indent

Change indentation in multiline Dart strings while preserving the existing relative indentation.

A GIF speaks more than a thousand words:

You can run the example app yourself by running cd example && pub get && webdev serve from the project root.

Usage

For convenience, the library adds the following extension members on Dart's String class.

You can also wrap a string with the Indentation class and call methods on that - this is what the extension methods do under the hood.

unindent()

If you found this library from a Google search, you're probably looking for the unindent() method. It's the use case this library was originally created for.

For example, this:

import 'package:indent/indent.dart';

print('''
          Hello
        there
             World!
'''.unindent());

outputs this:

  Hello
there
     World!

It gets rid of the common indentation while preserving the relative indentation. This is like Kotlin's trimIndent() or Java 12's align().

trimMargin(String marginPrefix = '|')

Trims the leading whitespace followed by the marginPrefix from each line.

For example, this:

import 'package:indent/indent.dart';

print('''
        |  Hello
        |there
        |    World!
'''.trimMargin());

outputs this:

  Hello
there
    World!

Behaves just like trimMargin in Kotlin.

indent(int indentationLevel)

Indents a string with the desired indentation level while preserving relative indentation.

For example, this:

import 'package:indent/indent.dart';

print('''
   Hello
World
'''.indent(2));

prints:

     Hello
  World

If the starting indentation level is higher than the desired one, the value will be unindented accordingly.

This:

import 'package:indent/indent.dart';

print('''
          Hello
       World
'''.indent(2));

also prints:

     Hello
  World

(calling indent(0) is equal to calling unindent().)

indentBy(int howMuch)

Changes the indentation level in a string by howMuch.

A positive value for howMuch adds indentation.

For example, this:

import 'package:indent/indent.dart';

print('''
   Hello
World
'''.indentBy(4));

prints this:

       Hello
    World

When a negative value for howMuch is given, indentation is removed accordingly.

This:

import 'package:indent/indent.dart';

print('''
       Hello
    World
'''.indentBy(-4));

prints this:

   Hello
World

getIndentationLevel()

Returns the common indentation level in a string.

For example, this:

import 'package:indent/indent.dart';

final int indentationLevel= '''
     Hello
  World
'''.getIndentationLevel();

returns 2 as the two spaces before World is the lowest common indentation in the string.