How to search roman numerals in string with dart language? - flutter

Question

I'm new to flutter. i have a string which have some roman numbers that indicate steps.. so i want to arrange that steps with new line and don't know how to do it. i tried string.replaceAll() but cannot get it since there are many roman number and some of then are the same such as i and ii. for example i have this string..
String text = 'some text here i) some step 1 ii) some step 2 iii) some step 3. some text after step blabla '
I want the output to have '\n' infront of the roman number which will arrange the output
some text here
i) some step 1
ii) some step 2
iii) some step 3
some text after step blabla
is there something i can use to detect the numeral numbers and add '\n' infront of it in the string or is there some other way.

Answer 1

There is probably a simpler way to do this with some sort of regex that I don't know about, but something like this should work.
String text = 'Your String'
List<String> words = text.split(' ');
String result = '';
for(var word in words){
if(word.endsWith(')')){
result += word + '\n';
}else{
result += word
}
}
//result now contains the desired string

Answer 2

Tricky to know when "some text after step blabla" should have line breaks in front because I don't know what to look for... That you would have to specify more closely.
Using the Numerus package to check for valid Roman Numeral.
Have this a go:
String text = 'some text here i) some step 1 ii) some step 2 iii) some step 3. ao) invalid roman numberal. some textafter';
RegExp regexp = new RegExp(r"((\w+)\))");
final stringWithLinebreaks = text.replaceAllMapped(regexp, (match) {
return match.group(2).isValidRomanNumeral()
? '\n${match.group(1)}'
: '${match.group(1)}';
});
print(stringWithLinebreaks);
That will print out:
some text here
i) some step 1
ii) some step 2
iii) some step 3. ao) invalid roman numberal. some textafter
You could of course make it better in several ways. Such as converting the roman numeral to int value using toRomanNumeralValue(), then sorting the steps accordingly if they are in the incorrect order in the text string. You could also make the RegExp more precise in several ways. For instance replacing \w with [iIvVxXlLcCdDmM] and so on..

Answer 3

i've found the answer from javascript and modify some of it... this is my answer... but i managed to search roman number from 1 to 10 only.. but its ok since the step never exceed more than 10
String formatText(String text) {
RegExp regExp = new RegExp(r'(?:viii?|i(?:ii?|[vx])?|vi?|x)\)');
String value = text.replaceAllMapped(regExp, (match) => "\n${match.group(0)}");
return value;
}