textwrap

Version 0.16.2 (2025-03-03)

This release fixes an unnecessary f64 cast, updates all dependencies, bumps
the minimum supported Rust version to 1.70.

• #540: Avoid spurious f64
  cast and comparison.
• #565: Configure automatic
  Dependabot updates.
• #579: Bump rust-version to
  1.70.

This release fixes an unnecessary f64 cast, updates all dependencies, bumps the minimum supported Rust version to 1.70.

• #540: Avoid spurious f64 cast and comparison.
• #565: Configure automatic Dependabot updates.
• #579: Bump rust-version to 1.70.

Version 0.16.1 (2024-02-17)

This release fixes display_width to ignore inline-hyperlinks. The minimum
supported version of Rust is now documented to be 1.56.

• #526: Ignore ANSI hyperlinks
  in display_width: calculations.
• #521: Add Options::width
  setter method.
• #520: Clarify that
  WordSeparator is an enum rather than a trait.
• #518: Test with latest stable
  and nightly Rust, but check that we can build with Rust 1.56.

This release fixes display_width to ignore inline-hyperlinks. The minimum supported version of Rust is now documented to be 1.56.

• #526: Ignore ANSI hyperlinks in display_width: calculations.
• #521: Add Options::width setter method.
• #520: Clarify that WordSeparator is an enum rather than a trait.
• #518: Test with latest stable and nightly Rust, but check that we can build with Rust 1.56.

Version 0.16.0 (2022-10-23)

This release marks Options as non_exhaustive and extends it to make line endings configurable, it adds new fast paths to fill and wrap, and it fixes crashes in unfill and refill.

• #480: Mark Options as non_exhaustive. This will allow us to extend the struct in the future without breaking backwards compatibility.
• #478: Add fast paths to fill and wrap. This makes the functions 10-25 times faster when the no wrapping is needed.
• #468: Fix refill to add back correct line ending.
• #467: Fix crashes in unfill and refill.
• #458: Test with Rust 1.56 (first compiler release with support for Rust 2021).
• #454: Make line endings configurable.
• #448: Migrate to the Rust 2021 edition.

This release marks Options as non_exhaustive and extends it to make line endings configurable, it adds new fast paths to fill and wrap, and it fixes crashes in unfill and refill.

• #480: Mark Options as non_exhaustive. This will allow us to extend the struct in the future without breaking backwards compatibility.
• #478: Add fast paths to fill and wrap. This makes the functions 10-25 times faster when the no wrapping is needed.
• #468: Fix refill to add back correct line ending.
• #467: Fix crashes in unfill and refill.
• #458: Test with Rust 1.56 (first compiler release with support for Rust 2021).
• #454: Make line endings configurable.
• #448: Migrate to the Rust 2021 edition.

Version 0.15.2 (2022-10-24)

This release is identical to 0.15.0 and is only there to give people a way to install crates which depend on the yanked 0.15.1 release. See #484 for details.

This release is identical to 0.15.0 and is only there to give people a way to install crates which depend on the yanked 0.15.1 release. See #484 for details.

Version 0.15.1 (2022-09-15)

This release which fixes crashes in unfill and refill. It also adds a new option to make the line endings (\n or \r\n) configurable:

• #448: Migrate to the Rust 2021 edition.
• #458: Test with Rust 1.56 (first compiler release with support for Rust 2021).
• #454: Make line endings configurable.
• #467: Fix unfill and refill crashes.
• #468: Fix refill to add back correct line ending.

This release was yanked since it accidentally broke backwards compatibility with 0.15.0.

Version 0.15.0 (2022-02-27)

This is a major feature release with two main changes:

• #421: Use f64 instead of usize for fragment widths.

  This fixes problems with overflows in the internal computations of wrap_optimal_fit when fragments (words) or line lengths had extreme values, such as usize::MAX.

• #438: Simplify Options by removing generic type parameters.

  This change removes the new generic parameters introduced in version 0.14, as well as the original WrapSplitter parameter which has been present since very early versions.

  The result is a simplification of function and struct signatures across the board. So what used to be

  let options: Options<
      wrap_algorithms::FirstFit,
      word_separators::AsciiSpace,
      word_splitters::HyphenSplitter,
  > = Options::new(80);

  if types are fully written out, is now simply

  let options: Options<'_> = Options::new(80);

  The anonymous lifetime represent the lifetime of the initial_indent and subsequent_indent strings. The change is nearly performance neutral (a 1-2% regression).

