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href="Tk.html"> <link title="Unix" rel="Chapter" href="Unix.html"> <link title="UnixLabels" rel="Chapter" href="UnixLabels.html"> <link title="Weak" rel="Chapter" href="Weak.html"><link title="Regular expressions" rel="Section" href="#6_Regularexpressions"> <link title="String matching and searching" rel="Section" href="#6_Stringmatchingandsearching"> <link title="Replacement" rel="Section" href="#6_Replacement"> <link title="Splitting" rel="Section" href="#6_Splitting"> <link title="Extracting substrings" rel="Section" href="#6_Extractingsubstrings"> <title>Str</title> </head> <body> <div class="navbar"><a class="pre" href="StdLabels.html" title="StdLabels">Previous</a> <a class="up" href="index.html" title="Index">Up</a> <a class="post" href="Stream.html" title="Stream">Next</a> </div> <h1>Module <a href="type_Str.html">Str</a></h1> <pre><span class="keyword">module</span> Str: <code class="code"><span class="keyword">sig</span></code> <a href="Str.html">..</a> <code class="code"><span class="keyword">end</span></code></pre><div class="info module top"> Regular expressions and high-level string processing<br> </div> <hr width="100%"> <br> <h6 id="6_Regularexpressions">Regular expressions</h6><br> <pre><span id="TYPEregexp"><span class="keyword">type</span> <code class="type"></code>regexp</span> </pre> <div class="info "> The type of compiled regular expressions.<br> </div> <pre><span id="VALregexp"><span class="keyword">val</span> regexp</span> : <code class="type">string -> <a href="Str.html#TYPEregexp">regexp</a></code></pre><div class="info "> Compile a regular expression. 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 preceding expression zero, one or several times</li> <li><code class="code">+ </code> (postfix) Matches the preceding expression one or several times</li> <li><code class="code">? </code> (postfix) Matches the preceding 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. To include a <code class="code">]</code> character in a set, make it the first character of the set. To include a <code class="code">-</code> character in a set, make it the first or the last character of the set.</li> <li><code class="code">^ </code> Matches at beginning of line (either at the beginning of the matched string, or just after a newline character).</li> <li><code class="code">$ </code> Matches at end of line (either at the end of the matched string, or just before a newline character).</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, and so on up to <code class="code">\9</code>).</li> <li><code class="code">\b </code> Matches word boundaries.</li> <li><code class="code">\ </code> Quotes special characters. The special characters are <code class="code">$^\.*+?[]</code>.</li> </ul> Note: the argument to <code class="code">regexp</code> is usually a string literal. In this case, any backslash character in the regular expression must be doubled to make it past the OCaml string parser. For example, the following expression: <pre class="codepre"><code class="code"> <span class="keyword">let</span> r = <span class="constructor">Str</span>.regexp <span class="string">"hello \\([A-Za-z]+\\)"</span> <span class="keyword">in</span><br> <span class="constructor">Str</span>.replace_first r <span class="string">"\\1"</span> <span class="string">"hello world"</span> </code></pre> returns the string <code class="code"><span class="string">"world"</span></code>. <p> In particular, if you want a regular expression that matches a single backslash character, you need to quote it in the argument to <code class="code">regexp</code> (according to the last item of the list above) by adding a second backslash. Then you need to quote both backslashes (according to the syntax of string constants in OCaml) by doubling them again, so you need to write four backslash characters: <code class="code"><span class="constructor">Str</span>.regexp <span class="string">"\\\\"</span></code>.<br> </div> <pre><span id="VALregexp_case_fold"><span class="keyword">val</span> regexp_case_fold</span> : <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 id="VALquote"><span class="keyword">val</span> quote</span> : <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 id="VALregexp_string"><span class="keyword">val</span> regexp_string</span> : <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 id="VALregexp_string_case_fold"><span class="keyword">val</span> regexp_string_case_fold</span> : <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> <h6 id="6_Stringmatchingandsearching">String matching and searching</h6><br> <pre><span id="VALstring_match"><span class="keyword">val</span> string_match</span> : <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 a substring of <code class="code">s</code> that starts at position <code class="code">start</code> matches 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 id="VALsearch_forward"><span class="keyword">val</span> search_forward</span> : <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> searches 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.