--- /dev/null
+// 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
+
+import (
+ "bytes"
+ "fmt"
+ "io"
+ "strings"
+ "text/template"
+)
+
+// print writes all the data structures as well as the code necessary to use the
+// trie to w.
+func (b *builder) print(w io.Writer) error {
+ b.Stats.NValueEntries = len(b.ValueBlocks) * blockSize
+ b.Stats.NValueBytes = len(b.ValueBlocks) * blockSize * b.ValueSize
+ b.Stats.NIndexEntries = len(b.IndexBlocks) * blockSize
+ b.Stats.NIndexBytes = len(b.IndexBlocks) * blockSize * b.IndexSize
+ b.Stats.NHandleBytes = len(b.Trie) * 2 * b.IndexSize
+
+ // If we only have one root trie, all starter blocks are at position 0 and
+ // we can access the arrays directly.
+ if len(b.Trie) == 1 {
+ // At this point we cannot refer to the generated tables directly.
+ b.ASCIIBlock = b.Name + "Values"
+ b.StarterBlock = b.Name + "Index"
+ } else {
+ // Otherwise we need to have explicit starter indexes in the trie
+ // structure.
+ b.ASCIIBlock = "t.ascii"
+ b.StarterBlock = "t.utf8Start"
+ }
+
+ b.SourceType = "[]byte"
+ if err := lookupGen.Execute(w, b); err != nil {
+ return err
+ }
+
+ b.SourceType = "string"
+ if err := lookupGen.Execute(w, b); err != nil {
+ return err
+ }
+
+ if err := trieGen.Execute(w, b); err != nil {
+ return err
+ }
+
+ for _, c := range b.Compactions {
+ if err := c.c.Print(w); err != nil {
+ return err
+ }
+ }
+
+ return nil
+}
+
+func printValues(n int, values []uint64) string {
+ w := &bytes.Buffer{}
+ boff := n * blockSize
+ fmt.Fprintf(w, "\t// Block %#x, offset %#x", n, boff)
+ var newline bool
+ for i, v := range values {
+ if i%6 == 0 {
+ newline = true
+ }
+ if v != 0 {
+ if newline {
+ fmt.Fprintf(w, "\n")
+ newline = false
+ }
+ fmt.Fprintf(w, "\t%#02x:%#04x, ", boff+i, v)
+ }
+ }
+ return w.String()
+}
+
+func printIndex(b *builder, nr int, n *node) string {
+ w := &bytes.Buffer{}
+ boff := nr * blockSize
+ fmt.Fprintf(w, "\t// Block %#x, offset %#x", nr, boff)
+ var newline bool
+ for i, c := range n.children {
+ if i%8 == 0 {
+ newline = true
+ }
+ if c != nil {
+ v := b.Compactions[c.index.compaction].Offset + uint32(c.index.index)
+ if v != 0 {
+ if newline {
+ fmt.Fprintf(w, "\n")
+ newline = false
+ }
+ fmt.Fprintf(w, "\t%#02x:%#02x, ", boff+i, v)
+ }
+ }
+ }
+ return w.String()
+}
+
+var (
+ trieGen = template.Must(template.New("trie").Funcs(template.FuncMap{
+ "printValues": printValues,
+ "printIndex": printIndex,
+ "title": strings.Title,
+ "dec": func(x int) int { return x - 1 },
+ "psize": func(n int) string {
+ return fmt.Sprintf("%d bytes (%.2f KiB)", n, float64(n)/1024)
+ },
+ }).Parse(trieTemplate))
+ lookupGen = template.Must(template.New("lookup").Parse(lookupTemplate))
+)
+
+// TODO: consider the return type of lookup. It could be uint64, even if the
+// internal value type is smaller. We will have to verify this with the
+// performance of unicode/norm, which is very sensitive to such changes.
+const trieTemplate = `{{$b := .}}{{$multi := gt (len .Trie) 1}}
+// {{.Name}}Trie. Total size: {{psize .Size}}. Checksum: {{printf "%08x" .Checksum}}.
+type {{.Name}}Trie struct { {{if $multi}}
+ ascii []{{.ValueType}} // index for ASCII bytes
+ utf8Start []{{.IndexType}} // index for UTF-8 bytes >= 0xC0
+{{end}}}
+
+func new{{title .Name}}Trie(i int) *{{.Name}}Trie { {{if $multi}}
+ h := {{.Name}}TrieHandles[i]
+ return &{{.Name}}Trie{ {{.Name}}Values[uint32(h.ascii)<<6:], {{.Name}}Index[uint32(h.multi)<<6:] }
+}
+
+type {{.Name}}TrieHandle struct {
+ ascii, multi {{.IndexType}}
+}
+
+// {{.Name}}TrieHandles: {{len .Trie}} handles, {{.Stats.NHandleBytes}} bytes
+var {{.Name}}TrieHandles = [{{len .Trie}}]{{.Name}}TrieHandle{
+{{range .Trie}} { {{.ASCIIIndex}}, {{.StarterIndex}} }, // {{printf "%08x" .Checksum}}: {{.Name}}
+{{end}}}{{else}}
+ return &{{.Name}}Trie{}
+}
+{{end}}
+// lookupValue determines the type of block n and looks up the value for b.
