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  27.       <h1 class="title">std/strscans</h1>
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  40.         <li><a href="manual.html">Manual</a></li>
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  52.     
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  53.     <ul class="simple simple-toc" id="toc-list">
    54. 

  54.   <li><a class="reference" id="startswith-vs-full-match_toc" href="#startswith-vs-full-match">Startswith vs full match</a></li>
    55. 

  55. <li><a class="reference" id="user-definable-matchers_toc" href="#user-definable-matchers">User definable matchers</a></li>
    56. 

  56. <li><a class="reference" id="the-scanp-macro_toc" href="#the-scanp-macro">The scanp macro</a></li>
    57. 

  57. <li>
    58. 

  58.   <a class="reference reference-toplevel" href="#6" id="56">Imports</a>
    59. 

  59. </li>
    60. 

  60. <li>
    61. 

  61.   <details open>
    62. 

  62.     <summary><a class="reference reference-toplevel" href="#17" id="67">Macros</a></summary>
    63. 

  63.     <ul class="simple simple-toc-section">
    64. 

  64.       <ul class="simple nested-toc-section">scanf
    65. 

  65.   <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>
    66. 

  66. 

  67. </ul>
    68. 

  68. <ul class="simple nested-toc-section">scanp
    69. 

  69.   <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>
    70. 

  70. 

  71. </ul>
    72. 

  72. <ul class="simple nested-toc-section">scanTuple
    73. 

  73.   <li><a class="reference" href="#scanTuple.m%2Cuntyped%2Cstatic%5Bstring%5D%2Cvarargs%5Buntyped%5D" title="scanTuple(input: untyped; pattern: static[string];
    74. 

  74.           matcherTypes: varargs[untyped]): untyped">scanTuple(input: untyped; pattern: static[string];
    75. 

  75.           matcherTypes: varargs[untyped]): untyped</a></li>
    76. 

  76. 

  77. </ul>
    78. 

  78. 

  79.     </ul>
    80. 

  80.   </details>
    81. 

  81. </li>
    82. 

  82. <li>
    83. 

  83.   <details open>
    84. 

  84.     <summary><a class="reference reference-toplevel" href="#18" id="68">Templates</a></summary>
    85. 

  85.     <ul class="simple simple-toc-section">
    86. 

  86.       <ul class="simple nested-toc-section">atom
    87. 

  87.   <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>
    88. 

  88. <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>
    89. 

  89. 

  90. </ul>
    91. 

  91. <ul class="simple nested-toc-section">hasNxt
    92. 

  92.   <li><a class="reference" href="#hasNxt.t%2Cstring%2Cint" title="hasNxt(input: string; idx: int): bool">hasNxt(input: string; idx: int): bool</a></li>
    93. 

  93. 

  94. </ul>
    95. 

  95. <ul class="simple nested-toc-section">nxt
    96. 

  96.   <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>
    97. 

  97. 

  98. </ul>
    99. 

  99. <ul class="simple nested-toc-section">success
    100. 

  100.   <li><a class="reference" href="#success.t%2Cint" title="success(x: int): bool">success(x: int): bool</a></li>
    101. 

  101. 

  102. </ul>
    103. 

  103. 

  104.     </ul>
    105. 

  105.   </details>
    106. 

  106. </li>
    107. 

  107. 

  108. </ul>
    109. 

  109. 

  110.   </div>
    111. 

  111.   <div class="nine columns" id="content">
    112. 

  112.     <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L1" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
    113. 

  113. <a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L1" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;
    114. 

  114. 

  115.     <div id="tocRoot"></div>
    116. 

  116.     
    117. 

  117.     <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>
    118. 

  118. <p><pre class="listing"><span class="Comment"># check if input string matches a triple of integers:</span>
    119. 

  119. <span class="Keyword">const</span> <span class="Identifier">input</span> <span class="Operator">=</span> <span class="StringLit">&quot;(1,2,4)&quot;</span>
    120. 

  120. <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>
    121. 

  121. <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>
    122. 

