diff --git a/vendor/golang.org/x/text/internal/colltab/contract.go b/vendor/golang.org/x/text/internal/colltab/contract.go
new file mode 100644
index 0000000..25649d4
--- /dev/null
+++ b/vendor/golang.org/x/text/internal/colltab/contract.go
@@ -0,0 +1,145 @@
+// Copyright 2012 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 colltab
+
+import "unicode/utf8"
+
+// For a description of ContractTrieSet, see text/collate/build/contract.go.
+
+type ContractTrieSet []struct{ L, H, N, I uint8 }
+
+// ctScanner is used to match a trie to an input sequence.
+// A contraction may match a non-contiguous sequence of bytes in an input string.
+// For example, if there is a contraction for <a, combining_ring>, it should match
+// the sequence <a, combining_cedilla, combining_ring>, as combining_cedilla does
+// not block combining_ring.
+// ctScanner does not automatically skip over non-blocking non-starters, but rather
+// retains the state of the last match and leaves it up to the user to continue
+// the match at the appropriate points.
+type ctScanner struct {
+	states ContractTrieSet
+	s      []byte
+	n      int
+	index  int
+	pindex int
+	done   bool
+}
+
+type ctScannerString struct {
+	states ContractTrieSet
+	s      string
+	n      int
+	index  int
+	pindex int
+	done   bool
+}
+
+func (t ContractTrieSet) scanner(index, n int, b []byte) ctScanner {
+	return ctScanner{s: b, states: t[index:], n: n}
+}
+
+func (t ContractTrieSet) scannerString(index, n int, str string) ctScannerString {
+	return ctScannerString{s: str, states: t[index:], n: n}
+}
+
+// result returns the offset i and bytes consumed p so far.  If no suffix
+// matched, i and p will be 0.
+func (s *ctScanner) result() (i, p int) {
+	return s.index, s.pindex
+}
+
+func (s *ctScannerString) result() (i, p int) {
+	return s.index, s.pindex
+}
+
+const (
+	final   = 0
+	noIndex = 0xFF
+)
+
+// scan matches the longest suffix at the current location in the input
+// and returns the number of bytes consumed.
+func (s *ctScanner) scan(p int) int {
+	pr := p // the p at the rune start
+	str := s.s
+	states, n := s.states, s.n
+	for i := 0; i < n && p < len(str); {
+		e := states[i]
+		c := str[p]
+		// TODO: a significant number of contractions are of a form that
+		// cannot match discontiguous UTF-8 in a normalized string. We could let
+		// a negative value of e.n mean that we can set s.done = true and avoid
+		// the need for additional matches.
+		if c >= e.L {
+			if e.L == c {
+				p++
+				if e.I != noIndex {
+					s.index = int(e.I)
+					s.pindex = p
+				}
+				if e.N != final {
+					i, states, n = 0, states[int(e.H)+n:], int(e.N)
+					if p >= len(str) || utf8.RuneStart(str[p]) {
+						s.states, s.n, pr = states, n, p
+					}
+				} else {
+					s.done = true
+					return p
+				}
+				continue
+			} else if e.N == final && c <= e.H {
+				p++
+				s.done = true
+				s.index = int(c-e.L) + int(e.I)
+				s.pindex = p
+				return p
+			}
+		}
+		i++
+	}
+	return pr
+}
+
+// scan is a verbatim copy of ctScanner.scan.
+func (s *ctScannerString) scan(p int) int {
+	pr := p // the p at the rune start
+	str := s.s
+	states, n := s.states, s.n
+	for i := 0; i < n && p < len(str); {
+		e := states[i]
+		c := str[p]
+		// TODO: a significant number of contractions are of a form that
+		// cannot match discontiguous UTF-8 in a normalized string. We could let
+		// a negative value of e.n mean that we can set s.done = true and avoid
+		// the need for additional matches.
+		if c >= e.L {
+			if e.L == c {
+				p++
+				if e.I != noIndex {
+					s.index = int(e.I)
+					s.pindex = p
+				}
+				if e.N != final {
+					i, states, n = 0, states[int(e.H)+n:], int(e.N)
+					if p >= len(str) || utf8.RuneStart(str[p]) {
+						s.states, s.n, pr = states, n, p
+					}
+				} else {
+					s.done = true
+					return p
+				}
+				continue
+			} else if e.N == final && c <= e.H {
+				p++
+				s.done = true
+				s.index = int(c-e.L) + int(e.I)
+				s.pindex = p
+				return p
+			}
+		}
+		i++
+	}
+	return pr
+}