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<link title="Weak" rel="Chapter" href="Weak.html"><link title="Regular expressions" rel="Section" href="#6_Regularexpressions">
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<title>Str</title>
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<center><h1>Module <a href="type_Str.html">Str</a></h1></center>
<br>
<pre><span class="keyword">module</span> Str: <code class="type">sig end</code></pre><div class="info">
Regular expressions and high-level string processing<br>
</div>
<hr width="100%">
<br>
<br>
<a name="6_Regularexpressions"></a>
<table cellpadding=5 cellspacing=5 width="100%">
<tr class="title6"><td><div align=center>
<span class="title6">Regular expressions</span>
</div>
</td>
</tr>
</table>
<br><br>
<br><code><span class="keyword">type</span> <a name="TYPEregexp"></a>regexp </code>
<div class="info">
The type of compiled regular expressions.<br>
</div>
<br>
<pre><span class="keyword">val</span> <a name="VALregexp"></a>regexp : <code class="type">string -> <a href="Str.html#TYPEregexp">regexp</a></code></pre><div class="info">
Compile a regular expression. The syntax for regular expressions
is the same as in Gnu Emacs. The special characters are
<code class="code">$^.*+?[]</code>. The following constructs are recognized:<ul>
<li><code class="code">. </code> matches any character except newline</li>
<li><code class="code">* </code> (postfix) matches the previous expression zero, one or
several times</li>
<li><code class="code">+ </code> (postfix) matches the previous expression one or
several times</li>
<li><code class="code">? </code> (postfix) matches the previous expression once or
not at all</li>
<li><code class="code">[..] </code> character set; ranges are denoted with <code class="code">-</code>, as in <code class="code">[a-z]</code>;
an initial <code class="code">^</code>, as in <code class="code">[^0-9]</code>, complements the set</li>
<li><code class="code">^ </code> matches at beginning of line</li>
<li><code class="code">$ </code> matches at end of line</li>
<li><code class="code">\| </code> (infix) alternative between two expressions</li>
<li><code class="code">\(..\)</code> grouping and naming of the enclosed expression</li>
<li><code class="code">\1 </code> the text matched by the first <code class="code">\(...\)</code> expression
(<code class="code">\2</code> for the second expression, etc)</li>
<li><code class="code">\b </code> matches word boundaries</li>
<li><code class="code">\ </code> quotes special characters.</li>
</ul>
<br>
</div>
<pre><span class="keyword">val</span> <a name="VALregexp_case_fold"></a>regexp_case_fold : <code class="type">string -> <a href="Str.html#TYPEregexp">regexp</a></code></pre><div class="info">
Same as <code class="code">regexp</code>, but the compiled expression will match text
in a case-insensitive way: uppercase and lowercase letters will
be considered equivalent.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALquote"></a>quote : <code class="type">string -> string</code></pre><div class="info">
<code class="code"><span class="constructor">Str</span>.quote s</code> returns a regexp string that matches exactly
<code class="code">s</code> and nothing else.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALregexp_string"></a>regexp_string : <code class="type">string -> <a href="Str.html#TYPEregexp">regexp</a></code></pre><div class="info">
<code class="code"><span class="constructor">Str</span>.regexp_string s</code> returns a regular expression
that matches exactly <code class="code">s</code> and nothing else.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALregexp_string_case_fold"></a>regexp_string_case_fold : <code class="type">string -> <a href="Str.html#TYPEregexp">regexp</a></code></pre><div class="info">
<code class="code"><span class="constructor">Str</span>.regexp_string_case_fold</code> is similar to <a href="Str.html#VALregexp_string"><code class="code"><span class="constructor">Str</span>.regexp_string</code></a>,
but the regexp matches in a case-insensitive way.<br>
</div>
<br>
<br>
<a name="6_Stringmatchingandsearching"></a>
<table cellpadding=5 cellspacing=5 width="100%">
<tr class="title6"><td><div align=center>
<span class="title6">String matching and searching</span>
</div>
</td>
</tr>
</table>
<br><br>
<pre><span class="keyword">val</span> <a name="VALstring_match"></a>string_match : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> int -> bool</code></pre><div class="info">
<code class="code">string_match r s start</code> tests whether the characters in <code class="code">s</code>
starting at position <code class="code">start</code> match the regular expression <code class="code">r</code>.