<br> <b>Raises</b> <code>Not_found</code> if no substring matches.<br> </div> <pre><span id="VALsearch_backward"><span class="keyword">val</span> search_backward</span> : <code class="type"><a href="Str.html#TYPEregexp">regexp</a> -> string -> int -> int</code></pre><div class="info "> <code class="code">search_backward r s last</code> searches the string <code class="code">s</code> for a substring matching the regular expression <code class="code">r</code>. The search first considers substrings that start at position <code class="code">last</code> and proceeds towards the beginning of string. Return the position of the first character of the matched substring.<br> <b>Raises</b> <code>Not_found</code> if no substring matches.<br> </div> <pre><span id="VALstring_partial_match"><span class="keyword">val</span> string_partial_match</span> : <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 also returns true if the argument string is a prefix of a string that matches. This includes the case of a true complete match.<br> </div> <pre><span id="VALmatched_string"><span class="keyword">val</span> matched_string</span> : <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 last call to one of the following matching or searching functions:<ul> <li><a href="Str.html#VALstring_match"><code class="code"><span class="constructor">Str</span>.string_match</code></a></li> <li><a href="Str.html#VALsearch_forward"><code class="code"><span class="constructor">Str</span>.search_forward</code></a></li> <li><a href="Str.html#VALsearch_backward"><code class="code"><span class="constructor">Str</span>.search_backward</code></a></li> <li><a href="Str.html#VALstring_partial_match"><code class="code"><span class="constructor">Str</span>.string_partial_match</code></a></li> <li><a href="Str.html#VALglobal_substitute"><code class="code"><span class="constructor">Str</span>.global_substitute</code></a></li> <li><a href="Str.html#VALsubstitute_first"><code class="code"><span class="constructor">Str</span>.substitute_first</code></a> provided that none of the following functions was called inbetween:</li> <li><a href="Str.html#VALglobal_replace"><code class="code"><span class="constructor">Str</span>.global_replace</code></a></li> <li><a href="Str.html#VALreplace_first"><code class="code"><span class="constructor">Str</span>.replace_first</code></a></li> <li><a href="Str.html#VALsplit"><code class="code"><span class="constructor">Str</span>.split</code></a></li> <li><a href="Str.html#VALbounded_split"><code class="code"><span class="constructor">Str</span>.bounded_split</code></a></li> <li><a href="Str.html#VALsplit_delim"><code class="code"><span class="constructor">Str</span>.split_delim</code></a></li> <li><a href="Str.html#VALbounded_split_delim"><code class="code"><span class="constructor">Str</span>.bounded_split_delim</code></a></li> <li><a href="Str.html#VALfull_split"><code class="code"><span class="constructor">Str</span>.full_split</code></a></li> <li><a href="Str.html#VALbounded_full_split"><code class="code"><span class="constructor">Str</span>.bounded_full_split</code></a></li> </ul> Note: in the case of <code class="code">global_substitute</code> and <code class="code">substitute_first</code>, a call to <code class="code">matched_string</code> is only valid within the <code class="code">subst</code> argument, not after <code class="code">global_substitute</code> or <code class="code">substitute_first</code> returns. <p> 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 id="VALmatch_beginning"><span class="keyword">val</span> match_beginning</span> : <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 the last call to a matching or searching function (see <a href="Str.html#VALmatched_string"><code class="code"><span class="constructor">Str</span>.matched_string</code></a> for details).<br> </div> <pre><span id="VALmatch_end"><span class="keyword">val</span> match_end</span> : <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 the last call to a matching or searching function (see <a href="Str.html#VALmatched_string"><code class="code"><span class="constructor">Str</span>.matched_string</code></a> for details).<br> </div> <pre><span id="VALmatched_group"><span class="keyword">val</span> matched_group</span> : <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 that was matched by the last call to a matching or searching function (see <a href="Str.html#VALmatched_string"><code class="code"><span class="constructor">Str</span>.matched_string</code></a> for details). 