1 //! Enables base64'd output anywhere you might use a `Display` implementation, like a format string. 2 //! 3 //! ``` 4 //! use base64::display::Base64Display; 5 //! 6 //! let data = vec![0x0, 0x1, 0x2, 0x3]; 7 //! let wrapper = Base64Display::with_config(&data, base64::STANDARD); 8 //! 9 //! assert_eq!("base64: AAECAw==", format!("base64: {}", wrapper)); 10 //! ``` 11 12 use super::chunked_encoder::ChunkedEncoder; 13 use super::Config; 14 use core::fmt::{Display, Formatter}; 15 use core::{fmt, str}; 16 17 /// A convenience wrapper for base64'ing bytes into a format string without heap allocation. 18 pub struct Base64Display<'a> { 19 bytes: &'a [u8], 20 chunked_encoder: ChunkedEncoder, 21 } 22 23 impl<'a> Base64Display<'a> { 24 /// Create a `Base64Display` with the provided config. with_config(bytes: &[u8], config: Config) -> Base64Display25 pub fn with_config(bytes: &[u8], config: Config) -> Base64Display { 26 Base64Display { 27 bytes, 28 chunked_encoder: ChunkedEncoder::new(config), 29 } 30 } 31 } 32 33 impl<'a> Display for Base64Display<'a> { fmt(&self, formatter: &mut Formatter) -> Result<(), fmt::Error>34 fn fmt(&self, formatter: &mut Formatter) -> Result<(), fmt::Error> { 35 let mut sink = FormatterSink { f: formatter }; 36 self.chunked_encoder.encode(self.bytes, &mut sink) 37 } 38 } 39 40 struct FormatterSink<'a, 'b: 'a> { 41 f: &'a mut Formatter<'b>, 42 } 43 44 impl<'a, 'b: 'a> super::chunked_encoder::Sink for FormatterSink<'a, 'b> { 45 type Error = fmt::Error; 46 write_encoded_bytes(&mut self, encoded: &[u8]) -> Result<(), Self::Error>47 fn write_encoded_bytes(&mut self, encoded: &[u8]) -> Result<(), Self::Error> { 48 // Avoid unsafe. If max performance is needed, write your own display wrapper that uses 49 // unsafe here to gain about 10-15%. 50 self.f 51 .write_str(str::from_utf8(encoded).expect("base64 data was not utf8")) 52 } 53 } 54 55 #[cfg(test)] 56 mod tests { 57 use super::super::chunked_encoder::tests::{ 58 chunked_encode_matches_normal_encode_random, SinkTestHelper, 59 }; 60 use super::super::*; 61 use super::*; 62 63 #[test] basic_display()64 fn basic_display() { 65 assert_eq!( 66 "~$Zm9vYmFy#*", 67 format!("~${}#*", Base64Display::with_config(b"foobar", STANDARD)) 68 ); 69 assert_eq!( 70 "~$Zm9vYmFyZg==#*", 71 format!("~${}#*", Base64Display::with_config(b"foobarf", STANDARD)) 72 ); 73 } 74 75 #[test] display_encode_matches_normal_encode()76 fn display_encode_matches_normal_encode() { 77 let helper = DisplaySinkTestHelper; 78 chunked_encode_matches_normal_encode_random(&helper); 79 } 80 81 struct DisplaySinkTestHelper; 82 83 impl SinkTestHelper for DisplaySinkTestHelper { encode_to_string(&self, config: Config, bytes: &[u8]) -> String84 fn encode_to_string(&self, config: Config, bytes: &[u8]) -> String { 85 format!("{}", Base64Display::with_config(bytes, config)) 86 } 87 } 88 } 89