package source import ( "context" "go/ast" "go/token" "sort" "golang.org/x/tools/internal/lsp/protocol" ) 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. pgh := snapshot.View().Session().Cache().ParseGoHandle(ctx, fh, ParseFull) file, _, m, _, err := pgh.Parse(ctx) if err != nil { return nil, err } fset := snapshot.View().Session().Cache().FileSet() // Get folding ranges for comments separately as they are not walked by ast.Inspect. ranges = append(ranges, commentsFoldingRange(fset, m, file)...) foldingFunc := foldingRange if lineFoldingOnly { foldingFunc = lineFoldingRange } visit := func(n ast.Node) bool { rng := foldingFunc(fset, m, n) if rng != nil { ranges = append(ranges, rng) } return true } // Walk the ast and collect folding ranges. ast.Inspect(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 } // foldingRange calculates the folding range for n. func foldingRange(fset *token.FileSet, m *protocol.ColumnMapper, n ast.Node) *FoldingRangeInfo { var kind protocol.FoldingRangeKind var start, end token.Pos switch n := n.(type) { case *ast.BlockStmt: // Fold from position of "{" to position of "}". start, end = n.Lbrace+1, n.Rbrace case *ast.CaseClause: // 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 from position of opening parenthesis/brace, to position of // closing parenthesis/brace. start, end = n.Opening+1, n.Closing case *ast.GenDecl: // If this is an import declaration, set the kind to be protocol.Imports. if n.Tok == token.IMPORT { kind = protocol.Imports } start, end = n.Lparen+1, n.Rparen case *ast.CompositeLit: // Fold from position of "{" to position of "}". start, end = n.Lbrace+1, n.Rbrace } if !start.IsValid() || !end.IsValid() { return nil } return &FoldingRangeInfo{ mappedRange: newMappedRange(fset, m, start, end), Kind: kind, } } // lineFoldingRange calculates the line folding range for n. func lineFoldingRange(fset *token.FileSet, m *protocol.ColumnMapper, n ast.Node) *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 lines between "{" and "}". if !n.Lbrace.IsValid() || !n.Rbrace.IsValid() { break } nStmts := len(n.List) if nStmts == 0 { break } // Don't want to fold if the start is on the same line as the brace. if fset.Position(n.Lbrace).Line == fset.Position(n.List[0].Pos()).Line { break } // Don't want to fold if the end is on the same line as the brace. if fset.Position(n.Rbrace).Line == fset.Position(n.List[nStmts-1].End()).Line { break } start, end = n.Lbrace+1, n.List[nStmts-1].End() case *ast.CaseClause: // Fold from position of ":" to end. start, end = n.Colon+1, n.End() case *ast.FieldList: // Fold lines between opening parenthesis/brace and closing parenthesis/brace. if !n.Opening.IsValid() || !n.Closing.IsValid() { break } nFields := len(n.List) if nFields == 0 { break } // Don't want to fold if the start is on the same line as the parenthesis/brace. if fset.Position(n.Opening).Line == fset.Position(n.List[nFields-1].End()).Line { break } // Don't want to fold if the end is on the same line as the parenthesis/brace. if fset.Position(n.Closing).Line == fset.Position(n.List[nFields-1].End()).Line { break } start, end = n.Opening+1, n.List[nFields-1].End() 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 from position of "(" to position of ")". if !n.Lparen.IsValid() || !n.Rparen.IsValid() { break } nSpecs := len(n.Specs) if nSpecs == 0 { break } // Don't want to fold if the end is on the same line as the parenthesis/brace. if fset.Position(n.Lparen).Line == fset.Position(n.Specs[0].Pos()).Line { break } // Don't want to fold if the end is on the same line as the parenthesis/brace. if fset.Position(n.Rparen).Line == fset.Position(n.Specs[nSpecs-1].End()).Line { break } start, end = n.Lparen+1, n.Specs[nSpecs-1].End() case *ast.CompositeLit: // Fold lines between "{" and "}". if !n.Lbrace.IsValid() || !n.Rbrace.IsValid() { break } if len(n.Elts) == 0 { break } start, end = n.Lbrace+1, n.Elts[len(n.Elts)-1].End() } // Check that folding positions are valid. if !start.IsValid() || !end.IsValid() { return nil } // Do not fold if the start and end lines are the same. if fset.Position(start).Line == fset.Position(end).Line { return nil } return &FoldingRangeInfo{ mappedRange: newMappedRange(fset, m, start, end), Kind: kind, } } // 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 }