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exp/locale/collate: added trie for associating colElems to runes.

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The trie code looks a lot like the trie in exp/norm. It uses different
types, however.  Also, there is only a lookup for []byte and the unsafe
lookup methods have been dropped, as well as sparse mode.
There is now a method for generating a trie. To output Go code, one now needs
to first generate a trie and then call print() on it.

R=r, r, mpvl
CC=golang-dev
https://golang.org/cl/5966064
This commit is contained in:
Marcel van Lohuizen 2012-04-25 13:16:57 +02:00
parent bb3f3c9775
commit bcf48c7971
4 changed files with 576 additions and 0 deletions
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265
src/pkg/exp/locale/collate/build/trie.go Normal file
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// 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 a UTF-8 string to a collation element.
// All but the last byte in a UTF-8 byte sequence are
// used to look up 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.
// This file contains the code for the generation of the trie.
package build
import (
"fmt"
"hash/fnv"
"io"
"log"
"reflect"
)
const blockSize = 64
type trie struct {
index []uint16
values []uint32
}
// trieNode is the intermediate trie structure used for generating a trie.
type trieNode struct {
table [256]*trieNode
value int64
b byte
leaf bool
}
func newNode() *trieNode {
return new(trieNode)
}
func (n *trieNode) isInternal() bool {
internal := true
for i := 0; i < 256; i++ {
if nn := n.table[i]; nn != nil {
if !internal && !nn.leaf {
log.Fatalf("trie:isInternal: node contains both leaf and non-leaf children (%v)", n)
}
internal = internal && !nn.leaf
}
}
return internal
}
func (n *trieNode) insert(r rune, value uint32) {
for _, b := range []byte(string(r)) {
if n.leaf {
log.Fatalf("trie:insert: node (%#v) should not be a leaf", n)
}
nn := n.table[b]
if nn == nil {
nn = newNode()
nn.b = b
n.table[b] = nn
}
n = nn
}
n.value = int64(value)
n.leaf = true
}
type nodeIndex struct {
lookupBlocks []*trieNode
valueBlocks []*trieNode
lookupBlockIdx map[uint32]int64
valueBlockIdx map[uint32]int64
}
func newIndex() *nodeIndex {
index := &nodeIndex{}
index.lookupBlocks = make([]*trieNode, 0)
index.valueBlocks = make([]*trieNode, 0)
index.lookupBlockIdx = make(map[uint32]int64)
index.valueBlockIdx = make(map[uint32]int64)
return index
}
func computeOffsets(index *nodeIndex, n *trieNode) int64 {
if n.leaf {
return n.value
}
hasher := fnv.New32()
// We only index continuation bytes.
for i := 0; i < blockSize; i++ {
v := int64(0)
if nn := n.table[0x80+i]; nn != nil {
v = computeOffsets(index, nn)
}
hasher.Write([]byte{byte(v >> 24), byte(v >> 16), byte(v >> 8), byte(v)})
}
h := hasher.Sum32()
if n.isInternal() {
v, ok := index.lookupBlockIdx[h]
if !ok {
v = int64(len(index.lookupBlocks))
index.lookupBlocks = append(index.lookupBlocks, n)
index.lookupBlockIdx[h] = v
}
n.value = v
} else {
v, ok := index.valueBlockIdx[h]
if !ok {
v = int64(len(index.valueBlocks))
index.valueBlocks = append(index.valueBlocks, n)
index.valueBlockIdx[h] = v
}
n.value = v
}
return n.value
}
func genValueBlock(t *trie, n *trieNode, offset int) error {
for i := 0; i < blockSize; i++ {
v := int64(0)
if nn := n.table[i+offset]; nn != nil {
v = nn.value
}
if v >= 1<<32 {
return fmt.Errorf("value %d at index %d does not fit in uint32", v, len(t.values))
}
t.values = append(t.values, uint32(v))
}
return nil
}
func genLookupBlock(t *trie, n *trieNode, offset int) error {
for i := 0; i < blockSize; i++ {
v := int64(0)
if nn := n.table[i+offset]; nn != nil {
v = nn.value
}
if v >= 1<<16 {
return fmt.Errorf("value %d at index %d does not fit in uint16", v, len(t.index))
}
t.index = append(t.index, uint16(v))
}
return nil
}
// generate generates and returns the trie for n.
