     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74
    75
    76
    77
    78
    79
    80
    81
    82
    83

    /// A set of ranges that corresponds to the set of all ideograph codepoints.
    ///
    /// These ranges are defined in Unicode 4.8 Table 4-13.
    pub const RANGE_IDEOGRAPH: &'static [(u32, u32)] = &[
        (0x3400, 0x4DB5),
        (0x4E00, 0x9FD5),
        (0x4E00, 0x9FD5),
        (0x20000, 0x2A6D6),
        (0x2A700, 0x2B734),
        (0x2B740, 0x2B81D),
        (0x2B820, 0x2CEA1),
        (0x17000, 0x187EC),
        (0xF900, 0xFA6D),
        (0xFA70, 0xFAD9),
        (0x2F800, 0x2FA1D),
    ];

    /// Return the character name of the given ideograph codepoint.
    ///
    /// This operation is only defined on ideographic codepoints. This includes
    /// precisely the following inclusive ranges:
    ///
    /// * `3400..4DB5`
    /// * `4E00..9FD5`
    /// * `20000..2A6D6`
    /// * `2A700..2B734`
    /// * `2B740..2B81D`
    /// * `2B820..2CEA1`
    /// * `17000..187EC`
    /// * `F900..FA6D`
    /// * `FA70..FAD9`
    /// * `2F800..2FA1D`
    ///
    /// If the given codepoint is not in any of the above ranges, then `None` is
    /// returned.
    ///
    /// This implements the algorithm described in Unicode 4.8.
    pub fn ideograph_name(cp: u32) -> Option<String> {
        // This match should be in sync with the `RANGE_IDEOGRAPH` constant.
        match cp {
            0x3400...0x4DB5
            | 0x4E00...0x9FD5
            | 0x20000...0x2A6D6
            | 0x2A700...0x2B734
            | 0x2B740...0x2B81D
            | 0x2B820...0x2CEA1 => {
                Some(format!("CJK UNIFIED IDEOGRAPH-{:04X}", cp))
            }
            0x17000...0x187EC => {
                Some(format!("TANGUT IDEOGRAPH-{:04X}", cp))
            }
            0xF900...0xFA6D | 0xFA70...0xFAD9 | 0x2F800...0x2FA1D => {
                Some(format!("CJK COMPATIBILITY IDEOGRAPH-{:04X}", cp))
            }
            _ => None,
        }
    }

    #[cfg(test)]
    mod tests {
        use super::ideograph_name;

        #[test]
        fn name() {
            assert_eq!(
                ideograph_name(0x4E00).unwrap(),
                "CJK UNIFIED IDEOGRAPH-4E00");
            assert_eq!(
                ideograph_name(0x9FD5).unwrap(),
                "CJK UNIFIED IDEOGRAPH-9FD5");
            assert_eq!(
                ideograph_name(0x17000).unwrap(),
                "TANGUT IDEOGRAPH-17000");
            assert_eq!(
                ideograph_name(0xF900).unwrap(),
                "CJK COMPATIBILITY IDEOGRAPH-F900");
        }

        #[test]
        fn invalid() {
            assert!(ideograph_name(0).is_none());
        }
    }

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)