simple-update-in 0.2.0

Immutable nested update with structural sharing
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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250

//! Predicate paths: branching, partial updates, auto-creation under each match,
//! and no-op when nothing matches or the parent is missing.

mod common;

use common::*;
use simple_update_in::{Accessor, Selector, Value};

/// Pull the number out of a value, or `0.0` if it is not a number.
fn num(v: &Value) -> f64 {
    match v {
        Value::Number(x) => *x,
        _ => 0.0,
    }
}

#[test]
fn update_array_using_predicate() {
    // value even and index odd
    let from = arr(vec![n(1.0), n(2.0), n(3.0), n(4.0), n(5.0)]);
    let pred = Accessor::predicate(|v, sel| {
        let even_value = num(v) % 2.0 == 0.0;
        let odd_index = matches!(sel, Selector::Index(i) if i % 2 == 1);
        even_value && odd_index
    });
    let actual = run(from, &[pred], multiply(10.0));
    assert_eq!(actual, arr(vec![n(1.0), n(20.0), n(3.0), n(40.0), n(5.0)]),);
}

#[test]
fn update_map_using_predicate() {
    let from = obj(vec![
        ("abc", n(123.0)),
        ("def", n(456.0)),
        ("ghi", n(789.0)),
    ]);
    let pred = Accessor::predicate(|v, sel| {
        let odd = (num(v) as i64) % 2 != 0;
        let key_ok = matches!(sel, Selector::Key(k) if *k == "abc" || *k == "ghi");
        odd && key_ok
    });
    let actual = run(from, &[pred], multiply(10.0));
    assert_eq!(
        actual,
        obj(vec![
            ("abc", n(1230.0)),
            ("def", n(456.0)),
            ("ghi", n(7890.0)),
        ]),
    );
}

#[test]
fn update_using_multiple_predicates() {
    let from = obj(vec![
        ("one", arr(vec![n(1.1), n(1.2), n(1.3)])),
        ("two", arr(vec![n(2.1), n(2.2), n(2.3)])),
    ]);
    let always = Accessor::predicate(|_, _| true);
    let pick = Accessor::predicate(|v, _| num(v) == 1.2 || num(v) == 2.2);
    let actual = run(from, &[always, pick], multiply(10.0));
    assert_eq!(
        actual,
        obj(vec![
            ("one", arr(vec![n(1.1), n(12.0), n(1.3)])),
            ("two", arr(vec![n(2.1), n(22.0), n(2.3)])),
        ]),
    );
}

#[test]
fn predicate_removal_splices_left_to_right() {
    // The predicate resolves concrete paths [[0], [1]] against the original
    // array. Writes fold left to right. Removing index 0 shifts index 1 down,
    // so the second write targets index 1 on a one-element array and is a
    // no-op. The result is [20], not [].
    let from = arr(vec![n(10.0), n(20.0)]);
    let always = Accessor::predicate(|_, _| true);
    let actual = remove(from, &[always]);
    assert_eq!(actual, arr(vec![n(20.0)]));
}

#[test]
fn predicate_without_match_in_array_is_no_op() {
    let from = arr(vec![n(1.0), n(2.0), n(3.0), n(4.0), n(5.0)]);
    let pred = Accessor::predicate(|_, _| false);
    let actual = run(from.clone(), &[pred], constant(n(0.0)));
    assert!(from.ptr_eq(&actual));
}

#[test]
fn predicate_without_match_in_map_is_no_op() {
    let from = obj(vec![
        ("abc", n(123.0)),
        ("def", n(456.0)),
        ("ghi", n(789.0)),
    ]);
    let pred = Accessor::predicate(|_, _| false);
    let actual = run(from.clone(), &[pred], constant(n(0.0)));
    assert!(from.ptr_eq(&actual));
}

#[test]
fn array_auto_creation_using_predicate() {
    let from = arr(vec![arr(vec![n(1.1)]), arr(vec![n(2.2)])]);
    let always = Accessor::predicate(|_, _| true);
    let actual = run(from, &[always, idx(1)], constant(s("fin")));
    assert_eq!(
        actual,
        arr(vec![
            arr(vec![n(1.1), s("fin")]),
            arr(vec![n(2.2), s("fin")]),
        ]),
    );
}

#[test]
fn map_auto_creation_using_predicate() {
    let from = obj(vec![("abc", obj(vec![])), ("def", obj(vec![]))]);
    let always = Accessor::predicate(|_, _| true);
    let actual = run(from, &[always, key("value")], constant(n(123.0)));
    assert_eq!(
        actual,
        obj(vec![
            ("abc", obj(vec![("value", n(123.0))])),
            ("def", obj(vec![("value", n(123.0))])),
        ]),
    );
}

