aboutsummaryrefslogtreecommitdiff
path: root/crates/ide/src/doc_links.rs
blob: 0608c2ac694a9dc2d8df618ca540a61aa23e40c6 (plain)
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
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
//! Resolves and rewrites links in markdown documentation.
//!
//! Most of the implementation can be found in [`hir::doc_links`].

use std::iter::once;

use itertools::Itertools;
use pulldown_cmark_to_cmark::{cmark_with_options, Options as CmarkOptions};
use pulldown_cmark::{CowStr, Event, LinkType, Options, Parser, Tag};
use url::Url;

use ide_db::{defs::Definition, RootDatabase};

use hir::{
    db::{DefDatabase, HirDatabase},
    Adt, AsName, AssocItem, Crate, Field, HasAttrs, ItemInNs, MethodOwner, ModuleDef,
};
use ide_db::{
    defs::{classify_name, classify_name_ref, Definition},
    RootDatabase,
};
use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset, T};

use crate::{FilePosition, Semantics};

pub type DocumentationLink = String;

/// Rewrite documentation links in markdown to point to an online host (e.g. docs.rs)
pub fn rewrite_links(db: &RootDatabase, markdown: &str, definition: &Definition) -> String {
    let doc = Parser::new_with_broken_link_callback(
        markdown,
        Options::empty(),
        Some(&|label, _| Some((/*url*/ label.to_string(), /*title*/ label.to_string()))),
    );

    let doc = map_links(doc, |target, title: &str| {
        // This check is imperfect, there's some overlap between valid intra-doc links
        // and valid URLs so we choose to be too eager to try to resolve what might be
        // a URL.
        if target.contains("://") {
            (target.to_string(), title.to_string())
        } else {
            // Two posibilities:
            // * path-based links: `../../module/struct.MyStruct.html`
            // * module-based links (AKA intra-doc links): `super::super::module::MyStruct`
            if let Some(rewritten) = rewrite_intra_doc_link(db, *definition, target, title) {
                return rewritten;
            }
            if let Definition::ModuleDef(def) = *definition {
                if let Some(target) = rewrite_url_link(db, def, target) {
                    return (target, title.to_string());
                }
            }

            (target.to_string(), title.to_string())
        }
    });
    let mut out = String::new();
    let mut options = CmarkOptions::default();
    options.code_block_backticks = 3;
    cmark_with_options(doc, &mut out, None, options).ok();
    out
}

/// Remove all links in markdown documentation.
pub fn remove_links(markdown: &str) -> String {
    let mut drop_link = false;

    let mut opts = Options::empty();
    opts.insert(Options::ENABLE_FOOTNOTES);

    let doc = Parser::new_with_broken_link_callback(
        markdown,
        opts,
        Some(&|_, _| Some((String::new(), String::new()))),
    );
    let doc = doc.filter_map(move |evt| match evt {
        Event::Start(Tag::Link(link_type, ref target, ref title)) => {
            if link_type == LinkType::Inline && target.contains("://") {
                Some(Event::Start(Tag::Link(link_type, target.clone(), title.clone())))
            } else {
                drop_link = true;
                None
            }
        }
        Event::End(_) if drop_link => {
            drop_link = false;
            None
        }
        _ => Some(evt),
    });

    let mut out = String::new();
    let mut options = CmarkOptions::default();
    options.code_block_backticks = 3;
    cmark_with_options(doc, &mut out, None, options).ok();
    out
}

pub fn get_doc_link<T: Resolvable + Clone>(db: &dyn HirDatabase, definition: &T) -> Option<String> {
    let module_def = definition.clone().try_into_module_def()?;

    get_doc_link_impl(db, &module_def)
}

// FIXME:
// BUG: For Option::Some
// Returns https://doc.rust-lang.org/nightly/core/prelude/v1/enum.Option.html#variant.Some
// Instead of https://doc.rust-lang.org/nightly/core/option/enum.Option.html
// This could be worked around by turning the `EnumVariant` into `Enum` before attempting resolution,
// but it's really just working around the problem. Ideally we need to implement a slightly different
// version of import map which follows the same process as rustdoc. Otherwise there'll always be some
// edge cases where we select the wrong import path.
fn get_doc_link(db: &RootDatabase, definition: Definition) -> Option<String> {
    // Get the outermost definition for the moduledef. This is used to resolve the public path to the type,
    // then we can join the method, field, etc onto it if required.
    let target_def: ModuleDef = match definition {
        Definition::ModuleDef(moddef) => match moddef {
            ModuleDef::Function(f) => {
                f.method_owner(db).map(|mowner| mowner.into()).unwrap_or_else(|| f.clone().into())
            }
            moddef => moddef,
        },
        Definition::Field(f) => f.parent_def(db).into(),
        // FIXME: Handle macros
        _ => return None,
    };

