klotzandrew / go_generics

Templates, generics engine for Go

Generics

This project is bazel-free version of Google go_generics tool released with gVisor project.

It allows for generating code from template while still working with standard Go code. A great example of using it is ScyllaDB go-set package.

Installation

go get -u github.com/mmatczuk/go_generics/cmd/go_generics
go get -u github.com/mmatczuk/go_generics/cmd/go_merge

go_generics

go_generics reads a Go source file and writes a new version of that file with a few transformations applied to each. Namely:

1. Global types can be explicitly renamed with the -t option. For example, if -t=A=B is passed in, all references to A will be replaced with references to B; a function declaration like:

func f(arg *A)

would be renamed to:

func f(arg *B)

2. Global type definitions and their method sets will be removed when they're being renamed with -t. For example, if -t=A=B is passed in, the following definition and methods that existed in the input file wouldn't exist at all in the output file:

type A struct{}

func (*A) f() {}

3. All global types, variables, constants and functions (not methods) are prefixed and suffixed based on the option -prefix and -suffix arguments. For example, if -suffix=A is passed in, the following globals:

func f()
type t struct{}

would be renamed to:

func fA()
type tA struct{}

Some special tags are also modified. For example:

"state:.(t)"

would become:

"state:.(tA)"

4. The package is renamed to the value via the -p argument.

5. Value of constants can be modified with -c argument. Note that not just the top-level declarations are renamed, all references to them are also properly renamed as well, taking into account visibility rules and shadowing. For example, if -suffix=A is passed in, the following:

var b = 100

func f() {

    g(b)
    b := 0
    g(b)

}

Would be replaced with:

var bA = 100

func f() {

    g(bA)
    b := 0
    g(b)

}

Note that the second call to g() kept "b" as an argument because it refers to the local variable "b".

Unfortunately, go_generics does not handle anonymous fields with renamed types.

go_merge

go_merge merges multiple Go files into one, may be used in a pipeline before go_generics.

License

This project is distributed under the Apache 2.0 license. See the LICENSE file for details. It contains software from:

• github.com/google/gvisor, licensed under the Apache 2.0 license.

GitHub star is always appreciated!