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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [exp/] [norm/] [triegen.go] - Rev 833
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// Copyright 2011 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.
// Trie table generator.
// Used by make*tables tools to generate a go file with trie data structures
// for mapping UTF-8 to a 16-bit value. 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 with 16-bit values.
package main
import (
"fmt"
"hash/crc32"
"log"
"unicode/utf8"
)
const blockSize = 64
const maxSparseEntries = 16
// Intermediate trie structure
type trieNode struct {
table [256]*trieNode
value int
b byte
leaf bool
}
func newNode() *trieNode {
return new(trieNode)
}
func (n trieNode) String() string {
s := fmt.Sprint("trieNode{table: { non-nil at index: ")
for i, v := range n.table {
if v != nil {
s += fmt.Sprintf("%d, ", i)
}
}
s += fmt.Sprintf("}, value:%#x, b:%#x leaf:%v}", n.value, n.b, n.leaf)
return s
}
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("triegen: isInternal: node contains both leaf and non-leaf children (%v)", n)
}
internal = internal && !nn.leaf
}
}
return internal
}
func (n trieNode) mostFrequentStride() int {
counts := make(map[int]int)
v := 0
for _, t := range n.table[0x80 : 0x80+blockSize] {
if t != nil {
if stride := t.value - v; v != 0 && stride >= 0 {
counts[stride]++
}
v = t.value
} else {
v = 0
}
}
var maxs, maxc int
for stride, cnt := range counts {
if cnt > maxc || (cnt == maxc && stride < maxs) {
maxs, maxc = stride, cnt
}
}
return maxs
}
func (n trieNode) countSparseEntries() int {
stride := n.mostFrequentStride()
var count, v int
for _, t := range n.table[0x80 : 0x80+blockSize] {
tv := 0
if t != nil {
tv = t.value
}
if tv-v != stride {
if tv != 0 {
count++
}
}
v = tv
}
return count
}
func (n *trieNode) insert(r rune, value uint16) {
var p [utf8.UTFMax]byte
sz := utf8.EncodeRune(p[:], r)
for i := 0; i < sz; i++ {
if n.leaf {
log.Fatalf("triegen: insert: node (%#v) should not be a leaf", n)
}
nn := n.table[p[i]]
if nn == nil {
nn = newNode()
nn.b = p[i]
n.table[p[i]] = nn
}
n = nn
}
n.value = int(value)
n.leaf = true
}
type nodeIndex struct {
lookupBlocks []*trieNode
valueBlocks []*trieNode
sparseBlocks []*trieNode
sparseOffset []uint16
sparseCount int
lookupBlockIdx map[uint32]int
valueBlockIdx map[uint32]int
}
func newIndex() *nodeIndex {
index := &nodeIndex{}
index.lookupBlocks = make([]*trieNode, 0)
index.valueBlocks = make([]*trieNode, 0)
index.sparseBlocks = make([]*trieNode, 0)
index.sparseOffset = make([]uint16, 1)
index.lookupBlockIdx = make(map[uint32]int)
index.valueBlockIdx = make(map[uint32]int)
return index
}
func computeOffsets(index *nodeIndex, n *trieNode) int {
if n.leaf {
return n.value
}
hasher := crc32.New(crc32.MakeTable(crc32.IEEE))
// We only index continuation bytes.
