web-api-cat 0.7.4

Bindings between boa-cat (JS engine) and the DOM (html-cat tree) plus fetch (net-cat). v0.7.4 ships the `EventTarget` mixin: `addEventListener(type, callback)` queues handlers under a lazy `__listeners__` slot; `removeEventListener` drops them by `Value::PartialEq`; `dispatchEvent(event)` walks the bubble chain via the v0.6.8 `__parent__` backref and invokes each handler through boa-cat 0.7.1's now-public `expression::call_function`. Listener throws are swallowed at the dispatch boundary per DOM spec. Seventh sub-crate of a Servo-replacement webview runtime targeting Tauri.
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
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318

//! `localStorage` / `sessionStorage` bridge between the host's
//! storage projection and JS.
//!
//! v0.7.0 ships both storages as `Storage`-shaped Objects exposing
//! `getItem(key)`, `setItem(key, value)`, `removeItem(key)`,
//! `clear()`, `key(index)`, and a read-only `length` accessor.
//! Each Storage Object owns a hidden `__items__` Object holding
//! the actual key->value pairs (always coerced to string per
//! spec).
//!
//! The host wires the JS-visible projection in two steps, mirror
//! of how `document.cookie` works:
//!
//!   1. Pre-eval: [`seed_storage`] seeds `__items__` from the
//!      host's persisted state.
//!   2. Post-eval: [`read_storage_items`] reads the final
//!      key/value pairs so the host can persist any
//!      `setItem` / `removeItem` / `clear` changes.
//!
//! Iteration order is `BTreeMap`-sorted-by-key.  The Storage spec
//! leaves `key(index)` order implementation-defined, so this is
//! conformant; the deterministic sort also makes the projection
//! easier to test.
//!
//! # Examples
//!
//! ```
//! # fn main() -> Result<(), web_api_cat::Error> {
//! use boa_cat::{env::Env, heap::Heap};
//! use web_api_cat::{install, storage};
//!
//! let html = html_cat::parse("<html><body></body></html>")?;
//! let (_env, heap) = install(Env::empty(), Heap::new(), &html);
//! # let _ = heap;
//! # Ok(())
//! # }
//! ```
//!
//! Hosts pre-seed and post-read via the storage Value returned
//! from [`build_storage_object`] (a per-Storage instance).

use std::collections::BTreeMap;

use boa_cat::Value;
use boa_cat::env::{Binding, Env};
use boa_cat::fuel::Fuel;
use boa_cat::heap::Heap;
use boa_cat::outcome::{EvalResult, Outcome};
use boa_cat::value::{AccessorPair, Object, ObjectId};

/// Hidden property key under which the Storage Object's items map
/// lives.  Exposed (for crate-internal use) because the install
/// module wires the seeding through it.
pub const ITEMS_KEY: &str = "__items__";

/// Look up `localStorage` in `env` and return its Value (the
/// Storage-shaped Object [`crate::install::install`] bound).
/// Hosts call this to get the handle they need for
/// [`seed_storage`] and [`read_storage_items`].  Returns `None`
/// if the binding is missing or the cell has been clobbered.
#[must_use]
pub fn lookup_local_storage(env: &Env, heap: &Heap) -> Option<Value> {
    lookup_storage(env, heap, "localStorage")
}

/// Mirror of [`lookup_local_storage`] for `sessionStorage`.
#[must_use]
pub fn lookup_session_storage(env: &Env, heap: &Heap) -> Option<Value> {
    lookup_storage(env, heap, "sessionStorage")
}

fn lookup_storage(env: &Env, heap: &Heap, name: &str) -> Option<Value> {
    env.lookup(name).and_then(|binding| match binding {
        Binding::Cell(cell_id) => heap.cell(*cell_id).map(|cell| cell.value().clone()),
        Binding::Direct(value) => Some(value.clone()),
    })
}

