198 lines
6.6 KiB
Go
198 lines
6.6 KiB
Go
// Copyright 2015 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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//go:generate go run gen.go gen_trieval.go gen_ranges.go
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// Package bidi contains functionality for bidirectional text support.
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//
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// See https://www.unicode.org/reports/tr9.
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//
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// NOTE: UNDER CONSTRUCTION. This API may change in backwards incompatible ways
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// and without notice.
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package bidi // import "golang.org/x/text/unicode/bidi"
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// TODO:
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// The following functionality would not be hard to implement, but hinges on
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// the definition of a Segmenter interface. For now this is up to the user.
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// - Iterate over paragraphs
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// - Segmenter to iterate over runs directly from a given text.
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// Also:
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// - Transformer for reordering?
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// - Transformer (validator, really) for Bidi Rule.
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// This API tries to avoid dealing with embedding levels for now. Under the hood
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// these will be computed, but the question is to which extent the user should
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// know they exist. We should at some point allow the user to specify an
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// embedding hierarchy, though.
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// A Direction indicates the overall flow of text.
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type Direction int
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const (
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// LeftToRight indicates the text contains no right-to-left characters and
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// that either there are some left-to-right characters or the option
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// DefaultDirection(LeftToRight) was passed.
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LeftToRight Direction = iota
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// RightToLeft indicates the text contains no left-to-right characters and
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// that either there are some right-to-left characters or the option
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// DefaultDirection(RightToLeft) was passed.
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RightToLeft
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// Mixed indicates text contains both left-to-right and right-to-left
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// characters.
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Mixed
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// Neutral means that text contains no left-to-right and right-to-left
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// characters and that no default direction has been set.
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Neutral
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)
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type options struct{}
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// An Option is an option for Bidi processing.
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type Option func(*options)
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// ICU allows the user to define embedding levels. This may be used, for example,
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// to use hierarchical structure of markup languages to define embeddings.
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// The following option may be a way to expose this functionality in this API.
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// // LevelFunc sets a function that associates nesting levels with the given text.
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// // The levels function will be called with monotonically increasing values for p.
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// func LevelFunc(levels func(p int) int) Option {
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// panic("unimplemented")
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// }
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// DefaultDirection sets the default direction for a Paragraph. The direction is
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// overridden if the text contains directional characters.
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func DefaultDirection(d Direction) Option {
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panic("unimplemented")
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}
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// A Paragraph holds a single Paragraph for Bidi processing.
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type Paragraph struct {
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// buffers
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}
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// SetBytes configures p for the given paragraph text. It replaces text
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// previously set by SetBytes or SetString. If b contains a paragraph separator
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// it will only process the first paragraph and report the number of bytes
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// consumed from b including this separator. Error may be non-nil if options are
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// given.
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func (p *Paragraph) SetBytes(b []byte, opts ...Option) (n int, err error) {
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panic("unimplemented")
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}
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// SetString configures p for the given paragraph text. It replaces text
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// previously set by SetBytes or SetString. If b contains a paragraph separator
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// it will only process the first paragraph and report the number of bytes
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// consumed from b including this separator. Error may be non-nil if options are
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// given.
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func (p *Paragraph) SetString(s string, opts ...Option) (n int, err error) {
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panic("unimplemented")
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}
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// IsLeftToRight reports whether the principle direction of rendering for this
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// paragraphs is left-to-right. If this returns false, the principle direction
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// of rendering is right-to-left.
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func (p *Paragraph) IsLeftToRight() bool {
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panic("unimplemented")
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}
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// Direction returns the direction of the text of this paragraph.
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//
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// The direction may be LeftToRight, RightToLeft, Mixed, or Neutral.
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func (p *Paragraph) Direction() Direction {
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panic("unimplemented")
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}
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// RunAt reports the Run at the given position of the input text.
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//
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// This method can be used for computing line breaks on paragraphs.
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func (p *Paragraph) RunAt(pos int) Run {
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panic("unimplemented")
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}
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// Order computes the visual ordering of all the runs in a Paragraph.
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func (p *Paragraph) Order() (Ordering, error) {
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panic("unimplemented")
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}
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// Line computes the visual ordering of runs for a single line starting and
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// ending at the given positions in the original text.
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func (p *Paragraph) Line(start, end int) (Ordering, error) {
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panic("unimplemented")
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}
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// An Ordering holds the computed visual order of runs of a Paragraph. Calling
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// SetBytes or SetString on the originating Paragraph invalidates an Ordering.
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// The methods of an Ordering should only be called by one goroutine at a time.
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type Ordering struct{}
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// Direction reports the directionality of the runs.
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//
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// The direction may be LeftToRight, RightToLeft, Mixed, or Neutral.
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func (o *Ordering) Direction() Direction {
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panic("unimplemented")
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}
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// NumRuns returns the number of runs.
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func (o *Ordering) NumRuns() int {
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panic("unimplemented")
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}
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// Run returns the ith run within the ordering.
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func (o *Ordering) Run(i int) Run {
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panic("unimplemented")
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}
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// TODO: perhaps with options.
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// // Reorder creates a reader that reads the runes in visual order per character.
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// // Modifiers remain after the runes they modify.
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// func (l *Runs) Reorder() io.Reader {
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// panic("unimplemented")
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// }
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// A Run is a continuous sequence of characters of a single direction.
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type Run struct {
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}
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// String returns the text of the run in its original order.
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func (r *Run) String() string {
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panic("unimplemented")
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}
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// Bytes returns the text of the run in its original order.
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func (r *Run) Bytes() []byte {
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panic("unimplemented")
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}
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// TODO: methods for
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// - Display order
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// - headers and footers
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// - bracket replacement.
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// Direction reports the direction of the run.
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func (r *Run) Direction() Direction {
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panic("unimplemented")
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}
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// Position of the Run within the text passed to SetBytes or SetString of the
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// originating Paragraph value.
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func (r *Run) Pos() (start, end int) {
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panic("unimplemented")
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}
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// AppendReverse reverses the order of characters of in, appends them to out,
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// and returns the result. Modifiers will still follow the runes they modify.
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// Brackets are replaced with their counterparts.
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func AppendReverse(out, in []byte) []byte {
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panic("unimplemented")
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}
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// ReverseString reverses the order of characters in s and returns a new string.
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// Modifiers will still follow the runes they modify. Brackets are replaced with
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// their counterparts.
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func ReverseString(s string) string {
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panic("unimplemented")
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}
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