The SPAN_REGEXP rule is similar to the SPAN rule except the start sequence is taken to be a regular expression. In addition to the attributes supported by the SPAN tag, the HASH_CHAR attribute must be specified. It must be set to the first character that the regular expression matches. This rules out using regular expressions which can match more than one character at the start position. The regular expression match cannot span more than one line, either.

Any text matched by groups in the BEGIN regular expression is substituted in the END string. See below for an example of where this is useful.

Regular expression syntax is described in Appendix E, Regular Expressions.

Here is a SPAN_REGEXP rule that highlights “read-ins” in shell scripts:

<SPAN_REGEXP HASH_CHAR="<" TYPE="LITERAL1" DELEGATE="LITERAL">
    <BEGIN><![CDATA[<<['"\s]*(\p\w+)[\s'"]*]]></BEGIN>
    <END>$1</END>
</SPAN_REGEXP>

Here is a SPAN_REGEXP rule that highlights constructs placed between <#ftl and >, as long as the <#ftl is followed by a word break:

<SPAN_REGEXP TYPE="KEYWORD1" HASH_CHAR="&lt;" DELEGATE="EXPRESSION">
    <BEGIN>&lt;#ftl\&gt;</BEGIN>
    <END>&gt;</END>
</SPAN_REGEXP>