comparison vendor/github.com/dlclark/regexp2/match.go @ 66:787b5ee0289d draft

Use vendored modules Signed-off-by: Izuru Yakumo <yakumo.izuru@chaotic.ninja>
author yakumo.izuru
date Sun, 23 Jul 2023 13:18:53 +0000
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65:6d985efa0f7a 66:787b5ee0289d
1 package regexp2
2
3 import (
4 "bytes"
5 "fmt"
6 )
7
8 // Match is a single regex result match that contains groups and repeated captures
9 // -Groups
10 // -Capture
11 type Match struct {
12 Group //embeded group 0
13
14 regex *Regexp
15 otherGroups []Group
16
17 // input to the match
18 textpos int
19 textstart int
20
21 capcount int
22 caps []int
23 sparseCaps map[int]int
24
25 // output from the match
26 matches [][]int
27 matchcount []int
28
29 // whether we've done any balancing with this match. If we
30 // have done balancing, we'll need to do extra work in Tidy().
31 balancing bool
32 }
33
34 // Group is an explicit or implit (group 0) matched group within the pattern
35 type Group struct {
36 Capture // the last capture of this group is embeded for ease of use
37
38 Name string // group name
39 Captures []Capture // captures of this group
40 }
41
42 // Capture is a single capture of text within the larger original string
43 type Capture struct {
44 // the original string
45 text []rune
46 // the position in the original string where the first character of
47 // captured substring was found.
48 Index int
49 // the length of the captured substring.
50 Length int
51 }
52
53 // String returns the captured text as a String
54 func (c *Capture) String() string {
55 return string(c.text[c.Index : c.Index+c.Length])
56 }
57
58 // Runes returns the captured text as a rune slice
59 func (c *Capture) Runes() []rune {
60 return c.text[c.Index : c.Index+c.Length]
61 }
62
63 func newMatch(regex *Regexp, capcount int, text []rune, startpos int) *Match {
64 m := Match{
65 regex: regex,
66 matchcount: make([]int, capcount),
67 matches: make([][]int, capcount),
68 textstart: startpos,
69 balancing: false,
70 }
71 m.Name = "0"
72 m.text = text
73 m.matches[0] = make([]int, 2)
74 return &m
75 }
76
77 func newMatchSparse(regex *Regexp, caps map[int]int, capcount int, text []rune, startpos int) *Match {
78 m := newMatch(regex, capcount, text, startpos)
79 m.sparseCaps = caps
80 return m
81 }
82
83 func (m *Match) reset(text []rune, textstart int) {
84 m.text = text
85 m.textstart = textstart
86 for i := 0; i < len(m.matchcount); i++ {
87 m.matchcount[i] = 0
88 }
89 m.balancing = false
90 }
91
92 func (m *Match) tidy(textpos int) {
93
94 interval := m.matches[0]
95 m.Index = interval[0]
96 m.Length = interval[1]
97 m.textpos = textpos
98 m.capcount = m.matchcount[0]
99 //copy our root capture to the list
100 m.Group.Captures = []Capture{m.Group.Capture}
101
102 if m.balancing {
103 // The idea here is that we want to compact all of our unbalanced captures. To do that we
104 // use j basically as a count of how many unbalanced captures we have at any given time
105 // (really j is an index, but j/2 is the count). First we skip past all of the real captures
106 // until we find a balance captures. Then we check each subsequent entry. If it's a balance
107 // capture (it's negative), we decrement j. If it's a real capture, we increment j and copy
108 // it down to the last free position.
109 for cap := 0; cap < len(m.matchcount); cap++ {
110 limit := m.matchcount[cap] * 2
111 matcharray := m.matches[cap]
112
113 var i, j int
114
115 for i = 0; i < limit; i++ {
116 if matcharray[i] < 0 {
117 break
118 }
119 }
120
121 for j = i; i < limit; i++ {
122 if matcharray[i] < 0 {
123 // skip negative values
124 j--
125 } else {
126 // but if we find something positive (an actual capture), copy it back to the last
127 // unbalanced position.
