diff --git a/vendor/golang.org/x/text/internal/colltab/trie.go b/vendor/golang.org/x/text/internal/colltab/trie.go
new file mode 100644
index 0000000..a0eaa0d
--- /dev/null
+++ b/vendor/golang.org/x/text/internal/colltab/trie.go
@@ -0,0 +1,159 @@
+// 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.
+
+// The trie in this file is used to associate the first full character in an
+// UTF-8 string to a collation element. All but the last byte in a UTF-8 byte
+// sequence are used to lookup offsets in the index table to be used for the
+// next byte. The last byte is used to index into a table of collation elements.
+// For a full description, see go.text/collate/build/trie.go.
+
+package colltab
+
+const blockSize = 64
+
+type Trie struct {
+	Index0  []uint16 // index for first byte (0xC0-0xFF)
+	Values0 []uint32 // index for first byte (0x00-0x7F)
+	Index   []uint16
+	Values  []uint32
+}
+
+const (
+	t1 = 0x00 // 0000 0000
+	tx = 0x80 // 1000 0000
+	t2 = 0xC0 // 1100 0000
+	t3 = 0xE0 // 1110 0000
+	t4 = 0xF0 // 1111 0000
+	t5 = 0xF8 // 1111 1000
+	t6 = 0xFC // 1111 1100
+	te = 0xFE // 1111 1110
+)
+
+func (t *Trie) lookupValue(n uint16, b byte) Elem {
+	return Elem(t.Values[int(n)<<6+int(b)])
+}
+
+// lookup returns the trie value for the first UTF-8 encoding in s and
+// the width in bytes of this encoding. The size will be 0 if s does not
+// hold enough bytes to complete the encoding. len(s) must be greater than 0.
+func (t *Trie) lookup(s []byte) (v Elem, sz int) {
+	c0 := s[0]
+	switch {
+	case c0 < tx:
+		return Elem(t.Values0[c0]), 1
+	case c0 < t2:
+		return 0, 1
+	case c0 < t3:
+		if len(s) < 2 {
+			return 0, 0
+		}
+		i := t.Index0[c0]
+		c1 := s[1]
+		if c1 < tx || t2 <= c1 {
+			return 0, 1
+		}
+		return t.lookupValue(i, c1), 2
+	case c0 < t4:
+		if len(s) < 3 {
+			return 0, 0
+		}
+		i := t.Index0[c0]
+		c1 := s[1]
+		if c1 < tx || t2 <= c1 {
+			return 0, 1
+		}
+		o := int(i)<<6 + int(c1)
+		i = t.Index[o]
+		c2 := s[2]
+		if c2 < tx || t2 <= c2 {
+			return 0, 2
+		}
+		return t.lookupValue(i, c2), 3
+	case c0 < t5:
+		if len(s) < 4 {
+			return 0, 0
+		}
+		i := t.Index0[c0]
+		c1 := s[1]
+		if c1 < tx || t2 <= c1 {
+			return 0, 1
+		}
+		o := int(i)<<6 + int(c1)
+		i = t.Index[o]
+		c2 := s[2]
+		if c2 < tx || t2 <= c2 {
+			return 0, 2
+		}
+		o = int(i)<<6 + int(c2)
+		i = t.Index[o]
+		c3 := s[3]
+		if c3 < tx || t2 <= c3 {
+			return 0, 3
+		}
+		return t.lookupValue(i, c3), 4
+	}
+	// Illegal rune
+	return 0, 1
+}
+
+// The body of lookupString is a verbatim copy of that of lookup.
+func (t *Trie) lookupString(s string) (v Elem, sz int) {
+	c0 := s[0]
+	switch {
+	case c0 < tx:
+		return Elem(t.Values0[c0]), 1
+	case c0 < t2:
+		return 0, 1
+	case c0 < t3:
+		if len(s) < 2 {
+			return 0, 0
+		}
+		i := t.Index0[c0]
+		c1 := s[1]
+		if c1 < tx || t2 <= c1 {
+			return 0, 1
+		}
+		return t.lookupValue(i, c1), 2
+	case c0 < t4:
+		if len(s) < 3 {
+			return 0, 0
+		}
+		i := t.Index0[c0]
+		c1 := s[1]
+		if c1 < tx || t2 <= c1 {
+			return 0, 1
+		}
+		o := int(i)<<6 + int(c1)
+		i = t.Index[o]
+		c2 := s[2]
+		if c2 < tx || t2 <= c2 {
+			return 0, 2
+		}
+		return t.lookupValue(i, c2), 3
+	case c0 < t5:
+		if len(s) < 4 {
+			return 0, 0
+		}
+		i := t.Index0[c0]
+		c1 := s[1]
+		if c1 < tx || t2 <= c1 {
+			return 0, 1
+		}
+		o := int(i)<<6 + int(c1)
+		i = t.Index[o]
+		c2 := s[2]
+		if c2 < tx || t2 <= c2 {
+			return 0, 2
+		}
+		o = int(i)<<6 + int(c2)
+		i = t.Index[o]
+		c3 := s[3]
+		if c3 < tx || t2 <= c3 {
+			return 0, 3
+		}
+		return t.lookupValue(i, c3), 4
+	}
+	// Illegal rune
+	return 0, 1
+}