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// Copyright 2022 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 lsppos
import (
"errors"
"go/ast"
"go/token"
"golang.org/x/tools/gopls/internal/lsp/protocol"
"golang.org/x/tools/gopls/internal/lsp/safetoken"
)
// TokenMapper maps token.Pos to LSP positions for a single file.
type TokenMapper struct {
// file is used for computing offsets.
file *token.File
// For now, just delegate to a Mapper for position calculation. As an
// optimization we could avoid building the mapper and just use the file, but
// then have to correctly adjust for newline-terminated files. It is easier
// to just delegate unless performance becomes a concern.
mapper *Mapper
}
// NewTokenMapper creates a new TokenMapper for the given content, using the
// provided file to compute offsets.
func NewTokenMapper(content []byte, file *token.File) *TokenMapper {
return &TokenMapper{
file: file,
mapper: NewMapper(content),
}
}
// Position returns the protocol position corresponding to the given pos. It
// returns false if pos is out of bounds for the file being mapped.
func (m *TokenMapper) Position(pos token.Pos) (protocol.Position, bool) {
offset, err := safetoken.Offset(m.file, pos)
if err != nil {
return protocol.Position{}, false
}
return m.mapper.Position(offset)
}
// Range returns the protocol range corresponding to the given start and end
// positions. It returns an error if start or end is out of bounds for the file
// being mapped.
func (m *TokenMapper) Range(start, end token.Pos) (protocol.Range, error) {
startPos, ok := m.Position(start)
if !ok {
return protocol.Range{}, errors.New("invalid start position")
}
endPos, ok := m.Position(end)
if !ok {
return protocol.Range{}, errors.New("invalid end position")
}
return protocol.Range{Start: startPos, End: endPos}, nil
}
// NodeRange returns the protocol range corresponding to the span of the given
// node.
func (m *TokenMapper) NodeRange(n ast.Node) (protocol.Range, error) {
return m.Range(n.Pos(), n.End())
}
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