    let ns = ItemInNs::Types(target_def.clone().into());

    let module = definition.module(db)?;
    let krate = module.krate();
    let import_map = db.import_map(krate.into());
    let base = once(krate.display_name(db).unwrap())
        .chain(import_map.path_of(ns).unwrap().segments.iter().map(|name| format!("{}", name)))
        .join("/");

    let filename = get_symbol_filename(db, &target_def);
    let fragment = match definition {
        Definition::ModuleDef(moddef) => match moddef {
            ModuleDef::Function(f) => {
                get_symbol_fragment(db, &FieldOrAssocItem::AssocItem(AssocItem::Function(f)))
            }
            ModuleDef::Const(c) => {
                get_symbol_fragment(db, &FieldOrAssocItem::AssocItem(AssocItem::Const(c)))
            }
            ModuleDef::TypeAlias(ty) => {
                get_symbol_fragment(db, &FieldOrAssocItem::AssocItem(AssocItem::TypeAlias(ty)))
            }
            _ => None,
        },
        Definition::Field(field) => get_symbol_fragment(db, &FieldOrAssocItem::Field(field)),
        _ => None,
    };

    get_doc_url(db, &krate)
        .and_then(|url| url.join(&base).ok())
        .and_then(|url| filename.as_deref().and_then(|f| url.join(f).ok()))
        .and_then(
            |url| if let Some(fragment) = fragment { url.join(&fragment).ok() } else { Some(url) },
        )
        .map(|url| url.into_string())
}

fn rewrite_intra_doc_link(
    db: &RootDatabase,
    def: Definition,
    target: &str,
    title: &str,
) -> Option<(String, String)> {
    let link = if target.is_empty() { title } else { target };
    let (link, ns) = parse_link(link);
    let resolved = match def {
        Definition::ModuleDef(def) => match def {
            ModuleDef::Module(it) => it.resolve_doc_path(db, link, ns),
            ModuleDef::Function(it) => it.resolve_doc_path(db, link, ns),
            ModuleDef::Adt(it) => it.resolve_doc_path(db, link, ns),
            ModuleDef::EnumVariant(it) => it.resolve_doc_path(db, link, ns),
            ModuleDef::Const(it) => it.resolve_doc_path(db, link, ns),
            ModuleDef::Static(it) => it.resolve_doc_path(db, link, ns),
            ModuleDef::Trait(it) => it.resolve_doc_path(db, link, ns),
            ModuleDef::TypeAlias(it) => it.resolve_doc_path(db, link, ns),
            ModuleDef::BuiltinType(_) => return None,
        },
        Definition::Macro(it) => it.resolve_doc_path(db, link, ns),
        Definition::Field(it) => it.resolve_doc_path(db, link, ns),
        Definition::SelfType(_) | Definition::Local(_) | Definition::TypeParam(_) => return None,
    }?;
    let krate = resolved.module(db)?.krate();
    let canonical_path = resolved.canonical_path(db)?;
    let new_target = get_doc_url(db, &krate)?
        .join(&format!("{}/", krate.declaration_name(db)?))
        .ok()?
        .join(&canonical_path.replace("::", "/"))
        .ok()?
        .join(&get_symbol_filename(db, &resolved)?)
        .ok()?
        .into_string();
    let new_title = strip_prefixes_suffixes(title);
    Some((new_target, new_title.to_string()))
}

/// Try to resolve path to local documentation via path-based links (i.e. `../gateway/struct.Shard.html`).
fn rewrite_url_link(db: &RootDatabase, def: ModuleDef, target: &str) -> Option<String> {
    if !(target.contains('#') || target.contains(".html")) {
        return None;
    }

    let module = def.module(db)?;
    let krate = module.krate();
    let canonical_path = def.canonical_path(db)?;
    let base = format!("{}/{}", krate.declaration_name(db)?, canonical_path.replace("::", "/"));

    get_doc_url(db, &krate)
        .and_then(|url| url.join(&base).ok())
        .and_then(|url| {
            get_symbol_filename(db, &def).as_deref().map(|f| url.join(f).ok()).flatten()
        })
        .and_then(|url| url.join(target).ok())
        .map(|url| url.into_string())
}