func (n *trieNode) generate() (t *trie, err error) {
seterr := func(e error) {
if err == nil {
err = e
}
}
index := newIndex()
// Values for 7-bit ASCII are stored in the first of two blocks, followed by a nil block.
index.valueBlocks = append(index.valueBlocks, nil, nil, nil)
// First byte of multi-byte UTF-8 codepoints are indexed in 4th block.
index.lookupBlocks = append(index.lookupBlocks, nil, nil, nil, nil)
// Index starter bytes of multi-byte UTF-8.
for i := 0xC0; i < 0x100; i++ {
if n.table[i] != nil {
computeOffsets(index, n.table[i])
}
}
t = &trie{}
seterr(genValueBlock(t, n, 0))
seterr(genValueBlock(t, n, 64))
seterr(genValueBlock(t, newNode(), 0))
for i := 3; i < len(index.valueBlocks); i++ {
seterr(genValueBlock(t, index.valueBlocks[i], 0x80))
}
if len(index.valueBlocks) >= 1<<16 {
seterr(fmt.Errorf("maximum number of value blocks exceeded (%d > %d)", len(index.valueBlocks), 1<<16))
return
}
seterr(genLookupBlock(t, newNode(), 0))
seterr(genLookupBlock(t, newNode(), 0))
seterr(genLookupBlock(t, newNode(), 0))
seterr(genLookupBlock(t, n, 0xC0))
for i := 4; i < len(index.lookupBlocks); i++ {
seterr(genLookupBlock(t, index.lookupBlocks[i], 0x80))
}
return
}
// print writes a compilable trie to w. It returns the number of characters
// printed and the size of the generated structure in bytes.
func (t *trie) print(w io.Writer, name string) (n, size int, err error) {
update3 := func(nn, sz int, e error) {
n += nn
if err == nil {
err = e
}
size += sz
}
update2 := func(nn int, e error) { update3(nn, 0, e) }
update3(t.printArrays(w, name))
update2(fmt.Fprintf(w, "var %sTrie = ", name))
update3(t.printStruct(w, name))
update2(fmt.Fprintln(w))
return
}
func (t *trie) printArrays(w io.Writer, name string) (n, size int, err error) {
p := func(f string, a ...interface{}) {
nn, e := fmt.Fprintf(w, f, a...)
n += nn
if err == nil {
err = e
}
}
nv := len(t.values)
p("// %sValues: %d entries, %d bytes\n", name, nv, nv*4)
p("// Block 2 is the null block.\n")
p("var %sValues = [%d]uint32 {", name, nv)
var printnewline bool
for i, v := range t.values {
if i%blockSize == 0 {
p("\n\t// Block %#x, offset %#x", i/blockSize, i)
}
if i%4 == 0 {
printnewline = true
}
if v != 0 {
if printnewline {
p("\n\t")
printnewline = false
}
p("%#04x:%#08x, ", i, v)
}
}
p("\n}\n\n")
ni := len(t.index)
p("// %sLookup: %d entries, %d bytes\n", name, ni, ni*2)
p("// Block 0 is the null block.\n")
p("var %sLookup = [%d]uint16 {", name, ni)
printnewline = false
for i, v := range t.index {
if i%blockSize == 0 {
p("\n\t// Block %#x, offset %#x", i/blockSize, i)
}
if i%8 == 0 {
printnewline = true
}
if v != 0 {
if printnewline {
p("\n\t")
printnewline = false
}
p("%#03x:%#02x, ", i, v)
}
}
p("\n}\n\n")
return n, nv*4 + ni*2, err
}
func (t *trie) printStruct(w io.Writer, name string) (n, sz int, err error) {
n, err = fmt.Fprintf(w, "trie{ %sLookup[:], %sValues[:]}", name, name)
sz += int(reflect.TypeOf(trie{}).Size())
return
}

103
src/pkg/exp/locale/collate/build/trie_test.go Normal file
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// 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 build
import (
"bytes"
"testing"
)
// We take the smallest, largest and an arbitrary value for each
// of the UTF-8 sequence lengths.
