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[bytom/vapor.git] / vendor / golang.org / x / text / internal / triegen / compact.go

diff --git a/vendor/golang.org/x/text/internal/triegen/compact.go b/vendor/golang.org/x/text/internal/triegen/compact.go
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+++ b/vendor/golang.org/x/text/internal/triegen/compact.go
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+// Copyright 2014 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 triegen
+
+// This file defines Compacter and its implementations.
+
+import "io"
+
+// A Compacter generates an alternative, more space-efficient way to store a
+// trie value block. A trie value block holds all possible values for the last
+// byte of a UTF-8 encoded rune. Excluding ASCII characters, a trie value block
+// always has 64 values, as a UTF-8 encoding ends with a byte in [0x80, 0xC0).
+type Compacter interface {
+       // Size returns whether the Compacter could encode the given block as well
+       // as its size in case it can. len(v) is always 64.
+       Size(v []uint64) (sz int, ok bool)
+
+       // Store stores the block using the Compacter's compression method.
+       // It returns a handle with which the block can be retrieved.
+       // len(v) is always 64.
+       Store(v []uint64) uint32
+
+       // Print writes the data structures associated to the given store to w.
+       Print(w io.Writer) error
+
+       // Handler returns the name of a function that gets called during trie
+       // lookup for blocks generated by the Compacter. The function should be of
+       // the form func (n uint32, b byte) uint64, where n is the index returned by
+       // the Compacter's Store method and b is the last byte of the UTF-8
+       // encoding, where 0x80 <= b < 0xC0, for which to do the lookup in the
+       // block.
+       Handler() string
+}
+
+// simpleCompacter is the default Compacter used by builder. It implements a
+// normal trie block.
+type simpleCompacter builder
+
+func (b *simpleCompacter) Size([]uint64) (sz int, ok bool) {
+       return blockSize * b.ValueSize, true
+}
+
+func (b *simpleCompacter) Store(v []uint64) uint32 {
+       h := uint32(len(b.ValueBlocks) - blockOffset)
+       b.ValueBlocks = append(b.ValueBlocks, v)
+       return h
+}
+
+func (b *simpleCompacter) Print(io.Writer) error {
+       // Structures are printed in print.go.
+       return nil
+}
+
+func (b *simpleCompacter) Handler() string {
+       panic("Handler should be special-cased for this Compacter")
+}