15 files changed, 258 insertions, 58 deletions

diff --git a/crates/ra_ide/src/display/structure.rs b/crates/ra_ide/src/display/structure.rs
index 967eee5d2..3f59b89bb 100644
--- a/crates/ra_ide/src/display/structure.rs
+++ b/crates/ra_ide/src/display/structure.rs
@@ -18,6 +18,19 @@ pub struct StructureNode {
     pub deprecated: bool,
 }
 
+// Feature: File Structure
+//
+// Provides a tree of the symbols defined in the file. Can be used to
+//
+// * fuzzy search symbol in a file (super useful)
+// * draw breadcrumbs to describe the context around the cursor
+// * draw outline of the file
+//
+// |===
+// | Editor  | Shortcut
+//
+// | VS Code | kbd:[Ctrl+Shift+O]
+// |===
 pub fn file_structure(file: &SourceFile) -> Vec<StructureNode> {
     let mut res = Vec::new();
     let mut stack = Vec::new();
diff --git a/crates/ra_ide/src/extend_selection.rs b/crates/ra_ide/src/extend_selection.rs
index 554594a43..cee0a19e1 100644
--- a/crates/ra_ide/src/extend_selection.rs
+++ b/crates/ra_ide/src/extend_selection.rs
@@ -14,6 +14,16 @@ use ra_syntax::{
 
 use crate::FileRange;
 
+// Feature: Extend Selection
+//
+// Extends the current selection to the encompassing syntactic construct
+// (expression, statement, item, module, etc). It works with multiple cursors.
+//
+// |===
+// | Editor  | Shortcut
+//
+// | VS Code | kbd:[Ctrl+Shift+→]
+// |===
 pub(crate) fn extend_selection(db: &RootDatabase, frange: FileRange) -> TextRange {
     let sema = Semantics::new(db);
     let src = sema.parse(frange.file_id);
diff --git a/crates/ra_ide/src/goto_definition.rs b/crates/ra_ide/src/goto_definition.rs
index 90e85d419..83ea5092c 100644
--- a/crates/ra_ide/src/goto_definition.rs
+++ b/crates/ra_ide/src/goto_definition.rs
@@ -17,6 +17,15 @@ use crate::{
     FilePosition, NavigationTarget, RangeInfo,
 };
 
+// Feature: Go To Definition
+//
+// Navigates to the definition of an identifier.
+//
+// |===
+// | Editor  | Shortcut
+//
+// | VS Code | kbd:[F12]
+// |===
 pub(crate) fn goto_definition(
     db: &RootDatabase,
     position: FilePosition,
diff --git a/crates/ra_ide/src/impls.rs b/crates/ra_ide/src/goto_implementation.rs
index ea2225f70..a5a296d22 100644
--- a/crates/ra_ide/src/impls.rs
+++ b/crates/ra_ide/src/goto_implementation.rs
@@ -6,6 +6,15 @@ use ra_syntax::{algo::find_node_at_offset, ast, AstNode};
 
 use crate::{display::ToNav, FilePosition, NavigationTarget, RangeInfo};
 
+// Feature: Go To Implementation
+//
+// Navigates to the impl block of structs, enums or traits. Also implemented as a code lens.
+//
+// |===
+// | Editor  | Shortcut
+//
+// | VS Code | kbd:[Ctrl+F12]
+// |===
 pub(crate) fn goto_implementation(
     db: &RootDatabase,
     position: FilePosition,
diff --git a/crates/ra_ide/src/goto_type_definition.rs b/crates/ra_ide/src/goto_type_definition.rs
index a84637489..eeadfa9ee 100644
--- a/crates/ra_ide/src/goto_type_definition.rs
+++ b/crates/ra_ide/src/goto_type_definition.rs
@@ -5,6 +5,9 @@ use ra_syntax::{ast, match_ast, AstNode, SyntaxKind::*, SyntaxToken, TokenAtOffs
 
 use crate::{display::ToNav, FilePosition, NavigationTarget, RangeInfo};
 
+// Feature: Go To Type Definition
+//
+// Navigates to the type of an identifier.
 pub(crate) fn goto_type_definition(
     db: &RootDatabase,
     position: FilePosition,
diff --git a/crates/ra_ide/src/lib.rs b/crates/ra_ide/src/lib.rs
index d983cd910..12d5716e8 100644
--- a/crates/ra_ide/src/lib.rs
+++ b/crates/ra_ide/src/lib.rs
@@ -23,6 +23,7 @@ mod completion;
 mod runnables;
 mod goto_definition;
 mod goto_type_definition;
+mod goto_implementation;
 mod extend_selection;
 mod hover;
 mod call_hierarchy;
@@ -30,7 +31,6 @@ mod call_info;
 mod syntax_highlighting;
 mod parent_module;
 mod references;
-mod impls;
 mod diagnostics;
 mod syntax_tree;
 mod folding_ranges;
@@ -373,7 +373,7 @@ impl Analysis {
         &self,
         position: FilePosition,
     ) -> Cancelable<Option<RangeInfo<Vec<NavigationTarget>>>> {
-        self.with_db(|db| impls::goto_implementation(db, position))
+        self.with_db(|db| goto_implementation::goto_implementation(db, position))
     }
 
