    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
    84
    85

    use std::fmt;

    use crate::{capitalize, lowercase, transform};

    /// This trait defines a lower camel case conversion.
    ///
    /// In lowerCamelCase, word boundaries are indicated by capital letters,
    /// excepting the first word.
    ///
    /// ## Example:
    ///
    /// ```rust
    /// use heck::ToLowerCamelCase;
    ///
    /// let sentence = "It is we who built these palaces and cities.";
    /// assert_eq!(sentence.to_lower_camel_case(), "itIsWeWhoBuiltThesePalacesAndCities");
    /// ```
    pub trait ToLowerCamelCase: ToOwned {
        /// Convert this type to lower camel case.
        fn to_lower_camel_case(&self) -> Self::Owned;
    }

    impl ToLowerCamelCase for str {
        fn to_lower_camel_case(&self) -> String {
            AsLowerCamelCase(self).to_string()
        }
    }

    /// This wrapper performs a lower camel case conversion in [`fmt::Display`].
    ///
    /// ## Example:
    ///
    /// ```
    /// use heck::AsLowerCamelCase;
    ///
    /// let sentence = "It is we who built these palaces and cities.";
    /// assert_eq!(format!("{}", AsLowerCamelCase(sentence)), "itIsWeWhoBuiltThesePalacesAndCities");
    /// ```
    pub struct AsLowerCamelCase<T: AsRef<str>>(pub T);

    impl<T: AsRef<str>> fmt::Display for AsLowerCamelCase<T> {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            let mut first = true;
            transform(
                self.0.as_ref(),
                |s, f| {
                    if first {
                        first = false;
                        lowercase(s, f)
                    } else {
                        capitalize(s, f)
                    }
                },
                |_| Ok(()),
                f,
            )
        }
    }

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

        macro_rules! t {
            ($t:ident : $s1:expr => $s2:expr) => {
                #[test]
                fn $t() {
                    assert_eq!($s1.to_lower_camel_case(), $s2)
                }
            };
        }

        t!(test1: "CamelCase" => "camelCase");
        t!(test2: "This is Human case." => "thisIsHumanCase");
        t!(test3: "MixedUP CamelCase, with some Spaces" => "mixedUpCamelCaseWithSomeSpaces");
        t!(test4: "mixed_up_ snake_case, with some _spaces" => "mixedUpSnakeCaseWithSomeSpaces");
        t!(test5: "kebab-case" => "kebabCase");
        t!(test6: "SHOUTY_SNAKE_CASE" => "shoutySnakeCase");
        t!(test7: "snake_case" => "snakeCase");
        t!(test8: "this-contains_ ALLKinds OfWord_Boundaries" => "thisContainsAllKindsOfWordBoundaries");
        #[cfg(feature = "unicode")]
        t!(test9: "XΣXΣ baﬄe" => "xσxςBaﬄe");
        t!(test10: "XMLHttpRequest" => "xmlHttpRequest");
        // TODO unicode tests
    }