| // Copyright 2018 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 ( |
| "bytes" |
| "context" |
| "fmt" |
| "go/ast" |
| "go/format" |
| |
| "golang.org/x/tools/go/ast/astutil" |
| ) |
| |
| // Format formats a document with a given range. |
| func Format(ctx context.Context, f *File, rng Range) ([]TextEdit, error) { |
| fAST, err := f.GetAST() |
| if err != nil { |
| return nil, err |
| } |
| path, exact := astutil.PathEnclosingInterval(fAST, rng.Start, rng.End) |
| if !exact || len(path) == 0 { |
| return nil, fmt.Errorf("no exact AST node matching the specified range") |
| } |
| node := path[0] |
| // format.Node can fail when the AST contains a bad expression or |
| // statement. For now, we preemptively check for one. |
| // TODO(rstambler): This should really return an error from format.Node. |
| var isBad bool |
| ast.Inspect(node, func(n ast.Node) bool { |
| switch n.(type) { |
| case *ast.BadDecl, *ast.BadExpr, *ast.BadStmt: |
| isBad = true |
| return false |
| default: |
| return true |
| } |
| }) |
| if isBad { |
| return nil, fmt.Errorf("unable to format file due to a badly formatted AST") |
| } |
| // format.Node changes slightly from one release to another, so the version |
| // of Go used to build the LSP server will determine how it formats code. |
| // This should be acceptable for all users, who likely be prompted to rebuild |
| // the LSP server on each Go release. |
| buf := &bytes.Buffer{} |
| if err := format.Node(buf, f.view.Config.Fset, node); err != nil { |
| return nil, err |
| } |
| // TODO(rstambler): Compute text edits instead of replacing whole file. |
| return []TextEdit{ |
| { |
| Range: rng, |
| NewText: buf.String(), |
| }, |
| }, nil |
| } |