for i := 0; i < blockSize; i++ {
v := 0
if nn := n.table[0x80+i]; nn != nil {
v = computeOffsets(index, nn)
}
hasher.Write([]byte{uint8(v >> 8), uint8(v)})
}
h := hasher.Sum32()
if n.isInternal() {
v, ok := index.lookupBlockIdx[h]
if !ok {
v = len(index.lookupBlocks)
index.lookupBlocks = append(index.lookupBlocks, n)
index.lookupBlockIdx[h] = v
}
n.value = v
} else {
v, ok := index.valueBlockIdx[h]
if !ok {
if c := n.countSparseEntries(); c > maxSparseEntries {
v = len(index.valueBlocks)
index.valueBlocks = append(index.valueBlocks, n)
index.valueBlockIdx[h] = v
} else {
v = -len(index.sparseOffset)
index.sparseBlocks = append(index.sparseBlocks, n)
index.sparseOffset = append(index.sparseOffset, uint16(index.sparseCount))
index.sparseCount += c + 1
index.valueBlockIdx[h] = v
}
}
n.value = v
}
return n.value
}
func printValueBlock(nr int, n *trieNode, offset int) {
boff := nr * blockSize
fmt.Printf("\n// Block %#x, offset %#x", nr, boff)
var printnewline bool
for i := 0; i < blockSize; i++ {
if i%6 == 0 {
printnewline = true
}
v := 0
if nn := n.table[i+offset]; nn != nil {
v = nn.value
}
if v != 0 {
if printnewline {
fmt.Printf("\n")
printnewline = false
}
fmt.Printf("%#04x:%#04x, ", boff+i, v)
}
}
}
func printSparseBlock(nr int, n *trieNode) {
boff := -n.value
fmt.Printf("\n// Block %#x, offset %#x", nr, boff)
v := 0
//stride := f(n)
stride := n.mostFrequentStride()
c := n.countSparseEntries()
fmt.Printf("\n{value:%#04x,lo:%#02x},", stride, uint8(c))
for i, nn := range n.table[0x80 : 0x80+blockSize] {
nv := 0
if nn != nil {
nv = nn.value
}
if nv-v != stride {
if v != 0 {
fmt.Printf(",hi:%#02x},", 0x80+i-1)
}
if nv != 0 {
fmt.Printf("\n{value:%#04x,lo:%#02x", nv, nn.b)
}
}
v = nv
}
if v != 0 {
fmt.Printf(",hi:%#02x},", 0x80+blockSize-1)
}
}
func printLookupBlock(nr int, n *trieNode, offset, cutoff int) {
boff := nr * blockSize
fmt.Printf("\n// Block %#x, offset %#x", nr, boff)
var printnewline bool
for i := 0; i < blockSize; i++ {
if i%8 == 0 {
printnewline = true
}
v := 0
if nn := n.table[i+offset]; nn != nil {
v = nn.value
}
if v != 0 {
if v < 0 {
v = -v - 1 + cutoff
}
if printnewline {
fmt.Printf("\n")
printnewline = false
}
fmt.Printf("%#03x:%#02x, ", boff+i, v)
}
}
}
// printTables returns the size in bytes of the generated tables.
func (t *trieNode) printTables(name string) int {
index := newIndex()
// Values for 7-bit ASCII are stored in first two block, followed by 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 t.table[i] != nil {
computeOffsets(index, t.table[i])
}
}
nv := len(index.valueBlocks) * blockSize
fmt.Printf("// %sValues: %d entries, %d bytes\n", name, nv, nv*2)
fmt.Printf("// Block 2 is the null block.\n")
fmt.Printf("var %sValues = [%d]uint16 {", name, nv)
printValueBlock(0, t, 0)
printValueBlock(1, t, 64)
printValueBlock(2, newNode(), 0)
for i := 3; i < len(index.valueBlocks); i++ {
printValueBlock(i, index.valueBlocks[i], 0x80)
}
fmt.Print("\n}\n\n")
ls := len(index.sparseBlocks)
fmt.Printf("// %sSparseOffset: %d entries, %d bytes\n", name, ls, ls*2)
fmt.Printf("var %sSparseOffset = %#v\n\n", name, index.sparseOffset[1:])
ns := index.sparseCount
fmt.Printf("// %sSparseValues: %d entries, %d bytes\n", name, ns, ns*4)
fmt.Printf("var %sSparseValues = [%d]valueRange {", name, ns)
for i, n := range index.sparseBlocks {
printSparseBlock(i, n)
}
fmt.Print("\n}\n\n")
cutoff := len(index.valueBlocks)
ni := len(index.lookupBlocks) * blockSize
fmt.Printf("// %sLookup: %d bytes\n", name, ni)
fmt.Printf("// Block 0 is the null block.\n")
fmt.Printf("var %sLookup = [%d]uint8 {", name, ni)
printLookupBlock(0, newNode(), 0, cutoff)
printLookupBlock(1, newNode(), 0, cutoff)
printLookupBlock(2, newNode(), 0, cutoff)
printLookupBlock(3, t, 0xC0, cutoff)
for i := 4; i < len(index.lookupBlocks); i++ {
printLookupBlock(i, index.lookupBlocks[i], 0x80, cutoff)
}
fmt.Print("\n}\n\n")
fmt.Printf("var %sTrie = trie{ %sLookup[:], %sValues[:], %sSparseValues[:], %sSparseOffset[:], %d}\n\n",
name, name, name, name, name, cutoff)
return nv*2 + ns*4 + ni + ls*2
}
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