ast-example.go

package main

import (
	"fmt"
	"go/ast"
	"go/parser"
)

func main() {
	expr := "or(eq(a,1),eq(a,2))"
	root, _ := parser.ParseExpr(expr)
	printExpr(root, "")

}

func printExpr(expr ast.Expr, prefix string) {
	switch e := expr.(type) {
	case *ast.CallExpr:
		fmt.Print(prefix, e.Fun, "(\n")
		for _, arg := range e.Args {
			printExpr(arg, prefix+"  ")
		}
		fmt.Print(prefix, ")\n")
	case *ast.Ident:
		fmt.Printf("%v%v\n", prefix, e.String())
	case *ast.BasicLit:
		fmt.Printf("%v%v\n", prefix, e.Value)
	default:
		fmt.Printf("%v%v (%T)\n", prefix, e, e)
	}
}