コメントに関連付けられたコードを取得する #golang ref: http://qiita.com/tenntenn/items/090922826c9164ac5496

file0.go

// Hoge です。
type Hoge struct {
     N int
}

file1.go

package main

// comment for hoge
var hoge int

// comment for main
func main() {
    // line comment 1/2
    // line comment 2/2

    /*


        block comment1
            block comment2
    */
}

file2.go

fset := token.NewFileSet()
f, err := parser.ParseFile(fset, "sample.go", src, parser.ParseComments)
if err != nil {
    log.Fatalln("Error:", err)
}

file3.go

type File struct {
        Doc        *CommentGroup   // associated documentation; or nil
        Package    token.Pos       // position of "package" keyword
        Name       *Ident          // package name
        Decls      []Decl          // top-level declarations; or nil
        Scope      *Scope          // package scope (this file only)
        Imports    []*ImportSpec   // imports in this file
        Unresolved []*Ident        // unresolved identifiers in this file
        Comments   []*CommentGroup // list of all comments in the source file
}

file4.txt

type CommentGroup struct {
        List []*Comment // len(List) > 0
}

file5.go

for _, cg := range f.Comments {
    fmt.Println(cg.Text())
}

file6.txt

comment for hoge

comment for main

line comment 1/2
line comment 2/2

        block comment1
            block comment2

file7.go

type CommentMap map[Node][]*CommentGroup

file8.go

func NewCommentMap(fset *token.FileSet, node Node, comments []*CommentGroup) CommentMap

file9.go

func (cmap CommentMap) Filter(node Node) CommentMap {
    umap := make(CommentMap)
    Inspect(node, func(n Node) bool {
        if g := cmap[n]; len(g) > 0 {
            umap[n] = g
        }
        return true
    })
    return umap
}