Smaller improvements and changes:

• #404: Make documentation for short last-line penalty more precise.
• #405: Cleanup and simplify Options docstring.
• #411: Default to OptimalFit in interactive example.
• #415: Add demo program to help compute binary sizes.
• #423: Add fuzz tests with fully arbitrary fragments.
• #424: Change wrap_optimal_fit penalties to non-negative numbers.
• #430: Add debug-words example.
• #432: Use precise dependency versions in Cargo.toml.

This is a major feature release with two main changes:

• #421: Use f64 instead of usize for fragment widths.

  This fixes problems with overflows in the internal computations of wrap_optimal_fit when fragments (words) or line lengths had extreme values, such as usize::MAX.

• #438: Simplify Options by removing generic type parameters.

  This change removes the new generic parameters introduced in version 0.14, as well as the original WrapSplitter parameter which has been present since very early versions.

  The result is a simplification of function and struct signatures across the board. So what used to be

  let options: Options<
      wrap_algorithms::FirstFit,
      word_separators::AsciiSpace,
      word_splitters::HyphenSplitter,
  > = Options::new(80);
  

  if types are fully written out, is now simply

  let options: Options<'_> = Options::new(80);
  

  The anonymous lifetime represent the lifetime of the initial_indent and subsequent_indent strings. The change is nearly performance neutral (a 1-2% regression).

Smaller improvements and changes:

• #404: Make documentation for short last-line penalty more precise.
• #405: Cleanup and simplify Options docstring.
• #411: Default to OptimalFit in interactive example.
• #415: Add demo program to help compute binary sizes.
• #423: Add fuzz tests with fully arbitrary fragments.
• #424: Change wrap_optimal_fit penalties to non-negative numbers.
• #430: Add debug-words example.
• #432: Use precise dependency versions in Cargo.toml.

Version 0.14.2 (2021-06-27)

The 0.14.1 release included more changes than intended and has been yanked. The change intended for 0.14.1 is now included in 0.14.2.

The 0.14.1 release included more changes than intended and has been yanked. The change intended for 0.14.1 is now included in 0.14.2.

Version 0.14.1 (2021-06-26)

This release fixes a panic reported by @makoto, thanks!

• #391: Fix panic in find_words due to string access outside of a character boundary.

This release fixes a panic reported by @Makoto, thanks!

• #391: Fix panic in find_words due to string access outside of a character boundary.

Version 0.14.0 (2021-06-05)

This is a major feature release which makes Textwrap more configurable and flexible. The high-level API of textwrap::wrap and textwrap::fill remains unchanged, but low-level structs have moved around.

The biggest change is the introduction of new generic type parameters to the Options struct. These parameters lets you statically configure the wrapping algorithm, the word separator, and the word splitter. If you previously spelled out the full type for Options, you now need to take the extra type parameters into account. This means that

let options: Options<HyphenSplitter> = Options::new(80);

changes to

let options: Options<
    wrap_algorithms::FirstFit,
    word_separators::AsciiSpace,
    word_splitters::HyphenSplitter,
> = Options::new(80);

This is quite a mouthful, so we suggest using type inferrence where possible. You won’t see any chance if you call wrap directly with a width or with an Options value constructed on the fly. Please open an issue if this causes problems for you!

New WordSeparator Trait

• #332: Add WordSeparator trait to allow customizing how words are found in a line of text. Until now, Textwrap would always assume that words are separated by ASCII space characters. You can now customize this as needed.

• #313: Add support for using the Unicode line breaking algorithm to find words. This is done by adding a second implementation of the new WordSeparator trait. The implementation uses the unicode-linebreak crate, which is a new optional dependency.

  With this, Textwrap can be used with East-Asian languages such as Chinese or Japanese where there are no spaces between words. Breaking a long sequence of emojis is another example where line breaks might be wanted even if there are no whitespace to be found. Feedback would be appreciated for this feature.

Indent

• #353: Trim trailing whitespace from prefix in indent.

  Before, empty lines would get no prefix added. Now, empty lines have a trimmed prefix added. This little trick makes indent much more useful since you can now safely indent with "# " without creating trailing whitespace in the output due to the trailing whitespace in your prefix.

• #354: Make indent about 20% faster by preallocating the output string.

Documentation

• #308: Document handling of leading and trailing whitespace when wrapping text.

WebAssembly Demo

• #310: Thanks to WebAssembly, you can now try out Textwrap directly in your browser: https://mgeisler.github.io/textwrap/.

New Generic Parameters

• #331: Remove outer boxing from Options.

