Enable DocumentSymbol (#170)

include/Protocol/Feature/DocumentSymbol.h

@@ -4,8 +4,109 @@
 
 namespace clice::proto {
 
-struct DocumentSymbolClientCapabilities {};
+enum class SymbolKind : std::uint8_t {
+    File = 1,
+    Module = 2,
+    Namespace = 3,
+    Package = 4,
+    Class = 5,
+    Method = 6,
+    Property = 7,
+    Field = 8,
+    Constructor = 9,
+    Enum = 10,
+    Interface = 11,
+    Function = 12,
+    Variable = 13,
+    Constant = 14,
+    String = 15,
+    Number = 16,
+    Boolean = 17,
+    Array = 18,
+    Object = 19,
+    Key = 20,
+    Null = 21,
+    EnumMember = 22,
+    Struct = 23,
+    Event = 24,
+    Operator = 25,
+    TypeParameter = 26,
+};
+
+enum class SymbolTag {
+    /// Render a symbol as obsolete, usually using a strike-out.
+    Deprecated = 1,
+};
+
+struct DocumentSymbolClientCapabilities {
+    /// Specific capabilities for the `SymbolKind` in the
+    /// `textDocument/documentSymbol` request.
+    struct {
+        /// The symbol kind values the client supports. When this
+        /// property exists the client also guarantees that it will
+        /// handle values outside its set gracefully and falls back
+        /// to a default value when unknown.
+        //
+        /// If this property is not present the client only supports
+        /// the symbol kinds from `File` to `Array` as defined in
+        /// the initial version of the protocol.
+        array<SymbolKind> valueSet;
+    } symbolKind;
+
+    /// The client supports hierarchical document symbols.
+    bool hierarchicalDocumentSymbolSupport;
+
+    /// The client supports tags on `SymbolInformation`. Tags are supported on
+    /// `DocumentSymbol` if `hierarchicalDocumentSymbolSupport` is set to true.
+    /// Clients supporting tags have to handle unknown tags gracefully.
+    struct {
+        /// The tags supported by the client.
+        array<SymbolTag> valueSet;
+    } tagSupport;
+
+    /// The client supports an additional label presented in the UI when
+    /// registering a document symbol provider.
+    bool labelSupport;
+};
 
 struct DocumentSymbolOptions {};
 
+struct DocumentSymbolParams {
+    /// The text document.
+    TextDocumentIdentifier textDocument;
+};
+
+/// Represents programming constructs like variables, classes, interfaces etc.
+/// that appear in a document. Document symbols can be hierarchical and they
+/// have two ranges: one that encloses its definition and one that points to its
+/// most interesting range, e.g. the range of an identifier.
+struct DocumentSymbol {
+    /// The name of this symbol. Will be displayed in the user interface and
+    /// therefore must not be an empty string or a string only consisting of
+    /// white spaces.
+    string name;
+
+    /// More detail for this symbol, e.g the signature of a function.
+    string detail;
+
+    /// The kind of this symbol.
+    SymbolKind kind;
+
+    /// Tags for this document symbol.
+    array<SymbolTag> tags;
+
+    /// The range enclosing this symbol not including leading/trailing whitespace
+    /// but everything else like comments. This information is typically used to
+    /// determine if the clients cursor is inside the symbol to reveal it  in the
+    /// UI.
+    Range range;
+
+    /// The range that should be selected and revealed when this symbol is being
+    /// picked, e.g. the name of a function. Must be contained by the `range`.
+    Range selectionRange;
+
+    /// Children of this symbol, e.g. properties of a class.
+    array<DocumentSymbol> children;
+};
+
 }  // namespace clice::proto

include/Protocol/Initialize.h

@@ -106,7 +106,7 @@ struct ServerCapabilities {
     /// FIXME: DocumentHighlightOptions documentHighlightProvider;
 
     /// The server provides document symbol support.
-    /// FIXME: DocumentSymbolOptions documentSymbolProvider;
+    DocumentSymbolOptions documentSymbolProvider;
 
     /// The server provides code actions. The `CodeActionOptions` return type is
     /// only valid if the client signals code action literal support via the