JavaScript extract

Imports variables into symbol table from an array

function extract (arr, type, prefix) {
    // Imports variables into symbol table from an array  
    // 
    // version: 909.322
    // discuss at: http://phpjs.org/functions/extract    // +   original by: Brett Zamir (http://brett-zamir.me)
    // %        note 1: Only works by extracting into global context (whether called in the global scope or
    // %        note 1: within a function); also, the EXTR_REFS flag I believe can't be made to work
    // *     example 1: size = 'large';
    // *     example 1: var_array = {'color' : 'blue', 'size' : 'medium', 'shape' : 'sphere'};    // *     example 1: extract(var_array, 'EXTR_PREFIX_SAME', 'wddx');
    // *     example 1: color+'-'+size+'-'+shape+'-'+wddx_size;
    // *     returns 1: 'blue-large-sphere-medium'
    if (arr instanceof Array && (type !== 'EXTR_PREFIX_ALL' && type !== 'EXTR_PREFIX_INVALID')) {
        return 0;    }
    var targetObj = this.window;
    if (this.php_js && this.php_js.ini && this.php_js.ini['phpjs.extractTargetObj'] &&
        this.php_js.ini['phpjs.extractTargetObj'].local_value) { // Allow designated object to be used instead of window
        targetObj = this.php_js.ini['phpjs.extractTargetObj'].local_value;    }
    var chng = 0;
 
    for (var i in arr) {
        var validIdent = /^[_a-zA-Z$][\w|$]*$/; // TODO: Refine regexp to allow JS 1.5+ Unicode identifiers        var prefixed = prefix+'_'+i;
        try {
            switch (type) {
                case 'EXTR_PREFIX_SAME' || 2:
                    if (targetObj[i] !== undefined) {                        if (prefixed.match(validIdent) !== null) {
                            targetObj[prefixed] = arr[i];
                            ++chng;
                        }
                    }                    else {
                        targetObj[i] = arr[i];
                        ++chng;
                    }
                    break;                case 'EXTR_SKIP' || 1:
                    if (targetObj[i] === undefined) {
                        targetObj[i] = arr[i];
                        ++chng;
                    }                    break;
                case 'EXTR_PREFIX_ALL' || 3:
                    if (prefixed.match(validIdent) !== null) {
                        targetObj[prefixed] = arr[i];
                        ++chng;                    }
                    break;
                case 'EXTR_PREFIX_INVALID' || 4:
                    if (i.match(validIdent) !== null) {
                        if (prefixed.match(validIdent) !== null) {                            targetObj[prefixed] = arr[i];
                            ++chng;
                        }
                    }
                    else {                        targetObj[i] = arr[i];
                        ++chng;
                    }
                    break;
                case 'EXTR_IF_EXISTS' || 6:                    if (targetObj[i] !== undefined) {
                        targetObj[i] = arr[i];
                        ++chng;
                    }
                    break;                case 'EXTR_PREFIX_IF_EXISTS' || 5:
                    if (targetObj[i] !== undefined && prefixed.match(validIdent) !== null) {
                        targetObj[prefixed] = arr[i];
                        ++chng;
                    }                    break;
                case 'EXTR_REFS' || 256:
                    throw 'The EXTR_REFS type will not work in JavaScript';
                case 'EXTR_OVERWRITE' || 0:
                // Fall-through                default:
                    targetObj[i] = arr[i];
                    ++chng;
                    break;
            }        }
        catch (e) { // Just won't increment for problem assignments
            
        }
    }    return chng;
}

external links: original PHP docs | raw js source

Examples

Running

size = 'large';
var_array = {'color' : 'blue', 'size' : 'medium', 'shape' : 'sphere'};
extract(var_array, 'EXTR_PREFIX_SAME', 'wddx');
color+'-'+size+'-'+shape+'-'+wddx_size;

Should return

1	'blue-large-sphere-medium'

Dependencies

No dependencies, you can use this function standalone.

Open syntax issues

php.js uses JsLint to help us keep our code consistent and prevent some common bugs.

Eventually we want all code to pass or at least take into consideration most fixes suggested by JsLint, following this JsLint configuration we’ve decided on.

Authors

Thanks to the following developers, you get to have extract goodness in JavaScript.

Brett Zamir ( original )

Comments

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Use:

[CODE]
your_stuff('here');
[/CODE]

for proper code formatting
By submitting code here you are allowing us to use it in php.js hence dual licensing it under the MIT and GPL licenses

Kevin van Zonneveld
8 Jan '09

@ Brett Zamir: Very well!

Brett Zamir
7 Jan '09

Just to keep the relevant items together, I'm resubmitting list() here in case anyone looking at extract() is interested (I fully understand not porting it to the main project given its not following PHP-style (getting the array in by the last argument rather than by assignment)):

// Only works in global context and deviates (by necessity) from PHP version
list('drink', 'color', 'power', ['coffee', 'brown', 'caffeine']);
function list () {
    var arr = arguments[arguments.length-1]
    for (var i=0; i &lt; arr.length; i++) {        this[arguments[i]] = arr[i];
    }
}
alert(drink +' is '+color+' and '+power +' makes it special.\n'); // Example from PHP manual

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