REGREPL statement

Char

Definition

.

(period) Matches any character, except the end-of-line.

^

(caret) Matches the actual beginning-of-line position or the preceding line-delimiter character pair (CHR$(13,10) or $CRLF), as taken from the start& character position.  The line-delimiter characters themselves are not replaced by repl$.  (also see [^] below for usage within a character class definition).

$

(dollar) Matches the end-of-line position, which may be the either the first line-delimiter character pair (CHR$(13,10) or $CRLF) that is encountered in the search to the right of the start& position, or the actual end of the target$ string, whichever occurs first.  The line-delimiter characters themselves are not replaced by repl$.

|

(stile) Specifies alternation (the OR operator), so that an expression on either side can match.  Precedence is from left-to-right, as encountered in the expression.

?

(question mark) Specifies that zero or one match of the preceding sub-pattern is allowed.  Cannot be used with a Tag.

+

(plus) Specifies that one or more matches of the preceding sub-pattern are allowed.  Cannot be used with a Tag.

*

(asterisk) Specifies that zero or more matches of the preceding sub-pattern are allowed.  Cannot be used with a Tag.

Character classes

[ ]

(square brackets) Identifies a user-defined class of characters, any of which will match:  [abc] will match a, b, or c.  Only three special metacharacters are recognized within a class definition, the caret (^) for complemented characters, the hyphen (-) for a range of characters, or one of the following \ backslash escape sequences:

\\  \-  \]  \e  \f  \n  \q  \r  \t  \v  \x##

Any other use of a backslash within a class definition yields an undefined operation that should be avoided.

 [-]

(hyphen) The hyphen identifies a range of characters to match.  For example, [a-f] will match a, b, c, d, e, or f.

Characters in an individual range must occur in the natural order as they appear in the character set.  For example, [f-a] will match nothing.

Lists of characters, and one or more ranges of characters, may be intermixed in a single class definition.  The start and end of a range may be specified by a literal character, or one of the \ backslash escape sequences:

\\  \-  \]  \e  \f  \n  \q  \r  \t  \v  \x##

Any other use of a backslash within a class definition yields an undefined operation.

Multiple ranges in a class are valid.  For example, [a-d2-5] matches a, b, c, d, 2, 3, 4, or 5.

When the hyphen is escaped, it is treated as a literal.  For example, [a\-c] is a list, not a range, and matches a, -, or c due to the \ backslash escape sequence.

[^]

(caret) When the caret appears as the first item in a class definition, it identifies a complemented class of characters, which will not match.  For example, [^abc] matches any character except a, b, or c.

A range can also be specified for the complemented class.  For example, [^a-z] matches any character except a through z.

A caret located in any position other than the first is treated as a literal character.

Tags/sub-patterns

( )

(parentheses) Parentheses are used to match a Tag, or sub-pattern, within the full search pattern, and remember the match.  The matched sub-pattern can be retrieved later in the mask, or in a replace operation, with \01 through \99, based upon the left-to-right position of the opening parentheses.

Parentheses may also be used to force precedence of evaluation with the alternation operator.  For example, "(Begin)|(End)File" would match either "BeginFile" or "EndFile", but without the Tag designations, "Begin|EndFile" would only match either "BeginndFile" or "BegiEndFile".

Note: Parentheses may not be used with ? + * as any match repetition could cause the tag value to be ambiguous.  To match repeated expressions, use parentheses followed by \01*.

Escaped characters

\

(backslash).  The escape operator (single-character quote). The following character will be treated as a literal value rather than being interpreted as a special character. Note that the character following the backslash must actually be a special character, as follows:

\b

A word boundary.  The start or end of a word, where a word is defined as one or more characters that include an alphabetic character (A-Z or a-z), a numeric character (0-9), and an underscore.  For example, "abc_123" is considered a single word and "abc-123" is considered two words.

\c

Case-sensitive search.  Without the \c operator, the default is to ignore case when matching.  Unlike some other implementations of regular expressions, case-insensitivity is recognized in all operations, even a range of characters such as "[6-Z]".  The \c operator may appear at any position in the mask.

\e

Escape character: CHR$(27) or $ESC.

\f

Formfeed character: CHR$(12) or $FF.

\n

Linefeed (or newline) character: CHR$(10) or $LF.

\q

Double-quote mark ("): CHR$(34) or $DQ.  \q is included for ease of inclusion within a literal string.  For example: "\qHello\q".

\r

Carriage-return character: CHR$(13) or $CR.

\s

Shortest match character: The \s flag causes the shortest matching string to be returned, rather than the longest (the default).  For example, when searching for the mask "abc.*abc" in "abcdabcabc", the default setting would return position 1 and length 10.  With the \s switch set, it returns position 1 and length 7.  This option may cause a slight increase in processing time.  The \S flag must appear at the beginning of the mask string.

\t

Horizontal tab character: CHR$(9) or $TAB.

\v

Vertical tab character: CHR$(11) or $VT.

\x##

Hex character code: Indicates that an ASCII code follows, given by two hexadecimal digits.  For example, \xFF = CHR$(&HFF) (which is equivalent to CHR$(255)).  XX must be in the range 0 through 255.

\##

Tag number: Evaluated as the characters matched by tag number ## (where ## is in the range 01 through 99, in decimal).  Tags are implicitly numbered from 01 through 99, based upon the left-to-right position of the left parenthesis.  "(…)w\01" would match "abcwabc" or "456w456".