     /// Returns the type definitions for the symbol at `position`.
diff --git a/crates/ra_ide/src/typing.rs b/crates/ra_ide/src/typing.rs
index 39bb3b357..67e2c33a0 100644
--- a/crates/ra_ide/src/typing.rs
+++ b/crates/ra_ide/src/typing.rs
@@ -32,6 +32,13 @@ pub(crate) use on_enter::on_enter;
 
 pub(crate) const TRIGGER_CHARS: &str = ".=>";
 
+// Feature: On Typing Assists
+//
+// Some features trigger on typing certain characters:
+//
+// - typing `let =` tries to smartly add `;` if `=` is followed by an existing expression
+// - Enter inside comments automatically inserts `///`
+// - typing `.` in a chain method call auto-indents
 pub(crate) fn on_char_typed(
     db: &RootDatabase,
     position: FilePosition,
diff --git a/crates/ra_ide_db/src/symbol_index.rs b/crates/ra_ide_db/src/symbol_index.rs
index 95be11134..acc31fe3b 100644
--- a/crates/ra_ide_db/src/symbol_index.rs
+++ b/crates/ra_ide_db/src/symbol_index.rs
@@ -110,6 +110,27 @@ fn file_symbols(db: &impl SymbolsDatabase, file_id: FileId) -> Arc<SymbolIndex>
     Arc::new(SymbolIndex::new(symbols))
 }
 
+// Feature: Workspace Symbol
+//
+// Uses fuzzy-search to find types, modules and functions by name across your
+// project and dependencies. This is **the** most useful feature, which improves code
+// navigation tremendously. It mostly works on top of the built-in LSP
+// functionality, however `#` and `*` symbols can be used to narrow down the
+// search. Specifically,
+//
+// - `Foo` searches for `Foo` type in the current workspace
+// - `foo#` searches for `foo` function in the current workspace
+// - `Foo*` searches for `Foo` type among dependencies, including `stdlib`
+// - `foo#*` searches for `foo` function among dependencies
+//
+// That is, `#` switches from "types" to all symbols, `*` switches from the current
+// workspace to dependencies.
+//
+// |===
+// | Editor  | Shortcut
+//
+// | VS Code | kbd:[Ctrl+T]
+// |===
 pub fn world_symbols(db: &RootDatabase, query: Query) -> Vec<FileSymbol> {
     /// Need to wrap Snapshot to provide `Clone` impl for `map_with`
     struct Snap(salsa::Snapshot<RootDatabase>);
diff --git a/docs/user/features.md b/docs/user/features.md
index 12ecdec13..4d9402252 100644
--- a/docs/user/features.md
+++ b/docs/user/features.md
@@ -2,58 +2,6 @@ This document is an index of features that the rust-analyzer language server
 provides. Shortcuts are for the default VS Code layout. If there's no shortcut,
 you can use <kbd>Ctrl+Shift+P</kbd> to search for the corresponding action.
 
-### Workspace Symbol <kbd>ctrl+t</kbd>
-
-Uses fuzzy-search to find types, modules and functions by name across your
-project and dependencies. This is **the** most useful feature, which improves code
-navigation tremendously. It mostly works on top of the built-in LSP
-functionality, however `#` and `*` symbols can be used to narrow down the
-search. Specifically,
-
-- `Foo` searches for `Foo` type in the current workspace
-- `foo#` searches for `foo` function in the current workspace
-- `Foo*` searches for `Foo` type among dependencies, including `stdlib`
-- `foo#*` searches for `foo` function among dependencies
-
-That is, `#` switches from "types" to all symbols, `*` switches from the current
-workspace to dependencies.
-
-### Document Symbol <kbd>ctrl+shift+o</kbd>
-
-Provides a tree of the symbols defined in the file. Can be used to
-
-* fuzzy search symbol in a file (super useful)
-* draw breadcrumbs to describe the context around the cursor
-* draw outline of the file
-
-### On Typing Assists
-
-Some features trigger on typing certain characters:
-
-- typing `let =` tries to smartly add `;` if `=` is followed by an existing expression
-- Enter inside comments automatically inserts `///`
-- typing `.` in a chain method call auto-indents
-
-### Extend Selection
-
-Extends the current selection to the encompassing syntactic construct
-(expression, statement, item, module, etc). It works with multiple cursors. This
-is a relatively new feature of LSP:
-https://github.com/Microsoft/language-server-protocol/issues/613, check your
-editor's LSP library to see if this feature is supported.
-
-### Go to Definition
-
-Navigates to the definition of an identifier.
-
-### Go to Implementation
-
-Navigates to the impl block of structs, enums or traits. Also implemented as a code lens.
-
-### Go to Type Defintion
-
-Navigates to the type of an identifier.
-
 ### Commands <kbd>ctrl+shift+p</kbd>
 
