gomacro

Procedural macro toolbox for Golang.

Install

go get github.com/tdakkota/gomacro

Example

package main
import (
    "go/ast"
    "io/ioutil"
    "os"
    builders "github.com/tdakkota/astbuilders"
    macro "github.com/tdakkota/gomacro"
    "github.com/tdakkota/gomacro/runner"
)
// hello() -> println("Hello, ", "World")
// hello(arg) -> println("Hello, ", arg)
// hello(args...) -> println("Hello, ", args...)
func Macro() macro.Handler {
    return macro.OnlyFunction("hello", func(ctx macro.Context, call *ast.CallExpr) error {
        args := append([]ast.Expr{builders.StringLit("hello, ")}, call.Args...)
        if len(call.Args) == 0 {
            args = append(args, builders.StringLit("world"))
        }
        toReplace := builders.CallName("println", args...)
        ctx.Replace(toReplace)
        return nil
    })
}
const src = `
package main
//procm:use=runme
func main() {
    hello()
}
`
func writeTempFile(src string) (string, error) {
    f, err := ioutil.TempFile("", "src.*.go")
    if err != nil {
        return "", err
    }
    defer f.Close()
    _, err = f.WriteString(src)
    if err != nil {
        return "", err
    }
    return f.Name(), nil
}
func main() {
    srcPath, err := writeTempFile(src)
    if err != nil {
        panic(err)
    }
    err = runner.Print(srcPath, os.Stdout, macro.Macros{
        "runme": Macro(),
    })
    if err != nil {
        panic(err)
    }
}

Output:

package main        
//procm:use=runme           
func main() {               
    println("hello, ", "world")          
}