goinject is a wrapper library for creating Go preprocessors.
goinject allows you to create custom preprocessors by defining a struct that satisfies the Modifier interface. This interface has only one method, Modify, which accepts a (*dst.File, *decorator.Decorator, *decorator.Restorer) representing the AST of a Go source file, file decorator and imports restorer. This method must return a modified *dst.File.
The goinject.Process function represents the generalized approach to preprocessing Go code. It performs the following steps:
- Checks if we are at the right stage of compilation.
- If not, runs the original command and returns.
- Extracts the files that Go is about to compile.
- Makes changes to the AST of all the files (without modifying the original source code).
- Writes the modified files to a temporary directory.
- Resolves all missing imports that were added as part of the modification.
- Substitutes the path to the original files with the path to the modified files and passes them to the compiler command.
- Runs the original command with the substituted files to be compiled.
Here's an example of how you can use goinject to modify a Go source file:
package main
import (
"github.com/pijng/goinject"
)
// CustomModifier implements the Modifier interface
type CustomModifier struct{}
// Modify implements the Modify method of the Modifier interface
func (cm CustomModifier) Modify(f *dst.File, dec *decorator.Decorator, res *decorator.Restorer) *dst.File {
// Add custom modification logic here
return f
}
func main() {
// Call goinject.Process with an instance of your modifier struct
goinject.Process(CustomModifier{})
}In this example, CustomModifier is a struct that satisfies the Modifier interface. It implements the Modify method, where you can define your custom modification logic.
- go_otel_auto_instrument:
go_otel_auto_instrumentis a preprocessor that automatically inject Opentelemtry tracing into your Go code. - prep:
prepis a small Go tool that enables compile-time function evaluation. - go-ifdef:
go-ifdefis a preprocessor that allows you to use trivial#ifdefand#elsedirectives based on the GOOS environment variable.