• #357: Replace core::WrapAlgorithm enum with a wrap_algorithms::WrapAlgorithm trait. This allows for arbitrary wrapping algorithms to be plugged into the library.

• #358: Switch wrapping functions to use a slice for line_widths.

• #368: Move WordSeparator and WordSplitter traits to separate modules. Before, Textwrap had several top-level structs such as NoHyphenation and HyphenSplitter. These implementations of WordSplitter now lives in a dedicated word_splitters module. Similarly, we have a new word_separators module for implementations of WordSeparator.

• #369: Rename Options::splitter to Options::word_splitter for consistency with the other fields backed by traits.

This is a major feature release which makes Textwrap more configurable and flexible. The high-level API of textwrap::wrap and textwrap::fill remains unchanged, but low-level structs have moved around.

The biggest change is the introduction of new generic type parameters to the Options struct. These parameters lets you statically configure the wrapping algorithm, the word separator, and the word splitter. If you previously spelled out the full type for Options, you now need to take the extra type parameters into account. This means that

let options: Options<HyphenSplitter> = Options::new(80);

changes to

let options: Options<
    wrap_algorithms::FirstFit,
    word_separators::AsciiSpace,
    word_splitters::HyphenSplitter,
> = Options::new(80);

This is quite a mouthful, so we suggest using type inference where possible. You won’t see any chance if you call wrap directly with a width or with an Options value constructed on the fly. Please open an issue if this causes problems for you!

New WordSeparator Trait

• #332: Add WordSeparator trait to allow customizing how words are found in a line of text. Until now, Textwrap would always assume that words are separated by ASCII space characters. You can now customize this as needed.

• #313: Add support for using the Unicode line breaking algorithm to find words. This is done by adding a second implementation of the new WordSeparator trait. The implementation uses the unicode-linebreak crate, which is a new optional dependency.

  With this, Textwrap can be used with East-Asian languages such as Chinese or Japanese where there are no spaces between words. Breaking a long sequence of emojis is another example where line breaks might be wanted even if there are no whitespace to be found. Feedback would be appreciated for this feature.

Indent

• #353: Trim trailing whitespace from prefix in indent.

  Before, empty lines would get no prefix added. Now, empty lines have a trimmed prefix added. This little trick makes indent much more useful since you can now safely indent with "# " without creating trailing whitespace in the output due to the trailing whitespace in your prefix.

• #354: Make indent about 20% faster by preallocating the output string.

Documentation

• #308: Document handling of leading and trailing whitespace when wrapping text.

WebAssembly Demo

• #310: Thanks to WebAssembly, you can now try out Textwrap directly in your browser. Please try it out: https://mgeisler.github.io/textwrap/.

New Generic Parameters

• #331: Remove outer boxing from Options.

• #357: Replace core::WrapAlgorithm enum with a wrap_algorithms::WrapAlgorithm trait. This allows for arbitrary wrapping algorithms to be plugged into the library.

• #358: Switch wrapping functions to use a slice for line_widths.

• #368: Move WordSeparator and WordSplitter traits to separate modules. Before, Textwrap had several top-level structs such as NoHyphenation and HyphenSplitter. These implementations of WordSplitter now lives in a dedicated word_splitters module. Similarly, we have a new word_separators module for implementations of WordSeparator.

• #369: Rename Options::splitter to Options::word_splitter for consistency with the other fields backed by traits.

Version 0.13.4 (2021-02-23)

This release removes println! statements which was left behind in
unfill by mistake.

• #296: Improve house
  building example with more comments.
• #297: Remove debug
  prints in the new unfill function.

This release removes println! statements which was left behind in unfill by mistake.

• #296: Improve house building example with more comments.
• #297: Remove debug prints in the new unfill function.

This release contains a bugfix for indent and improved handling of emojis. We’ve also added a new function for formatting text in columns and functions for reformatting already wrapped text.

• #276: Extend core::display_width to handle emojis when the unicode-width Cargo feature is disabled.
• #279: Make indent preserve existing newlines in the input string. Before, indent("foo", "") would return "foo\n" by mistake. It now returns "foo" instead.
• #281: Ensure all Options fields have examples.
• #282: Add a wrap_columns function.
• #294: Add new unfill and refill functions.

This release primarily makes all dependencies optional. This makes it possible to slim down textwrap as needed.

• #254: impl WordSplitter for Box<T> where T: WordSplitter.
• #255: Use command line arguments as initial text in interactive example.
• #256: Introduce fuzz tests for wrap_optimal_fit and wrap_first_fit.
• #260: Make the unicode-width dependency optional.
• #261: Make the smawk dependency optional.