var testRunes = []rune{
0x01, 0x0C, 0x7F, // 1-byte sequences
0x80, 0x100, 0x7FF, // 2-byte sequences
0x800, 0x999, 0xFFFF, // 3-byte sequences
0x10000, 0x10101, 0x10FFFF, // 4-byte sequences
0x200, 0x201, 0x202, 0x210, 0x215, // five entries in one sparse block
}
func makeTestTrie(t *testing.T) trie {
n := newNode()
for i, r := range testRunes {
n.insert(r, uint32(i))
}
tr, err := n.generate()
if err != nil {
t.Errorf(err.Error())
}
return *tr
}
func TestGenerateTrie(t *testing.T) {
testdata := makeTestTrie(t)
buf := &bytes.Buffer{}
testdata.print(buf, "test")
if output != buf.String() {
t.Errorf("output differs")
}
}
var output = `// testValues: 832 entries, 3328 bytes
// Block 2 is the null block.
var testValues = [832]uint32 {
// Block 0x0, offset 0x0
0x000c:0x00000001,
// Block 0x1, offset 0x40
0x007f:0x00000002,
// Block 0x2, offset 0x80
// Block 0x3, offset 0xc0
0x00c0:0x00000003,
// Block 0x4, offset 0x100
0x0100:0x00000004,
// Block 0x5, offset 0x140
0x0140:0x0000000c, 0x0141:0x0000000d, 0x0142:0x0000000e,
0x0150:0x0000000f,
0x0155:0x00000010,
// Block 0x6, offset 0x180
0x01bf:0x00000005,
// Block 0x7, offset 0x1c0
0x01c0:0x00000006,
// Block 0x8, offset 0x200
0x0219:0x00000007,
// Block 0x9, offset 0x240
0x027f:0x00000008,
// Block 0xa, offset 0x280
0x0280:0x00000009,
// Block 0xb, offset 0x2c0
0x02c1:0x0000000a,
// Block 0xc, offset 0x300
0x033f:0x0000000b,
}
// testLookup: 640 entries, 1280 bytes
// Block 0 is the null block.
var testLookup = [640]uint16 {
// Block 0x0, offset 0x0
// Block 0x1, offset 0x40
// Block 0x2, offset 0x80
// Block 0x3, offset 0xc0
0x0c2:0x03, 0x0c4:0x04,
0x0c8:0x05,
0x0df:0x06,
0x0e0:0x04,
0x0ef:0x05,
0x0f0:0x07, 0x0f4:0x09,
// Block 0x4, offset 0x100
0x120:0x07, 0x126:0x08,
// Block 0x5, offset 0x140
0x17f:0x09,
// Block 0x6, offset 0x180
0x180:0x0a, 0x184:0x0b,
// Block 0x7, offset 0x1c0
0x1d0:0x06,
// Block 0x8, offset 0x200
0x23f:0x0c,
// Block 0x9, offset 0x240
0x24f:0x08,
}
var testTrie = trie{ testLookup[:], testValues[:]}
`

102
src/pkg/exp/locale/collate/trie.go Normal file
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// 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 exp/locale/collate/build/trie.go.
