span><span class="Identifier">body</span><span class="Punctuation">)</span><span class="Punctuation">:</span>
  <span class="Identifier">echo</span> <span class="Identifier">r</span></pre></p>
<p>In this example both macros are combined seamlessly in order to maximise efficiency and perform different checks.</p>
<p><pre class="listing"><span class="Keyword">iterator</span> <span class="Identifier">parseIps</span><span class="Operator">*</span><span class="Punctuation">(</span><span class="Identifier">soup</span><span class="Punctuation">:</span> <span class="Identifier">string</span><span class="Punctuation">)</span><span class="Punctuation">:</span> <span class="Identifier">string</span> <span class="Operator">=</span>
  <span class="Comment">## ipv4 only!</span>
  <span class="Keyword">const</span> <span class="Identifier">digits</span> <span class="Operator">=</span> <span class="Punctuation">{</span><span class="Punctuation">'</span><span class="DecNumber">0'</span><span class="Operator">..</span><span class="CharLit">'9'</span><span class="Punctuation">}</span>
  <span class="Keyword">var</span> <span class="Identifier">a</span><span class="Punctuation">,</span> <span class="Identifier">b</span><span class="Punctuation">,</span> <span class="Identifier">c</span><span class="Punctuation">,</span> <span class="Identifier">d</span><span class="Punctuation">:</span> <span class="Identifier">int</span>
  <span class="Keyword">var</span> <span class="Identifier">buf</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
  <span class="Keyword">var</span> <span class="Identifier">idx</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
  <span class="Keyword">while</span> <span class="Identifier">idx</span> <span class="Operator">&lt;</span> <span class="Identifier">soup</span><span class="Operator">.</span><span class="Identifier">len</span><span class="Punctuation">:</span>
    <span class="Keyword">if</span> <span class="Identifier">scanp</span><span class="Punctuation">(</span><span class="Identifier">soup</span><span class="Punctuation">,</span> <span class="Identifier">idx</span><span class="Punctuation">,</span> <span class="Punctuation">(</span><span class="Punctuation">`</span><span class="Identifier">digits</span><span class="Punctuation">`</span><span class="Punctuation">{</span><span class="DecNumber">1</span><span class="Punctuation">,</span><span class="DecNumber">3</span><span class="Punctuation">}</span><span class="Punctuation">,</span> <span class="CharLit">'.'</span><span class="Punctuation">,</span> <span class="Punctuation">`</span><span class="Identifier">digits</span><span class="Punctuation">`</span><span class="Punctuation">{</span><span class="DecNumber">1</span><span class="Punctuation">,</span><span class="DecNumber">3</span><span class="Punctuation">}</span><span class="Punctuation">,</span> <span class="CharLit">'.'</span><span class="Punctuation">,</span>
             <span class="Punctuation">`</span><span class="Identifier">digits</span><span class="Punctuation">`</span><span class="Punctuation">{</span><span class="DecNumber">1</span><span class="Punctuation">,</span><span class="DecNumber">3</span><span class="Punctuation">}</span><span class="Punctuation">,</span> <span class="CharLit">'.'</span><span class="Punctuation">,</span> <span class="Punctuation">`</span><span class="Identifier">digits</span><span class="Punctuation">`</span><span class="Punctuation">{</span><span class="DecNumber">1</span><span class="Punctuation">,</span><span class="DecNumber">3</span><span class="Punctuation">}</span><span class="Punctuation">)</span> <span class="Operator">-&gt;</span> <span class="Identifier">buf</span><span class="Operator">.</span><span class="Identifier">add</span><span class="Punctuation">(</span><span class="Operator">$</span><span class="Identifier">_</span><span class="Punctuation">)</span><span class="Punctuation">)</span><span class="Punctuation">:</span>
