blob: 643d59922764fdd7251eab76f6ca99f33f314c32 [file] [log] [blame]
// 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"
"go/ast"
"go/format"
"go/parser"
"go/scanner"
"go/token"
"golang.org/x/tools/internal/imports"
"golang.org/x/tools/internal/lsp/diff"
"golang.org/x/tools/internal/lsp/protocol"
"golang.org/x/tools/internal/span"
"golang.org/x/tools/internal/telemetry/event"
errors "golang.org/x/xerrors"
)
// Format formats a file with a given range.
func Format(ctx context.Context, snapshot Snapshot, fh FileHandle) ([]protocol.TextEdit, error) {
ctx, done := event.StartSpan(ctx, "source.Format")
defer done()
pgh := snapshot.View().Session().Cache().ParseGoHandle(fh, ParseFull)
file, _, m, parseErrors, err := pgh.Parse(ctx)
if err != nil {
return nil, err
}
// Even if this file has parse errors, it might still be possible to format it.
// Using format.Node on an AST with errors may result in code being modified.
// Attempt to format the source of this file instead.
if parseErrors != nil {
formatted, err := formatSource(ctx, snapshot, fh)
if err != nil {
return nil, err
}
return computeTextEdits(ctx, snapshot.View(), pgh.File(), m, string(formatted))
}
fset := snapshot.View().Session().Cache().FileSet()
buf := &bytes.Buffer{}
// 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.
if err := format.Node(buf, fset, file); err != nil {
return nil, err
}
return computeTextEdits(ctx, snapshot.View(), pgh.File(), m, buf.String())
}
func formatSource(ctx context.Context, s Snapshot, fh FileHandle) ([]byte, error) {
ctx, done := event.StartSpan(ctx, "source.formatSource")
defer done()
data, _, err := fh.Read(ctx)
if err != nil {
return nil, err
}
return format.Source(data)
}
type ImportFix struct {
Fix *imports.ImportFix
Edits []protocol.TextEdit
}
// AllImportsFixes formats f for each possible fix to the imports.
// In addition to returning the result of applying all edits,
// it returns a list of fixes that could be applied to the file, with the
// corresponding TextEdits that would be needed to apply that fix.
func AllImportsFixes(ctx context.Context, snapshot Snapshot, fh FileHandle) (allFixEdits []protocol.TextEdit, editsPerFix []*ImportFix, err error) {
ctx, done := event.StartSpan(ctx, "source.AllImportsFixes")
defer done()
pgh := snapshot.View().Session().Cache().ParseGoHandle(fh, ParseFull)
err = snapshot.View().RunProcessEnvFunc(ctx, func(opts *imports.Options) error {
allFixEdits, editsPerFix, err = computeImportEdits(ctx, snapshot.View(), pgh, opts)
return err
})
if err != nil {
return nil, nil, errors.Errorf("computing fix edits: %v", err)
}
return allFixEdits, editsPerFix, nil
}
// computeImportEdits computes a set of edits that perform one or all of the
// necessary import fixes.
func computeImportEdits(ctx context.Context, view View, ph ParseGoHandle, options *imports.Options) (allFixEdits []protocol.TextEdit, editsPerFix []*ImportFix, err error) {
filename := ph.File().Identity().URI.Filename()
// Build up basic information about the original file.
origData, _, err := ph.File().Read(ctx)
if err != nil {
return nil, nil, err
}
origAST, _, origMapper, _, err := ph.Parse(ctx)
if err != nil {
return nil, nil, err
}
allFixes, err := imports.FixImports(filename, origData, options)
if err != nil {
return nil, nil, err
}
origImports, origImportOffset := trimToImports(view.Session().Cache().FileSet(), origAST, origData)
allFixEdits, err = computeFixEdits(view, ph, options, origData, origAST, origMapper, origImports, origImportOffset, allFixes)
if err != nil {
return nil, nil, err
}
// Apply all of the import fixes to the file.