The first character of a string has position <code class="code">0</code>, as usual.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALsearch_forward"></a>search_forward : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> int -> int</code></pre><div class="info">
<code class="code">search_forward r s start</code> searchs the string <code class="code">s</code> for a substring
matching the regular expression <code class="code">r</code>. The search starts at position
<code class="code">start</code> and proceeds towards the end of the string.
Return the position of the first character of the matched
substring, or raise <code class="code"><span class="constructor">Not_found</span></code> if no substring matches.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALsearch_backward"></a>search_backward : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> int -> int</code></pre><div class="info">
Same as <a href="Str.html#VALsearch_forward"><code class="code"><span class="constructor">Str</span>.search_forward</code></a>, but the search proceeds towards the
beginning of the string.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALstring_partial_match"></a>string_partial_match : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> int -> bool</code></pre><div class="info">
Similar to <a href="Str.html#VALstring_match"><code class="code"><span class="constructor">Str</span>.string_match</code></a>, but succeeds whenever the argument
string is a prefix of a string that matches. This includes
the case of a true complete match.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALmatched_string"></a>matched_string : <code class="type">string -> string</code></pre><div class="info">
<code class="code">matched_string s</code> returns the substring of <code class="code">s</code> that was matched
by the latest <a href="Str.html#VALstring_match"><code class="code"><span class="constructor">Str</span>.string_match</code></a>, <a href="Str.html#VALsearch_forward"><code class="code"><span class="constructor">Str</span>.search_forward</code></a> or
<a href="Str.html#VALsearch_backward"><code class="code"><span class="constructor">Str</span>.search_backward</code></a>.
The user must make sure that the parameter <code class="code">s</code> is the same string
that was passed to the matching or searching function.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALmatch_beginning"></a>match_beginning : <code class="type">unit -> int</code></pre><div class="info">
<code class="code">match_beginning()</code> returns the position of the first character
of the substring that was matched by <a href="Str.html#VALstring_match"><code class="code"><span class="constructor">Str</span>.string_match</code></a>,
<a href="Str.html#VALsearch_forward"><code class="code"><span class="constructor">Str</span>.search_forward</code></a> or <a href="Str.html#VALsearch_backward"><code class="code"><span class="constructor">Str</span>.search_backward</code></a>.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALmatch_end"></a>match_end : <code class="type">unit -> int</code></pre><div class="info">
<code class="code">match_end()</code> returns the position of the character following the
last character of the substring that was matched by <code class="code">string_match</code>,
<code class="code">search_forward</code> or <code class="code">search_backward</code>.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALmatched_group"></a>matched_group : <code class="type">int -> string -> string</code></pre><div class="info">
<code class="code">matched_group n s</code> returns the substring of <code class="code">s</code> that was matched
by the <code class="code">n</code>th group <code class="code">\(...\)</code> of the regular expression during
the latest <a href="Str.html#VALstring_match"><code class="code"><span class="constructor">Str</span>.string_match</code></a>, <a href="Str.html#VALsearch_forward"><code class="code"><span class="constructor">Str</span>.search_forward</code></a> or
<a href="Str.html#VALsearch_backward"><code class="code"><span class="constructor">Str</span>.search_backward</code></a>.
The user must make sure that the parameter <code class="code">s</code> is the same string
that was passed to the matching or searching function.
<code class="code">matched_group n s</code> raises <code class="code"><span class="constructor">Not_found</span></code> if the <code class="code">n</code>th group
of the regular expression was not matched. This can happen
with groups inside alternatives <code class="code">\|</code>, options <code class="code">?</code>
or repetitions <code class="code">*</code>. For instance, the empty string will match
<code class="code">\(a\)*</code>, but <code class="code">matched_group 1 <span class="string">""</span></code> will raise <code class="code"><span class="constructor">Not_found</span></code>
because the first group itself was not matched.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALgroup_beginning"></a>group_beginning : <code class="type">int -> int</code></pre><div class="info">
<code class="code">group_beginning n</code> returns the position of the first character
of the substring that was matched by the <code class="code">n</code>th group of
the regular expression.<br>
<b>Raises</b> <code>Not_found</code> if the <code class="code">n</code>th group of the regular expression
was not matched.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALgroup_end"></a>group_end : <code class="type">int -> int</code></pre><div class="info">
<code class="code">group_end n</code> returns
the position of the character following the last character of
substring that was matched by the <code class="code">n</code>th group of the regular expression.<br>
<b>Raises</b> <code>Not_found</code> if the <code class="code">n</code>th group of the regular expression
was not matched.<br>
</div>
<br>
<br>
<a name="6_Replacement"></a>
<table cellpadding=5 cellspacing=5 width="100%">
<tr class="title6"><td><div align=center>
<span class="title6">Replacement</span>
</div>
</td>
</tr>
</table>
<br><br>
<pre><span class="keyword">val</span> <a name="VALglobal_replace"></a>global_replace : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> string -> string</code></pre><div class="info">
<code class="code">global_replace regexp templ s</code> returns a string identical to <code class="code">s</code>,
except that all substrings of <code class="code">s</code> that match <code class="code">regexp</code> have been
replaced by <code class="code">templ</code>. The replacement template <code class="code">templ</code> can contain
<code class="code">\1</code>, <code class="code">\2</code>, etc; these sequences will be replaced by the text
matched by the corresponding group in the regular expression.