 #### Run
diff --git a/docs/user/generated_features.adoc b/docs/user/generated_features.adoc
new file mode 100644
index 000000000..e1eb5d88a
--- /dev/null
+++ b/docs/user/generated_features.adoc
@@ -0,0 +1,98 @@
+=== Extend Selection
+**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/ra_ide/src/extend_selection.rs[extend_selection.rs]
+
+
+Extends the current selection to the encompassing syntactic construct
+(expression, statement, item, module, etc). It works with multiple cursors.
+
+|===
+| Editor  | Shortcut
+
+| VS Code | kbd:[Ctrl+Shift+→]
+|===
+
+
+=== File Structure
+**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/ra_ide/src/display/structure.rs[structure.rs]
+
+
+Provides a tree of the symbols defined in the file. Can be used to
+
+* fuzzy search symbol in a file (super useful)
+* draw breadcrumbs to describe the context around the cursor
+* draw outline of the file
+
+|===
+| Editor  | Shortcut
+
+| VS Code | kbd:[Ctrl+Shift+O]
+|===
+
+
+=== Go To Definition
+**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/ra_ide/src/goto_definition.rs[goto_definition.rs]
+
+
+Navigates to the definition of an identifier.
+
+|===
+| Editor  | Shortcut
+
+| VS Code | kbd:[F12]
+|===
+
+
+=== Go To Implementation
+**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/ra_ide/src/goto_implementation.rs[goto_implementation.rs]
+
+
+Navigates to the impl block of structs, enums or traits. Also implemented as a code lens.
+
+|===
+| Editor  | Shortcut
+
+| VS Code | kbd:[Ctrl+F12]
+|===
+
+
+=== Go To Type Definition
+**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/ra_ide/src/goto_type_definition.rs[goto_type_definition.rs]
+
+
+Navigates to the type of an identifier.
+
+
+=== On Typing Assists
+**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/ra_ide/src/typing.rs[typing.rs]
+
+
+Some features trigger on typing certain characters:
+
+- typing `let =` tries to smartly add `;` if `=` is followed by an existing expression
+- Enter inside comments automatically inserts `///`
+- typing `.` in a chain method call auto-indents
+
+
+=== Workspace Symbol
+**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/crates/ra_ide_db/src/symbol_index.rs[symbol_index.rs]
+
+
+Uses fuzzy-search to find types, modules and functions by name across your
+project and dependencies. This is **the** most useful feature, which improves code
+navigation tremendously. It mostly works on top of the built-in LSP
+functionality, however `#` and `*` symbols can be used to narrow down the
+search. Specifically,
+
+- `Foo` searches for `Foo` type in the current workspace
+- `foo#` searches for `foo` function in the current workspace
+- `Foo*` searches for `Foo` type among dependencies, including `stdlib`
+- `foo#*` searches for `foo` function among dependencies
+
+That is, `#` switches from "types" to all symbols, `*` switches from the current
+workspace to dependencies.
+
+|===
+| Editor  | Shortcut
+
+| VS Code | kbd:[Ctrl+T]
+|===
diff --git a/docs/user/readme.adoc b/docs/user/readme.adoc
index 64bd0feb1..7b159bfc6 100644
--- a/docs/user/readme.adoc
+++ b/docs/user/readme.adoc
@@ -8,6 +8,7 @@
 :important-caption: :heavy_exclamation_mark:
 :caution-caption: :fire:
 :warning-caption: :warning:
+:experimental:
 
 // Master copy of this document lives in the https://github.com/rust-analyzer/rust-analyzer repository
 
@@ -268,6 +269,6 @@ Gnome Builder currently has support for RLS, and there's no way to configure the
 1. Rename, symlink or copy the `rust-analyzer` binary to `rls` and place it somewhere Builder can find (in `PATH`, or under `~/.cargo/bin`).
 2. Enable the Rust Builder plugin.
 
