Character Sets

Percent-encode a string

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Encode an input string with percent-encoding using the utf8_percent_encode function from the percent-encoding crate. Then decode using the percent_decode function.

use percent_encoding::{utf8_percent_encode, percent_decode, AsciiSet, CONTROLS}; use std::str::Utf8Error; /// https://url.spec.whatwg.org/#fragment-percent-encode-set const FRAGMENT: &AsciiSet = &CONTROLS.add(b' ').add(b'"').add(b'<').add(b'>').add(b'`'); fn main() -> Result<(), Utf8Error> { let input = "confident, productive systems programming"; let iter = utf8_percent_encode(input, FRAGMENT); let encoded: String = iter.collect(); assert_eq!(encoded, "confident,%20productive%20systems%20programming"); let iter = percent_decode(encoded.as_bytes()); let decoded = iter.decode_utf8()?; assert_eq!(decoded, "confident, productive systems programming"); Ok(()) }

The encode set defines which bytes (in addition to non-ASCII and controls) need to be percent-encoded. The choice of this set depends on context. For example, url encodes ? in a URL path but not in a query string.

The return value of encoding is an iterator of &str slices which collect into a String.

Encode a string as application/x-www-form-urlencoded

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Encodes a string into application/x-www-form-urlencoded syntax using the form_urlencoded::byte_serialize and subsequently decodes it with form_urlencoded::parse. Both functions return iterators that collect into a String.

use url::form_urlencoded::{byte_serialize, parse}; fn main() { let urlencoded: String = byte_serialize("What is ❤?".as_bytes()).collect(); assert_eq!(urlencoded, "What+is+%E2%9D%A4%3F"); println!("urlencoded:'{}'", urlencoded); let decoded: String = parse(urlencoded.as_bytes()) .map(|(key, val)| [key, val].concat()) .collect(); assert_eq!(decoded, "What is ❤?"); println!("decoded:'{}'", decoded); }

Encode and decode hex

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The data_encoding crate provides a HEXUPPER::encode method which takes a &[u8] and returns a String containing the hexadecimal representation of the data.

Similarly, a HEXUPPER::decode method is provided which takes a &[u8] and returns a Vec<u8> if the input data is successfully decoded.

The example below converts &[u8] data to hexadecimal equivalent. Compares this value to the expected value.

use data_encoding::{HEXUPPER, DecodeError}; fn main() -> Result<(), DecodeError> { let original = b"The quick brown fox jumps over the lazy dog."; let expected = "54686520717569636B2062726F776E20666F78206A756D7073206F76\ 657220746865206C617A7920646F672E"; let encoded = HEXUPPER.encode(original); assert_eq!(encoded, expected); let decoded = HEXUPPER.decode(&encoded.into_bytes())?; assert_eq!(&decoded[..], &original[..]); Ok(()) }

Encode and decode base64

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Encodes byte slice into base64 String using encode and decodes it with decode.

use error_chain::error_chain; use std::str; use base64::{encode, decode}; error_chain! { foreign_links { Base64(base64::DecodeError); Utf8Error(str::Utf8Error); } } fn main() -> Result<()> { let hello = b"hello rustaceans"; let encoded = encode(hello); let decoded = decode(&encoded)?; println!("origin: {}", str::from_utf8(hello)?); println!("base64 encoded: {}", encoded); println!("back to origin: {}", str::from_utf8(&decoded)?); Ok(()) }