Generate Go source code

Question

I am looking for a way to generate Go source code.

I found go/parser to generate an AST form a Go source file but couldn't find a way to generate Go source from AST.

Guaiacol

Answer 1

To convert an AST to the source form one can use the go/printer package.

Example (adapted form of another example)

package main

import (
        "go/parser"
        "go/printer"
        "go/token"
        "os"
)

func main() {
        // src is the input for which we want to print the AST.
        src := `
package main
func main() {
        println("Hello, World!")
}
`

        // Create the AST by parsing src.
        fset := token.NewFileSet() // positions are relative to fset
        f, err := parser.ParseFile(fset, "", src, 0)
        if err != nil {
                panic(err)
        }

        printer.Fprint(os.Stdout, fset, f)

}

(also here)

---

Output:

package main

func main() {
        println("Hello, World!")
}

Threw

Cant see the benefits. I could just write the string to a file and run go fmt on it? – Michelle

@Michelle I know its a few years old, but code generation. you could build up an AST programmatically, then write out a file of the results. – Wargo