/// Build a Storage-shaped Object on `heap`.  Used twice by
/// [`crate::install::install`] (once for `localStorage`, once for
/// `sessionStorage`).  The returned Value can be passed back to
/// [`seed_storage`] / [`read_storage_items`] by the host.
#[must_use]
pub fn build_storage_object(heap: Heap) -> (Value, Heap) {
    let (items_id, heap) = heap.alloc_object(Object::from_properties(BTreeMap::new()));
    let mut props = BTreeMap::new();
    let _ = props.insert(ITEMS_KEY.to_owned(), Value::Object(items_id));
    let _ = props.insert("getItem".to_owned(), Value::Native(get_item_impl));
    let _ = props.insert("setItem".to_owned(), Value::Native(set_item_impl));
    let _ = props.insert("removeItem".to_owned(), Value::Native(remove_item_impl));
    let _ = props.insert("clear".to_owned(), Value::Native(clear_impl));
    let _ = props.insert("key".to_owned(), Value::Native(key_impl));
    let (id, heap) = heap.alloc_object(Object::from_properties(props));
    let storage_value = Value::Object(id);
    let heap = install_length_accessor(&storage_value, heap);
    (storage_value, heap)
}

/// Seed the Storage Object's `__items__` Object with `entries`,
/// overwriting any previous state.  Hosts call this once per
/// evaluation, before the script runs, with whatever the user has
/// persisted to disk (or whatever the per-session jar is for
/// `sessionStorage`).
#[must_use]
pub fn seed_storage(storage_value: &Value, heap: Heap, entries: &[(String, String)]) -> Heap {
    let Some(items_id) = items_id_of(storage_value, &heap) else {
        return heap;
    };
    let new_items = entries
        .iter()
        .map(|(k, v)| (k.clone(), Value::String(v.clone())))
        .collect();
    heap.store_object(items_id, Object::from_properties(new_items))
        .unwrap_or_else(|h| h)
}

/// Read every `(key, value)` pair in `storage_value`'s `__items__`
/// Object, in `BTreeMap`-sorted-by-key order.  Hosts call this
/// post-eval to pick up `setItem` / `removeItem` / `clear` changes.
#[must_use]
pub fn read_storage_items(storage_value: &Value, heap: &Heap) -> Vec<(String, String)> {
    let Some(items_id) = items_id_of(storage_value, heap) else {
        return Vec::new();
    };
    let Some(items) = heap.object(items_id) else {
        return Vec::new();
    };
    items
        .properties()
        .iter()
        .filter_map(|(k, v)| match v {
            Value::String(s) => Some((k.clone(), s.clone())),
            Value::Undefined
            | Value::Null
            | Value::Boolean(_)
            | Value::Number(_)
            | Value::Object(_)
            | Value::Function(_)
            | Value::Native(_)
            | Value::Promise(_) => None,
        })
        .collect()
}

fn install_length_accessor(storage_value: &Value, heap: Heap) -> Heap {
    let Some(storage_id) = object_id_of(storage_value) else {
        return heap;
    };
    let Some(storage) = heap.object(storage_id).cloned() else {
        return heap;
    };
    let pair = AccessorPair::new(Some(Value::Native(length_getter_impl)), None);
    let updated = storage.with_accessor("length".to_owned(), pair);
    heap.store_object(storage_id, updated).unwrap_or_else(|h| h)
}

#[allow(clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
fn length_getter_impl(_args: Vec<Value>, this: Value, heap: Heap, fuel: Fuel) -> EvalResult {
    let count = items_id_of(&this, &heap)
        .and_then(|id| heap.object(id))
        .map_or(0, |items| items.properties().len());
    let count_u32 = u32::try_from(count).unwrap_or(u32::MAX);
    Ok((
        Outcome::Normal(Value::Number(f64::from(count_u32))),
        heap,
        fuel,
    ))
}

#[allow(clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
fn get_item_impl(args: Vec<Value>, this: Value, heap: Heap, fuel: Fuel) -> EvalResult {
    let key = string_arg(&args, 0);
    let value = read_item(&this, &key, &heap).map_or(Value::Null, Value::String);
    Ok((Outcome::Normal(value), heap, fuel))
}

#[allow(clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
fn set_item_impl(args: Vec<Value>, this: Value, heap: Heap, fuel: Fuel) -> EvalResult {
    let key = string_arg(&args, 0);
    let value = string_arg(&args, 1);
    let new_heap = write_item(&this, &key, &value, heap);
    Ok((Outcome::Normal(Value::Undefined), new_heap, fuel))
}

#[allow(clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
fn remove_item_impl(args: Vec<Value>, this: Value, heap: Heap, fuel: Fuel) -> EvalResult {
    let key = string_arg(&args, 0);
    let new_heap = delete_item(&this, &key, heap);
    Ok((Outcome::Normal(Value::Undefined), new_heap, fuel))
}