      <span class="Keyword">discard</span> <span class="Identifier">buf</span><span class="Operator">.</span><span class="Identifier">scanf</span><span class="Punctuation">(</span><span class="StringLit">&quot;$i.$i.$i.$i&quot;</span><span class="Punctuation">,</span> <span class="Identifier">a</span><span class="Punctuation">,</span> <span class="Identifier">b</span><span class="Punctuation">,</span> <span class="Identifier">c</span><span class="Punctuation">,</span> <span class="Identifier">d</span><span class="Punctuation">)</span>
      <span class="Keyword">if</span> <span class="Punctuation">(</span><span class="Identifier">a</span> <span class="Operator">&gt;=</span> <span class="DecNumber">0</span> <span class="Keyword">and</span> <span class="Identifier">a</span> <span class="Operator">&lt;=</span> <span class="DecNumber">254</span><span class="Punctuation">)</span> <span class="Keyword">and</span>
         <span class="Punctuation">(</span><span class="Identifier">b</span> <span class="Operator">&gt;=</span> <span class="DecNumber">0</span> <span class="Keyword">and</span> <span class="Identifier">b</span> <span class="Operator">&lt;=</span> <span class="DecNumber">254</span><span class="Punctuation">)</span> <span class="Keyword">and</span>
         <span class="Punctuation">(</span><span class="Identifier">c</span> <span class="Operator">&gt;=</span> <span class="DecNumber">0</span> <span class="Keyword">and</span> <span class="Identifier">c</span> <span class="Operator">&lt;=</span> <span class="DecNumber">254</span><span class="Punctuation">)</span> <span class="Keyword">and</span>
         <span class="Punctuation">(</span><span class="Identifier">d</span> <span class="Operator">&gt;=</span> <span class="DecNumber">0</span> <span class="Keyword">and</span> <span class="Identifier">d</span> <span class="Operator">&lt;=</span> <span class="DecNumber">254</span><span class="Punctuation">)</span><span class="Punctuation">:</span>
        <span class="Keyword">yield</span> <span class="Identifier">buf</span>
    <span class="Identifier">buf</span><span class="Operator">.</span><span class="Identifier">setLen</span><span class="Punctuation">(</span><span class="DecNumber">0</span><span class="Punctuation">)</span> <span class="Comment"># need to clear `buf` each time, cause it might contain garbage</span>
    <span class="Identifier">idx</span><span class="Operator">.</span><span class="Identifier">inc</span></pre></p>
</p>
    <div class="section" id="6">
  <h1><a class="toc-backref" href="#6">Imports</a></h1>
  <dl class="item">
    <a class="reference external" href="macros.html">macros</a>, <a class="reference external" href="parseutils.html">parseutils</a>, <a class="reference external" href="since.html">since</a>, <a class="reference external" href="assertions.html">assertions</a>
  </dl>
</div>
<div class="section" id="17">
  <h1><a class="toc-backref" href="#17">Macros</a></h1>
  <dl class="item">
    <div id="scanf-macros-all">
  <div id="scanf.m,string,static[string],varargs[typed]">
  <dt><pre><span class="Keyword">macro</span> <a href="#scanf.m%2Cstring%2Cstatic%5Bstring%5D%2Cvarargs%5Btyped%5D"><span class="Identifier">scanf</span></a><span class="Other">(</span><span class="Identifier">input</span><span class="Other">:</span> <a href="system.html#string"><span class="Identifier">string</span></a><span class="Other">;</span> <span class="Identifier">pattern</span><span class="Other">:</span> <a href="system.html#static"><span class="Identifier">static</span></a><span class="Other">[</span><a href="system.html#string"><span class="Identifier">string</span></a><span class="Other">]</span><span class="Other">;</span> <span class="Identifier">results</span><span class="Other">:</span> <a href="system.html#varargs"><span class="Identifier">varargs</span></a><span class="Other">[</span><a href="system.html#typed"><span class="Identifier">typed</span></a><span class="Other">]</span><span class="Other">)</span><span class="Other">:</span> <a href="system.html#bool"><span class="Identifier">bool</span></a></pre></dt>
  <dd>
    