This is a bugfix release which fixes a regression in 0.13.0. The bug meant that colored text was wrapped incorrectly.

• #245: Support deleting a word with Ctrl-Backspace in the interactive demo.
• #246: Show build type (debug/release) in interactive demo.
• #249: Correctly compute width while skipping over ANSI escape sequences.

This is a major release which rewrites the core logic, adds many new features, and fixes a couple of bugs. Most programs which use textwrap stays the same, incompatibilities and upgrade notes are given below.

Clone the repository and run the following to explore the new features in an interactive demo (Linux only):

$ cargo run --example interactive --all-features

Bug Fixes

Rewritten core wrapping algorithm

• #221: Reformulate wrapping in terms of words with whitespace and penalties.

The core wrapping algorithm has been completely rewritten. This fixed bugs and simplified the code, while also making it possible to use textwrap outside the context of the terminal.

As part of this, trailing whitespace is now discarded consistently from wrapped lines. Before we would inconsistently remove whitespace at the end of wrapped lines, except for the last. Leading whitespace is still preserved.

New Features

Optimal-fit wrapping

• #234: Introduce wrapping using an optimal-fit algorithm.

This release adds support for new wrapping algorithm which finds a globally optimal set of line breaks, taking certain penalties into account. As an example, the old algorithm would produce

"To be, or"
"not to be:"
"that is"
"the"
"question"

Notice how the fourth line with “the” is very short. The new algorithm shortens the previous lines slightly to produce fewer short lines:

"To be,"
"or not to"
"be: that"
"is the"
"question"

Use the new textwrap::core::WrapAlgorithm enum to select between the new and old algorithm. By default, the new algorithm is used.

The optimal-fit algorithm is inspired by the line breaking algorithm used in TeX, described in the 1981 article Breaking Paragraphs into Lines by Knuth and Plass.

In-place wrapping

• #226: Add a fill_inplace function.

When the text you want to fill is already a temporary String, you can now mutate it in-place with fill_inplace:

let mut greeting = format!("Greetings {}, welcome to the game! You have {} lives left.",
                           player.name, player.lives);
fill_inplace(&mut greeting, line_width);

This is faster than calling fill and it will reuse the memory already allocated for the string.

Changed Features

Wrapper is replaced with Options

• #213: Simplify API with only top-level functions.
• #215: Reintroducing the type parameter on Options (previously known as Wrapper).
• #219: Allow using trait objects with fill & wrap.
• #227: Replace WrapOptions with Into<Options>.

The Wrapper struct held the options (line width, indentation, etc) for wrapping text. It was also the entry point for actually wrapping the text via its methods such as wrap, wrap_iter, into_wrap_iter, and fill methods.

The struct has been replaced by a simpler Options struct which only holds options. The Wrapper methods are gone, their job has been taken over by the top-level wrap and fill functions. The signature of these functions have changed from

fn fill(s: &str, width: usize) -> String;

fn wrap(s: &str, width: usize) -> Vec<Cow<'_, str>>;

to the more general

fn fill<'a, S, Opt>(text: &str, options: Opt) -> String
where
    S: WordSplitter,
    Opt: Into<Options<'a, S>>;

fn wrap<'a, S, Opt>(text: &str, options: Opt) -> Vec<Cow<'_, str>>
where
    S: WordSplitter,
    Opt: Into<Options<'a, S>>;

The Into<Options<'a, S> bound allows you to pass an usize (which is interpreted as the line width) and a full Options object. This allows the new functions to work like the old, plus you can now fully customize the behavior of the wrapping via Options when needed.

Code that call textwrap::wrap or textwrap::fill can remain unchanged. Code that calls into Wrapper::wrap or Wrapper::fill will need to be update. This is a mechanical change, please see #213 for examples.

Thanks to @CryptJar and @Koxiat for their support in the PRs above!

Removed Features

• The wrap_iter and into_wrap_iter methods are gone. This means that lazy iteration is no longer supported: you always get all wrapped lines back as a Vec. This was done to simplify the code and to support the optimal-fit algorithm.

  The first-fit algorithm could still be implemented in an incremental fashion. Please let us know if this is important to you.

Other Changes

• #206: Change Wrapper.splitter from T: WordSplitter to Box<dyn WordSplitter>.
• #216: Forbid the use of unsafe code.

This is a bugfix release.

