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// 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 provides core features for use by Go editors and tools.
package source
import (
"bytes"
"context"
"fmt"
"go/ast"
"go/format"
"golang.org/x/tools/go/ast/astutil"
"golang.org/x/tools/imports"
)
// Format formats a file 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.
fset, err := f.GetFileSet()
if err != nil {
return nil, err
}
buf := &bytes.Buffer{}
if err := format.Node(buf, fset, node); err != nil {
return nil, err
}
return computeTextEdits(rng, buf.String()), nil
}
// Imports formats a file using the goimports tool.
func Imports(ctx context.Context, filename string, content []byte, rng Range) ([]TextEdit, error) {
content, err := imports.Process(filename, content, nil)
if err != nil {
return nil, err
}
return computeTextEdits(rng, string(content)), nil
}
// TODO(rstambler): Compute text edits instead of replacing whole file.
func computeTextEdits(rng Range, content string) []TextEdit {
return []TextEdit{
{
Range: rng,
NewText: content,
},
}
}
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