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dtolnay
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Indented document literals for Rust

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Indented Documents (indoc)

github crates.io docs.rs build status

This crate provides a procedural macro for indented string literals. The

indoc!()
macro takes a multiline string literal and un-indents it at compile time so the leftmost non-space character is in the first column.
[dependencies]
indoc = "1.0"

Compiler requirement: rustc 1.45 or greater.


Using indoc

use indoc::indoc;

fn main() { let testing = indoc! {" def hello(): print('Hello, world!')

    hello()
"};
let expected = "def hello():\n    print('Hello, world!')\n\nhello()\n";
assert_eq!(testing, expected);

}

Indoc also works with raw string literals:

use indoc::indoc;

fn main() { let testing = indoc! {r#" def hello(): print("Hello, world!")

    hello()
"#};
let expected = "def hello():\n    print(\"Hello, world!\")\n\nhello()\n";
assert_eq!(testing, expected);

}

And byte string literals:

use indoc::indoc;

fn main() { let testing = indoc! {b" def hello(): print('Hello, world!')

    hello()
"};
let expected = b"def hello():\n    print('Hello, world!')\n\nhello()\n";
assert_eq!(testing[..], expected[..]);

}


Formatting macros

The indoc crate exports four additional macros to substitute conveniently for the standard library's formatting macros:

  • formatdoc!($fmt, ...)
     — equivalent to
    format!(indoc!($fmt), ...)
  • printdoc!($fmt, ...)
     — equivalent to
    print!(indoc!($fmt), ...)
  • eprintdoc!($fmt, ...)
     — equivalent to
    eprint!(indoc!($fmt), ...)
  • writedoc!($dest, $fmt, ...)
     — equivalent to
    write!($dest, indoc!($fmt), ...)
use indoc::printdoc;

fn main() { printdoc! {" GET {url} Accept: {mime} ", url = "http://localhost:8080", mime = "application/json", } }


Explanation

The following rules characterize the behavior of the

indoc!()
macro:
  1. Count the leading spaces of each line, ignoring the first line and any lines that are empty or contain spaces only.
  2. Take the minimum.
  3. If the first line is empty i.e. the string begins with a newline, remove the first line.
  4. Remove the computed number of spaces from the beginning of each line.


Unindent

Indoc's indentation logic is available in the

unindent
crate. This may be useful for processing strings that are not statically known at compile time.

The crate exposes two functions:

  • unindent(&str) -> String
  • unindent_bytes(&[u8]) -> Vec
use unindent::unindent;

fn main() { let indented = " line one line two"; assert_eq!("line one\nline two", unindent(indented)); }


License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

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