  122.   <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>
    123. 

  123. 

  124. <span class="Comment"># check if input string matches an ISO date followed by an identifier followed</span>
    125. 

  125. <span class="Comment"># by whitespace and a floating point number:</span>
    126. 

  126. <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>
    127. 

  127. <span class="Keyword">var</span> <span class="Identifier">identifier</span><span class="Punctuation">:</span> <span class="Identifier">string</span>
    128. 

  128. <span class="Keyword">var</span> <span class="Identifier">myfloat</span><span class="Punctuation">:</span> <span class="Identifier">float</span>
    129. 

  129. <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>
    130. 

  130.   <span class="Identifier">echo</span> <span class="StringLit">&quot;yes, we have a match!&quot;</span></pre></p>
    131. 

  131. <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>
    132. 

  132. <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>
    133. 

  133. <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>
    134. 

  134. <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>
    135. 

  135. <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>
    136. 

  136. <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>
    137. 

  137. <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>
    138. 

  138. <tr><td><tt class="docutils literal"><span class="pre">$c</span></tt></td><td>Matches a single ASCII character.</td></tr>
    139. 

  139. <tr><td><tt class="docutils literal"><span class="pre">$s</span></tt></td><td>Skips optional whitespace.</td></tr>
    140. 

  140. <tr><td><tt class="docutils literal"><span class="pre">$$</span></tt></td><td>Matches a single dollar sign.</td></tr>
    141. 

  141. <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>
    142. 

  142. <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>
    143. 

  143. <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>
    144. 

  144. <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>
    145. 

  145. <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>
    146. 

  146. </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>
    147. 

  147. <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>
    148. 

  148. 

  149. <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>
    150. 

  150. 

  151. <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>
    152. 

  152. <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>
    153. 

  153. <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>
    154. 

  154.   <span class="Comment"># Note: The parameters and return value must match to what ``scanf`` requires</span>
    155. 

  155.   <span class="Identifier">result</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
    156. 

  156.   <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>
    157. 

  157. 

  158. <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>
    159. 

  159.   <span class="Operator">...</span></pre></p>
    160. 

  160. <p>It is also possible to pass arguments to a user definable matcher:</p>
    161. 

  161. <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>
    162. 

  162.   <span class="Comment"># matches exactly ``n`` digits. Matchers need to return 0 if nothing</span>
    163. 

  163.   <span class="Comment"># matched or otherwise the number of processed chars.</span>
    164. 

  164.   <span class="Keyword">var</span> <span class="Identifier">x</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
    165. 

  165.   <span class="Keyword">var</span> <span class="Identifier">i</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
    166. 

  166.   <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>
    167. 

  167.     <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>
    168. 

  168.     <span class="Identifier">inc</span> <span class="Identifier">i</span>
    169. 

  169.   <span class="Comment"># only overwrite if we had a match</span>
    170. 

  170.   <span class="Keyword">if</span> <span class="Identifier">i</span> <span class="Operator">==</span> <span class="Identifier">n</span><span class="Punctuation">:</span>
    171. 

  171.     <span class="Identifier">result</span> <span class="Operator">=</span> <span class="Identifier">n</span>
    172. 

  172.     <span class="Identifier">intVal</span> <span class="Operator">=</span> <span class="Identifier">x</span>
    173. 

  173. 

  174. <span class="Comment"># match an ISO date extracting year, month, day at the same time.</span>
    175. 

  175. <span class="Comment"># Also ensure the input ends after the ISO date:</span>
    176. 

  176. <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>
    177. 

  177. <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>
    178. 

  178.   <span class="Operator">...</span></pre></p>
    179. 

  179. 

  180. <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>
    181. 

  181. <table border="1" class="docutils"><tr><td><tt class="docutils literal"><span class="pre">(E)</span></tt></td><td>Grouping</td></tr>
    182. 

  182. <tr><td><tt class="docutils literal"><span class="pre">*E</span></tt></td><td>Zero or more</td></tr>
    183. 

