diff --git a/go/vendor/golang.org/x/text/width/gen.go b/go/vendor/golang.org/x/text/width/gen.go
new file mode 100644
index 0000000..092277e
--- /dev/null
+++ b/go/vendor/golang.org/x/text/width/gen.go
@@ -0,0 +1,115 @@
+// Copyright 2015 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.
+
+// +build ignore
+
+// This program generates the trie for width operations. The generated table
+// includes width category information as well as the normalization mappings.
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"math"
+	"unicode/utf8"
+
+	"golang.org/x/text/internal/gen"
+	"golang.org/x/text/internal/triegen"
+)
+
+// See gen_common.go for flags.
+
+func main() {
+	gen.Init()
+	genTables()
+	genTests()
+	gen.Repackage("gen_trieval.go", "trieval.go", "width")
+	gen.Repackage("gen_common.go", "common_test.go", "width")
+}
+
+func genTables() {
+	t := triegen.NewTrie("width")
+	// fold and inverse mappings. See mapComment for a description of the format
+	// of each entry. Add dummy value to make an index of 0 mean no mapping.
+	inverse := [][4]byte{{}}
+	mapping := map[[4]byte]int{[4]byte{}: 0}
+
+	getWidthData(func(r rune, tag elem, alt rune) {
+		idx := 0
+		if alt != 0 {
+			var buf [4]byte
+			buf[0] = byte(utf8.EncodeRune(buf[1:], alt))
+			s := string(r)
+			buf[buf[0]] ^= s[len(s)-1]
+			var ok bool
+			if idx, ok = mapping[buf]; !ok {
+				idx = len(mapping)
+				if idx > math.MaxUint8 {
+					log.Fatalf("Index %d does not fit in a byte.", idx)
+				}
+				mapping[buf] = idx
+				inverse = append(inverse, buf)
+			}
+		}
+		t.Insert(r, uint64(tag|elem(idx)))
+	})
+
+	w := &bytes.Buffer{}
+	gen.WriteUnicodeVersion(w)
+
+	sz, err := t.Gen(w)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	sz += writeMappings(w, inverse)
+
+	fmt.Fprintf(w, "// Total table size %d bytes (%dKiB)\n", sz, sz/1024)
+
+	gen.WriteVersionedGoFile(*outputFile, "width", w.Bytes())
+}
+
+const inverseDataComment = `
+// inverseData contains 4-byte entries of the following format:
+//   <length> <modified UTF-8-encoded rune> <0 padding>
+// The last byte of the UTF-8-encoded rune is xor-ed with the last byte of the
+// UTF-8 encoding of the original rune. Mappings often have the following
+// pattern:
+//   Ａ -> A  (U+FF21 -> U+0041)
+//   Ｂ -> B  (U+FF22 -> U+0042)
+//   ...
+// By xor-ing the last byte the same entry can be shared by many mappings. This
+// reduces the total number of distinct entries by about two thirds.
+// The resulting entry for the aforementioned mappings is
+//   { 0x01, 0xE0, 0x00, 0x00 }
+// Using this entry to map U+FF21 (UTF-8 [EF BC A1]), we get
+//   E0 ^ A1 = 41.
+// Similarly, for U+FF22 (UTF-8 [EF BC A2]), we get
+//   E0 ^ A2 = 42.
+// Note that because of the xor-ing, the byte sequence stored in the entry is
+// not valid UTF-8.`
+
+func writeMappings(w io.Writer, data [][4]byte) int {
+	fmt.Fprintln(w, inverseDataComment)
+	fmt.Fprintf(w, "var inverseData = [%d][4]byte{\n", len(data))
+	for _, x := range data {
+		fmt.Fprintf(w, "{ 0x%02x, 0x%02x, 0x%02x, 0x%02x },\n", x[0], x[1], x[2], x[3])
+	}
+	fmt.Fprintln(w, "}")
+	return len(data) * 4
+}
+
+func genTests() {
+	w := &bytes.Buffer{}
+	fmt.Fprintf(w, "\nvar mapRunes = map[rune]struct{r rune; e elem}{\n")
+	getWidthData(func(r rune, tag elem, alt rune) {
+		if alt != 0 {
+			fmt.Fprintf(w, "\t0x%X: {0x%X, 0x%X},\n", r, alt, tag)
+		}
+	})
+	fmt.Fprintln(w, "}")
+	gen.WriteGoFile("runes_test.go", "width", w.Bytes())
+}