rsass 0.29.2

Sass implementation in pure rust (not complete yet)
Documentation 
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

use super::super::FunctionMap;
use super::hsl::percentage;
use super::{
    check_alpha, check_expl_pct_norange, eval_inner, is_not, relative_color,
    CallError, CheckedArg, ResolvedArgs,
};
use crate::css::{CallArgs, Value};
use crate::output::Format;
use crate::sass::FormalArgs;
use crate::value::{Color, Hwba, ListSeparator, Numeric, Rgba, Unit};
use crate::Scope;

pub fn register(f: &mut Scope) {
    def_va!(f, hwb(kwargs), hwb);
    def!(f, blackness(color), |s| {
        let color: Color = s.get(name!(color))?;
        let hwb = color.to_hwba();
        Ok(percentage(hwb.blackness()))
    });
    def!(f, whiteness(color), |s| {
        let color: Color = s.get(name!(color))?;
        let hwb = color.to_hwba();
        Ok(percentage(hwb.whiteness()))
    });
}

pub fn expose(m: &Scope, global: &mut FunctionMap) {
    global.insert(name!(hwb), m.get_lfunction(&name!(hwb)));
}

fn hwb(s: &ResolvedArgs) -> Result<Value, CallError> {
    let args = s.get_map(name!(kwargs), CallArgs::from_value)?;
    if relative_color(&args) {
        return Ok(Value::Call("hwb".to_string(), args));
    }
    let (hue, w, b, a) = if args.len() < 3 {
        let a1 = FormalArgs::new(vec![one_arg!(channels)]);
        eval_inner(&name!(hwb), &a1, s, args)
            .and_then(|s| hwb_from_channels(s.get(name!(channels))?))?
    } else {
        let a2 = FormalArgs::new(vec![
            one_arg!(hue),
            one_arg!(whiteness),
            one_arg!(blackness),
            one_arg!(alpha = b"1"),
        ]);
        eval_inner(&name!(hwb), &a2, s, args).and_then(|s| {
            Ok((
                s.get(name!(hue))?,
                s.get(name!(whiteness))?,
                s.get(name!(blackness))?,
                s.get(name!(alpha))?,
            ))
        })?
    };
    let hue = check_hue(hue).named(name!(hue))?;
    let w = check_expl_pct_norange(w).named(name!(whiteness))?;
    let b = check_expl_pct_norange(b).named(name!(blackness))?;
    let a = check_alpha(a).named(name!(alpha))?;
    // I don't really agree with this, but it makes tests pass.
    let hue = if w + b >= 1. { 0. } else { hue };
    let hwba = Hwba::new(hue, w, b, a);
    let rgba = Rgba::from(&hwba);
    if rgba.is_integer() && w >= 0. {
        Ok(rgba.into())
    } else {
        Ok(hwba.into())
    }
}

fn hwb_from_channels(
    v: Value,
) -> Result<(Value, Value, Value, Value), CallError> {
    match v {
        Value::List(_, _, true) => {
            Err(CallError::msg("$channels must be an unbracketed list."))
        }
        Value::List(_, Some(ListSeparator::Comma), _) => {
            Err(CallError::msg("$channels must be a space-separated list."))
        }
        Value::List(vec, s, p) => {
            use crate::value::Operator::Div;
            match vec.len() {
                0 => Err(CallError::msg("Missing element $hue.")),
                1 => Err(CallError::msg("Missing element $whiteness.")),
                2 => Err(CallError::msg("Missing element $blackness.")),
                3 => {
                    if let Value::BinOp(op) = &vec[2] {
                        if let (
                            Div,
                            a @ Value::Numeric(..),
                            b @ Value::Numeric(..),
                        ) = (op.op(), op.a(), op.b())
                        {
                            Ok((
                                vec[0].clone(),
                                vec[1].clone(),
                                a.clone(),
                                b.clone(),
                            ))
                        } else {
                            Err(badchannels(&Value::List(vec, s, p)))
                        }
                    } else {
                        Ok((
                            vec[0].clone(),
                            vec[1].clone(),
                            vec[2].clone(),
                            Value::Null,
                        ))
                    }
                }
                n => Err(CallError::msg(format!(
                    "Only 3 elements allowed, but {n} were passed.",
                ))),
            }
        }
        _hue => Err(CallError::msg("Missing element $whiteness.")),
    }
}

fn badchannels(v: &Value) -> CallError {
    CallError::msg(format!(
        "Expected numeric channels, got \"hwb({})\".",
        v.format(Format::introspect()),
    ))
}

fn check_hue(v: Value) -> Result<f64, String> {
    let vv = Numeric::try_from(v)?;
    if let Some(scaled) = vv.as_unit_def(Unit::Deg) {
        Ok(scaled.into())
    } else {
        Err(is_not(&vv, "an angle"))
    }
}