| // Copyright 2019 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 source |
| |
| import ( |
| "context" |
| "go/ast" |
| "go/token" |
| "sort" |
| |
| "golang.org/x/tools/internal/lsp/protocol" |
| ) |
| |
| // FoldingRangeInfo holds range and kind info of folding for an ast.Node |
| type FoldingRangeInfo struct { |
| MappedRange |
| Kind protocol.FoldingRangeKind |
| } |
| |
| // FoldingRange gets all of the folding range for f. |
| func FoldingRange(ctx context.Context, snapshot Snapshot, fh FileHandle, lineFoldingOnly bool) (ranges []*FoldingRangeInfo, err error) { |
| // TODO(suzmue): consider limiting the number of folding ranges returned, and |
| // implement a way to prioritize folding ranges in that case. |
| pgf, err := snapshot.ParseGo(ctx, fh, ParseFull) |
| if err != nil { |
| return nil, err |
| } |
| fset := snapshot.FileSet() |
| |
| // Get folding ranges for comments separately as they are not walked by ast.Inspect. |
| ranges = append(ranges, commentsFoldingRange(fset, pgf.Mapper, pgf.File)...) |
| |
| visit := func(n ast.Node) bool { |
| rng := foldingRangeFunc(fset, pgf.Mapper, n, lineFoldingOnly) |
| if rng != nil { |
| ranges = append(ranges, rng) |
| } |
| return true |
| } |
| // Walk the ast and collect folding ranges. |
| ast.Inspect(pgf.File, visit) |
| |
| sort.Slice(ranges, func(i, j int) bool { |
| irng, _ := ranges[i].Range() |
| jrng, _ := ranges[j].Range() |
| return protocol.CompareRange(irng, jrng) < 0 |
| }) |
| |
| return ranges, nil |
| } |
| |
| // foldingRangeFunc calculates the line folding range for ast.Node n |
| func foldingRangeFunc(fset *token.FileSet, m *protocol.ColumnMapper, n ast.Node, lineFoldingOnly bool) *FoldingRangeInfo { |
| // TODO(suzmue): include trailing empty lines before the closing |
| // parenthesis/brace. |
| var kind protocol.FoldingRangeKind |
| var start, end token.Pos |
| switch n := n.(type) { |
| case *ast.BlockStmt: |
| // Fold between positions of or lines between "{" and "}". |
| var startList, endList token.Pos |
| if num := len(n.List); num != 0 { |
| startList, endList = n.List[0].Pos(), n.List[num-1].End() |
| } |
| start, end = validLineFoldingRange(fset, n.Lbrace, n.Rbrace, startList, endList, lineFoldingOnly) |
| case *ast.CaseClause: |
| // Fold from position of ":" to end. |
| start, end = n.Colon+1, n.End() |
| case *ast.CommClause: |
| // Fold from position of ":" to end. |
| start, end = n.Colon+1, n.End() |
| case *ast.CallExpr: |
| // Fold from position of "(" to position of ")". |
| start, end = n.Lparen+1, n.Rparen |
| case *ast.FieldList: |
| // Fold between positions of or lines between opening parenthesis/brace and closing parenthesis/brace. |
| var startList, endList token.Pos |
| if num := len(n.List); num != 0 { |
| startList, endList = n.List[0].Pos(), n.List[num-1].End() |
| } |
| start, end = validLineFoldingRange(fset, n.Opening, n.Closing, startList, endList, lineFoldingOnly) |
| case *ast.GenDecl: |
| // If this is an import declaration, set the kind to be protocol.Imports. |
| if n.Tok == token.IMPORT { |
| kind = protocol.Imports |
| } |
| // Fold between positions of or lines between "(" and ")". |
| var startSpecs, endSpecs token.Pos |
| if num := len(n.Specs); num != 0 { |
| startSpecs, endSpecs = n.Specs[0].Pos(), n.Specs[num-1].End() |
| } |
| start, end = validLineFoldingRange(fset, n.Lparen, n.Rparen, startSpecs, endSpecs, lineFoldingOnly) |
| case *ast.CompositeLit: |
| // Fold between positions of or lines between "{" and "}". |
| var startElts, endElts token.Pos |
| if num := len(n.Elts); num != 0 { |
| startElts, endElts = n.Elts[0].Pos(), n.Elts[num-1].End() |
| } |
| start, end = validLineFoldingRange(fset, n.Lbrace, n.Rbrace, startElts, endElts, lineFoldingOnly) |
| } |
| |
| // Check that folding positions are valid. |
| if !start.IsValid() || !end.IsValid() { |
| return nil |
| } |
| // in line folding mode, do not fold if the start and end lines are the same. |
| if lineFoldingOnly && fset.Position(start).Line == fset.Position(end).Line { |
| return nil |
| } |
| return &FoldingRangeInfo{ |
| MappedRange: NewMappedRange(fset, m, start, end), |
| Kind: kind, |
| } |
| } |
| |
| // validLineFoldingRange returns start and end token.Pos for folding range if the range is valid. |
| // returns token.NoPos otherwise, which fails token.IsValid check |
| func validLineFoldingRange(fset *token.FileSet, open, close, start, end token.Pos, lineFoldingOnly bool) (token.Pos, token.Pos) { |
| if lineFoldingOnly { |
| if !open.IsValid() || !close.IsValid() { |
| return token.NoPos, token.NoPos |
| } |
| |
| // Don't want to fold if the start/end is on the same line as the open/close |
| // as an example, the example below should *not* fold: |
| // var x = [2]string{"d", |
| // "e" } |
| if fset.Position(open).Line == fset.Position(start).Line || |
| fset.Position(close).Line == fset.Position(end).Line { |
| return token.NoPos, token.NoPos |
| } |
| |
| return open + 1, end |
| } |
| return open + 1, close |
| } |
| |
| // commentsFoldingRange returns the folding ranges for all comment blocks in file. |
| // The folding range starts at the end of the first comment, and ends at the end of the |
| // comment block and has kind protocol.Comment. |
| func commentsFoldingRange(fset *token.FileSet, m *protocol.ColumnMapper, file *ast.File) (comments []*FoldingRangeInfo) { |
| for _, commentGrp := range file.Comments { |
| // Don't fold single comments. |
| if len(commentGrp.List) <= 1 { |
| continue |
| } |
| comments = append(comments, &FoldingRangeInfo{ |
| // Fold from the end of the first line comment to the end of the comment block. |
| MappedRange: NewMappedRange(fset, m, commentGrp.List[0].End(), commentGrp.End()), |
| Kind: protocol.Comment, |
| }) |
| } |
| return comments |
| } |