  183. <tr><td><tt class="docutils literal"><span class="pre">+E</span></tt></td><td>One or more</td></tr>
    184. 

  184. <tr><td><tt class="docutils literal"><span class="pre">?E</span></tt></td><td>Zero or One</td></tr>
    185. 

  185. <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>
    186. 

  186. <tr><td><tt class="docutils literal"><span class="pre">~E</span></tt></td><td>Not predicate</td></tr>
    187. 

  187. <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>
    188. 

  188. <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>
    189. 

  189. <tr><td><tt class="docutils literal"><span class="pre">'a'</span></tt></td><td>Matches a single character</td></tr>
    190. 

  190. <tr><td><tt class="docutils literal"><span class="pre">{'a'..'b'}</span></tt></td><td>Matches a character set</td></tr>
    191. 

  191. <tr><td><tt class="docutils literal"><span class="pre">&quot;s&quot;</span></tt></td><td>Matches a string</td></tr>
    192. 

  192. <tr><td><tt class="docutils literal"><span class="pre">E -&gt; a</span></tt></td><td>Bind matching to some action</td></tr>
    193. 

  193. <tr><td><tt class="docutils literal"><span class="pre">$_</span></tt></td><td>Access the currently matched character</td></tr>
    194. 

  194. </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>
    195. 

  195. <p>Simple example that parses the <tt class="docutils literal"><span class="pre">/etc/passwd</span></tt> file line by line:</p>
    196. 

  196. <p><pre class="listing"><span class="Keyword">const</span>
    197. 

  197.   <span class="Identifier">etc_passwd</span> <span class="Operator">=</span> <span class="LongStringLit">&quot;&quot;&quot;root:x:0:0:root:/root:/bin/bash
    198. 

  198. daemon:x:1:1:daemon:/usr/sbin:/bin/sh
    199. 

  199. bin:x:2:2:bin:/bin:/bin/sh
    200. 

  200. sys:x:3:3:sys:/dev:/bin/sh
    201. 

  201. nobody:x:65534:65534:nobody:/nonexistent:/bin/sh
    202. 

  202. messagebus:x:103:107::/var/run/dbus:/bin/false
    203. 

  203. &quot;&quot;&quot;</span>
    204. 

  204. 

  205. <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>
    206. 

  206.   <span class="Identifier">result</span> <span class="Operator">=</span> <span class="Operator">@</span><span class="Punctuation">[</span><span class="Punctuation">]</span>
    207. 

  207.   <span class="Keyword">var</span> <span class="Identifier">idx</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
    208. 

  208.   <span class="Keyword">while</span> <span class="Identifier">true</span><span class="Punctuation">:</span>
    209. 

  209.     <span class="Keyword">var</span> <span class="Identifier">entry</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
    210. 

  210.     <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>
    211. 

  211.       <span class="Identifier">result</span><span class="Operator">.</span><span class="Identifier">add</span> <span class="Identifier">entry</span>
    212. 

  212.     <span class="Keyword">else</span><span class="Punctuation">:</span>
    213. 

  213.       <span class="Keyword">break</span></pre></p>
    214. 

  214. <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>
    215. 

  215. <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>
    216. 

  216. <p><pre class="listing"><span class="Keyword">import</span> <span class="Identifier">std</span><span class="Operator">/</span><span class="Identifier">streams</span>
    217. 

  217. 

  218. <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>
    219. 

  219.   <span class="Comment">## Used in scanp for the matching of atoms (usually chars).</span>
    220. 

  220.   <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>
    221. 

  221. 

  222. <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>
    223. 

  223.   <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>
    224. 

  224. 

  225. <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>
    226. 

  226.   <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>
    227. 

  227.   <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>
    228. 

  228. 

  229. <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>
    230. 

  230.   <span class="Identifier">result</span><span class="Operator">.</span><span class="Identifier">add</span> <span class="Identifier">entry</span></pre></p>
    231. 

  231. <p>Calling ordinary Nim procs inside the macro is possible:</p>
    232. 