package collate
const blockSize = 64
type trie struct {
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
maskx = 0x3F // 0011 1111
mask2 = 0x1F // 0001 1111
mask3 = 0x0F // 0000 1111
mask4 = 0x07 // 0000 0111
)
func (t *trie) lookupValue(n uint16, b byte) colElem {
return colElem(t.values[int(n)<<6+int(b&maskx)])
}
// 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 colElem, sz int) {
c0 := s[0]
switch {
case c0 < tx:
return colElem(t.values[c0]), 1
case c0 < t2:
return 0, 1
case c0 < t3:
if len(s) < 2 {
return 0, 0
}
i := t.index[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.index[c0]
c1 := s[1]
if c1 < tx || t2 <= c1 {
return 0, 1
}
o := int(i)<<6 + int(c1)&maskx
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.index[c0]
c1 := s[1]
if c1 < tx || t2 <= c1 {
return 0, 1
}
o := int(i)<<6 + int(c1)&maskx
i = t.index[o]
c2 := s[2]
if c2 < tx || t2 <= c2 {
return 0, 2
}
o = int(i)<<6 + int(c2)&maskx
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
}

106
src/pkg/exp/locale/collate/trie_test.go Normal file
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// 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 collate
import (
"testing"
)
// We take the smallest, largest and an arbitrary value for each
// of the UTF-8 sequence lengths.
var testRunes = []rune{
0x01, 0x0C, 0x7F, // 1-byte sequences
0x80, 0x100, 0x7FF, // 2-byte sequences
0x800, 0x999, 0xFFFF, // 3-byte sequences
0x10000, 0x10101, 0x10FFFF, // 4-byte sequences
0x200, 0x201, 0x202, 0x210, 0x215, // five entries in one sparse block
}
// Test cases for illegal runes.
type trietest struct {
size int
bytes []byte
}
var tests = []trietest{
// illegal runes
{1, []byte{0x80}},
{1, []byte{0xFF}},
{1, []byte{t2, tx - 1}},
{1, []byte{t2, t2}},
{2, []byte{t3, tx, tx - 1}},
{2, []byte{t3, tx, t2}},
{1, []byte{t3, tx - 1, tx}},
{3, []byte{t4, tx, tx, tx - 1}},
{3, []byte{t4, tx, tx, t2}},
{1, []byte{t4, t2, tx, tx - 1}},
{2, []byte{t4, tx, t2, tx - 1}},
// short runes
{0, []byte{t2}},
{0, []byte{t3, tx}},
{0, []byte{t4, tx, tx}},
// we only support UTF-8 up to utf8.UTFMax bytes (4 bytes)
{1, []byte{t5, tx, tx, tx, tx}},
{1, []byte{t6, tx, tx, tx, tx, tx}},
}
func TestLookupTrie(t *testing.T) {
for i, r := range testRunes {
b := []byte(string(r))
v, sz := testTrie.lookup(b)
if int(v) != i {
t.Errorf("lookup(%U): found value %#x, expected %#x", r, v, i)
}
if sz != len(b) {
t.Errorf("lookup(%U): found size %d, expected %d", r, sz, len(b))
}
}
for i, tt := range tests {
v, sz := testTrie.lookup(tt.bytes)
if int(v) != 0 {
t.Errorf("lookup of illegal rune, case %d: found value %#x, expected 0", i, v)
}
if sz != tt.size {
t.Errorf("lookup of illegal rune, case %d: found size %d, expected %d", i, sz, tt.size)
}
}
}
// test data is taken from exp/collate/locale/build/trie_test.go
var testValues = [832]uint32{
0x000c: 0x00000001,
0x007f: 0x00000002,
0x00c0: 0x00000003,
0x0100: 0x00000004,
0x0140: 0x0000000c, 0x0141: 0x0000000d, 0x0142: 0x0000000e,
0x0150: 0x0000000f,
0x0155: 0x00000010,
0x01bf: 0x00000005,
0x01c0: 0x00000006,
0x0219: 0x00000007,
0x027f: 0x00000008,
0x0280: 0x00000009,
0x02c1: 0x0000000a,
0x033f: 0x0000000b,
}
var testLookup = [640]uint16{
0x0c2: 0x03, 0x0c4: 0x04,
0x0c8: 0x05,
0x0df: 0x06,
0x0e0: 0x04,
0x0ef: 0x05,
0x0f0: 0x07, 0x0f4: 0x09,
0x120: 0x07, 0x126: 0x08,
0x17f: 0x09,
0x180: 0x0a, 0x184: 0x0b,
0x1d0: 0x06,
0x23f: 0x0c,
0x24f: 0x08,
}
var testTrie = trie{testLookup[:], testValues[:]}