playing around with go's ast

gistfile1.go

package main

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

const src = `
package main

import (
	"fmt"
	"math"
)

func main() {
	fmt.Println(math.Pi)
}

`

type Dependencies struct {
	Packages map[string][]string
}

func (d *Dependencies) Has(p, n string) bool {
	if pk, ok := d.Packages[p]; ok {
		for _, name := range pk {
			if n == name {
				return true
			}
		}
	}

	return false

}

func (d *Dependencies) Visit(node ast.Node) ast.Visitor {
	switch v := node.(type) {

	case *ast.SelectorExpr:
		var p string
		if ident, ok := v.X.(*ast.Ident); ok {
			p = ident.Name
		} else {
			break
		}
		n := v.Sel.Name
		if pk, ok := d.Packages[p]; ok {
			if !d.Has(p, n) {
				d.Packages[p] = append(pk, n)
			}
		} else {
			d.Packages[p] = []string{n}
		}
	}

	return ast.Visitor(d)
}

func main() {
	// src is the input for which we want to print the AST.

	// 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)
	}

	v := &Dependencies{make(map[string][]string)}

	ast.Walk(v, f)

	fmt.Printf("%#v", *v)
}