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354 lines
10 KiB
Go
354 lines
10 KiB
Go
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// Copyright 2017 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package cldrtree builds and generates a CLDR index file, including all
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// inheritance.
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//
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package cldrtree
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//go:generate go test -gen
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// cldrtree stores CLDR data in a tree-like structure called Tree. In the CLDR
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// data each branch in the tree is indicated by either an element name or an
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// attribute value. A Tree does not distinguish between these two cases, but
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// rather assumes that all branches can be accessed by an enum with a compact
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// range of positive integer values starting from 0.
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//
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// Each Tree consists of three parts:
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// - a slice mapping compact language identifiers to an offset into a set of
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// indices,
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// - a set of indices, stored as a large blob of uint16 values that encode
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// the actual tree structure of data, and
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// - a set of buckets that each holds a collection of strings.
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// each of which is explained in more detail below.
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//
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//
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// Tree lookup
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// A tree lookup is done by providing a locale and a "path", which is a
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// sequence of enum values. The search starts with getting the index for the
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// given locale and then incrementally jumping into the index using the path
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// values. If an element cannot be found in the index, the search starts anew
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// for the locale's parent locale. The path may change during lookup by means
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// of aliasing, described below.
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//
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// Buckets
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// Buckets hold the actual string data of the leaf values of the CLDR tree.
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// This data is stored in buckets, rather than one large string, for multiple
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// reasons:
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// - it allows representing leaf values more compactly, by storing all leaf
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// values in a single bucket and then needing only needing a uint16 to index
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// into this bucket for all leaf values,
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// - (TBD) allow multiple trees to share subsets of buckets, mostly to allow
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// linking in a smaller amount of data if only a subset of the buckets is
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// needed,
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// - to be nice to go fmt and the compiler.
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//
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// indices
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// An index is a slice of uint16 for which the values are interpreted in one of
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// two ways: as a node or a set of leaf values.
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// A set of leaf values has the following form:
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// <max_size>, <bucket>, <offset>...
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// max_size indicates the maximum enum value for which an offset is defined.
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// An offset value of 0xFFFF (missingValue) also indicates an undefined value.
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// If defined offset indicates the offset within the given bucket of the string.
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// A node value has the following form:
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// <max_size>, <offset_or_alias>...
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// max_size indicates the maximum value for which an offset is defined.
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// A missing offset may also be indicated with 0. If the high bit (0x8000, or
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// inheritMask) is not set, the offset points to the offset within the index
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// for the current locale.
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// An offset with high bit set is an alias. In this case the uint16 has the form
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// bits:
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// 15: 1
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// 14-12: negative offset into path relative to current position
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// 0-11: new enum value for path element.
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// On encountering an alias, the path is modified accordingly and the lookup is
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// restarted for the given locale.
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import (
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"fmt"
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"reflect"
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"regexp"
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"strings"
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"unicode/utf8"
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"golang.org/x/text/internal/gen"
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"golang.org/x/text/language"
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"golang.org/x/text/unicode/cldr"
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)
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// TODO:
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// - allow two Trees to share the same set of buckets.
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// A Builder allows storing CLDR data in compact form.
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type Builder struct {
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table []string
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rootMeta *metaData
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locales []locale
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strToBucket map[string]stringInfo
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buckets [][]byte
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enums []*enum
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err error
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// Stats
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size int
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sizeAll int
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bucketWaste int
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}
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const (
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maxBucketSize = 8 * 1024 // 8K
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maxStrlen = 254 // allow 0xFF sentinel
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)
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func (b *Builder) setError(err error) {
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if b.err == nil {
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b.err = err
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}
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}
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func (b *Builder) addString(data string) stringInfo {
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data = b.makeString(data)
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info, ok := b.strToBucket[data]
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if !ok {
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b.size += len(data)
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x := len(b.buckets) - 1
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bucket := b.buckets[x]
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if len(bucket)+len(data) < maxBucketSize {
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info.bucket = uint16(x)
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info.bucketPos = uint16(len(bucket))
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b.buckets[x] = append(bucket, data...)
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} else {
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info.bucket = uint16(len(b.buckets))
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info.bucketPos = 0
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b.buckets = append(b.buckets, []byte(data))
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}
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b.strToBucket[data] = info
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}
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return info
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}
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func (b *Builder) addStringToBucket(data string, bucket uint16) stringInfo {
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data = b.makeString(data)
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info, ok := b.strToBucket[data]
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if !ok || info.bucket != bucket {
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if ok {
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b.bucketWaste += len(data)
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}
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b.size += len(data)
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bk := b.buckets[bucket]
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info.bucket = bucket
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info.bucketPos = uint16(len(bk))
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b.buckets[bucket] = append(bk, data...)
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b.strToBucket[data] = info
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}
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return info
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}
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func (b *Builder) makeString(data string) string {
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if len(data) > maxStrlen {
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b.setError(fmt.Errorf("string %q exceeds maximum length of %d", data, maxStrlen))
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data = data[:maxStrlen]
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for i := len(data) - 1; i > len(data)-4; i-- {
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if utf8.RuneStart(data[i]) {
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data = data[:i]
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break
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}
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}
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}
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data = string([]byte{byte(len(data))}) + data
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b.sizeAll += len(data)
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return data
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}
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type stringInfo struct {
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bufferPos uint32
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bucket uint16
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bucketPos uint16
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}
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// New creates a new Builder.
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func New(tableName string) *Builder {
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b := &Builder{
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strToBucket: map[string]stringInfo{},
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buckets: [][]byte{nil}, // initialize with first bucket.
