Get backreferences values and modificate these values
- by roasted
Could you please explain why im not able to get values of backreferences from a matched regex result and apply it some modification before effective replacement?
The expected result is replacing for example string ".coord('X','Y')" by "X * Y". But if X to some value, divide this value by 2 and then use this new value in replacement.
Here the code im currently testing:
See /*>>1<<*/ & /*>>2<<*/ & /*>>3<<*/, this is where im stuck!
I would like to be able to apply modification on backrefrences before replacement depending of backreferences values.
Difference between /*>>2<<*/ & /*>>3<<*/ is just the self call anonymous function param
The method /*>>2<<*/ is the expected working solution as i can understand it. But strangely, the replacement is not working correctly, replacing by alias $1 * $2 and not by value...?
You can test the jsfiddle
//string to test
".coord('125','255')"
//array of regex pattern and replacement //just one for the example
//for this example, pattern matching alphanumerics is not necessary (only decimal in coord) but keep it as it
var regexes = [ //FORMAT is array of [PATTERN,REPLACEMENT]
/*.coord("X","Y")*/ [/\.coord\(['"]([\w]+)['"],['"]?([\w:\.\\]+)['"]?\)/g, '$1 * $2']
];
function testReg(inputText, $output) {
//using regex
for (var i = 0; i < regexes.length; i++) {
/*==>**1**/ //this one works as usual but dont let me get backreferences values
$output.val(inputText.replace(regexes[i][0], regexes[i][2]));
/*==>**2**/ //this one should works as i understand it
$output.val(inputText.replace(regexes[i][0], function(match, $1, $2, $3, $4) {
$1 = checkReplace(match, $1, $2, $3, $4);
//here want using $1 modified value in replacement
return regexes[i][3];
}));
/*==>**3**/ //this one is just a test by self call anonymous function
$output.val(inputText.replace(regexes[i][0], function(match, $1, $2, $3, $4) {
$1 = checkReplace(match, $1, $2, $3, $4);
//here want using $1 modified value in replacement
return regexes[i][4];
}()));
inputText = $output.val();
}
}
function checkReplace(match, $1, $2, $3, $4) {
console.log(match + ':::' + $1 + ':::' + $2 + ':::' + $3 + ':::' + $4);
//HERE i should be able if lets say $1 > 200 divide it by 2
//then returning $1 value
if($1 > 200) $1 = parseInt($1 / 2);
return $1;
}?
Sure I'm missing something, but cannot get it!
Thanks for your help, regards.
EDIT WORKING METHOD:
Finally get it, as mentionned by Eric:
The key thing is that the function returns the literal text to
substitute, not a string which is parsed for backreferences.??
JSFIDDLE
So complete working code: (please note as pattern replacement will change for each matched pattern and optimisation of speed code is not an issue here, i will keep it like that)
$('#btn').click(function() {
testReg($('#input').val(), $('#output'));
});
//array of regex pattern and replacement //just one for the example
var regexes = [ //FORMAT is array of [PATTERN,REPLACEMENT] /*.coord("X","Y")*/
[/\.coord\(['"]([\w]+)['"],['"]?([\w:\.\\]+)['"]?\)/g, '$1 * $2']
];
function testReg(inputText, $output) {
//using regex
for (var i = 0; i < regexes.length; i++) {
$output.val(inputText.replace(regexes[i][0], function(match, $1, $2, $3, $4) {
var checkedValues = checkReplace(match, $1, $2, $3, $4);
$1 = checkedValues[0];
$2 = checkedValues[1];
regexes[i][1] = regexes[i][1].replace('$1', $1).replace('$2', $2);
return regexes[i][1];
}));
inputText = $output.val();
}
}
function checkReplace(match, $1, $2, $3, $4) {
console.log(match + ':::' + $1 + ':::' + $2 + ':::' + $3 + ':::' + $4);
if ($1 > 200) $1 = parseInt($1 / 2);
if ($2 > 200) $2 = parseInt($2 / 2);
return [$1,$2];
}