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> <b>Raises</b> <code>Not_found</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 id="VALgroup_beginning"><span class="keyword">val</span> group_beginning</span> : <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 that was matched by the last call to a matching or searching function (see <a href="Str.html#VALmatched_string"><code class="code"><span class="constructor">Str</span>.matched_string</code></a> for details).<br> <b>Raises</b><ul><li><code>Not_found</code> if the <code class="code">n</code>th group of the regular expression was not matched.</li> <li><code>Invalid_argument</code> if there are fewer than <code class="code">n</code> groups in the regular expression.</li> </ul> </div> <pre><span id="VALgroup_end"><span class="keyword">val</span> group_end</span> : <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 that was matched by the last call to a matching or searching function (see <a href="Str.html#VALmatched_string"><code class="code"><span class="constructor">Str</span>.matched_string</code></a> for details).<br> <b>Raises</b><ul><li><code>Not_found</code> if the <code class="code">n</code>th group of the regular expression was not matched.</li> <li><code>Invalid_argument</code> if there are fewer than <code class="code">n</code> groups in the regular expression.</li> </ul> </div> <br> <h6 id="6_Replacement">Replacement</h6><br> <pre><span id="VALglobal_replace"><span class="keyword">val</span> global_replace</span> : <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 id="VALreplace_first"><span class="keyword">val</span> replace_first</span> : <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 id="VALglobal_substitute"><span class="keyword">val</span> global_substitute</span> : <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 id="VALsubstitute_first"><span class="keyword">val</span> substitute_first</span> : <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 id="VALreplace_matched"><span class="keyword">val</span> replace_matched</span> : <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 regular expression that was matched by the last call to a matching or searching function (see <a href="Str.html#VALmatched_string"><code class="code"><span class="constructor">Str</span>.matched_string</code></a> for details). <code class="code">s</code> must be the same string that was passed to the matching or searching function.<br> </div> <br> <h6 id="6_Splitting">Splitting</h6><br> <pre><span id="VALsplit"><span class="keyword">val</span> split</span> : <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 or at the end of the string is ignored.<br> </div> <pre><span id="VALbounded_split"><span class="keyword">val</span> bounded_split</span> : <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 id="VALsplit_delim"><span class="keyword">val</span> split_delim</span> : <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 id="VALbounded_split_delim"><span class="keyword">val</span> bounded_split_delim</span> : <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.<br> </div> <pre><code><span id="TYPEsplit_result"><span class="keyword">type</span> <code class="type"></code>split_result</span> = </code></pre><table class="typetable"> <tr> <td align="left" valign="top" > <code><span class="keyword">|</span></code></td> <td align="left" valign="top" > <code><span id="TYPEELTsplit_result.Text"><span class="constructor">Text</span></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 id="TYPEELTsplit_result.Delim"><span class="constructor">Delim</span></span> <span class="keyword">of</span> <code class="type">string</code></code></td> </tr></table> <pre><span id="VALfull_split"><span class="keyword">val</span> full_split</span> : <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 id="VALbounded_full_split"><span class="keyword">val</span> bounded_full_split</span> : <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>.<br> </div> <br> <h6 id="6_Extractingsubstrings">Extracting substrings</h6><br> <pre><span id="VALstring_before"><span class="keyword">val</span> string_before</span> : <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 id="VALstring_after"><span class="keyword">val</span> string_after</span> : <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 id="VALfirst_chars"><span class="keyword">val</span> first_chars</span> : <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> </div> <pre><span id="VALlast_chars"><span class="keyword">val</span> last_chars</span> : <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> </div> </body></html>