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ANTLR4 Language Target, Runtime for Swift

Performance Note

To use ANTLR4 Swift target in production environment, make sure to turn on compiler optimizations by following these instructions if you use SwiftPM to build your project. If you are using Xcode to build your project, it's unlikely you will not use release build for production build.

Conclusion is, you need to turn on release mode (which will have all the optimization pre configured for you) so the ANTLR4 Swift target can have reasonable parsing speed.

Install ANTLR4

Make sure you have the ANTLR installed. The getting started guide should get you started.

Create a Swift lexer or parser

This is pretty much the same as creating a Java lexer or parser, except you need to specify the language target, for example:

$ antlr4 -Dlanguage=Swift MyGrammar.g4

For a full list of antlr4 tool options, please visit the tool documentation page.

Build your Swift project with ANTLR runtime

The following instructions assume Xcode as the IDE.

Note that even if you are otherwise using ANTLR from a binary distribution, you should compile the ANTLR Swift runtime from source, because the Swift language does not yet have a stable ABI.

ANTLR uses Swift Package Manager to generate Xcode project files. Note that Swift Package Manager does not currently support iOS, watchOS, or tvOS, so if you wish to use those platforms, you will need to alter the project build settings manually as appropriate.

Download source code for ANTLR

git clone https://github.com/antlr/antlr4

Generate Xcode project for ANTLR runtime

The boot.py script includes a wrapper around swift package generate-xcodeproj. Use this to generate Antlr4.xcodeproj for the ANTLR Swift runtime.

cd antlr4/runtime/Swift
python boot.py --gen-xcodeproj

Import ANTLR Swift runtime into your project

Open your own project in Xcode.

Open Finder in the runtime/Swift directory:

# From antlr4/runtime/Swift
open .

Drag Antlr4.xcodeproj into your project.

After this is done, your Xcode project navigator will be something like the screenshot below. In this example, your own project is "Smalltalk", and you will be able to see Antlr4.xcodeproj shown as a contained project.

Edit the build settings if necessary

Swift Package Manager currently does not support iOS, watchOS, or tvOS. If you wish to build for those platforms, you will need to alter the project build settings manually.

Add generated parser and lexer to project

Make sure the parsers/lexers generated in step 2 are added to the project. To do this, you can drag the generated files from Finder to the Xcode IDE. Remember to check Copy items if needed to make sure the files are actually moved into the project folder instead of symbolic links (see the screenshot below). After moving you will be able to see your files in the project navigator. Make sure that the Target Membership settings are correct for your project.

Add the ANTLR Swift runtime as a dependency

Select your own project in Xcode and go to the Build Phases settings panel. Add the ANTLR runtime under Target Dependencies and Link Binary With Libraries.

Build your project

The runtime and generated grammar should now build correctly.

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