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go/internal/lsp/source/format.go
Ian Cottrell 2f43c6d1a2 internal/span: change to private fields
Change span to hide its fields and have validating accessors
This catches the cases where either the offset or the position is being used
when it was not set.
It also normalizes the forms as the API now controls them, and allows us to
simplify some of the logic.
The converters are now allowed to return an error, which lets us cleanly
propagate bad cases.
The lsp was then converted to the new format, and also had some error checking
of its own added on the top.
All this allowed me to find and fix a few issues, most notably a case where the
wrong column mapper was being used during the conversion of definition results.

Change-Id: Iebdf8901e8269b28aaef60caf76574baa25c46d4
Reviewed-on: https://go-review.googlesource.com/c/tools/+/167858
Run-TryBot: Ian Cottrell <iancottrell@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
2019-03-15 18:05:47 +00:00

83 lines
2.6 KiB
Go

// 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"
"strings"
"golang.org/x/tools/go/ast/astutil"
"golang.org/x/tools/imports"
"golang.org/x/tools/internal/lsp/diff"
"golang.org/x/tools/internal/span"
)
// Format formats a file with a given range.
func Format(ctx context.Context, f File, rng span.Range) ([]TextEdit, error) {
fAST := f.GetAST(ctx)
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 := f.GetFileSet(ctx)
buf := &bytes.Buffer{}
if err := format.Node(buf, fset, node); err != nil {
return nil, err
}
return computeTextEdits(ctx, f, buf.String()), nil
}
// Imports formats a file using the goimports tool.
func Imports(ctx context.Context, f File, rng span.Range) ([]TextEdit, error) {
formatted, err := imports.Process(f.GetToken(ctx).Name(), f.GetContent(ctx), nil)
if err != nil {
return nil, err
}
return computeTextEdits(ctx, f, string(formatted)), nil
}
func computeTextEdits(ctx context.Context, file File, formatted string) (edits []TextEdit) {
u := strings.SplitAfter(string(file.GetContent(ctx)), "\n")
f := strings.SplitAfter(formatted, "\n")
for _, op := range diff.Operations(u, f) {
s := span.New(file.URI(), span.NewPoint(op.I1+1, 1, 0), span.NewPoint(op.I2+1, 1, 0))
switch op.Kind {
case diff.Delete:
// Delete: unformatted[i1:i2] is deleted.
edits = append(edits, TextEdit{Span: s})
case diff.Insert:
// Insert: formatted[j1:j2] is inserted at unformatted[i1:i1].
edits = append(edits, TextEdit{Span: s, NewText: op.Content})
}
}
return edits
}