<code class="code">\0</code> stands for the text matched by the whole regular expression.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALreplace_first"></a>replace_first : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> string -> string</code></pre><div class="info">
Same as <a href="Str.html#VALglobal_replace"><code class="code"><span class="constructor">Str</span>.global_replace</code></a>, except that only the first substring
matching the regular expression is replaced.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALglobal_substitute"></a>global_substitute : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> (string -> string) -> string -> string</code></pre><div class="info">
<code class="code">global_substitute regexp subst s</code> returns a string identical
to <code class="code">s</code>, except that all substrings of <code class="code">s</code> that match <code class="code">regexp</code>
have been replaced by the result of function <code class="code">subst</code>. The
function <code class="code">subst</code> is called once for each matching substring,
and receives <code class="code">s</code> (the whole text) as argument.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALsubstitute_first"></a>substitute_first : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> (string -> string) -> string -> string</code></pre><div class="info">
Same as <a href="Str.html#VALglobal_substitute"><code class="code"><span class="constructor">Str</span>.global_substitute</code></a>, except that only the first substring
matching the regular expression is replaced.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALreplace_matched"></a>replace_matched : <code class="type">string -> string -> string</code></pre><div class="info">
<code class="code">replace_matched repl s</code> returns the replacement text <code class="code">repl</code>
in which <code class="code">\1</code>, <code class="code">\2</code>, etc. have been replaced by the text
matched by the corresponding groups in the most recent matching
operation. <code class="code">s</code> must be the same string that was matched during
this matching operation.<br>
</div>
<br>
<br>
<a name="6_Splitting"></a>
<table cellpadding=5 cellspacing=5 width="100%">
<tr class="title6"><td><div align=center>
<span class="title6">Splitting</span>
</div>
</td>
</tr>
</table>
<br><br>
<pre><span class="keyword">val</span> <a name="VALsplit"></a>split : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> string list</code></pre><div class="info">
<code class="code">split r s</code> splits <code class="code">s</code> into substrings, taking as delimiters
the substrings that match <code class="code">r</code>, and returns the list of substrings.
For instance, <code class="code">split (regexp <span class="string">"[ \t]+"</span>) s</code> splits <code class="code">s</code> into
blank-separated words. An occurrence of the delimiter at the
beginning and at the end of the string is ignored.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALbounded_split"></a>bounded_split : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> int -> string list</code></pre><div class="info">
Same as <a href="Str.html#VALsplit"><code class="code"><span class="constructor">Str</span>.split</code></a>, but splits into at most <code class="code">n</code> substrings,
where <code class="code">n</code> is the extra integer parameter.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALsplit_delim"></a>split_delim : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> string list</code></pre><div class="info">
Same as <a href="Str.html#VALsplit"><code class="code"><span class="constructor">Str</span>.split</code></a> but occurrences of the
delimiter at the beginning and at the end of the string are
recognized and returned as empty strings in the result.
For instance, <code class="code">split_delim (regexp <span class="string">" "</span>) <span class="string">" abc "</span></code>
returns <code class="code">[<span class="string">""</span>; <span class="string">"abc"</span>; <span class="string">""</span>]</code>, while <code class="code">split</code> with the same
arguments returns <code class="code">[<span class="string">"abc"</span>]</code>.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALbounded_split_delim"></a>bounded_split_delim : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> int -> string list</code></pre><div class="info">
Same as <a href="Str.html#VALbounded_split"><code class="code"><span class="constructor">Str</span>.bounded_split</code></a>, but occurrences of the
delimiter at the beginning and at the end of the string are
recognized and returned as empty strings in the result.
