mirror of
https://github.com/go-gitea/gitea.git
synced 2024-12-04 14:46:57 -05:00
285 lines
9.8 KiB
Go
285 lines
9.8 KiB
Go
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// Copyright (c) 2015 Couchbase, Inc.
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// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
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// except in compliance with the License. You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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// Unless required by applicable law or agreed to in writing, software distributed under the
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// License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
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// either express or implied. See the License for the specific language governing permissions
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// and limitations under the License.
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package segment
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import (
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"errors"
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"io"
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)
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// Autogenerate the following:
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// 1. Ragel rules from subset of Unicode script properties
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// 2. Ragel rules from Unicode word segmentation properties
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// 3. Ragel machine for word segmentation
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// 4. Test tables from Unicode
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//
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// Requires:
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// 1. Ruby (to generate ragel rules from unicode spec)
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// 2. Ragel (only v6.9 tested)
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// 3. sed (to rewrite build tags)
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//
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//go:generate ragel/unicode2ragel.rb -u http://www.unicode.org/Public/8.0.0/ucd/Scripts.txt -m SCRIPTS -p Hangul,Han,Hiragana -o ragel/uscript.rl
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//go:generate ragel/unicode2ragel.rb -u http://www.unicode.org/Public/8.0.0/ucd/auxiliary/WordBreakProperty.txt -m WB -p Double_Quote,Single_Quote,Hebrew_Letter,CR,LF,Newline,Extend,Format,Katakana,ALetter,MidLetter,MidNum,MidNumLet,Numeric,ExtendNumLet,Regional_Indicator -o ragel/uwb.rl
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//go:generate ragel -T1 -Z segment_words.rl -o segment_words.go
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//go:generate sed -i "" -e "s/BUILDTAGS/!prod/" segment_words.go
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//go:generate sed -i "" -e "s/RAGELFLAGS/-T1/" segment_words.go
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//go:generate ragel -G2 -Z segment_words.rl -o segment_words_prod.go
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//go:generate sed -i "" -e "s/BUILDTAGS/prod/" segment_words_prod.go
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//go:generate sed -i "" -e "s/RAGELFLAGS/-G2/" segment_words_prod.go
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//go:generate go run maketesttables.go -output tables_test.go
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// NewWordSegmenter returns a new Segmenter to read from r.
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func NewWordSegmenter(r io.Reader) *Segmenter {
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return NewSegmenter(r)
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}
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// NewWordSegmenterDirect returns a new Segmenter to work directly with buf.
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func NewWordSegmenterDirect(buf []byte) *Segmenter {
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return NewSegmenterDirect(buf)
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}
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func SplitWords(data []byte, atEOF bool) (int, []byte, error) {
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advance, token, _, err := SegmentWords(data, atEOF)
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return advance, token, err
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}
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func SegmentWords(data []byte, atEOF bool) (int, []byte, int, error) {
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vals := make([][]byte, 0, 1)
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types := make([]int, 0, 1)
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tokens, types, advance, err := segmentWords(data, 1, atEOF, vals, types)
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if len(tokens) > 0 {
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return advance, tokens[0], types[0], err
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}
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return advance, nil, 0, err
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}
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func SegmentWordsDirect(data []byte, val [][]byte, types []int) ([][]byte, []int, int, error) {
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return segmentWords(data, -1, true, val, types)
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}
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// *** Core Segmenter
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const maxConsecutiveEmptyReads = 100
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// NewSegmenter returns a new Segmenter to read from r.
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// Defaults to segment using SegmentWords
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func NewSegmenter(r io.Reader) *Segmenter {
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return &Segmenter{
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r: r,
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segment: SegmentWords,
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maxTokenSize: MaxScanTokenSize,
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buf: make([]byte, 4096), // Plausible starting size; needn't be large.
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}
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}
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// NewSegmenterDirect returns a new Segmenter to work directly with buf.
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// Defaults to segment using SegmentWords
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func NewSegmenterDirect(buf []byte) *Segmenter {
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return &Segmenter{
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segment: SegmentWords,
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maxTokenSize: MaxScanTokenSize,
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buf: buf,
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start: 0,
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end: len(buf),
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err: io.EOF,
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}
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}
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// Segmenter provides a convenient interface for reading data such as
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// a file of newline-delimited lines of text. Successive calls to
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// the Segment method will step through the 'tokens' of a file, skipping
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// the bytes between the tokens. The specification of a token is
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// defined by a split function of type SplitFunc; the default split
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// function breaks the input into lines with line termination stripped. Split
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// functions are defined in this package for scanning a file into
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// lines, bytes, UTF-8-encoded runes, and space-delimited words. The
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// client may instead provide a custom split function.
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//
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// Segmenting stops unrecoverably at EOF, the first I/O error, or a token too
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// large to fit in the buffer. When a scan stops, the reader may have
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// advanced arbitrarily far past the last token. Programs that need more
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// control over error handling or large tokens, or must run sequential scans
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// on a reader, should use bufio.Reader instead.
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//
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type Segmenter struct {
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r io.Reader // The reader provided by the client.
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segment SegmentFunc // The function to split the tokens.
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maxTokenSize int // Maximum size of a token; modified by tests.
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token []byte // Last token returned by split.
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buf []byte // Buffer used as argument to split.
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start int // First non-processed byte in buf.
