nixfmt_rs 0.1.2

Rust implementation of nixfmt with exact Haskell compatibility
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

use crate::predoc::{
    Doc, DocE, GroupAnn, Pretty, hardline, hardspace, line, push_group, push_group_ann,
    push_nested, push_surrounded,
};
use crate::types::{Binder, Expression, Items, Leaf, Parameter, Trivia, Trivium};

use super::term::push_pretty_items;

use super::absorb::{is_absorbable_expr, push_absorb_expr};
use super::util::{Width, move_trailing_comment_up};

pub(super) fn push_absorb_abs(doc: &mut Doc, depth: usize, expr: &Expression) {
    match expr {
        Expression::Abstraction(Parameter::ID(param), colon, body) => {
            doc.push(hardspace());
            param.pretty(doc);
            colon.pretty(doc);
            push_absorb_abs(doc, depth + 1, body);
        }
        _ if is_absorbable_expr(expr) => {
            doc.push(hardspace());
            push_group_ann(doc, GroupAnn::Priority, |priority_group| {
                push_absorb_expr(priority_group, Width::Regular, expr);
            });
        }
        _ => {
            let separator = if depth <= 2 { line() } else { hardline() };
            doc.push(separator);
            expr.pretty(doc);
        }
    }
}

/// Prepend an expression as the function head of a (possibly nested) application.
/// Mirrors Haskell `insertIntoApp` used by the `Assert` pretty instance.
pub(super) fn insert_into_app(insert: Expression, expr: Expression) -> (Expression, Expression) {
    match expr {
        Expression::Application(f, a) => {
            let (f2, a2) = insert_into_app(insert, *f);
            (Expression::Application(Box::new(f2), Box::new(a2)), *a)
        }
        other => (insert, other),
    }
}

/// Render a `with` expression.
/// Mirrors Haskell `prettyWith False` (Pretty.hs); the `prettyWith True`
/// path is open-coded inside `push_absorb_expr`.
/// `instance Pretty Expression` clause for `Let` (Pretty.hs).
pub(super) fn pretty_let(
    doc: &mut Doc,
    let_kw: &Leaf,
    binders: &Items<Binder>,
    in_kw: &Leaf,
    expr: &Expression,
) {
    // Strip trivia/trailing from `in` and move it down to the body.
    let mut in_kw_clean = in_kw.clone();
    in_kw_clean.pre_trivia = Trivia::new();
    in_kw_clean.trail_comment = None;

    // convertTrailing
    let mut moved_trivia_vec: Vec<Trivium> = in_kw.pre_trivia.clone().into();
    if let Some(trailing) = &in_kw.trail_comment {
        moved_trivia_vec.push(trailing.into());
    }
    let moved_trivia: Trivia = moved_trivia_vec.into();

    // letPart = group $ pretty let_ <> hardline <> nest (renderItems hardline binders)
    push_group(doc, |g| {
        let_kw.pretty(g);
        g.push(hardline());
        push_nested(g, |n| push_pretty_items(n, binders));
    });
    doc.push(hardline());
    // inPart = group $ pretty in_ <> hardline <> trivia <> pretty expr
    push_group(doc, |g| {
        in_kw_clean.pretty(g);
        g.push(hardline());
        moved_trivia.pretty(g);
        expr.pretty(g);
    });
}

pub(super) fn pretty_with(
    doc: &mut Doc,
    with: &Leaf,
    expr0: &Expression,
    semicolon: &Leaf,
    expr1: &Expression,
) {
    push_group(doc, |g| {
        with.pretty(g);
        g.push(hardspace());
        push_nested(g, |n| {
            push_group(n, |inner| expr0.pretty(inner));
        });
        semicolon.pretty(g);
    });
    doc.push(line());
    expr1.pretty(doc);
}

/// Recursive renderer for `if`/`else if` chains.
/// Mirrors Haskell `prettyIf` (Pretty.hs, inside the `If` clause).
pub(super) fn pretty_if(doc: &mut Doc, sep: DocE, expr: &Expression) {
    match expr {
        Expression::If(if_kw, cond, then_kw, expr0, else_kw, expr1) => {
            push_group(doc, |g| {
                if_kw.pretty(g);
                g.push(line());
                push_nested(g, |n| cond.pretty(n));
                g.push(line());
                then_kw.pretty(g);
            });
            push_surrounded(doc, &vec![sep], |d| {
                push_nested(d, |n| {
                    push_group(n, |g| expr0.pretty(g));
                });
            });
            move_trailing_comment_up(else_kw).pretty(doc);
            doc.push(hardspace());
            pretty_if(doc, hardline(), expr1);
        }
        x => {
            doc.push(line());
            push_nested(doc, |n| {
                push_group(n, |g| x.pretty(g));
            });
        }
    }
}