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
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147

//! A module which exports a few traits for converting types to elements and attributes.

use element::{Element, ElementBuilder};

/// A struct which is used for emitting `Element`s and text nodes into an `Element` without
/// exposing more functionality than necessary.
pub struct ElementEmitter<'a>(&'a mut Element);

impl<'a> ElementEmitter<'a> {
    /// Creates a new `ElementEmitter`.
    pub fn new(root: &'a mut Element) -> ElementEmitter<'a> {
        ElementEmitter(root)
    }

    /// Appends an `Element` to the target.
    pub fn append_child(&mut self, element: Element) {
        self.0.append_child(element);
    }

    /// Appends a text node to the target.
    pub fn append_text_node(&mut self, text: String) {
        self.0.append_text_node(text);
    }
}

/// A trait for types which can be converted to one or multiple `Element`s.
pub trait IntoElements {
    /// Emits this as a sequence of text nodes and `Element`s.
    fn into_elements(self, emitter: &mut ElementEmitter);
}

impl<T: IntoElements> IntoElements for Vec<T> {
    fn into_elements(self, emitter: &mut ElementEmitter) {
        for elem in self {
            elem.into_elements(emitter);
        }
    }
}

impl<'a, T: IntoElements + Clone> IntoElements for &'a [T] {
    fn into_elements(self, emitter: &mut ElementEmitter) {
        self.to_vec().into_elements(emitter);
    }
}

impl<T: IntoElements> IntoElements for Option<T> {
    fn into_elements(self, emitter: &mut ElementEmitter) {
        if let Some(e) = self {
            e.into_elements(emitter);
        }
    }
}

impl IntoElements for Element {
    fn into_elements(self, emitter: &mut ElementEmitter) {
        emitter.append_child(self);
    }
}

impl IntoElements for ElementBuilder {
    fn into_elements(self, emitter: &mut ElementEmitter) {
        emitter.append_child(self.build());
    }
}

impl IntoElements for String {
    fn into_elements(self, emitter: &mut ElementEmitter) {
        emitter.append_text_node(self);
    }
}

impl<'a> IntoElements for &'a String {
    fn into_elements(self, emitter: &mut ElementEmitter) {
        emitter.append_text_node(self.to_owned());
    }
}

impl<'a> IntoElements for &'a str {
    fn into_elements(self, emitter: &mut ElementEmitter) {
        emitter.append_text_node(self.to_owned());
    }
}

/// A trait for types which can be converted to an attribute value.
pub trait IntoAttributeValue {
    /// Turns this into an attribute string, or None if it shouldn't be added.
    fn into_attribute_value(self) -> Option<String>;
}

macro_rules! impl_into_attribute_value {
    ($t:ty) => {
        impl IntoAttributeValue for $t {
            fn into_attribute_value(self) -> Option<String> {
                Some(format!("{}", self))
            }
        }
    }
}

macro_rules! impl_into_attribute_values {
    ($($t:ty),*) => {
        $(impl_into_attribute_value!($t);)*
    }
}

impl_into_attribute_values!(usize, u64, u32, u16, u8, isize, i64, i32, i16, i8);

impl IntoAttributeValue for String {
    fn into_attribute_value(self) -> Option<String> {
        Some(self)
    }
}

impl<'a> IntoAttributeValue for &'a String {
    fn into_attribute_value(self) -> Option<String> {
        Some(self.to_owned())
    }
}

impl<'a> IntoAttributeValue for &'a str {
    fn into_attribute_value(self) -> Option<String> {
        Some(self.to_owned())
    }
}

impl<T: IntoAttributeValue> IntoAttributeValue for Option<T> {
    fn into_attribute_value(self) -> Option<String> {
        self.and_then(|t| t.into_attribute_value())
    }
}

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

    #[test]
    fn test_into_attribute_value_on_ints() {
        assert_eq!(16u8.into_attribute_value().unwrap()    , "16");
        assert_eq!(17u16.into_attribute_value().unwrap()   , "17");
        assert_eq!(18u32.into_attribute_value().unwrap()   , "18");
        assert_eq!(19u64.into_attribute_value().unwrap()   , "19");
        assert_eq!(   16i8.into_attribute_value().unwrap() , "16");
        assert_eq!((-17i16).into_attribute_value().unwrap(), "-17");
        assert_eq!(   18i32.into_attribute_value().unwrap(), "18");
        assert_eq!((-19i64).into_attribute_value().unwrap(), "-19");
    }
}