RegExpr_Parse

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Updated2023-02-21
3 minute(s) read

int RegExpr_Parse (const char *regularExpressionText, int caseSensitive, RegExprHandle *regularExpressionHandle);

Purpose

This function parses a regular expression string.

If the string is a valid regular expression, this function returns a value as the regularExpressionHandle parameter, which you can pass to the following functions:

RegExpr_MatchText
RegExpr_Destroy

If the string is not a valid regular expression, RegExpr_Parse returns a negative error number. You can pass this error number to the RegExpr_GetErrorString function. However, in some cases there is more error information than can be encoded in the error number. You can get more detailed information about the result of the last call to this function by calling RegExpr_GetErrorElaboration.

Parameters

Input

Name Type Description

regularExpressionText

const char *

A nul–terminated string containing a regular expression.

A regular expression consists of the following tokens:

. (period)	match 1 character	a.t matches act and apt but not abort or at
* (asterisk)	match 0 or more occurrences of the preceding character or {expression}	01 matches 1, 01, 001, etc. a. matches act, apt, abort, and at
+ (plus sign)	match 1 or more occurrences of the preceding character or {expression}	0+1 matches 01, 001, 0001, etc. {ab}+c matches abc, ababc, but not c
? (question mark)	match 0 or 1 occurrences of the preceding character or {expression}	0?1 matches 1, 01, but not 001
\| (pipe)	matches either the preceding or following character or {expression}	a3\|4b matches a3b or a4b
^ (caret)	matches the beginning of a line	^int matches any line that begins with int
$ (dollar sign)	matches the end of a line	done$ matches any line that ends with done
{} (curly braces)	groups characters or expressions	{a3}\|{4b} matches a3 or 4b
[] (brackets)	matches any one character or range listed within the brackets	[a–z] matches every occurrence of lowercase letters [abc] matches every occurrence of a, b or c
~ (tilde)	when appearing immediately after the left bracket, negates the contents of the set	[~a–z] matches anything except lowercase letters [a–z~A–Z] matches all letters and the '~' character
\t (backslash t)	matches any tab character	\t3 matches every occurrence of a tab followed by a 3
\x (backslash x)	matches any character specified in hex	\x2a matches every occurrence of the '*' specified in hexcharacter
\ (backslash)	used if any of the above characters themselves are to be included in the search	\–\?\\ matches every occurrence of '–' followed by '?' and '\'

caseSensitive int Specify a nonzero value or select Yes in the function panel to match characters on a case–sensitive basis. For example, "chr" matches only "chr" and not "CHR".

Specify 0 or select No in the function panel to match characters on a case–insensitive basis. For example, "chr" matches "chr", "CHR", and "Chr".

This parameter does apply to ranges. For example, if this parameter is non–zero, then "[a–z]" in the regular expression string would match any lowercase letter. If this parameter is zero, then "[a–z]" matches any letter.

Output

Name Type Description

regularExpressionHandle RegExprHandle A handle that represents the parse regular expression.

You can pass this handle to the following functions:

RegExpr_GetFirstCharVec
RegExpr_MatchText
RegExpr_Destroy

When you are done with the regular expression, call RegExpr_Destroy on the handle. Otherwise, you will lose some memory.

Return Value

Name Type Description

parseStatus

int

Indicates if the regular expression was parsed successfully.

If the string is not a valid regular expression, a negative error number is returned. You can pass this error number to the RegExpr_GetErrorString function. However, in some cases there is more error information than can be encoded in the error number. You can get more detailed information about the result of the last call to this function by calling RegExpr_GetErrorElaboration.

The error numbers are:

0	success
–12	out of memory
–7900	unmatched character
–7901	invalid character in range
–7902	regular expression ends with backslash
–7903	invalid hex character (after \x)
–7904	operator applied to an empty pattern
–7905	empty left side of '\|'
–7906	empty right side of '\|'
–7907	empty group
–7908	invalid range
–7909	empty set ([])
–7910	empty input string
–7911	NULL input string
–7912	multibyte characters not allowed in range

Additional Information

Library: Regular Expressions

Include file: toolbox\regexpr.h

LabWindows/CVI compatibility: LabWindows/CVI 4.0 and later