  232. <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>
    233. 

  233.   <span class="Keyword">var</span> <span class="Identifier">x</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
    234. 

  234.   <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>
    235. 

  235.     <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>
    236. 

  236.     <span class="Identifier">inc</span> <span class="Identifier">result</span>
    237. 

  237.   <span class="Identifier">intVal</span> <span class="Operator">=</span> <span class="Identifier">x</span>
    238. 

  238. 

  239. <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>
    240. 

  240.   <span class="Comment"># Extracts the username and home directory</span>
    241. 

  241.   <span class="Comment"># of each entry (with UID greater than 1000)</span>
    242. 

  242.   <span class="Keyword">const</span>
    243. 

  243.     <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>
    244. 

  244.   <span class="Identifier">result</span> <span class="Operator">=</span> <span class="Operator">@</span><span class="Punctuation">[</span><span class="Punctuation">]</span>
    245. 

  245.   <span class="Keyword">var</span> <span class="Identifier">idx</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
    246. 

  246.   <span class="Keyword">while</span> <span class="Identifier">true</span><span class="Punctuation">:</span>
    247. 

  247.     <span class="Keyword">var</span> <span class="Identifier">login</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
    248. 

  248.     <span class="Keyword">var</span> <span class="Identifier">uid</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
    249. 

  249.     <span class="Keyword">var</span> <span class="Identifier">homedir</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
    250. 

  250.     <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>
    251. 

  251.             <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>
    252. 

  252.             <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>
    253. 

  253.       <span class="Keyword">if</span> <span class="Identifier">uid</span> <span class="Operator">&gt;=</span> <span class="DecNumber">1000</span><span class="Punctuation">:</span>
    254. 

  254.         <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>
    255. 

  255.     <span class="Keyword">else</span><span class="Punctuation">:</span>
    256. 

  256.       <span class="Keyword">break</span></pre></p>
    257. 

  257. <p>When used for matching, keep in mind that likewise scanf, no backtracking is performed.</p>
    258. 

  258. <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>
    259. 

  259.   <span class="Comment"># Skips all characters until the string `until` is found. Returns 0</span>
    260. 

  260.   <span class="Comment"># if the char `unless` is found first or the end is reached.</span>
    261. 

  261.   <span class="Keyword">var</span> <span class="Identifier">i</span> <span class="Operator">=</span> <span class="Identifier">start</span>
    262. 

  262.   <span class="Keyword">var</span> <span class="Identifier">u</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
    263. 

  263.   <span class="Keyword">while</span> <span class="Identifier">true</span><span class="Punctuation">:</span>
    264. 

  264.     <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>
    265. 

  265.       <span class="Keyword">return</span> <span class="DecNumber">0</span>
    266. 

  266.     <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>
    267. 

  267.       <span class="Identifier">u</span> <span class="Operator">=</span> <span class="DecNumber">1</span>
    268. 

  268.       <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>
    269. 

  269.         <span class="Identifier">inc</span> <span class="Identifier">u</span>
    270. 

  270.       <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>
    271. 

  271.     <span class="Identifier">inc</span><span class="Punctuation">(</span><span class="Identifier">i</span><span class="Punctuation">)</span>
    272. 

  272.   <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>
    273. 

  273. 

  274. <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>
    275. 

  275.   <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>
    276. 

  276.   <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>
    277. 

  277.   <span class="Keyword">var</span> <span class="Identifier">res</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
    278. 

  278.   <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>
    279. 

  279.     <span class="Identifier">old</span> <span class="Operator">=</span> <span class="Identifier">idx</span>
    280. 

  280.     <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>
    281. 

  281.             <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>
    282. 

  282.       <span class="Keyword">yield</span> <span class="Identifier">res</span>
    283. 

  283.       <span class="Identifier">res</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
    284. 

  284.     <span class="Identifier">idx</span> <span class="Operator">=</span> <span class="Identifier">old</span> <span class="Operator">+</span> <span class="DecNumber">1</span>
    285. 

