将项目添加到 Go AST 后评论乱序
以下测试尝试使用 AST 向结构添加字段。字段添加正确，但注释添加顺序不正确。我认为可能需要手动指定位置，但到目前为止我已经找到了答案。
这是一个失败的测试：http : //play.golang.org/p/RID4N30FZK
这是代码：
package generator
import (
"bytes"
"fmt"
"go/ast"
"go/parser"
"go/printer"
"go/token"
"testing"
)
func TestAst(t *testing.T) {
source := `package a
// B comment
type B struct {
// C comment
C string
}`
fset := token.NewFileSet()
file, err := parser.ParseFile(fset, "", []byte(source), parser.ParseComments)
if err != nil {
t.Error(err)
}
v := &visitor{
file: file,
}
ast.Walk(v, file)
var output []byte
buf := bytes.NewBuffer(output)
if err := printer.Fprint(buf, fset, file); err != nil {
t.Error(err)
}
expected := `package a
// B comment
type B struct {
// C comment
C string
// D comment
D int
// E comment
E float64
}
`
if buf.String() != expected {
t.Error(fmt.Sprintf("Test failed. Expected:\n%s\nGot:\n%s", expected, buf.String()))
}
/*
actual output = `package a
// B comment
type B struct {
// C comment
// D comment
// E comment
C string
D int
E float64
}
`
*/
}
type visitor struct {
file *ast.File
}
func (v *visitor) Visit(node ast.Node) (w ast.Visitor) {
if node == nil {
return v
}
switch n := node.(type) {
case *ast.GenDecl:
if n.Tok != token.TYPE {
break
}
ts := n.Specs[0].(*ast.TypeSpec)
if ts.Name.Name == "B" {
fields := ts.Type.(*ast.StructType).Fields
addStructField(fields, v.file, "int", "D", "D comment")
addStructField(fields, v.file, "float64", "E", "E comment")
}
}
return v
}
慕妹32420032回答
-
明月笑刀无情
我相信我已经让它发挥作用了。正如我在上面的评论中所述，所需的要点是：具体设置缓冲区位置包括Slash和NamePos用于token.File.AddLine在特定偏移处添加新行（使用第 1 项中的位置计算）过度分配源缓冲区token.File.Position（由源缓冲区使用，printer.Printer并且token.File.Addline不会使源缓冲区的范围检查失败代码：package mainimport ( "bytes" "fmt" "go/ast" "go/parser" "go/printer" "go/token" "testing")func main() { tests := []testing.InternalTest{{"TestAst", TestAst}} matchAll := func(t string, pat string) (bool, error) { return true, nil } testing.Main(matchAll, tests, nil, nil)}func TestAst(t *testing.T) { source := `package a// B commenttype B struct { // C comment C string}` buffer := make([]byte, 1024, 1024) for idx,_ := range buffer { buffer[idx] = 0x20 } copy(buffer[:], source) fset := token.NewFileSet() file, err := parser.ParseFile(fset, "", buffer, parser.ParseComments) if err != nil { t.Error(err) } v := &visitor{ file: file, fset: fset, } ast.Walk(v, file) var output []byte buf := bytes.NewBuffer(output) if err := printer.Fprint(buf, fset, file); err != nil { t.Error(err) } expected := `package a// B commenttype B struct { // C comment C string // D comment D int // E comment E float64}` if buf.String() != expected { t.Error(fmt.Sprintf("Test failed. Expected:\n%s\nGot:\n%s", expected, buf.String())) }}type visitor struct { file *ast.File fset *token.FileSet}func (v *visitor) Visit(node ast.Node) (w ast.Visitor) { if node == nil { return v } switch n := node.(type) { case *ast.GenDecl: if n.Tok != token.TYPE { break } ts := n.Specs[0].(*ast.TypeSpec) if ts.Name.Name == "B" { fields := ts.Type.(*ast.StructType).Fields addStructField(v.fset, fields, v.file, "int", "D", "D comment") addStructField(v.fset, fields, v.file, "float64", "E", "E comment") } } return v}func addStructField(fset *token.FileSet, fields *ast.FieldList, file *ast.File, typ string, name string, comment string) { prevField := fields.List[fields.NumFields()-1] c := &ast.Comment{Text: fmt.Sprint("// ", comment), Slash: prevField.End() + 1} cg := &ast.CommentGroup{List: []*ast.Comment{c}} o := ast.NewObj(ast.Var, name) f := &ast.Field{ Doc: cg, Names: []*ast.Ident{&ast.Ident{Name: name, Obj: o, NamePos: cg.End() + 1}}, } o.Decl = f f.Type = &ast.Ident{Name: typ, NamePos: f.Names[0].End() + 1} fset.File(c.End()).AddLine(int(c.End())) fset.File(f.End()).AddLine(int(f.End())) fields.List = append(fields.List, f) file.Comments = append(file.Comments, cg)}示例：http : //play.golang.org/p/_q1xh3giHm对于Item (3)，将所有过度分配的字节设置为空格 ( 0x20)也很重要，以便打印机在处理它们时不会抱怨空字节。
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相关分类
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