#[allow(clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
fn clear_impl(_args: Vec<Value>, this: Value, heap: Heap, fuel: Fuel) -> EvalResult {
    let new_heap = clear_items(&this, heap);
    Ok((Outcome::Normal(Value::Undefined), new_heap, fuel))
}

#[allow(clippy::needless_pass_by_value, clippy::unnecessary_wraps)]
fn key_impl(args: Vec<Value>, this: Value, heap: Heap, fuel: Fuel) -> EvalResult {
    let index = u32_arg(&args, 0);
    let value = items_id_of(&this, &heap)
        .and_then(|id| heap.object(id))
        .and_then(|items| {
            items
                .properties()
                .keys()
                .nth(usize::try_from(index).unwrap_or(usize::MAX))
                .cloned()
        })
        .map_or(Value::Null, Value::String);
    Ok((Outcome::Normal(value), heap, fuel))
}

fn read_item(this: &Value, key: &str, heap: &Heap) -> Option<String> {
    let items_id = items_id_of(this, heap)?;
    let items = heap.object(items_id)?;
    items.get(key).and_then(|v| match v {
        Value::String(s) => Some(s.clone()),
        Value::Undefined
        | Value::Null
        | Value::Boolean(_)
        | Value::Number(_)
        | Value::Object(_)
        | Value::Function(_)
        | Value::Native(_)
        | Value::Promise(_) => None,
    })
}

fn write_item(this: &Value, key: &str, value: &str, heap: Heap) -> Heap {
    let Some(items_id) = items_id_of(this, &heap) else {
        return heap;
    };
    let Some(items) = heap.object(items_id).cloned() else {
        return heap;
    };
    let updated = items.with(key.to_owned(), Value::String(value.to_owned()));
    heap.store_object(items_id, updated).unwrap_or_else(|h| h)
}

fn delete_item(this: &Value, key: &str, heap: Heap) -> Heap {
    let Some(items_id) = items_id_of(this, &heap) else {
        return heap;
    };
    let Some(items) = heap.object(items_id) else {
        return heap;
    };
    let new_items: BTreeMap<String, Value> = items
        .properties()
        .iter()
        .filter(|(k, _)| k.as_str() != key)
        .map(|(k, v)| (k.clone(), v.clone()))
        .collect();
    heap.store_object(items_id, Object::from_properties(new_items))
        .unwrap_or_else(|h| h)
}

fn clear_items(this: &Value, heap: Heap) -> Heap {
    let Some(items_id) = items_id_of(this, &heap) else {
        return heap;
    };
    heap.store_object(items_id, Object::from_properties(BTreeMap::new()))
        .unwrap_or_else(|h| h)
}

fn items_id_of(storage_value: &Value, heap: &Heap) -> Option<ObjectId> {
    let storage_id = object_id_of(storage_value)?;
    let storage = heap.object(storage_id)?;
    storage.get(ITEMS_KEY).and_then(|v| match v {
        Value::Object(id) => Some(*id),
        Value::Undefined
        | Value::Null
        | Value::Boolean(_)
        | Value::Number(_)
        | Value::String(_)
        | Value::Function(_)
        | Value::Native(_)
        | Value::Promise(_) => None,
    })
}

fn object_id_of(value: &Value) -> Option<ObjectId> {
    match value {
        Value::Object(id) => Some(*id),
        Value::Undefined
        | Value::Null
        | Value::Boolean(_)
        | Value::Number(_)
        | Value::String(_)
        | Value::Function(_)
        | Value::Native(_)
        | Value::Promise(_) => None,
    }
}

fn string_arg(args: &[Value], idx: usize) -> String {
    match args.get(idx) {
        Some(Value::String(s)) => s.clone(),
        Some(Value::Number(n)) => format!("{n}"),
        Some(Value::Boolean(b)) => format!("{b}"),
        Some(Value::Null) => "null".to_owned(),
        Some(Value::Undefined) | None => String::new(),
        Some(Value::Object(_) | Value::Function(_) | Value::Native(_) | Value::Promise(_)) => {
            "[object]".to_owned()
        }
    }
}

fn u32_arg(args: &[Value], idx: usize) -> u32 {
    match args.get(idx) {
        Some(Value::Number(n)) if n.is_finite() && *n >= 0.0 => {
            #[allow(clippy::cast_possible_truncation, clippy::cast_sign_loss)]
            let value = *n as u32;
            value
        }
        Some(_) | None => 0,
    }
}