• Fixed [#176][issue-176]: Mention compile-time wrapping by linking to the [textwrap-macros crate].
• Fixed [#193][issue-193]: Wrapping with break_words(false) was broken and would cause extra whitespace to be inserted when words were longer than the line width.

The code has been updated to the [Rust 2018 edition][rust-2018] and each new release of textwrap will only support the latest stable version of Rust. Trying to support older Rust versions is a fool's errand: our dependencies keep releasing new patch versions that require newer and newer versions of Rust.

The term_size feature has been replaced by terminal_size. The API is unchanged, it is just the name of the Cargo feature that changed.

The hyphenation feature now only embeds the hyphenation patterns for US-English. This slims down the dependency.

• Fixed [#140][issue-140]: Ignore ANSI escape sequences.
• Fixed [#158][issue-158]: Unintended wrapping when using external splitter.
• Fixed [#177][issue-177]: Update examples to the 2018 edition.

Due to our dependencies bumping their minimum supported version of Rust, the minimum version of Rust we test against is now 1.22.0.

• Merged [#141][issue-141]: Fix dedent handling of empty lines and trailing newlines. Thanks @bbqsrc!
• Fixed [#151][issue-151]: Release of version with hyphenation 0.7.

Due to our dependencies bumping their minimum supported version of Rust, the minimum version of Rust we test against is now 1.17.0.

• Fixed [#99][issue-99]: Word broken even though it would fit on line.
• Fixed [#107][issue-107]: Automatic hyphenation is off by one.
• Fixed [#122][issue-122]: Take newlines into account when wrapping.
• Fixed [#129][issue-129]: Panic on string with em-dash.

The dependency on term_size is now optional, and by default this feature is not enabled. This is a breaking change for users of Wrapper::with_termwidth. Enable the term_size feature to restore the old functionality.

Added a regression test for the case where width is set to usize::MAX, thanks @Fraser999! All public structs now implement Debug, thanks @hcpl!

• Fixed [#101][issue-101]: Make term_size an optional dependency.

The Wrapper struct is now generic over the type of word splitter being used. This means less boxing and a nicer API. The Wrapper::word_splitter method has been removed. This is a breaking API change if you used the method to change the word splitter.

The Wrapper struct has two new methods that will wrap the input text lazily: Wrapper::wrap_iter and Wrapper::into_wrap_iter. Use those if you will be iterating over the wrapped lines one by one.

• Fixed [#59][issue-59]: wrap could return an iterator. Thanks @hcpl!
• Fixed [#81][issue-81]: Set html_root_url.

Version 0.7.0 changes the return type of Wrapper::wrap from Vec<String> to Vec<Cow<'a, str>>. This means that the output lines borrow data from the input string. This is a breaking API change if you relied on the exact return type of Wrapper::wrap. Callers of the textwrap::fill convenience function will see no breakage.

The above change and other optimizations makes version 0.7.0 roughly 15-30% faster than version 0.6.0.

The squeeze_whitespace option has been removed since it was complicating the above optimization. Let us know if this option is important for you so we can provide a work around.

• Fixed [#58][issue-58]: Add a "fast_wrap" function.
• Fixed [#61][issue-61]: Documentation errors.

Version 0.6.0 adds builder methods to Wrapper for easy one-line initialization and configuration:

let wrapper = Wrapper::new(60).break_words(false);

It also add a new NoHyphenation word splitter that will never split words, not even at existing hyphens.

• Fixed [#28][issue-28]: Support not squeezing whitespace.

Version 0.5.0 has breaking API changes. However, this only affects code using the hyphenation feature. The feature is now optional, so you will first need to enable the hyphenation feature as described above. Afterwards, please change your code from

wrapper.corpus = Some(&corpus);

to

wrapper.splitter = Box::new(corpus);

Other changes include optimizations, so version 0.5.0 is roughly 10-15% faster than version 0.4.0.

• Fixed [#19][issue-19]: Add support for finding terminal size.
• Fixed [#25][issue-25]: Handle words longer than self.width.
• Fixed [#26][issue-26]: Support custom indentation.
• Fixed [#36][issue-36]: Support building without hyphenation.
• Fixed [#39][issue-39]: Respect non-breaking spaces.

Documented complexities and tested these via cargo bench.

• Fixed [#13][issue-13]: Immediately add word if it fits.
• Fixed [#14][issue-14]: Avoid splitting on initial hyphens.

Added support for automatic hyphenation.

Introduced Wrapper struct. Added support for wrapping on hyphens.

First public release with support for wrapping strings on whitespace.