Is it possible to generate both the Swift and Objective-C signature for a token?

[jverkoey]

Asking in case anyone knows the answer already, but digging in right now :)

[jpsim]

The very very first version of jazzy used an internal binary to do this called sourcekitd-test that shipped with the first two betas of Xcode 6 IIRC: https://github.com/realm/jazzy/blob/0.0.4/bin/generate_swift_header.sh

This first version of jazzy was designed to just build docs for Objective-C headers with both Swift and Objective-C interface declarations.

When this private binary disappeared, I shifted gears with jazzy to just generate docs for Swift projects. I've never actively tried to reproduce the original behavior of generating the Swift interface to an Objective-C declaration, but it would most certainly be done via SourceKit.

[jpsim]

Running Xcode with the SOURCEKIT_LOGGING=3 environment variable just now to see what XPC request is sent when requesting the Swift interface to an Objective-C file, here's what the request looks like:

{
  key.request: source.request.editor.open.interface.header,
  key.name: "6FFBEC1C-2E70-43C9-BE02-3F9CF2F7A313",
  key.filepath: "/Users/jp/Projects/SourceKitten/Source/SourceKittenFramework/clang-c/Documentation.h",
  key.compilerargs: [
    "-x",
    "objective-c",
    "/Users/jp/Projects/SourceKitten/Source/SourceKittenFramework/clang-c/Documentation.h",
    "-isysroot",
    "/Applications/Xcode-7.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk"
  ]
}

and the response:

{
  key.sourcetext: "/*==-- clang-c/Documentation.h - Utilities for comment processing -*- C -*-===*\
|*                                                                            *|
|*                     The LLVM Compiler Infrastructure                       *|
|*                                                                            *|
|* This file is distributed under the University of Illinois Open Source      *|
|* License. See LICENSE.TXT for details.                                      *|
|*                                                                            *|
|*===----------------------------------------------------------------------===*|
|*                                                                            *|
|* This header provides a supplementary interface for inspecting              *|
|* documentation comments.                                                    *|
|*                                                                            *|
\*===----------------------------------------------------------------------===*/

/**
 * \defgroup CINDEX_COMMENT Comment introspection
 *
 * The routines in this group provide access to information in documentation
 * comments. These facilities are distinct from the core and may be subject to
 * their own schedule of stability and deprecation.
 *
 * @{
 */

/**
 * \brief A parsed comment.
 */
public struct CXComment {
    public var ASTNode: UnsafePointer<Void>
    public var TranslationUnit: Int32
    public init()
    public init(ASTNode: UnsafePointer<Void>, TranslationUnit: Int32)
}

// this goes on for a while
// ...

/**
 * \brief Convert a given full parsed comment to an XML document.
 *
 * A Relax NG schema for the XML can be found in comment-xml-schema.rng file
 * inside clang source tree.
 *
 * \param Comment a \c CXComment_FullComment AST node.
 *
 * \returns string containing an XML document.
 */
public var CXString: Int32
",
  key.annotations: [
    {
      key.kind: source.lang.swift.ref.struct,
      key.offset: 1419,
      key.length: 13,
      key.is_system: 1
    },
    {
      key.kind: source.lang.swift.ref.typealias,
      key.offset: 1433,
      key.length: 4,
      key.is_system: 1
    },
    {
      key.kind: source.lang.swift.ref.struct,
      key.offset: 1471,
      key.length: 5,
      key.is_system: 1
    },

// also goes on for a while
// ...

    {
      key.kind: source.lang.swift.ref.struct,
      key.offset: 13118,
      key.length: 5,
      key.is_system: 1
    }
  ],
  key.syntaxmap: [
    {
      key.kind: source.lang.swift.syntaxtype.comment,
      key.offset: 0,
      key.length: 1052
    },
    {
      key.kind: source.lang.swift.syntaxtype.doccomment,
      key.offset: 1054,
      key.length: 277
    },

// etc...