  285. 

  286. <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>
    287. 

  287.   <span class="Identifier">echo</span> <span class="Identifier">r</span></pre></p>
    288. 

  288. <p>In this example both macros are combined seamlessly in order to maximise efficiency and perform different checks.</p>
    289. 

  289. <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>
    290. 

  290.   <span class="Comment">## ipv4 only!</span>
    291. 

  291.   <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>
    292. 

  292.   <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>
    293. 

  293.   <span class="Keyword">var</span> <span class="Identifier">buf</span> <span class="Operator">=</span> <span class="StringLit">&quot;&quot;</span>
    294. 

  294.   <span class="Keyword">var</span> <span class="Identifier">idx</span> <span class="Operator">=</span> <span class="DecNumber">0</span>
    295. 

  295.   <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>
    296. 

  296.     <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>
    297. 

  297.              <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>
    298. 

  298.       <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>
    299. 

  299.       <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>
    300. 

  300.          <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>
    301. 

  301.          <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>
    302. 

  302.          <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>
    303. 

  303.         <span class="Keyword">yield</span> <span class="Identifier">buf</span>
    304. 

  304.     <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>
    305. 

  305.     <span class="Identifier">idx</span><span class="Operator">.</span><span class="Identifier">inc</span></pre></p>
    306. 

  306. </p>
    307. 

  307.     <div class="section" id="6">
    308. 

  308.   <h1><a class="toc-backref" href="#6">Imports</a></h1>
    309. 

  309.   <dl class="item">
    310. 

  310.     <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>
    311. 

  311.   </dl>
    312. 

  312. </div>
    313. 

  313. <div class="section" id="17">
    314. 

  314.   <h1><a class="toc-backref" href="#17">Macros</a></h1>
    315. 

  315.   <dl class="item">
    316. 

  316.     <div id="scanf-macros-all">
    317. 

  317.   <div id="scanf.m,string,static[string],varargs[typed]">
    318. 

  318.   <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>
    319. 

  319.   <dd>
    320. 

  320.     
    321. 

  321.     See top level documentation of this module about how <tt class="docutils literal"><span class="pre">scanf</span></tt> works.
    322. 

  322.     <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L316" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
    323. 

  323. <a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L316" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;
    324. 

  324. 

  325.   </dd>
    326. 

  326. </div>
    327. 

  327. 

  328. </div>
    329. 

  329. <div id="scanp-macros-all">
    330. 

  330.   <div id="scanp.m,typed,typed,varargs[untyped]">
    331. 

  331.   <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>
    332. 

  332.   <dd>
    333. 

  333.     
    334. 

  334.     See top level documentation of this module about how <tt class="docutils literal"><span class="pre">scanp</span></tt> works.
    335. 

  335.     <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L536" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
    336. 

  336. <a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L536" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;
    337. 

  337. 

  338.   </dd>
    339. 

  339. </div>
    340. 

  340. 

  341. </div>
    342. 

  342. <div id="scanTuple-macros-all">
    343. 

  343.   <div id="scanTuple.m,untyped,static[string],varargs[untyped]">
    344. 

  344.   <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>
    345. 

  345.                 <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>
    346. 

  346.   <dd>
    347. 

  347.     
    348. 

  348.     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>
    349. 

  349. <p><strong class="examples_text">Example:</strong></p>
    350. 

  350. <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>
    351. 

  351. <span class="Keyword">if</span> <span class="Identifier">success</span><span class="Punctuation">:</span>
    352. 

  352.   <span class="Identifier">assert</span> <span class="Identifier">year</span> <span class="Operator">==</span> <span class="DecNumber">1000</span>
    353. 

  353.   <span class="Identifier">assert</span> <span class="Identifier">month</span> <span class="Operator">==</span> <span class="DecNumber">1</span>
    354. 

  354.   <span class="Identifier">assert</span> <span class="Identifier">day</span> <span class="Operator">==</span> <span class="DecNumber">1</span>
    355. 

