diff --git a/go/vendor/github.com/golang/protobuf/protoc-gen-go/generator/internal/remap/remap.go b/go/vendor/github.com/golang/protobuf/protoc-gen-go/generator/internal/remap/remap.go
new file mode 100644
index 0000000..a9b6103
--- /dev/null
+++ b/go/vendor/github.com/golang/protobuf/protoc-gen-go/generator/internal/remap/remap.go
@@ -0,0 +1,117 @@
+// Go support for Protocol Buffers - Google's data interchange format
+//
+// Copyright 2017 The Go Authors.  All rights reserved.
+// https://github.com/golang/protobuf
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+/*
+Package remap handles tracking the locations of Go tokens in a source text
+across a rewrite by the Go formatter.
+*/
+package remap
+
+import (
+	"fmt"
+	"go/scanner"
+	"go/token"
+)
+
+// A Location represents a span of byte offsets in the source text.
+type Location struct {
+	Pos, End int // End is exclusive
+}
+
+// A Map represents a mapping between token locations in an input source text
+// and locations in the correspnding output text.
+type Map map[Location]Location
+
+// Find reports whether the specified span is recorded by m, and if so returns
+// the new location it was mapped to. If the input span was not found, the
+// returned location is the same as the input.
+func (m Map) Find(pos, end int) (Location, bool) {
+	key := Location{
+		Pos: pos,
+		End: end,
+	}
+	if loc, ok := m[key]; ok {
+		return loc, true
+	}
+	return key, false
+}
+
+func (m Map) add(opos, oend, npos, nend int) {
+	m[Location{Pos: opos, End: oend}] = Location{Pos: npos, End: nend}
+}
+
+// Compute constructs a location mapping from input to output.  An error is
+// reported if any of the tokens of output cannot be mapped.
+func Compute(input, output []byte) (Map, error) {
+	itok := tokenize(input)
+	otok := tokenize(output)
+	if len(itok) != len(otok) {
+		return nil, fmt.Errorf("wrong number of tokens, %d ≠ %d", len(itok), len(otok))
+	}
+	m := make(Map)
+	for i, ti := range itok {
+		to := otok[i]
+		if ti.Token != to.Token {
+			return nil, fmt.Errorf("token %d type mismatch: %s ≠ %s", i+1, ti, to)
+		}
+		m.add(ti.pos, ti.end, to.pos, to.end)
+	}
+	return m, nil
+}
+
+// tokinfo records the span and type of a source token.
+type tokinfo struct {
+	pos, end int
+	token.Token
+}
+
+func tokenize(src []byte) []tokinfo {
+	fs := token.NewFileSet()
+	var s scanner.Scanner
+	s.Init(fs.AddFile("src", fs.Base(), len(src)), src, nil, scanner.ScanComments)
+	var info []tokinfo
+	for {
+		pos, next, lit := s.Scan()
+		switch next {
+		case token.SEMICOLON:
+			continue
+		}
+		info = append(info, tokinfo{
+			pos:   int(pos - 1),
+			end:   int(pos + token.Pos(len(lit)) - 1),
+			Token: next,
+		})
+		if next == token.EOF {
+			break
+		}
+	}
+	return info
+}