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regexactionscript-3curly-braces

actionscript3.0 replace curly brace pair

var strToBeReplace:String= "Hi! I am {0}, and I like {1}, I used to be a {2}"; // many {\d} like curly brace to be replace
trace(replaceCurlyBrace(strToBeReplace, "tom", "eating", "techer"));
// expect output: Hi! I am tom, and I like eating, I used to be a teacher

function replaceCurlyBrace(str:String, ... args):void
{
     // ... how to implement

}

I had tried this:

var str:String = "bla bla {0} bla";
var reg:Regexp = new Regexp("{0}");
trace(strToBeReplace.replace(reg,"tim"));
// real output : bla bla {0} bla

but it did't work.

I had tried double slash style regexp : /{0}/, but ide complains syntax error.

Solution

  • Let's start by what you have tried : 

    var reg:RegExp = new RegExp('{0}');     // you can write it : var reg:RegExp = /{0}/;
var str:String = 'bla bla {0} bla';

trace(str.replace(reg, 'tim'));

    Here you should know that {} is a quantifier metacharacter which is used to specify a numeric quantifier or quantifier range for a previous item, so for example, if you write /a{3}/ you tell the compiler that you are looking for any 'aaa' string, so in reality writing /{0}/ doesn't have any sens or utility.

    So to indicate to the compiler that you are looking for the string "{0}", you can do like this : 

    var reg:RegExp = /{[0]}/;   // you can write it : var reg:RegExp = new RegExp('{[0]}');

    OR, you can escape the {} using a single \ ( \\ if using a string ) : 

    var reg:RegExp = /\{0}/;    // you can write it : var reg:RegExp = new RegExp('\\{0}');

    Which give you this code : 

    var reg:RegExp = new RegExp('\\{0}');
var str:String = 'bla bla {0} bla';

trace(str.replace(reg, 'tim'));     // gives : bla bla tim bla

    Returning to your question, you have n words to replace within your string, so you can do like this :

    var str:String = 'Welcome to {0}, the free {1} that {2} can {3}.';
    str = replaceCurlyBrace(str, 'Wikipedia', 'encyclopedia', 'anyone', 'edit');

trace(str); // gives : Welcome to Wikipedia, the free encyclopedia that anyone can edit.

function replaceCurlyBrace(str:String, ... args): String {

    var exp0:RegExp = /\{/,     //  or : /{[/
        exp1:RegExp = /}/,      //  or : /]}/
        regex:RegExp;

    // if we have words
    if(args.length > 0) {   
        for(var i:int = 0; i<args.length; i++){
            // you can also write it : regex = new RegExp('\\{' + i + '}');
            // or                      regex = new RegExp('{[' + i + ']}');
            regex = new RegExp(exp0.source + i + exp1.source);  
            str = str.replace(regex, args[i]);
        }       
    }   
    return str;

}

    For more details about RegExp, you can take a look on :

    Hope that can help.