    See top level documentation of this module about how <tt class="docutils literal"><span class="pre">scanf</span></tt> works.
    <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L316" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
<a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L316" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;

  </dd>
</div>

</div>
<div id="scanp-macros-all">
  <div id="scanp.m,typed,typed,varargs[untyped]">
  <dt><pre><span class="Keyword">macro</span> <a href="#scanp.m%2Ctyped%2Ctyped%2Cvarargs%5Buntyped%5D"><span class="Identifier">scanp</span></a><span class="Other">(</span><span class="Identifier">input</span><span class="Other">,</span> <span class="Identifier">idx</span><span class="Other">:</span> <a href="system.html#typed"><span class="Identifier">typed</span></a><span class="Other">;</span> <span class="Identifier">pattern</span><span class="Other">:</span> <a href="system.html#varargs"><span class="Identifier">varargs</span></a><span class="Other">[</span><a href="system.html#untyped"><span class="Identifier">untyped</span></a><span class="Other">]</span><span class="Other">)</span><span class="Other">:</span> <a href="system.html#bool"><span class="Identifier">bool</span></a></pre></dt>
  <dd>
    
    See top level documentation of this module about how <tt class="docutils literal"><span class="pre">scanp</span></tt> works.
    <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L536" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
<a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L536" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;

  </dd>
</div>

</div>
<div id="scanTuple-macros-all">
  <div id="scanTuple.m,untyped,static[string],varargs[untyped]">
  <dt><pre><span class="Keyword">macro</span> <a href="#scanTuple.m%2Cuntyped%2Cstatic%5Bstring%5D%2Cvarargs%5Buntyped%5D"><span class="Identifier">scanTuple</span></a><span class="Other">(</span><span class="Identifier">input</span><span class="Other">:</span> <a href="system.html#untyped"><span class="Identifier">untyped</span></a><span class="Other">;</span> <span class="Identifier">pattern</span><span class="Other">:</span> <a href="system.html#static"><span class="Identifier">static</span></a><span class="Other">[</span><a href="system.html#string"><span class="Identifier">string</span></a><span class="Other">]</span><span class="Other">;</span>
                <span class="Identifier">matcherTypes</span><span class="Other">:</span> <a href="system.html#varargs"><span class="Identifier">varargs</span></a><span class="Other">[</span><a href="system.html#untyped"><span class="Identifier">untyped</span></a><span class="Other">]</span><span class="Other">)</span><span class="Other">:</span> <a href="system.html#untyped"><span class="Identifier">untyped</span></a></pre></dt>
  <dd>
    
    Works identically as scanf, but instead of predeclaring variables it returns a tuple. Tuple is started with a bool which indicates if the scan was successful followed by the requested data. If using a user defined matcher, provide the types in order they appear after pattern: <tt class="docutils literal"><span class="pre"><span class="Identifier">line</span><span class="Operator">.</span><span class="Identifier">scanTuple</span><span class="Punctuation">(</span><span class="StringLit">&quot;${yourMatcher()}&quot;</span><span class="Punctuation">,</span> <span class="Identifier">int</span><span class="Punctuation">)</span></span></tt>
<p><strong class="examples_text">Example:</strong></p>
<pre class="listing"><span class="Keyword">let</span> <span class="Punctuation">(</span><span class="Identifier">success</span><span class="Punctuation">,</span> <span class="Identifier">year</span><span class="Punctuation">,</span> <span class="Identifier">month</span><span class="Punctuation">,</span> <span class="Identifier">day</span><span class="Punctuation">,</span> <span class="Identifier">time</span><span class="Punctuation">)</span> <span class="Operator">=</span> <span class="Identifier">scanTuple</span><span class="Punctuation">(</span><span class="StringLit">&quot;1000-01-01 00:00:00&quot;</span><span class="Punctuation">,</span> <span class="StringLit">&quot;$i-$i-$i$s$+&quot;</span><span class="Punctuation">)</span>
<span class="Keyword">if</span> <span class="Identifier">success</span><span class="Punctuation">:</span>
  <span class="Identifier">assert</span> <span class="Identifier">year</span> <span class="Operator">==</span> <span class="DecNumber">1000</span>
  <span class="Identifier">assert</span> <span class="Identifier">month</span> <span class="Operator">==</span> <span class="DecNumber">1</span>
  <span class="Identifier">assert</span> <span class="Identifier">day</span> <span class="Operator">==</span> <span class="DecNumber">1</span>
  <span class="Identifier">assert</span> <span class="Identifier">time</span> <span class="Operator">==</span> <span class="StringLit">&quot;00:00:00&quot;</span></pre>
    <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L473" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
<a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L473" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;