-== Usage
+== Features
 
-See https://github.com/rust-analyzer/rust-analyzer/blob/master/docs/user/features.md[features.md].
+include::./generated_features.adoc[]
diff --git a/xtask/src/codegen.rs b/xtask/src/codegen.rs
index 2e8fd3494..3e2a66979 100644
--- a/xtask/src/codegen.rs
+++ b/xtask/src/codegen.rs
@@ -8,14 +8,15 @@
 mod gen_syntax;
 mod gen_parser_tests;
 mod gen_assists_docs;
+mod gen_feature_docs;
 
 use std::{mem, path::Path};
 
 use crate::{not_bash::fs2, Result};
 
 pub use self::{
-    gen_assists_docs::generate_assists_docs, gen_parser_tests::generate_parser_tests,
-    gen_syntax::generate_syntax,
+    gen_assists_docs::generate_assists_docs, gen_feature_docs::generate_feature_docs,
+    gen_parser_tests::generate_parser_tests, gen_syntax::generate_syntax,
 };
 
 const GRAMMAR_DIR: &str = "crates/ra_parser/src/grammar";
diff --git a/xtask/src/codegen/gen_feature_docs.rs b/xtask/src/codegen/gen_feature_docs.rs
new file mode 100644
index 000000000..583185648
--- /dev/null
+++ b/xtask/src/codegen/gen_feature_docs.rs
@@ -0,0 +1,72 @@
+//! Generates `assists.md` documentation.
+
+use std::{fmt, fs, path::PathBuf};
+
+use crate::{
+    codegen::{self, extract_comment_blocks_with_empty_lines, Mode},
+    project_root, rust_files, Result,
+};
+
+pub fn generate_feature_docs(mode: Mode) -> Result<()> {
+    let features = Feature::collect()?;
+    let contents = features.into_iter().map(|it| it.to_string()).collect::<Vec<_>>().join("\n\n");
+
+    let dst = project_root().join("docs/user/generated_features.adoc");
+    codegen::update(&dst, &contents, mode)?;
+    Ok(())
+}
+
+#[derive(Debug)]
+struct Feature {
+    id: String,
+    path: PathBuf,
+    doc: String,
+}
+
+impl Feature {
+    fn collect() -> Result<Vec<Feature>> {
+        let mut res = Vec::new();
+        for path in rust_files(&project_root()) {
+            collect_file(&mut res, path)?;
+        }
+        res.sort_by(|lhs, rhs| lhs.id.cmp(&rhs.id));
+        return Ok(res);
+
+        fn collect_file(acc: &mut Vec<Feature>, path: PathBuf) -> Result<()> {
+            let text = fs::read_to_string(&path)?;
+            let comment_blocks = extract_comment_blocks_with_empty_lines("Feature", &text);
+
+            for block in comment_blocks {
+                let id = block.id;
+                assert!(
+                    id.split_ascii_whitespace().all(|it| it.starts_with(char::is_uppercase)),
+                    "bad feature: {}",
+                    id
+                );
+                let doc = block.contents.join("\n");
+                acc.push(Feature { id, path: path.clone(), doc })
+            }
+
+            Ok(())
+        }
+    }
+}
+
+impl fmt::Display for Feature {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        writeln!(f, "=== {}", self.id)?;
+        let path = self.path.strip_prefix(&project_root()).unwrap();
+        let name = self.path.file_name().unwrap();
+
+        //FIXME: generate line number as well
+        writeln!(
+            f,
+            "**Source:** https://github.com/rust-analyzer/rust-analyzer/blob/master/{}[{}]",
+            path.display(),
+            name.to_str().unwrap(),
+        )?;
+
+        writeln!(f, "\n{}", self.doc)?;
+        Ok(())
+    }
+}
diff --git a/xtask/src/main.rs b/xtask/src/main.rs
index dff3ce4a1..9d7cdd114 100644
--- a/xtask/src/main.rs
+++ b/xtask/src/main.rs
@@ -75,6 +75,7 @@ FLAGS:
             codegen::generate_syntax(Mode::Overwrite)?;
             codegen::generate_parser_tests(Mode::Overwrite)?;
             codegen::generate_assists_docs(Mode::Overwrite)?;
+            codegen::generate_feature_docs(Mode::Overwrite)?;
             Ok(())
         }
         "format" => {
diff --git a/xtask/tests/tidy.rs b/xtask/tests/tidy.rs
index 2e9fcf07c..06ff45d99 100644
--- a/xtask/tests/tidy.rs
+++ b/xtask/tests/tidy.rs
@@ -31,6 +31,13 @@ fn generated_assists_are_fresh() {
 }
 
 #[test]
+fn generated_features_are_fresh() {
+    if let Err(error) = codegen::generate_feature_docs(Mode::Verify) {
+        panic!("{}. Please update features by running `cargo xtask codegen`", error);
+    }
+}
+
+#[test]
 fn check_code_formatting() {
     if let Err(error) = run_rustfmt(Mode::Verify) {
         panic!("{}. Please format the code by running `cargo format`", error);