// Add the edits for each fix to the result.
for _, fix := range allFixes {
edits, err := computeFixEdits(view, ph, options, origData, origAST, origMapper, origImports, origImportOffset, []*imports.ImportFix{fix})
if err != nil {
return nil, nil, err
}
editsPerFix = append(editsPerFix, &ImportFix{
Fix: fix,
Edits: edits,
})
}
return allFixEdits, editsPerFix, nil
}
func computeOneImportFixEdits(ctx context.Context, view View, ph ParseGoHandle, fix *imports.ImportFix) ([]protocol.TextEdit, error) {
origData, _, err := ph.File().Read(ctx)
if err != nil {
return nil, err
}
origAST, _, origMapper, _, err := ph.Parse(ctx)
if err != nil {
return nil, err
}
origImports, origImportOffset := trimToImports(view.Session().Cache().FileSet(), origAST, origData)
options := &imports.Options{
// Defaults.
AllErrors: true,
Comments: true,
Fragment: true,
FormatOnly: false,
TabIndent: true,
TabWidth: 8,
}
return computeFixEdits(view, ph, options, origData, origAST, origMapper, origImports, origImportOffset, []*imports.ImportFix{fix})
}
func computeFixEdits(view View, ph ParseGoHandle, options *imports.Options, origData []byte, origAST *ast.File, origMapper *protocol.ColumnMapper, origImports []byte, origImportOffset int, fixes []*imports.ImportFix) ([]protocol.TextEdit, error) {
filename := ph.File().Identity().URI.Filename()
// Apply the fixes and re-parse the file so that we can locate the
// new imports.
fixedData, err := imports.ApplyFixes(fixes, filename, origData, options, parser.ImportsOnly)
fixedData = append(fixedData, '\n') // ApplyFixes comes out missing the newline, go figure.
if err != nil {
return nil, err
}
fixedFset := token.NewFileSet()
fixedAST, err := parser.ParseFile(fixedFset, filename, fixedData, parser.ImportsOnly)
// Any error here prevents us from computing the edits.
if err != nil {
return nil, err
}
fixedImports, fixedImportsOffset := trimToImports(fixedFset, fixedAST, fixedData)
// Prepare the diff. If both sides had import statements, we can diff
// just those sections against each other, then shift the resulting
// edits to the right lines in the original file.
left, right := origImports, fixedImports
converter := span.NewContentConverter(filename, origImports)
offset := origImportOffset
// If one side or the other has no imports, we won't know where to
// anchor the diffs. Instead, use the beginning of the file, up to its
// first non-imports decl. We know the imports code will insert
// somewhere before that.
if origImportOffset == 0 || fixedImportsOffset == 0 {
left, _ = trimToFirstNonImport(view.Session().Cache().FileSet(), origAST, origData, nil)
fixedData, err = imports.ApplyFixes(fixes, filename, origData, options, 0)
if err != nil {
return nil, err
}
// We need the whole file here, not just the ImportsOnly versions we made above.
fixedAST, err = parser.ParseFile(fixedFset, filename, fixedData, 0)
if fixedAST == nil {
return nil, err
}
var ok bool
right, ok = trimToFirstNonImport(fixedFset, fixedAST, fixedData, err)
if !ok {
return nil, errors.Errorf("error %v detected in the import block", err)
}
// We're now working with a prefix of the original file, so we can
// use the original converter, and there is no offset on the edits.
converter = origMapper.Converter
offset = 0
}
// Perform the diff and adjust the results for the trimming, if any.
edits := view.Options().ComputeEdits(ph.File().Identity().URI, string(left), string(right))
for i := range edits {
s, err := edits[i].Span.WithPosition(converter)
if err != nil {
return nil, err
}
start := span.NewPoint(s.Start().Line()+offset, s.Start().Column(), -1)
end := span.NewPoint(s.End().Line()+offset, s.End().Column(), -1)
edits[i].Span = span.New(s.URI(), start, end)
}
return ToProtocolEdits(origMapper, edits)
}
// trimToImports returns a section of the source file that covers all of the
// import declarations, and the line offset into the file that section starts at.
