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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package ast
import (
"go/token"
"sort"
"strconv"
)
// SortImports sorts runs of consecutive import lines in import blocks in f.
func SortImports(fset *token.FileSet, f *File) {
for _, d := range f.Decls {
d, ok := d.(*GenDecl)
if !ok || d.Tok != token.IMPORT {
// Not an import declaration, so we're done.
// Imports are always first.
break
}
if !d.Lparen.IsValid() {
// Not a block: sorted by default.
continue
}
// Identify and sort runs of specs on successive lines.
i := 0
for j, s := range d.Specs {
if j > i && fset.Position(s.Pos()).Line > 1+fset.Position(d.Specs[j-1].End()).Line {
// j begins a new run. End this one.
sortSpecs(fset, f, d.Specs[i:j])
i = j
}
}
sortSpecs(fset, f, d.Specs[i:])
}
}
func importPath(s Spec) string {
t, err := strconv.Unquote(s.(*ImportSpec).Path.Value)
if err == nil {
return t
}
return ""
}
type posSpan struct {
Start token.Pos
End token.Pos
}
func sortSpecs(fset *token.FileSet, f *File, specs []Spec) {
// Avoid work if already sorted (also catches < 2 entries).
sorted := true
for i, s := range specs {
if i > 0 && importPath(specs[i-1]) > importPath(s) {
sorted = false
break
}
}
if sorted {
return
}
// Record positions for specs.
pos := make([]posSpan, len(specs))
for i, s := range specs {
pos[i] = posSpan{s.Pos(), s.End()}
}
// Identify comments in this range.
// Any comment from pos[0].Start to the final line counts.
lastLine := fset.Position(pos[len(pos)-1].End).Line
cstart := len(f.Comments)
cend := len(f.Comments)
for i, g := range f.Comments {
if g.Pos() < pos[0].Start {
continue
}
if i < cstart {
cstart = i
}
if fset.Position(g.End()).Line > lastLine {
cend = i
break
}
}
comments := f.Comments[cstart:cend]
// Assign each comment to the import spec preceding it.
importComment := map[*ImportSpec][]*CommentGroup{}
specIndex := 0
for _, g := range comments {
for specIndex+1 < len(specs) && pos[specIndex+1].Start <= g.Pos() {
specIndex++
}
s := specs[specIndex].(*ImportSpec)
importComment[s] = append(importComment[s], g)
}
// Sort the import specs by import path.
// Reassign the import paths to have the same position sequence.
// Reassign each comment to abut the end of its spec.
// Sort the comments by new position.
sort.Sort(byImportPath(specs))
for i, s := range specs {
s := s.(*ImportSpec)
if s.Name != nil {
s.Name.NamePos = pos[i].Start
}
s.Path.ValuePos = pos[i].Start
s.EndPos = pos[i].End
for _, g := range importComment[s] {
for _, c := range g.List {
c.Slash = pos[i].End
}
}
}
sort.Sort(byCommentPos(comments))
}
type byImportPath []Spec // slice of *ImportSpec
func (x byImportPath) Len() int { return len(x) }
func (x byImportPath) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x byImportPath) Less(i, j int) bool { return importPath(x[i]) < importPath(x[j]) }
type byCommentPos []*CommentGroup
func (x byCommentPos) Len() int { return len(x) }
func (x byCommentPos) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x byCommentPos) Less(i, j int) bool { return x[i].Pos() < x[j].Pos() }
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