src/vendor/serde/src/utils.rs

   1 //! Private utility functions
   2
   3 const TAG_CONT: u8 = 0b1000_0000;
   4 const TAG_TWO_B: u8 = 0b1100_0000;
   5 const TAG_THREE_B: u8 = 0b1110_0000;
   6 const TAG_FOUR_B: u8 = 0b1111_0000;
   7 const MAX_ONE_B: u32 = 0x80;
   8 const MAX_TWO_B: u32 = 0x800;
   9 const MAX_THREE_B: u32 = 0x10000;
  10
  11 #[inline]
  12 pub fn encode_utf8(c: char) -> EncodeUtf8 {
  13     let code = c as u32;
  14     let mut buf = [0; 4];
  15     let pos = if code < MAX_ONE_B {
  16         buf[3] = code as u8;
  17         3
  18     } else if code < MAX_TWO_B {
  19         buf[2] = (code >> 6 & 0x1F) as u8 | TAG_TWO_B;
  20         buf[3] = (code & 0x3F) as u8 | TAG_CONT;
  21         2
  22     } else if code < MAX_THREE_B {
  23         buf[1] = (code >> 12 & 0x0F) as u8 | TAG_THREE_B;
  24         buf[2] = (code >> 6 & 0x3F) as u8 | TAG_CONT;
  25         buf[3] = (code & 0x3F) as u8 | TAG_CONT;
  26         1
  27     } else {
  28         buf[0] = (code >> 18 & 0x07) as u8 | TAG_FOUR_B;
  29         buf[1] = (code >> 12 & 0x3F) as u8 | TAG_CONT;
  30         buf[2] = (code >> 6 & 0x3F) as u8 | TAG_CONT;
  31         buf[3] = (code & 0x3F) as u8 | TAG_CONT;
  32         0
  33     };
  34     EncodeUtf8 {
  35         buf: buf,
  36         pos: pos,
  37     }
  38 }
  39
  40 pub struct EncodeUtf8 {
  41     buf: [u8; 4],
  42     pos: usize,
  43 }
  44
  45 impl EncodeUtf8 {
  46     // FIXME: use this from_utf8_unchecked, since we know it can never fail
  47     pub fn as_str(&self) -> &str {
  48         ::core::str::from_utf8(&self.buf[self.pos..]).unwrap()
  49     }
  50 }
  51
  52 #[allow(non_upper_case_globals)]
  53 const Pattern_White_Space_table: &'static [(char, char)] = &[('\u{9}', '\u{d}'),
  54                                                              ('\u{20}', '\u{20}'),
  55                                                              ('\u{85}', '\u{85}'),
  56                                                              ('\u{200e}', '\u{200f}'),
  57                                                              ('\u{2028}', '\u{2029}')];
  58
  59 fn bsearch_range_table(c: char, r: &'static [(char, char)]) -> bool {
  60     use core::cmp::Ordering::{Equal, Less, Greater};
  61     r.binary_search_by(|&(lo, hi)| if c < lo {
  62             Greater
  63         } else if hi < c {
  64             Less
  65         } else {
  66             Equal
  67         })
  68         .is_ok()
  69 }
  70
  71 #[allow(non_snake_case)]
  72 pub fn Pattern_White_Space(c: char) -> bool {
  73     bsearch_range_table(c, Pattern_White_Space_table)
  74 }