gir2swift
A simple GIR parser in Swift for creating Swift types for a .gir file
Getting Started
To start a project that uses Swift wrappers around low-level libraries that utilise gobject-introspection, you need to create some scripts that use gir2swift
to convert the information within gobject-introspection XML (.gir
) files into Swift. Here is a brief overview of the basic steps:
- Install the prerequisites on your system (see Prerequisites below)
- Compile
gir2swift
(see Building below) - Create a Swift Package Manager module that contains a system target for your underlying low-level library and a library target for the Swift Wrapper library that you want to build
- Create the necessary Module files (see Module Files below)
- Create a script that runs
gir2swift
(see Usage below) and then builds your project usingswift build
- If the build phase fails (more likely than not), add code that patches the generated Swift source files (e.g. using
awk
orsed
) to correct the errors the compiler complains about
What is new?
Version 14 automates post-processing using sed
and awk
, simplifying build-system integration.
Version 13 uses swift-argument-parser instead of getopt()
.
As of version 12.2, init(raw:)
is now required by the protocol and init(retainingRaw:)
is required for classes, closing PR#6.
Version 12 pulls in PR#10, addressing several issues:
- Improvements to the Build experience and LSP rhx/SwiftGtk#34
- Fix issues with LLDB rhx/SwiftGtk#39
- Controversial: Implicitly marks all declarations named "priv" as if they had attribute
private=1
- Prevents all "Private" records from generating unless generated in their instance record
-a
option generates all records
- Introduces CI
- For Class metadata types no longer generates class wrappers. Ref structs now contain static method which returnes the GType of the class and instance of the Class metatype wrapped in the Ref struct.
- Adds final class GWeak where T could be any Ref struct of a type which supports ARC. This class is a property wrapper which contains weak reference to any instance of T. This is especially beneficial for capture lists.
- Adds support for weak observation.
- Constructors and factories of GObjectInitiallyUnowned classes now consume floating reference upon initialisation as advised by the GObject documentation
Partially implemented:
- Typed signal generation. Issues shown in rhx/SwiftGtk#35 hat remain to be addressed are listed here: mikolasstuchlik/gir2swift#2.
Other Notable changes
Version 11 introduces a new type system into gir2swift
,
to ensure it has a representation of the underlying types.
This is necessary for Swift 5.3 onwards, which requires more stringent casts.
As a consequence, accessors can accept and return idiomatic Swift rather than
underlying types or pointers.
This means that a lot of the changes will be source-breaking for code that
was compiled against libraries built with earlier versions of gir2swift
.
- Parameters use idiomatic Swift names (e.g. camel case instead of snake case, splitting out of "for", "from", etc.)
- Requires Swift 5.2 or later
- Uses the namespace referenced in the
gir
file - Wrapper code is now
@inlinable
to enable the compiler to optimise away most of the wrappers - Parameters and return types use more idiomatic Swift (e.g.
Ref
wrappers instead of pointers,Int
instead ofgint
, etc.) - Functions that take or return records now are templated instead of using the type-erased Protocol
ErrorType
has been renamedGLibError
to ensure it neither clashes withSwift.Error
nor theGLib.ErrorType
scanner enum- Parameters or return types for records/classes now use the corresponding, lightweight Swift
Ref
wrapper instead of the underlying pointer
Usage
Synopsis
gir2swift [-v][-s][-m module_boilerplate.swift]{-p file.gir}[file.gir ...]
Description
gir2swift
takes the information from a gobject-introspection XML (file.gir
) file and creates corresponding Swift wrappers. When reading the .gir
file, gir2swift
also reads a number of Module Files that you create with additional information.
The following options are available:
-m Module.swift
AddModule.swift
as the main (hand-crafted) Swift file for your library target.
-o directory
Specify the output directory to put the generated files into.
-p pre.gir
Addpre.gir
as a pre-requisite.gir
file to ensure the types infile.gir
are known
-s
Create a single.swift
file per class
-v
Produce verbose output.
Examples
The following command generates a Swift Wrapper in Sources/GIO
from the information in /usr/share/gir-1.0/Gio-2.0.gir
, copying the content from Gio-2.0.module
and taking into account information in GLib-2.0.gir
and GObject-2.0.gir
:
gir2swift -o Sources/GIO -m Gio-2.0.module -p /usr/share/gir-1.0/GLib-2.0.gir -p /usr/share/gir-1.0/GObject-2.0.gir /usr/share/gir-1.0/Gio-2.0.gir
The Gio-2.0.module
file would need to contain the code that you would want to manually add to your Swift module, for example:
import CGLib
import GLib
import GLibObject
public struct GDatagramBased {}
public struct GUnixConnectionPrivate {}
public struct GUnixCredentialsMessagePrivate {}
public struct GUnixFDListPrivate {}
public struct GUnixFDMessagePrivate {}
public struct GUnixInputStreamPrivate {}
public struct GUnixOutputStreamPrivate {}
public struct GUnixSocketAddressPrivate {}
func g_io_module_load(_ module: UnsafeMutablePointer<GIOModule>) {
fatalError("private g_io_module_load called")
}
func g_io_module_unload(_ module: UnsafeMutablePointer<GIOModule>) {
fatalError("private g_io_module_unload called")
}
Also you would need a corresponding preamble file Gio-2.0.preamble
that imports the necessary low-level libraries, e.g.:
import CGLib
import GLib
import GLibObject
Module Files
In addition to reading a given Module.gir
file, gir2swift
also reads a number of module files from the current working directory that contain additional information. These module files need to have the same name as the .gir
file, but have a different file extension:
Module.preamble
This file contains the Swift code that you need to as the preamble for every generated .swift
file (e.g. the import
statements for all the modules you want to import).
