more_complex_ast.go

package main

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

func main() {
	//Create a new token set for the file
	fset := token.NewFileSet()
	//Parse the file and create an AST
	file, err := parser.ParseFile(fset, "../nats_publisher/main.go", nil, parser.ParseComments)
	if err != nil {
		panic(err)
	}
	ast.Inspect(file, func(n ast.Node) bool {
		// Find Return Statements
		funcCall, ok := n.(*ast.CallExpr)
		if ok {
			mthd, ok := funcCall.Fun.(*ast.SelectorExpr)
			if ok {
				_, ok = mthd.X.(*ast.Ident)
				if ok {
					if mthd.Sel.Name == "Publish" && mthd.X.(*ast.Ident).Name == "ec" {
						fmt.Printf("Topic: %s \n", funcCall.Args[0].(*ast.BasicLit).Value)
					}
				}
			}
		}
		return true
	})
}