For instance, <code class="code">split_delim (regexp <span class="string">" "</span>) <span class="string">" abc "</span></code>
returns <code class="code">[<span class="string">""</span>; <span class="string">"abc"</span>; <span class="string">""</span>]</code>, while <code class="code">split</code> with the same
arguments returns <code class="code">[<span class="string">"abc"</span>]</code>.<br>
</div>
<br><code><span class="keyword">type</span> <a name="TYPEsplit_result"></a>split_result =<br></code><table border="0" cellpadding="1">
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Text</span> <span class="keyword">of</span> <code class="type">string</code></code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code><span class="keyword">|</span></code></td>
<td align="left" valign="top" >
<code><span class="constructor">Delim</span> <span class="keyword">of</span> <code class="type">string</code></code></td>
</tr></table>
<br>
<pre><span class="keyword">val</span> <a name="VALfull_split"></a>full_split : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> <a href="Str.html#TYPEsplit_result">split_result</a> list</code></pre><div class="info">
Same as <a href="Str.html#VALsplit_delim"><code class="code"><span class="constructor">Str</span>.split_delim</code></a>, but returns
the delimiters as well as the substrings contained between
delimiters. The former are tagged <code class="code"><span class="constructor">Delim</span></code> in the result list;
the latter are tagged <code class="code"><span class="constructor">Text</span></code>. For instance,
<code class="code">full_split (regexp <span class="string">"[{}]"</span>) <span class="string">"{ab}"</span></code> returns
<code class="code">[<span class="constructor">Delim</span> <span class="string">"{"</span>; <span class="constructor">Text</span> <span class="string">"ab"</span>; <span class="constructor">Delim</span> <span class="string">"}"</span>]</code>.<br>
</div>
<pre><span class="keyword">val</span> <a name="VALbounded_full_split"></a>bounded_full_split : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> int -> <a href="Str.html#TYPEsplit_result">split_result</a> list</code></pre><div class="info">
Same as <a href="Str.html#VALbounded_split_delim"><code class="code"><span class="constructor">Str</span>.bounded_split_delim</code></a>, but returns
the delimiters as well as the substrings contained between
delimiters. The former are tagged <code class="code"><span class="constructor">Delim</span></code> in the result list;
the latter are tagged <code class="code"><span class="constructor">Text</span></code>. For instance,
<code class="code">full_split (regexp <span class="string">"[{}]"</span>) <span class="string">"{ab}"</span></code> returns
<code class="code">[<span class="constructor">Delim</span> <span class="string">"{"</span>; <span class="constructor">Text</span> <span class="string">"ab"</span>; <span class="constructor">Delim</span> <span class="string">"}"</span>]</code>.<br>
</div>
<br>
<br>
<a name="6_Extractingsubstrings"></a>
<table cellpadding=5 cellspacing=5 width="100%">
<tr class="title6"><td><div align=center>
<span class="title6">Extracting substrings</span>
</div>
</td>
</tr>
</table>
<br><br>
<pre><span class="keyword">val</span> <a name="VALstring_before"></a>string_before : <code class="type">string -> int -> string</code></pre><div class="info">
<code class="code">string_before s n</code> returns the substring of all characters of <code class="code">s</code>
that precede position <code class="code">n</code> (excluding the character at
position <code class="code">n</code>).<br>
</div>
<pre><span class="keyword">val</span> <a name="VALstring_after"></a>string_after : <code class="type">string -> int -> string</code></pre><div class="info">
<code class="code">string_after s n</code> returns the substring of all characters of <code class="code">s</code>
that follow position <code class="code">n</code> (including the character at
position <code class="code">n</code>).<br>
</div>
<pre><span class="keyword">val</span> <a name="VALfirst_chars"></a>first_chars : <code class="type">string -> int -> string</code></pre><div class="info">
<code class="code">first_chars s n</code> returns the first <code class="code">n</code> characters of <code class="code">s</code>.
This is the same function as <a href="Str.html#VALstring_before"><code class="code"><span class="constructor">Str</span>.string_before</code></a>.<br>
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<pre><span class="keyword">val</span> <a name="VALlast_chars"></a>last_chars : <code class="type">string -> int -> string</code></pre><div class="info">
<code class="code">last_chars s n</code> returns the last <code class="code">n</code> characters of <code class="code">s</code>.<br>
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