Module.blacklist
This file contains the symbols (separated by newline) that you want to suppress in your output. Here you should include all the symbols in the .gir
file that the Swift compiler cannot import from the relevant C language headers.
Module.whitelist
This file contains the symbols (separated by newline) that would otherwise be suppressed (e.g. because gir2swift
thinks they are duplicates), but you would like to include in the gir2swift
output.
Module.verbatim
Normally, gir2swift
tries to translate constants from C to Swift, as per the definitions in the .gir
files. Names of constants listed (and separated by newline) in this file will not be translated.
Prerequisites
Swift
To build, you need at least Swift 5.2 (but some Linux distributions have issues and seem to require at least Swift 5.5), download from https://swift.org/download/ -- if you are using macOS, make sure you have the command line tools installed as well). Test that your compiler works using swift --version
, which should give you something like
$ swift --version
Apple Swift version 5.3.2 (swiftlang-1200.0.45 clang-1200.0.32.28)
Target: x86_64-apple-darwin20.3.0
on macOS, or on Linux you should get something like:
$ swift --version
Swift version 5.3.2 (swift-5.3.2-RELEASE)
Target: x86_64-unknown-linux-gnu
LibXML 2.9.4 or higher
These Swift wrappers have been tested with libxml-2.9.4 and 2.9.9. They should work with higher versions, but YMMV. Also make sure you have gobject-introspection
and its .gir
files installed.
macOS
On current versions of macOS, you need to install libxml2
using HomeBrew (the version that comes with the system does not include the necessary development headers -- for HomeBrew setup instructions, see http://brew.sh):
brew update
brew install libxml2 gobject-introspection
Linux
Ubuntu
On Ubuntu 16.04, 18.04 and 20.04, you can use the gtk that comes with the distribution. Just install with the apt
package manager:
sudo apt update
sudo apt install libxml2-dev gobject-introspection libgirepository1.0-dev
Fedora
On Fedora 29, you can use the gtk that comes with the distribution. Just install with the dnf
package manager:
sudo dnf install libxml2-devel gobject-introspection-devel
Building
Normally, you don't build this package directly, but you embed it into your own project (see 'Embedding' below). However, you can build and test this module separately to ensure that everything works. Make sure you have all the prerequisites installed (see above). After that, you can simply clone this repository and build the command line executable (be patient, this will download all the required dependencies and take a while to compile) using
git clone https://github.com/rhx/gir2swift.git
cd gir2swift
./build.sh
Xcode
On macOS, you can build the project using Xcode instead. To do this, you need to create an Xcode project first, then open the project in the Xcode IDE:
./xcodegen.sh
open gir2swift.xcodeproj
After that, use the (usual) Build and Test buttons to build/test this package.
Troubleshooting
Here are some common errors you might encounter and how to fix them.
.gir
Files
Missing If you get an error such as
Girs located at
Cannot open '/GLib-2.0.gir': No such file or directory
Make sure that you have the relevant gobject-introspection
packages installed (as per the Pre-requisites section), including their .gir
and .pc
files.
Old Swift toolchain or Xcode
If, when you run swift build
, you get a Segmentation fault (core dumped)
or circular dependency error such as
warning: circular dependency detected while parsing pangocairo: harfbuzz -> freetype2 -> harfbuzz
this probably means that your Swift toolchain is too old, particularly on Linux (at the time of this writing, some Linux distributions require at least Swift 5.5). Make sure the latest toolchain is the one that is found when you run the Swift compiler (see above).
If you get an older version, make sure that the right version of the swift compiler is found first in your PATH
. On macOS, use xcode-select to select and install the latest version, e.g.:
sudo xcode-select -s /Applications/Xcode.app
xcode-select --install
Known Issues
- The new build system scripts do not support directory paths with spaces (e.g. the
My Drive
directory used by Google Drive File Stream). As a workaround, use the old build scripts, e.g../build.sh
instead ofrun-gir2swift.sh
andswift build
to build a package. - BUILD_DIR is not suported in the new build system.