Rename ide::link_rewrite -> ide::doc_links & tidy imports

1 files changed, 433 insertions, 0 deletions

diff --git a/crates/ide/src/doc_links.rs b/crates/ide/src/doc_links.rs
new file mode 100644
index 000000000..1e102997f
--- /dev/null
+++ b/crates/ide/src/doc_links.rs
@@ -0,0 +1,433 @@
+//! Resolves and rewrites links in markdown documentation.
+//!
+//! Most of the implementation can be found in [`hir::doc_links`].
+
+use hir::{Adt, Crate, HasAttrs, ModuleDef};
+use ide_db::{defs::Definition, RootDatabase};
+use pulldown_cmark::{CowStr, Event, LinkType, Options, Parser, Tag};
+use pulldown_cmark_to_cmark::{cmark_with_options, Options as CmarkOptions};
+use url::Url;
+
+use crate::{FilePosition, Semantics};
+use hir::{get_doc_link, resolve_doc_link};
+use ide_db::{
+    defs::{classify_name, classify_name_ref, Definition},
+    RootDatabase,
+};
+use syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffset, T};
+
+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)
+}
+
+// TODO:
+// BUG: For Option
+// 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
+//
+// BUG: For methods
+// import_map.path_of(ns) fails, is not designed to resolve methods
+fn get_doc_link_impl(db: &dyn HirDatabase, moddef: &ModuleDef) -> 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 moddef {
+        ModuleDef::Function(f) => match f.as_assoc_item(db).map(|assoc| assoc.container(db)) {
+            Some(AssocItemContainer::Trait(t)) => t.into(),
+            Some(AssocItemContainer::ImplDef(imp)) => {
+                let resolver = ModuleId::from(imp.module(db)).resolver(db.upcast());
+                let ctx = TyLoweringContext::new(db, &resolver);
+                Adt::from(
+                    Ty::from_hir(
+                        &ctx,
+                        &imp.target_trait(db).unwrap_or_else(|| imp.target_type(db)),
+                    )
+                    .as_adt()
+                    .map(|t| t.0)
+                    .unwrap(),
+                )
+                .into()
+            }
+            None => ModuleDef::Function(*f),
+        },
+        moddef => *moddef,
+    };
+
+    let ns = ItemInNs::Types(target_def.clone().into());
+
+    let module = moddef.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("/");
+
+    get_doc_url(db, &krate)
+        .and_then(|url| url.join(&base).ok())
+        .and_then(|url| {
+            get_symbol_filename(db, &target_def).as_deref().and_then(|f| url.join(f).ok())
+        })
+        .and_then(|url| match moddef {
+            ModuleDef::Function(f) => {
+                get_symbol_fragment(db, &FieldOrAssocItem::AssocItem(AssocItem::Function(*f)))
+                    .as_deref()
+                    .and_then(|f| url.join(f).ok())
+            }
+            ModuleDef::Const(c) => {
+                get_symbol_fragment(db, &FieldOrAssocItem::AssocItem(AssocItem::Const(*c)))
+                    .as_deref()
+                    .and_then(|f| url.join(f).ok())
+            }
+            ModuleDef::TypeAlias(ty) => {
+                get_symbol_fragment(db, &FieldOrAssocItem::AssocItem(AssocItem::TypeAlias(*ty)))
+                    .as_deref()
+                    .and_then(|f| url.join(f).ok())
+            }
+            // TODO:  Field <- this requires passing in a definition or something
+            _ => 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())
+}
+
+// FIXME: This should either be moved, or the module should be renamed.
+/// Retrieve a link to documentation for the given symbol.
+pub fn get_doc_url(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,
+        }
+    };
+
+    match definition? {
+        Definition::Macro(t) => get_doc_link(db, &t),
+        Definition::Field(t) => get_doc_link(db, &t),
+        Definition::ModuleDef(t) => get_doc_link(db, &t),
+        Definition::SelfType(t) => get_doc_link(db, &t),
+        Definition::Local(t) => get_doc_link(db, &t),
+        Definition::TypeParam(t) => get_doc_link(db, &t),
+    }
+}
+
+/// 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 {
+            // TODO: Rustdoc sometimes uses tymethod instead of method. This case needs to be investigated.
+            AssocItem::Function(function) => format!("#method.{}", function.name(db)),
+            // TODO: This might be the old method for documenting associated constants, i32::MAX uses a separate page...
+            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,
+        }
+    }
+}