#[test]
fn array_partial_update_using_predicate_shares_others() {
    let from = arr(vec![obj(vec![]), obj(vec![]), obj(vec![])]);
    let pick = Accessor::predicate(|_, sel| matches!(sel, Selector::Index(0)));
    let actual = run(from.clone(), &[pick, key("value")], constant(n(123.0)));
    assert_eq!(
        actual,
        arr(vec![
            obj(vec![("value", n(123.0))]),
            obj(vec![]),
            obj(vec![]),
        ]),
    );
    assert!(from.as_array().unwrap()[1].ptr_eq(&actual.as_array().unwrap()[1]));
    assert!(from.as_array().unwrap()[2].ptr_eq(&actual.as_array().unwrap()[2]));
}

#[test]
fn map_partial_update_using_predicate_shares_others() {
    let from = obj(vec![
        ("abc", obj(vec![])),
        ("def", obj(vec![])),
        ("ghi", obj(vec![])),
    ]);
    let pick = Accessor::predicate(|_, sel| matches!(sel, Selector::Key(k) if *k == "abc"));
    let actual = run(from.clone(), &[pick, key("value")], constant(n(123.0)));
    assert_eq!(
        actual,
        obj(vec![
            ("abc", obj(vec![("value", n(123.0))])),
            ("def", obj(vec![])),
            ("ghi", obj(vec![])),
        ]),
    );
    let f = from.as_object().unwrap();
    let a = actual.as_object().unwrap();
    assert!(f.get("def").unwrap().ptr_eq(a.get("def").unwrap()));
    assert!(f.get("ghi").unwrap().ptr_eq(a.get("ghi").unwrap()));
}

#[test]
fn array_with_non_existing_index_then_predicate_is_no_op() {
    let from = arr(vec![]);
    let always = Accessor::predicate(|_, _| true);
    let actual = run(from.clone(), &[idx(0), always], constant(n(1.0)));
    assert!(from.ptr_eq(&actual));
}

#[test]
fn map_with_non_existing_key_then_predicate_is_no_op() {
    let from = obj(vec![]);
    let always = Accessor::predicate(|_, _| true);
    let actual = run(from.clone(), &[key("abc"), always], constant(n(1.0)));
    assert!(from.ptr_eq(&actual));
}

#[test]
fn literal_into_existing_container_then_non_matching_predicate_is_no_op() {
    // The literal key descends into a real array, then the predicate matches no
    // index. Resolution descends one real level and still yields no concrete
    // path, so the call returns the root by pointer. This differs from a
    // missing parent: here the container exists.
    let from = obj(vec![("a", arr(vec![n(1.0), n(2.0)]))]);
    let never = Accessor::predicate(|_, _| false);
    let actual = run(from.clone(), &[key("a"), never], constant(n(9.0)));
    assert!(from.ptr_eq(&actual));
    assert_eq!(actual, obj(vec![("a", arr(vec![n(1.0), n(2.0)]))]));
}

#[test]
fn predicate_reads_index_through_accessor() {
    // value even and index even, read through Selector::as_index.
    let from = arr(vec![n(1.0), n(2.0), n(3.0), n(4.0), n(6.0)]);
    let pred = Accessor::predicate(|v, sel| {
        let even_value = num(v) % 2.0 == 0.0;
        let even_index = sel.as_index().is_some_and(|i| i % 2 == 0);
        even_value && even_index
    });
    let actual = run(from, &[pred], multiply(10.0));
    assert_eq!(actual, arr(vec![n(1.0), n(2.0), n(3.0), n(4.0), n(60.0)]));
}

#[test]
fn predicate_reads_key_through_accessor() {
    // Match a map key by reading Selector::as_key, no enum match needed.
    let from = obj(vec![("keep", n(1.0)), ("hit", n(2.0))]);
    let pred = Accessor::predicate(|_, sel| sel.as_key() == Some("hit"));
    let actual = run(from, &[pred], multiply(10.0));
    assert_eq!(actual, obj(vec![("keep", n(1.0)), ("hit", n(20.0))]));
}

// README examples.

#[test]
fn readme_truthiness_predicate() {
    // odd values get multiplied
    let from = arr(vec![n(1.0), n(2.0), n(3.0), n(4.0), n(5.0)]);
    let pred = Accessor::predicate(|v, _| (num(v) as i64) % 2 != 0);
    let actual = run(from, &[pred], multiply(10.0));
    assert_eq!(actual, arr(vec![n(10.0), n(2.0), n(30.0), n(4.0), n(50.0)]),);
}

#[test]
fn readme_branch_then_key() {
    let from = arr(vec![
        obj(vec![("v", n(1.0))]),
        obj(vec![("v", n(2.0))]),
        obj(vec![("v", n(3.0))]),
    ]);
    let always = Accessor::predicate(|_, _| true);
    let actual = run(from, &[always, key("v")], multiply(10.0));
    assert_eq!(
        actual,
        arr(vec![
            obj(vec![("v", n(10.0))]),
            obj(vec![("v", n(20.0))]),
            obj(vec![("v", n(30.0))]),
        ]),
    );
}