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}
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b.rootMeta = &metaData{
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b: b,
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typeInfo: &typeInfo{},
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}
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return b
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}
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// Gen writes all the tables and types for the collected data.
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func (b *Builder) Gen(w *gen.CodeWriter) error {
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t, err := build(b)
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if err != nil {
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return err
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}
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return generate(b, t, w)
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}
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// GenTestData generates tables useful for testing data generated with Gen.
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func (b *Builder) GenTestData(w *gen.CodeWriter) error {
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return generateTestData(b, w)
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}
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type locale struct {
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tag language.Tag
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root *Index
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}
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// Locale creates an index for the given locale.
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func (b *Builder) Locale(t language.Tag) *Index {
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index := &Index{
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meta: b.rootMeta,
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}
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b.locales = append(b.locales, locale{tag: t, root: index})
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return index
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}
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// An Index holds a map of either leaf values or other indices.
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type Index struct {
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meta *metaData
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subIndex []*Index
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values []keyValue
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}
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func (i *Index) setError(err error) { i.meta.b.setError(err) }
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type keyValue struct {
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key enumIndex
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value stringInfo
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}
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// Element is a CLDR XML element.
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type Element interface {
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GetCommon() *cldr.Common
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}
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// Index creates a subindex where the type and enum values are not shared
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// with siblings by default. The name is derived from the elem. If elem is
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// an alias reference, the alias will be resolved and linked. If elem is nil
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// Index returns nil.
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func (i *Index) Index(elem Element, opt ...Option) *Index {
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if elem == nil || reflect.ValueOf(elem).IsNil() {
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return nil
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}
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c := elem.GetCommon()
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o := &options{
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parent: i,
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name: c.GetCommon().Element(),
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}
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o.fill(opt)
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o.setAlias(elem)
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return i.subIndexForKey(o)
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}
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// IndexWithName is like Section but derives the name from the given name.
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func (i *Index) IndexWithName(name string, opt ...Option) *Index {
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o := &options{parent: i, name: name}
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o.fill(opt)
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return i.subIndexForKey(o)
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}
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// IndexFromType creates a subindex the value of tye type attribute as key. It
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// will also configure the Index to share the enumeration values with all
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// sibling values. If elem is an alias, it will be resolved and linked.
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func (i *Index) IndexFromType(elem Element, opts ...Option) *Index {
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o := &options{
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parent: i,
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name: elem.GetCommon().Type,
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}
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o.fill(opts)
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o.setAlias(elem)
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useSharedType()(o)
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return i.subIndexForKey(o)
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}
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// IndexFromAlt creates a subindex the value of tye alt attribute as key. It
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// will also configure the Index to share the enumeration values with all
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// sibling values. If elem is an alias, it will be resolved and linked.
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func (i *Index) IndexFromAlt(elem Element, opts ...Option) *Index {
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o := &options{
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parent: i,
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name: elem.GetCommon().Alt,
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}
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o.fill(opts)
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o.setAlias(elem)
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useSharedType()(o)
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return i.subIndexForKey(o)
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}
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func (i *Index) subIndexForKey(opts *options) *Index {
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key := opts.name
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if len(i.values) > 0 {
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panic(fmt.Errorf("cldrtree: adding Index for %q when value already exists", key))
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}
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meta := i.meta.sub(key, opts)
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for _, x := range i.subIndex {
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if x.meta == meta {
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return x
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}
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}
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if alias := opts.alias; alias != nil {
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if a := alias.GetCommon().Alias; a != nil {
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if a.Source != "locale" {
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i.setError(fmt.Errorf("cldrtree: non-locale alias not supported %v", a.Path))
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}
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if meta.inheritOffset < 0 {
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i.setError(fmt.Errorf("cldrtree: alias was already set %v", a.Path))
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}
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path := a.Path
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for ; strings.HasPrefix(path, "../"); path = path[len("../"):] {
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meta.inheritOffset--
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}
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m := aliasRe.FindStringSubmatch(path)
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if m == nil {
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i.setError(fmt.Errorf("cldrtree: could not parse alias %q", a.Path))
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} else {
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key := m[4]
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if key == "" {
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key = m[1]
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}
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meta.inheritIndex = key
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}
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}
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}
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x := &Index{meta: meta}
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i.subIndex = append(i.subIndex, x)
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return x
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}
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var aliasRe = regexp.MustCompile(`^([a-zA-Z]+)(\[@([a-zA-Z-]+)='([a-zA-Z-]+)'\])?`)
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// SetValue sets the value, the data from a CLDR XML element, for the given key.
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func (i *Index) SetValue(key string, value Element, opt ...Option) {
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if len(i.subIndex) > 0 {
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panic(fmt.Errorf("adding value for key %q when index already exists", key))
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}
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o := &options{parent: i}
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o.fill(opt)
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c := value.GetCommon()
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if c.Alias != nil {
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i.setError(fmt.Errorf("cldrtree: alias not supported for SetValue %v", c.Alias.Path))
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}
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i.setValue(key, c.Data(), o)
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}
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func (i *Index) setValue(key, data string, o *options) {
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index, _ := i.meta.typeInfo.lookupSubtype(key, o)
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kv := keyValue{key: index}
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if len(i.values) > 0 {
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// Add string to the same bucket as the other values.
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bucket := i.values[0].value.bucket
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kv.value = i.meta.b.addStringToBucket(data, bucket)
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} else {
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kv.value = i.meta.b.addString(data)
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}
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i.values = append(i.values, kv)
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}
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