| // 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. |
| // It also removes duplicate imports when it is possible to do so without data loss. |
| 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 |
| specs := d.Specs[: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. |
| specs = append(specs, sortSpecs(fset, f, d.Specs[i:j])...) |
| i = j |
| } |
| } |
| specs = append(specs, sortSpecs(fset, f, d.Specs[i:])...) |
| d.Specs = specs |
| |
| // Deduping can leave a blank line before the rparen; clean that up. |
| if len(d.Specs) > 0 { |
| lastSpec := d.Specs[len(d.Specs)-1] |
| lastLine := fset.Position(lastSpec.Pos()).Line |
| if rParenLine := fset.Position(d.Rparen).Line; rParenLine > lastLine+1 { |
| fset.File(d.Rparen).MergeLine(rParenLine - 1) |
| } |
| } |
| } |
| } |
| |
| func importPath(s Spec) string { |
| t, err := strconv.Unquote(s.(*ImportSpec).Path.Value) |
| if err == nil { |
| return t |
| } |
| return "" |
| } |
| |
| func importName(s Spec) string { |
| n := s.(*ImportSpec).Name |
| if n == nil { |
| return "" |
| } |
| return n.Name |
| } |
| |
| func importComment(s Spec) string { |
| c := s.(*ImportSpec).Comment |
| if c == nil { |
| return "" |
| } |
| return c.Text() |
| } |
| |
| // collapse indicates whether prev may be removed, leaving only next. |
| func collapse(prev, next Spec) bool { |
| if importPath(next) != importPath(prev) || importName(next) != importName(prev) { |
| return false |
| } |
| return prev.(*ImportSpec).Comment == nil |
| } |
| |
| type posSpan struct { |
| Start token.Pos |
| End token.Pos |
| } |
| |
| func sortSpecs(fset *token.FileSet, f *File, specs []Spec) []Spec { |
| // Can't short-circuit here even if specs are already sorted, |
| // since they might yet need deduplication. |
| // A lone import, however, may be safely ignored. |
| if len(specs) <= 1 { |
| return specs |
| } |
| |
| // 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. |
| // Remove duplicates, when possible without data loss. |
| // 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(byImportSpec(specs)) |
| |
| // Dedup. Thanks to our sorting, we can just consider |
| // adjacent pairs of imports. |
| deduped := specs[:0] |
| for i, s := range specs { |
| if i == len(specs)-1 || !collapse(s, specs[i+1]) { |
| deduped = append(deduped, s) |
| } else { |
| p := s.Pos() |
| fset.File(p).MergeLine(fset.Position(p).Line) |
| } |
| } |
| specs = deduped |
| |
| // Fix up comment positions |
| 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)) |
| |
| return specs |
| } |
| |
| type byImportSpec []Spec // slice of *ImportSpec |
| |
| func (x byImportSpec) Len() int { return len(x) } |
| func (x byImportSpec) Swap(i, j int) { x[i], x[j] = x[j], x[i] } |
| func (x byImportSpec) Less(i, j int) bool { |
| ipath := importPath(x[i]) |
| jpath := importPath(x[j]) |
| if ipath != jpath { |
| return ipath < jpath |
| } |
| iname := importName(x[i]) |
| jname := importName(x[j]) |
| if iname != jname { |
| return iname < jname |
| } |
| return importComment(x[i]) < importComment(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() } |