Option Matching

10.3 Regular Expressions

Haxe has built-in support for regular expressions. They can be used to verify the format of a string, transform a string or extract some regular data from a given text.

Haxe has special syntax for creating regular expressions. We can create a regular expression object by typing it between the ~/ combination and a single / character:

var r = ~/haxe/i;

Alternatively, we can create regular expression with regular syntax:

var r = new EReg("haxe", "i");

The first argument is a string with a regular expression pattern, the second one is a string with flags (see below).

We can use standard regular expression patterns such as:

. any character
* repeat zero-or-more
+ repeat one-or-more
? optional zero-or-one
[A-Z0-9] character ranges
[^\r\n\t] character not-in-range
(...) parenthesis to match groups of characters
^ beginning of the string (beginning of a line in multiline matching mode)
$ end of the string (end of a line in multiline matching mode)
| "OR" statement.

For example, the following regular expression matches valid email addresses:

~/[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z][A-Z][A-Z]*/i;

Please notice that the i at the end of the regular expression is a flag that enables case-insensitive matching.

The possible flags are the following:

i case insensitive matching
g global replace or split, see below
m multiline matching, ^ and $ represent the beginning and end of a line
s the dot . will also match newlines (not supported by C# and JavaScript versions before ES2018)
u use UTF-8 matching (Neko and C++ targets only)