func trimToImports(fset *token.FileSet, f *ast.File, src []byte) ([]byte, int) {
var firstImport, lastImport ast.Decl
for _, decl := range f.Decls {
if gen, ok := decl.(*ast.GenDecl); ok && gen.Tok == token.IMPORT {
if firstImport == nil {
firstImport = decl
}
lastImport = decl
}
}
if firstImport == nil {
return nil, 0
}
tok := fset.File(f.Pos())
start := firstImport.Pos()
end := lastImport.End()
// The parser will happily feed us nonsense. See golang/go#36610.
tokStart, tokEnd := token.Pos(tok.Base()), token.Pos(tok.Base()+tok.Size())
if start < tokStart || start > tokEnd || end < tokStart || end > tokEnd {
return nil, 0
}
if nextLine := fset.Position(end).Line + 1; tok.LineCount() >= nextLine {
end = fset.File(f.Pos()).LineStart(nextLine)
}
startLineOffset := fset.Position(start).Line - 1 // lines are 1-indexed.
return src[fset.Position(firstImport.Pos()).Offset:fset.Position(end).Offset], startLineOffset
}
// trimToFirstNonImport returns src from the beginning to the first non-import
// declaration, or the end of the file if there is no such decl.
func trimToFirstNonImport(fset *token.FileSet, f *ast.File, src []byte, err error) ([]byte, bool) {
var firstDecl ast.Decl
for _, decl := range f.Decls {
if gen, ok := decl.(*ast.GenDecl); ok && gen.Tok == token.IMPORT {
continue
}
firstDecl = decl
break
}
tok := fset.File(f.Pos())
if tok == nil {
return nil, false
}
end := f.End()
if firstDecl != nil {
if firstDeclLine := fset.Position(firstDecl.Pos()).Line; firstDeclLine > 1 {
end = tok.LineStart(firstDeclLine - 1)
}
}
// Any errors in the file must be after the part of the file that we care about.
switch err := err.(type) {
case *scanner.Error:
pos := tok.Pos(err.Pos.Offset)
if pos <= end {
return nil, false
}
case scanner.ErrorList:
if err.Len() > 0 {
pos := tok.Pos(err[0].Pos.Offset)
if pos <= end {
return nil, false
}
}
}
return src[0:fset.Position(end).Offset], true
}
func computeTextEdits(ctx context.Context, view View, fh FileHandle, m *protocol.ColumnMapper, formatted string) ([]protocol.TextEdit, error) {
ctx, done := event.StartSpan(ctx, "source.computeTextEdits")
defer done()
data, _, err := fh.Read(ctx)
if err != nil {
return nil, err
}
edits := view.Options().ComputeEdits(fh.Identity().URI, string(data), formatted)
return ToProtocolEdits(m, edits)
}
func ToProtocolEdits(m *protocol.ColumnMapper, edits []diff.TextEdit) ([]protocol.TextEdit, error) {
if edits == nil {
return nil, nil
}
result := make([]protocol.TextEdit, len(edits))
for i, edit := range edits {
rng, err := m.Range(edit.Span)
if err != nil {
return nil, err
}
result[i] = protocol.TextEdit{
Range: rng,
NewText: edit.NewText,
}
}
return result, nil
}
func FromProtocolEdits(m *protocol.ColumnMapper, edits []protocol.TextEdit) ([]diff.TextEdit, error) {
if edits == nil {
return nil, nil
}
result := make([]diff.TextEdit, len(edits))
for i, edit := range edits {
spn, err := m.RangeSpan(edit.Range)
if err != nil {
return nil, err
}
result[i] = diff.TextEdit{
Span: spn,
NewText: edit.NewText,
}
}
return result, nil
}