  355.   <span class="Identifier">assert</span> <span class="Identifier">time</span> <span class="Operator">==</span> <span class="StringLit">&quot;00:00:00&quot;</span></pre>
    356. 

  356.     <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L473" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
    357. 

  357. <a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L473" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;
    358. 

  358. 

  359.   </dd>
    360. 

  360. </div>
    361. 

  361. 

  362. </div>
    363. 

  363. 

  364.   </dl>
    365. 

  365. </div>
    366. 

  366. <div class="section" id="18">
    367. 

  367.   <h1><a class="toc-backref" href="#18">Templates</a></h1>
    368. 

  368.   <dl class="item">
    369. 

  369.     <div id="atom-templates-all">
    370. 

  370.   <div id="atom.t,string,int,char">
    371. 

  371.   <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>
    372. 

  372.   <dd>
    373. 

  373.     
    374. 

  374.     Used in scanp for the matching of atoms (usually chars). EOF is matched as <tt class="docutils literal"><span class="pre">'\0'</span></tt>.
    375. 

  375.     <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L521" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
    376. 

  376. <a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L521" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;
    377. 

  377. 

  378.   </dd>
    379. 

  379. </div>
    380. 

  380. <div id="atom.t,string,int,set[char]">
    381. 

  381.   <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>
    382. 

  382.   <dd>
    383. 

  383.     
    384. 

  384.     
    385. 

  385.     <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L526" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
    386. 

  386. <a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L526" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;
    387. 

  387. 

  388.   </dd>
    389. 

  389. </div>
    390. 

  390. 

  391. </div>
    392. 

  392. <div id="hasNxt-templates-all">
    393. 

  393.   <div id="hasNxt.t,string,int">
    394. 

  394.   <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>
    395. 

  395.   <dd>
    396. 

  396.     
    397. 

  397.     
    398. 

  398.     <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L529" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
    399. 

  399. <a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L529" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;
    400. 

  400. 

  401.   </dd>
    402. 

  402. </div>
    403. 

  403. 

  404. </div>
    405. 

  405. <div id="nxt-templates-all">
    406. 

  406.   <div id="nxt.t,string,int,int">
    407. 

  407.   <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>
    408. 

  408.   <dd>
    409. 

  409.     
    410. 

  410.     
    411. 

  411.     <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L534" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
    412. 

  412. <a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L534" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;
    413. 

  413. 

  414.   </dd>
    415. 

  415. </div>
    416. 

  416. 

  417. </div>
    418. 

  418. <div id="success-templates-all">
    419. 

  419.   <div id="success.t,int">
    420. 

  420.   <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>
    421. 

  421.   <dd>
    422. 

  422.     
    423. 

  423.     
    424. 

  424.     <a href="https://github.com/nim-lang/Nim/tree/devel/lib/pure/strscans.nim#L532" class="link-seesrc" target="_blank">Source</a>&nbsp;&nbsp;
    425. 

  425. <a href="https://github.com/nim-lang/Nim/edit/devel/lib/pure/strscans.nim#L532" class="link-seesrc" target="_blank" >Edit</a>&nbsp;&nbsp;
    426. 

  426. 

  427.   </dd>
    428. 

  428. </div>
    429. 

  429. 

  430. </div>
    431. 

  431. 

  432.   </dl>
    433. 

  433. </div>
    434. 

  434. 

  435.   </div>
    436. 

  436. </div>
    437. 

  437. 

  438.       <div class="twelve-columns footer">
    439. 

  439.         <span class="nim-sprite"></span>
    440. 

  440.         <br>
    441. 

  441.         <small style="color: var(--hint);">Made with Nim. Generated: 2025-02-03 14:56:51 UTC</small>
    442. 

  442.       </div>
    443. 

  443.     </div>
    444. 

  444.   </div>
    445. 

  445.       <script defer data-domain="nim-lang.org" src="https://plausible.io/js/plausible.js"></script>
    446. 

  446.     
    447. 

  447. </body>
    448. 

  448. </html>
    449. 

  449.