  </dd>
</div>

</div>

  </dl>
</div>
<div class="section" id="18">
  <h1><a class="toc-backref" href="#18">Templates</a></h1>
  <dl class="item">
    <div id="atom-templates-all">
  <div id="atom.t,string,int,char">
  <dt><pre><span class="Keyword">template</span> <a href="#atom.t%2Cstring%2Cint%2Cchar"><span class="Identifier">atom</span></a><span class="Other">(</span><span class="Identifier">input</span><span class="Other">:</span> <a href="system.html#string"><span class="Identifier">string</span></a><span class="Other">;</span> <span class="Identifier">idx</span><span class="Other">:</span> <a href="system.html#int"><span class="Identifier">int</span></a><span class="Other">;</span> <span class="Identifier">c</span><span class="Other">:</span> <a href="system.html#char"><span class="Identifier">char</span></a><span class="Other">)</span><span class="Other">:</span> <a href="system.html#bool"><span class="Identifier">bool</span></a></pre></dt>
  <dd>
    
    Used in scanp for the matching of atoms (usually chars). EOF is matched as <tt class="docutils literal"><span class="pre">'\0'</span></tt>.
    <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L521" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
<a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L521" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;

  </dd>
</div>
<div id="atom.t,string,int,set[char]">
  <dt><pre><span class="Keyword">template</span> <a href="#atom.t%2Cstring%2Cint%2Cset%5Bchar%5D"><span class="Identifier">atom</span></a><span class="Other">(</span><span class="Identifier">input</span><span class="Other">:</span> <a href="system.html#string"><span class="Identifier">string</span></a><span class="Other">;</span> <span class="Identifier">idx</span><span class="Other">:</span> <a href="system.html#int"><span class="Identifier">int</span></a><span class="Other">;</span> <span class="Identifier">s</span><span class="Other">:</span> <a href="system.html#set"><span class="Identifier">set</span></a><span class="Other">[</span><a href="system.html#char"><span class="Identifier">char</span></a><span class="Other">]</span><span class="Other">)</span><span class="Other">:</span> <a href="system.html#bool"><span class="Identifier">bool</span></a></pre></dt>
  <dd>
    
    
    <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L526" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
<a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L526" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;

  </dd>
</div>

</div>
<div id="hasNxt-templates-all">
  <div id="hasNxt.t,string,int">
  <dt><pre><span class="Keyword">template</span> <a href="#hasNxt.t%2Cstring%2Cint"><span class="Identifier">hasNxt</span></a><span class="Other">(</span><span class="Identifier">input</span><span class="Other">:</span> <a href="system.html#string"><span class="Identifier">string</span></a><span class="Other">;</span> <span class="Identifier">idx</span><span class="Other">:</span> <a href="system.html#int"><span class="Identifier">int</span></a><span class="Other">)</span><span class="Other">:</span> <a href="system.html#bool"><span class="Identifier">bool</span></a></pre></dt>
  <dd>
    
    
    <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L529" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
<a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L529" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;

  </dd>
</div>

</div>
<div id="nxt-templates-all">
  <div id="nxt.t,string,int,int">
  <dt><pre><span class="Keyword">template</span> <a href="#nxt.t%2Cstring%2Cint%2Cint"><span class="Identifier">nxt</span></a><span class="Other">(</span><span class="Identifier">input</span><span class="Other">:</span> <a href="system.html#string"><span class="Identifier">string</span></a><span class="Other">;</span> <span class="Identifier">idx</span><span class="Other">:</span> <a href="system.html#int"><span class="Identifier">int</span></a><span class="Other">;</span> <span class="Identifier">step</span><span class="Other">:</span> <a href="system.html#int"><span class="Identifier">int</span></a> <span class="Other">=</span> <span class="DecNumber">1</span><span class="Other">)</span></pre></dt>
  <dd>
    
    
    <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L534" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
<a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L534" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;

  </dd>
</div>

</div>
<div id="success-templates-all">
  <div id="success.t,int">
  <dt><pre><span class="Keyword">template</span> <a href="#success.t%2Cint"><span class="Identifier">success</span></a><span class="Other">(</span><span class="Identifier">x</span><span class="Other">:</span> <a href="system.html#int"><span class="Identifier">int</span></a><span class="Other">)</span><span class="Other">:</span> <a href="system.html#bool"><span class="Identifier">bool</span></a></pre></dt>
  <dd>
    
    
    <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L532" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
<a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L532" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;

  </dd>
</div>

</div>

  </dl>
</div>

  </div>
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