Foreachkey

WarningThe scope of applications for UnigineScript is limited to implementing materials-related logic (material expressions, scriptable materials, brush materials). Do not use UnigineScript as a language for application logic, please consider C#/C++ instead, as these APIs are the preferred ones. Availability of new Engine features in UnigineScipt (beyond its scope of applications) is not guaranteed, as the current level of support assumes only fixing critical issues.

The foreachkey construct provides another way to iterate over vectors and maps. It is used to execute some code for each index or key in a given container.

Syntax

Source code (UnigineScript)

foreachkey(key_variable; map; loop_increment) {
	// some_code;
 }

Parts

key_variable is the current key (or index). The internal container cursor is moved to point at the next key-value pair (or indexed item).
The type of key_variable doesn't matter.
loop_increment is executed at the end of each iteration. It is optional.

Examples

Source code (UnigineScript)

int map[] = ( "begin" : "flower", "middle" : "fruit", "end" : "tree" );
foreachkey(int i; map) {
	log.message("%s\t=>\t%s\n",i,map[i]);
}

The result is:

Output

begin   =>      flower
end     =>      tree
middle  =>      fruit

Source code (UnigineScript)

int map[] = ( "begin" : "flower", "middle" : "fruit", "end" : "tree" );
foreachkey(int i, j = 0; map; j++) {
	log.message("%d: %s\t=>\t%s\n",j,i,map[i]);
}

The result is:

Output

0: begin   =>      flower
1: end     =>      tree
2: middle  =>      fruit

Notice

Before the execution keys are sorted in the ascending order.

Modifications of keys inside the foreachkey block do not affect the map, however, values can be modified directly.

Source code (UnigineScript)

int map[] = ( "begin" : "flower", "middle" : "fruit", "end" : "tree" );
foreachkey(int i; map) {
	i = "first";	// it doesn't affect the map
	map[i] = -9.6;	// it's ok, map is changed
}

Nesting foreachkey#

In case foreachkey structure is called within another foreachkey structure, for each block a copy of the map should be stored. (Such approach allows for higher performance.)

Source code (UnigineScript)

int map[] = ( "1" : "head", "2" : "foot" );

int copy[];
copy.copy(map);

foreachkey(int i; map) {
	foreachkey(int j; copy)	// foreachkey(int j; map) will generate an error
	{
		log.message("%s\t->\t%s\t%s\t->\t%s\n",i,map[i],j,map[j]);
	}
}

The output of the example is:

Output

1	->	head	1	->	head
1	->	head    2	->	foot
2	->	foot	1	->	head
2	->	foot	2	->	foot

Last update: 31.07.2020

Помогите сделать статью лучше

Была ли эта статья полезной?

Сообщить о проблеме в этой статье

(или выберите слово/фразу и нажмите Ctrl+Enter