Gamemaker Regular Expression

My custom and pretty readable version of a RegEx like string manipulator made in GM for GM 2.3+
Suitable for quick searches or string validations

Expressions can be written in two modes: exact and simple

What can it do?

• Match
  gmre_match(ex, string) -> bool
• Find
  gmre_find(ex, str) -> string
• Find all
  gmre_find_all(ex, str) -> array of strings
• Find position
  gmre_find_pos(ex, str) -> real
• Find all positions
  gmre_find_pos_all(ex, str) -> array of reals
• Replace
  gmre_replace(ex, str, substr) -> string
• Replace all
  gmre_replace_all(ex, str, substr_or_array) -> string
• Check if contains
  gmre_contains(ex, str) -> bool
• Split
  gmre_split(ex, str) -> array of strings

How do I use it?

simple - bool (optional, default: false)

Creating an expression:
var ex1 = new gmre_ex(expr_string, simple*);
var ex2 = new gmre_ex(expr_string, simple*);
var ex3 = new gmre_ex(expr_string, simple*);

Using an expression:
var result1 = gmre_*(ex1, string, ...)
var result2 = gmre_*(ex2, string, ...)
var result3 = gmre_*(ex3, string, ...)

Editing an existing expression
gmre_ex_parse(ex, new_expr_string, simple*)

You can check if the expression was parsed successfully with variable ex.ok
If ex.ok returns false you can show the error message using variable ex.err which returns a string that will tell you what and where it went wrong

Rules

The entire system works around rules
There are 3 types of rules: charset [], string ||, loop () + position subrule {}
Each rule can be negated, chained using repeats and can have a position subrule added to it

Spaces between rules are allowed except between >rule and repeat< and >negation and rule<

* - optional
<negation>* <rule> <repeats>* <pos>*

Charset rule

[] Any characters
[xyz] Characters "x","y" and "z"
[x-y] Char range from "x" to "y"
[x-yz] Char range from "x" to "y" + character "z"
[xy ] Characters "x","y" and " " (space)

Range:
Only works for basic alphabet A-Z a-z and numbers 0-9
x-y Lowercase only
X-Y Uppercase only
X-y or x-Y Both lowercase and uppercase are allowed (case insensitive)

String rule

|x| String "x"
|x z| String "x z"
|xYz| String "xYz"

Loop rule

Loop cannot contain another loop
() Empty loop
(|x|[y-z]) Loop containing a string rule and a charset rule

Position subrule

This subrule cannot be alone
Having loop rules inside isn't supported
<rule> {x=|a|} The xth character of the rule on the left must be equal to the rule |a|
<rule> {x=|a|,[b]} The xth character of the rule on the left must be equal to the rule |a| OR to the rule [b]
<rule> {x,y=[a],|b|} The xth character AND the yth character of the rule on the left must be equal to the rule [a] OR to the rule |b|

The lowercase "n" stands for the last character and + or - can be added to it to add or subtract a number from this position
<rule> {n=|a|} The last character of the rule on the left must be equal to the rule |a|
<rule> {n-1=|a|} The penultimate character of the rule on the left must be equal to the rule |a|

Rules can be also used to find a position and + or - can be added to it to add or subtract a number from this position
<rule> {[a]+1=[b]} All positions of characters that meet the condition of the rule [a]+1 must be equal to the rule |b|
<rule> {[a]-1,|b|+2=[b],|c|} Positions of [a]-1 AND |b|+2 must be equal to rules [b] OR |c|

Good-to-know stuff

You can simply do var result = gmre_do_something(new gmre_ex(...), ...) but it's always faster to create expressions in the Create event so you don't parse rules AND process strings at the same time (like every step)
[a][b][c] is the same as |abc|
A rule with min 0 repeats isn't mandatory: [a][b]0-2[c] matches with "abc", "abbc" and also "ac"
Characters used for parsing rules [ ] { } ( ) | inside charsets/strings require \ before them to prevent parsing mistakes -> [A-z0-9\[\]\{\}\|], |abc\(d\)efg|

Examples

Email validator

With all valid special characters according to this site: https://help.returnpath.com/hc/en-us/articles/220560587-What-are-the-rules-for-email-address-syntax-
Create:

mval_str = "[A-z0-9.!#$%&'*+-/=?^_`\{\|]1-64 {1,n,[.!#$%&'*+-/=?^_`\{\|]+1=![.!#$%&'*+-/=?^_`\{\|]} |@| ([A-z0-9-]1-40{1,n=![-]}|.|)1-4 [A-z0-9-]1-10 {1,n=![-]}";
ex_mail_validator = new gmre_ex(mval_str);

Step or whatever:

var is_valid = gmre_match(ex_mail_validator, "[email protected]");

is_valid = true

String splitter

Create:

ex_split_spaces = new gmre_ex("| |"); // or in simple syntax: new gmre_ex(" ", true);

Step or whatever:

var split_arr = gmre_split(ex_split_spaces, "blah blah blah");

split_arr = ["blah", "blah", "blah"]

Inventory search

In simple mode
^{You can get Foreach for GM here ;)}
Create:

inventory = ["pickaxe", "axe", "red potion", "blue potion"]
ex_inv_search = new gmre_ex();
found_results = [];

Step or whatever:

if keyboard_check_released(vk_anykey) {
	gmre_ex_parse(ex_inv_search, <some_keyboard_input>, true);
	found_results = [];
	foreach inventory into item exec {
		var cont = gmre_contains(ex_inv_search, item);
		if cont array_push(found_results, item);
	}
}

found_results = ["pickaxe", "axe"] if some_keyboard_input = "axe"
found_results = ["pickaxe", "red potion", "blue potion"] if some_keyboard_input = "p"
found_results = ["red potion", "blue potion"] if some_keyboard_input = "pot"

Cheat sheet