/// Retrieve a link to documentation for the given symbol.
pub fn external_docs(db: &RootDatabase, position: &FilePosition) -> Option<DocumentationLink> {
    let sema = Semantics::new(db);
    let file = sema.parse(position.file_id).syntax().clone();
    let token = pick_best(file.token_at_offset(position.offset))?;
    let token = sema.descend_into_macros(token);

    let node = token.parent();
    let definition = match_ast! {
        match node {
            ast::NameRef(name_ref) => classify_name_ref(&sema, &name_ref).map(|d| d.definition(sema.db)),
            ast::Name(name) => classify_name(&sema, &name).map(|d| d.definition(sema.db)),
            _ => None,
        }
    };

    get_doc_link(db, definition?)
}

/// Rewrites a markdown document, applying 'callback' to each link.
fn map_links<'e>(
    events: impl Iterator<Item = Event<'e>>,
    callback: impl Fn(&str, &str) -> (String, String),
) -> impl Iterator<Item = Event<'e>> {
    let mut in_link = false;
    let mut link_target: Option<CowStr> = None;

    events.map(move |evt| match evt {
        Event::Start(Tag::Link(_link_type, ref target, _)) => {
            in_link = true;
            link_target = Some(target.clone());
            evt
        }
        Event::End(Tag::Link(link_type, _target, _)) => {
            in_link = false;
            Event::End(Tag::Link(link_type, link_target.take().unwrap(), CowStr::Borrowed("")))
        }
        Event::Text(s) if in_link => {
            let (link_target_s, link_name) = callback(&link_target.take().unwrap(), &s);
            link_target = Some(CowStr::Boxed(link_target_s.into()));
            Event::Text(CowStr::Boxed(link_name.into()))
        }
        Event::Code(s) if in_link => {
            let (link_target_s, link_name) = callback(&link_target.take().unwrap(), &s);
            link_target = Some(CowStr::Boxed(link_target_s.into()));
            Event::Code(CowStr::Boxed(link_name.into()))
        }
        _ => evt,
    })
}

fn parse_link(s: &str) -> (&str, Option<hir::Namespace>) {
    let path = strip_prefixes_suffixes(s);
    let ns = ns_from_intra_spec(s);
    (path, ns)
}

/// Strip prefixes, suffixes, and inline code marks from the given string.
fn strip_prefixes_suffixes(mut s: &str) -> &str {
    s = s.trim_matches('`');

    [
        (TYPES.0.iter(), TYPES.1.iter()),
        (VALUES.0.iter(), VALUES.1.iter()),
        (MACROS.0.iter(), MACROS.1.iter()),
    ]
    .iter()
    .for_each(|(prefixes, suffixes)| {
        prefixes.clone().for_each(|prefix| s = s.trim_start_matches(*prefix));
        suffixes.clone().for_each(|suffix| s = s.trim_end_matches(*suffix));
    });
    s.trim_start_matches('@').trim()
}

static TYPES: ([&str; 7], [&str; 0]) =
    (["type", "struct", "enum", "mod", "trait", "union", "module"], []);
static VALUES: ([&str; 8], [&str; 1]) =
    (["value", "function", "fn", "method", "const", "static", "mod", "module"], ["()"]);
static MACROS: ([&str; 1], [&str; 1]) = (["macro"], ["!"]);

/// Extract the specified namespace from an intra-doc-link if one exists.
///
/// # Examples
///
/// * `struct MyStruct` -> `Namespace::Types`
/// * `panic!` -> `Namespace::Macros`
/// * `fn@from_intra_spec` -> `Namespace::Values`
fn ns_from_intra_spec(s: &str) -> Option<hir::Namespace> {
    [
        (hir::Namespace::Types, (TYPES.0.iter(), TYPES.1.iter())),
        (hir::Namespace::Values, (VALUES.0.iter(), VALUES.1.iter())),
        (hir::Namespace::Macros, (MACROS.0.iter(), MACROS.1.iter())),
    ]
    .iter()
    .filter(|(_ns, (prefixes, suffixes))| {
        prefixes
            .clone()
            .map(|prefix| {
                s.starts_with(*prefix)
                    && s.chars()
                        .nth(prefix.len() + 1)
                        .map(|c| c == '@' || c == ' ')
                        .unwrap_or(false)
            })
            .any(|cond| cond)
            || suffixes
                .clone()
                .map(|suffix| {
                    s.starts_with(*suffix)
                        && s.chars()
                            .nth(suffix.len() + 1)
                            .map(|c| c == '@' || c == ' ')
                            .unwrap_or(false)
                })
                .any(|cond| cond)
    })
    .map(|(ns, (_, _))| *ns)
    .next()
}