    {
      key.kind: source.lang.swift.syntaxtype.identifier,
      key.offset: 13108,
      key.length: 8
    },
    {
      key.kind: source.lang.swift.syntaxtype.typeidentifier,
      key.offset: 13118,
      key.length: 5
    }
  ],
  key.substructure: [
    {
      key.kind: source.lang.swift.decl.struct,
      key.accessibility: source.lang.swift.accessibility.public,
      key.name: "CXComment",
      key.offset: 1376,
      key.length: 190,
      key.nameoffset: 1383,
      key.namelength: 9,
      key.bodyoffset: 1394,
      key.bodylength: 171,
      key.substructure: [
        {
          key.kind: source.lang.swift.decl.var.instance,
          key.accessibility: source.lang.swift.accessibility.public,
          key.setter_accessibility: source.lang.swift.accessibility.public,
          key.name: "ASTNode",
          key.offset: 1406,
          key.length: 32,
          key.typename: "UnsafePointer<Void>",
          key.nameoffset: 1410,
          key.namelength: 7
        },
        {
          key.kind: source.lang.swift.decl.var.instance,
          key.accessibility: source.lang.swift.accessibility.public,
          key.setter_accessibility: source.lang.swift.accessibility.public,
          key.name: "TranslationUnit",
          key.offset: 1450,
          key.length: 26,
          key.typename: "Int32",
          key.nameoffset: 1454,
          key.namelength: 15
        },
        {
          key.kind: source.lang.swift.decl.function.method.instance,
          key.accessibility: source.lang.swift.accessibility.public,
          key.name: "init()",
          key.offset: 1488,
          key.length: 6,
          key.nameoffset: 1488,
          key.namelength: 6
        },

// etc...

    {
      key.kind: source.lang.swift.decl.var.global,
      key.accessibility: source.lang.swift.accessibility.public,
      key.setter_accessibility: source.lang.swift.accessibility.public,
      key.name: "CXString",
      key.offset: 13104,
      key.length: 19,
      key.typename: "Int32",
      key.nameoffset: 13108,
      key.namelength: 8
    }
  ]
}

So this is kind of promising, but sadly I don't see a surefire way of mapping from an Objective-C declaration to its Swift declaration. Only to get the Swift interface for a full Objective-C header.

However, if I option-click one of the generated tokens, the following XPC request is sent to SourceKit:

sourcekit: [2:sourcekitd_send_request-before:1295:151.0139] {
  key.request: source.request.cursorinfo,
  key.compilerargs: [
    "-x",
    "objective-c",
    "/Users/jp/Projects/SourceKitten/Source/SourceKittenFramework/clang-c/Index.h",
    "-isysroot",
    "/Applications/Xcode-7.1.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk"
  ],
  key.offset: 96274,
  key.sourcefile: "F5592DAF-75FC-407D-A282-9278702EA348"
}

which then generates this response:

sourcekit: [2:sourcekitd_send_request-after:48971:151.0153] {
  key.kind: source.lang.swift.decl.function.free,
  key.name: "clang_visitChildrenWithBlock(_:_:)",
  key.usr: "c:@F@clang_visitChildrenWithBlock",
  key.doc.full_as_xml: "<Function file="/Users/jp/Projects/SourceKitten/Source/SourceKittenFramework/clang-c/Index.h" line="3560" column="10"><Name>clang_visitChildrenWithBlock</Name><USR>c:@F@clang_visitChildrenWithBlock</USR><Declaration>func clang_visitChildrenWithBlock(parent: CXCursor, _ block: CXCursorVisitorBlock!) -> UInt32</Declaration><Abstract><Para> Visits the children of a cursor using the specified block.  Behaves identically to clang_visitChildren() in all other respects.</Para></Abstract></Function>",
  key.filepath: "/Users/jp/Projects/SourceKitten/Source/SourceKittenFramework/clang-c/Index.h",
  key.offset: 119462,
  key.length: 28,
  key.typename: "(CXCursor, CXCursorVisitorBlock!) -> UInt32",
  key.annotated_decl: "<Declaration>func clang_visitChildrenWithBlock(parent: <Type usr="c:@SA@CXCursor">CXCursor</Type>, _ block: <Type usr="c:Index.h@T@CXCursorVisitorBlock">CXCursorVisitorBlock</Type>!) -&gt; <Type usr="s:VSs6UInt32">UInt32</Type></Declaration>"
}

Which leads me to believe we should be able to map from Objective-C USR to the Swift USR if we perform the necessary shenanigans.

[jverkoey]

Hm, thanks for the background :) Looks like additional shenanigans are indeed required.

[jpsim]

Proof of concept: jpsim/SourceKitten#95

[jpsim]

Closing as a duplicate of #136.