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end int // End of data in buf.
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typ int // The token type
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err error // Sticky error.
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}
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// SegmentFunc is the signature of the segmenting function used to tokenize the
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// input. The arguments are an initial substring of the remaining unprocessed
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// data and a flag, atEOF, that reports whether the Reader has no more data
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// to give. The return values are the number of bytes to advance the input
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// and the next token to return to the user, plus an error, if any. If the
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// data does not yet hold a complete token, for instance if it has no newline
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// while scanning lines, SegmentFunc can return (0, nil, nil) to signal the
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// Segmenter to read more data into the slice and try again with a longer slice
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// starting at the same point in the input.
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//
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// If the returned error is non-nil, segmenting stops and the error
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// is returned to the client.
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//
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// The function is never called with an empty data slice unless atEOF
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// is true. If atEOF is true, however, data may be non-empty and,
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// as always, holds unprocessed text.
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type SegmentFunc func(data []byte, atEOF bool) (advance int, token []byte, segmentType int, err error)
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// Errors returned by Segmenter.
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var (
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ErrTooLong = errors.New("bufio.Segmenter: token too long")
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ErrNegativeAdvance = errors.New("bufio.Segmenter: SplitFunc returns negative advance count")
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ErrAdvanceTooFar = errors.New("bufio.Segmenter: SplitFunc returns advance count beyond input")
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)
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const (
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// Maximum size used to buffer a token. The actual maximum token size
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// may be smaller as the buffer may need to include, for instance, a newline.
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MaxScanTokenSize = 64 * 1024
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)
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// Err returns the first non-EOF error that was encountered by the Segmenter.
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func (s *Segmenter) Err() error {
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if s.err == io.EOF {
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return nil
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}
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return s.err
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}
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func (s *Segmenter) Type() int {
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return s.typ
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}
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// Bytes returns the most recent token generated by a call to Segment.
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// The underlying array may point to data that will be overwritten
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// by a subsequent call to Segment. It does no allocation.
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func (s *Segmenter) Bytes() []byte {
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return s.token
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}
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// Text returns the most recent token generated by a call to Segment
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// as a newly allocated string holding its bytes.
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func (s *Segmenter) Text() string {
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return string(s.token)
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}
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// Segment advances the Segmenter to the next token, which will then be
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// available through the Bytes or Text method. It returns false when the
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// scan stops, either by reaching the end of the input or an error.
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// After Segment returns false, the Err method will return any error that
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// occurred during scanning, except that if it was io.EOF, Err
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// will return nil.
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func (s *Segmenter) Segment() bool {
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// Loop until we have a token.
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for {
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// See if we can get a token with what we already have.
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if s.end > s.start {
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advance, token, typ, err := s.segment(s.buf[s.start:s.end], s.err != nil)
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if err != nil {
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s.setErr(err)
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return false
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}
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s.typ = typ
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if !s.advance(advance) {
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return false
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}
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s.token = token
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if token != nil {
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return true
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}
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}
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// We cannot generate a token with what we are holding.
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// If we've already hit EOF or an I/O error, we are done.
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if s.err != nil {
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// Shut it down.
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s.start = 0
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s.end = 0
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return false
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}
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// Must read more data.
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// First, shift data to beginning of buffer if there's lots of empty space
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// or space is needed.
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if s.start > 0 && (s.end == len(s.buf) || s.start > len(s.buf)/2) {
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copy(s.buf, s.buf[s.start:s.end])
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s.end -= s.start
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s.start = 0
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}
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// Is the buffer full? If so, resize.
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if s.end == len(s.buf) {
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if len(s.buf) >= s.maxTokenSize {
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s.setErr(ErrTooLong)
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return false
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}
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newSize := len(s.buf) * 2
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if newSize > s.maxTokenSize {
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newSize = s.maxTokenSize
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}
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newBuf := make([]byte, newSize)
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copy(newBuf, s.buf[s.start:s.end])
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s.buf = newBuf
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s.end -= s.start
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s.start = 0
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continue
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}
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// Finally we can read some input. Make sure we don't get stuck with
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// a misbehaving Reader. Officially we don't need to do this, but let's
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// be extra careful: Segmenter is for safe, simple jobs.
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for loop := 0; ; {
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n, err := s.r.Read(s.buf[s.end:len(s.buf)])
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s.end += n
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if err != nil {
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s.setErr(err)
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break
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}
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if n > 0 {
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break
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}
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loop++
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if loop > maxConsecutiveEmptyReads {
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s.setErr(io.ErrNoProgress)
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break
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}
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}
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}
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}
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// advance consumes n bytes of the buffer. It reports whether the advance was legal.
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func (s *Segmenter) advance(n int) bool {
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if n < 0 {
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s.setErr(ErrNegativeAdvance)
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return false
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}
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if n > s.end-s.start {
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s.setErr(ErrAdvanceTooFar)
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return false
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}
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s.start += n
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return true
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}
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// setErr records the first error encountered.
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func (s *Segmenter) setErr(err error) {
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if s.err == nil || s.err == io.EOF {
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s.err = err
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}
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}
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// SetSegmenter sets the segment function for the Segmenter. If called, it must be
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// called before Segment.
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func (s *Segmenter) SetSegmenter(segmenter SegmentFunc) {
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s.segment = segmenter
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}
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