/// Get the root URL for the documentation of a crate.
///
/// ```
/// https://doc.rust-lang.org/std/iter/trait.Iterator.html#tymethod.next
/// ^^^^^^^^^^^^^^^^^^^^^^^^^^
/// ```
fn get_doc_url(db: &RootDatabase, krate: &Crate) -> Option<Url> {
    krate
        .get_html_root_url(db)
        .or_else(|| {
            // Fallback to docs.rs. This uses `display_name` and can never be
            // correct, but that's what fallbacks are about.
            //
            // FIXME: clicking on the link should just open the file in the editor,
            // instead of falling back to external urls.
            Some(format!("https://docs.rs/{}/*/", krate.declaration_name(db)?))
        })
        .and_then(|s| Url::parse(&s).ok())
}

/// Get the filename and extension generated for a symbol by rustdoc.
///
/// ```
/// https://doc.rust-lang.org/std/iter/trait.Iterator.html#tymethod.next
///                                    ^^^^^^^^^^^^^^^^^^^
/// ```
fn get_symbol_filename(db: &dyn HirDatabase, definition: &ModuleDef) -> Option<String> {
    Some(match definition {
        ModuleDef::Adt(adt) => match adt {
            Adt::Struct(s) => format!("struct.{}.html", s.name(db)),
            Adt::Enum(e) => format!("enum.{}.html", e.name(db)),
            Adt::Union(u) => format!("union.{}.html", u.name(db)),
        },
        ModuleDef::Module(_) => "index.html".to_string(),
        ModuleDef::Trait(t) => format!("trait.{}.html", t.name(db)),
        ModuleDef::TypeAlias(t) => format!("type.{}.html", t.name(db)),
        ModuleDef::BuiltinType(t) => format!("primitive.{}.html", t.as_name()),
        ModuleDef::Function(f) => format!("fn.{}.html", f.name(db)),
        ModuleDef::EnumVariant(ev) => {
            format!("enum.{}.html#variant.{}", ev.parent_enum(db).name(db), ev.name(db))
        }
        ModuleDef::Const(c) => format!("const.{}.html", c.name(db)?),
        ModuleDef::Static(s) => format!("static.{}.html", s.name(db)?),
    })
}

enum FieldOrAssocItem {
    Field(Field),
    AssocItem(AssocItem),
}

/// Get the fragment required to link to a specific field, method, associated type, or associated constant.
///
/// ```
/// https://doc.rust-lang.org/std/iter/trait.Iterator.html#tymethod.next
///                                                       ^^^^^^^^^^^^^^
/// ```
fn get_symbol_fragment(db: &dyn HirDatabase, field_or_assoc: &FieldOrAssocItem) -> Option<String> {
    Some(match field_or_assoc {
        FieldOrAssocItem::Field(field) => format!("#structfield.{}", field.name(db)),
        FieldOrAssocItem::AssocItem(assoc) => match assoc {
            AssocItem::Function(function) => {
                let is_trait_method =
                    matches!(function.method_owner(db), Some(MethodOwner::Trait(..)));
                // This distinction may get more complicated when specialisation is available.
                // Rustdoc makes this decision based on whether a method 'has defaultness'.
                // Currently this is only the case for provided trait methods.
                if is_trait_method && !function.has_body(db) {
                    format!("#tymethod.{}", function.name(db))
                } else {
                    format!("#method.{}", function.name(db))
                }
            }
            AssocItem::Const(constant) => format!("#associatedconstant.{}", constant.name(db)?),
            AssocItem::TypeAlias(ty) => format!("#associatedtype.{}", ty.name(db)),
        },
    })
}

fn pick_best(tokens: TokenAtOffset<SyntaxToken>) -> Option<SyntaxToken> {
    return tokens.max_by_key(priority);
    fn priority(n: &SyntaxToken) -> usize {
        match n.kind() {
            IDENT | INT_NUMBER => 3,
            T!['('] | T![')'] => 2,
            kind if kind.is_trivia() => 0,
            _ => 1,
        }
    }
}