+func (t *{{.Name}}Trie) lookupValue(n uint32, b byte) {{.ValueType}}{{$last := dec (len .Compactions)}} {
+ switch { {{range $i, $c := .Compactions}}
+ {{if eq $i $last}}default{{else}}case n < {{$c.Cutoff}}{{end}}:{{if ne $i 0}}
+ n -= {{$c.Offset}}{{end}}
+ return {{print $b.ValueType}}({{$c.Handler}}){{end}}
+ }
+}
+
+// {{.Name}}Values: {{len .ValueBlocks}} blocks, {{.Stats.NValueEntries}} entries, {{.Stats.NValueBytes}} bytes
+// The third block is the zero block.
+var {{.Name}}Values = [{{.Stats.NValueEntries}}]{{.ValueType}} {
+{{range $i, $v := .ValueBlocks}}{{printValues $i $v}}
+{{end}}}
+
+// {{.Name}}Index: {{len .IndexBlocks}} blocks, {{.Stats.NIndexEntries}} entries, {{.Stats.NIndexBytes}} bytes
+// Block 0 is the zero block.
+var {{.Name}}Index = [{{.Stats.NIndexEntries}}]{{.IndexType}} {
+{{range $i, $v := .IndexBlocks}}{{printIndex $b $i $v}}
+{{end}}}
+`
+
+// TODO: consider allowing zero-length strings after evaluating performance with
+// unicode/norm.
+const lookupTemplate = `
+// lookup{{if eq .SourceType "string"}}String{{end}} 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 *{{.Name}}Trie) lookup{{if eq .SourceType "string"}}String{{end}}(s {{.SourceType}}) (v {{.ValueType}}, sz int) {
+ c0 := s[0]
+ switch {
+ case c0 < 0x80: // is ASCII
+ return {{.ASCIIBlock}}[c0], 1
+ case c0 < 0xC2:
+ return 0, 1 // Illegal UTF-8: not a starter, not ASCII.
+ case c0 < 0xE0: // 2-byte UTF-8
+ if len(s) < 2 {
+ return 0, 0
+ }
+ i := {{.StarterBlock}}[c0]
+ c1 := s[1]
+ if c1 < 0x80 || 0xC0 <= c1 {
+ return 0, 1 // Illegal UTF-8: not a continuation byte.
+ }
+ return t.lookupValue(uint32(i), c1), 2
+ case c0 < 0xF0: // 3-byte UTF-8
+ if len(s) < 3 {
+ return 0, 0
+ }
+ i := {{.StarterBlock}}[c0]
+ c1 := s[1]
+ if c1 < 0x80 || 0xC0 <= c1 {
+ return 0, 1 // Illegal UTF-8: not a continuation byte.
+ }
+ o := uint32(i)<<6 + uint32(c1)
+ i = {{.Name}}Index[o]
+ c2 := s[2]
+ if c2 < 0x80 || 0xC0 <= c2 {
+ return 0, 2 // Illegal UTF-8: not a continuation byte.
+ }
+ return t.lookupValue(uint32(i), c2), 3
+ case c0 < 0xF8: // 4-byte UTF-8
+ if len(s) < 4 {
+ return 0, 0
+ }
+ i := {{.StarterBlock}}[c0]
+ c1 := s[1]
+ if c1 < 0x80 || 0xC0 <= c1 {
+ return 0, 1 // Illegal UTF-8: not a continuation byte.
+ }
+ o := uint32(i)<<6 + uint32(c1)
+ i = {{.Name}}Index[o]
+ c2 := s[2]
+ if c2 < 0x80 || 0xC0 <= c2 {
+ return 0, 2 // Illegal UTF-8: not a continuation byte.
+ }
+ o = uint32(i)<<6 + uint32(c2)
+ i = {{.Name}}Index[o]
+ c3 := s[3]
+ if c3 < 0x80 || 0xC0 <= c3 {
+ return 0, 3 // Illegal UTF-8: not a continuation byte.
+ }
+ return t.lookupValue(uint32(i), c3), 4
+ }
+ // Illegal rune
+ return 0, 1
+}
+
+// lookup{{if eq .SourceType "string"}}String{{end}}Unsafe returns the trie value for the first UTF-8 encoding in s.
+// s must start with a full and valid UTF-8 encoded rune.
+func (t *{{.Name}}Trie) lookup{{if eq .SourceType "string"}}String{{end}}Unsafe(s {{.SourceType}}) {{.ValueType}} {
+ c0 := s[0]
+ if c0 < 0x80 { // is ASCII
+ return {{.ASCIIBlock}}[c0]
+ }
+ i := {{.StarterBlock}}[c0]
+ if c0 < 0xE0 { // 2-byte UTF-8
+ return t.lookupValue(uint32(i), s[1])
+ }
+ i = {{.Name}}Index[uint32(i)<<6+uint32(s[1])]
+ if c0 < 0xF0 { // 3-byte UTF-8
+ return t.lookupValue(uint32(i), s[2])
+ }
+ i = {{.Name}}Index[uint32(i)<<6+uint32(s[2])]
+ if c0 < 0xF8 { // 4-byte UTF-8
+ return t.lookupValue(uint32(i), s[3])
+ }
+ return 0
+}
+`
Code Review / barometer.git / blobdiff