UnicodeReplace (Regex function): Difference between revisions
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The only characters you can escape in a replacement string are dollar sign (<code>$</code>), backslash (<code>\</code>), and the digits <code>0</code> through <code>9</code>. So only these escapes are respected: <code>\\</code>, <code>\$</code>, and <code>\0</code> through <code>\9</code>. No other escapes are allowed in a replacement string — this includes "shorthand" escapes like <code>\d</code> — and an "unaccompanied" backslash (<code>\</code>) is an error. For example, since the scan for the number that accompanies the meta-$ stops at the first non-numeric, you use <code>1$1\2</code> to indicate that the first captured string should go between the numbers 1 and 2 in the replacement string. | The only characters you can escape in a replacement string are dollar sign (<code>$</code>), backslash (<code>\</code>), and the digits <code>0</code> through <code>9</code>. So only these escapes are respected: <code>\\</code>, <code>\$</code>, and <code>\0</code> through <code>\9</code>. No other escapes are allowed in a replacement string — this includes "shorthand" escapes like <code>\d</code> — and an "unaccompanied" backslash (<code>\</code>) is an error. For example, since the scan for the number that accompanies the meta-$ stops at the first non-numeric, you use <code>1$1\2</code> to indicate that the first captured string should go between the numbers 1 and 2 in the replacement string. | ||
<p>An invalid replacement string results in request cancellation.</p></td></tr> | <p>An invalid replacement string results in request cancellation.</p></td></tr> | ||
<tr><th><var> | <tr><th><var>Options</var></th> | ||
<td> | |||
A string of single letter options, which may be specified in uppercase or lowercase, in any combination, and blank separated or not. These options are a subset of [[Regex_processing#Common_regex_options|Common regex options]]. The only acceptable options (case-independent) are <code>A</code> for "as-is", <code>G</code> for "global" (replace all occurrences), and <code>T</code> for trace.</td></tr> | A string of single letter options, which may be specified in uppercase or lowercase, in any combination, and blank separated or not. These options are a subset of [[Regex_processing#Common_regex_options|Common regex options]]. The only acceptable options (case-independent) are <code>A</code> for "as-is", <code>G</code> for "global" (replace all occurrences), and <code>T</code> for trace.</td></tr> | ||
</table> | </table> | ||
==Usage notes== | ==Usage notes== | ||
<ul> | <ul> | ||
<li>If the regular | <li>If the regular expression specified in the constructor call was not Unicode, this method causes request cancellation. To test if a <var>Regex</var> object was created with a Unicode regular expression check the [[IsUnicode (Regex property)|IsUnicode property]].</li> | ||
<li>There is no way to undo the <code>A</code>, <code>G</code>, and <code>T</code> options if they were specified on the constructor so if a <var>Regex</var> objects sometimes needs these options and sometimes not, they should be specified on each <var>UnicodeReplace</var> call.</li> | <li>There is no way to undo the <code>A</code>, <code>G</code>, and <code>T</code> options if they were specified on the constructor so if a <var>Regex</var> objects sometimes needs these options and sometimes not, they should be specified on each <var>UnicodeReplace</var> call.</li> | ||
</ul> | </ul> |
Latest revision as of 14:57, 24 March 2022
Replace regex match(es) for Unicode (Regex class)
This function replaces the parts of a Unicode string that match the regular expression in the Regex object and returns the Unicode string with the replacements.
Syntax
%unicode = regex:UnicodeReplace( unicode, [replacement], [Options= string])
Syntax terms
%unicode | A copy of the input unicode after matches are replaced using the appropriate replacement unicode. | ||||
---|---|---|---|---|---|
regex | The Regex object. | ||||
unicode | The unicode to test against the Regex object. | ||||
replacement | The unicode that replaces the substrings of string that regex matches. Except when the A option is specified (as described at Common regex options), you can include markers in the replacement value to indicate where to insert corresponding captured strings — strings matched by capturing groups (parenthesized subexpressions) in the regular expression, if any.
These markers are in the form $n, where n is the number of the capture group, and 1 is the number of the first capture group. n must not be 0 or contain more than 9 digits. If there was no nth capture group corresponding to the $n marker in a replacement string, the (literal) value of $n is used in the replacement string instead of the empty string.
The only characters you can escape in a replacement string are dollar sign ( An invalid replacement string results in request cancellation. | ||||
Options |
A string of single letter options, which may be specified in uppercase or lowercase, in any combination, and blank separated or not. These options are a subset of Common regex options. The only acceptable options (case-independent) are A for "as-is", G for "global" (replace all occurrences), and T for trace. |
Usage notes
- If the regular expression specified in the constructor call was not Unicode, this method causes request cancellation. To test if a Regex object was created with a Unicode regular expression check the IsUnicode property.
- There is no way to undo the
A
,G
, andT
options if they were specified on the constructor so if a Regex objects sometimes needs these options and sometimes not, they should be specified on each UnicodeReplace call.
Examples
The following example:
b %regex is object regex %regex = new("([α-ω]{3,})(\d{3,})":u, replace="$2–$1":u) print %regex:unicodeReplace("My license plate says φβκ7643":u) print %regex:unicodeReplace("My license plate says φβκ7643":u, "nothing") end
displays:
My license plate says 7643–φβκ My license plate says nothing