128 if i != j {
129 matcharray[j] = matcharray[i]
130 }
131 j++
132 }
133 }
134
135 m.matchcount[cap] = j / 2
136 }
137
138 m.balancing = false
139 }
140 }
141
142 // isMatched tells if a group was matched by capnum
143 func (m *Match) isMatched(cap int) bool {
144 return cap < len(m.matchcount) && m.matchcount[cap] > 0 && m.matches[cap][m.matchcount[cap]*2-1] != (-3+1)
145 }
146
147 // matchIndex returns the index of the last specified matched group by capnum
148 func (m *Match) matchIndex(cap int) int {
149 i := m.matches[cap][m.matchcount[cap]*2-2]
150 if i >= 0 {
151 return i
152 }
153
154 return m.matches[cap][-3-i]
155 }
156
157 // matchLength returns the length of the last specified matched group by capnum
158 func (m *Match) matchLength(cap int) int {
159 i := m.matches[cap][m.matchcount[cap]*2-1]
160 if i >= 0 {
161 return i
162 }
163
164 return m.matches[cap][-3-i]
165 }
166
167 // Nonpublic builder: add a capture to the group specified by "c"
168 func (m *Match) addMatch(c, start, l int) {
169
170 if m.matches[c] == nil {
171 m.matches[c] = make([]int, 2)
172 }
173
174 capcount := m.matchcount[c]
175
176 if capcount*2+2 > len(m.matches[c]) {
177 oldmatches := m.matches[c]
178 newmatches := make([]int, capcount*8)
179 copy(newmatches, oldmatches[:capcount*2])
180 m.matches[c] = newmatches
181 }
182
183 m.matches[c][capcount*2] = start
184 m.matches[c][capcount*2+1] = l
185 m.matchcount[c] = capcount + 1
186 //log.Printf("addMatch: c=%v, i=%v, l=%v ... matches: %v", c, start, l, m.matches)
187 }
188
189 // Nonpublic builder: Add a capture to balance the specified group. This is used by the
190 // balanced match construct. (?<foo-foo2>...)
191 //
192 // If there were no such thing as backtracking, this would be as simple as calling RemoveMatch(c).
193 // However, since we have backtracking, we need to keep track of everything.
194 func (m *Match) balanceMatch(c int) {
195 m.balancing = true
196
197 // we'll look at the last capture first
198 capcount := m.matchcount[c]
199 target := capcount*2 - 2
200
201 // first see if it is negative, and therefore is a reference to the next available
202 // capture group for balancing. If it is, we'll reset target to point to that capture.
203 if m.matches[c][target] < 0 {
204 target = -3 - m.matches[c][target]
205 }
206
207 // move back to the previous capture
208 target -= 2
209
210 // if the previous capture is a reference, just copy that reference to the end. Otherwise, point to it.
211 if target >= 0 && m.matches[c][target] < 0 {
212 m.addMatch(c, m.matches[c][target], m.matches[c][target+1])
213 } else {
214 m.addMatch(c, -3-target, -4-target /* == -3 - (target + 1) */)
215 }
216 }
217
218 // Nonpublic builder: removes a group match by capnum
219 func (m *Match) removeMatch(c int) {
220 m.matchcount[c]--
221 }
222
223 // GroupCount returns the number of groups this match has matched
224 func (m *Match) GroupCount() int {
225 return len(m.matchcount)
226 }
227
228 // GroupByName returns a group based on the name of the group, or nil if the group name does not exist
229 func (m *Match) GroupByName(name string) *Group {
230 num := m.regex.GroupNumberFromName(name)
231 if num < 0 {
232 return nil
233 }
234 return m.GroupByNumber(num)
235 }
236
237 // GroupByNumber returns a group based on the number of the group, or nil if the group number does not exist
238 func (m *Match) GroupByNumber(num int) *Group {
239 // check our sparse map
240 if m.sparseCaps != nil {
241 if newNum, ok := m.sparseCaps[num]; ok {
242 num = newNum
243 }
244 }
245 if num >= len(m.matchcount) || num < 0 {
246 return nil
247 }
248
249 if num == 0 {
250 return &m.Group
251 }
252
253 m.populateOtherGroups()
254
255 return &m.otherGroups[num-1]
256 }
257
258 // Groups returns all the capture groups, starting with group 0 (the full match)
259 func (m *Match) Groups() []Group {
260 m.populateOtherGroups()
261 g := make([]Group, len(m.otherGroups)+1)
262 g[0] = m.Group
263 copy(g[1:], m.otherGroups)
264 return g
265 }
266
267 func (m *Match) populateOtherGroups() {
268 // Construct all the Group objects first time called
269 if m.otherGroups == nil {
270 m.otherGroups = make([]Group, len(m.matchcount)-1)
271 for i := 0; i < len(m.otherGroups); i++ {
272 m.otherGroups[i] = newGroup(m.regex.GroupNameFromNumber(i+1), m.text, m.matches[i+1], m.matchcount[i+1])
273 }
274 }
275 }
276
277 func (m *Match) groupValueAppendToBuf(groupnum int, buf *bytes.Buffer) {
278 c := m.matchcount[groupnum]
279 if c == 0 {
280 return
281 }
282
283 matches := m.matches[groupnum]
284
285 index := matches[(c-1)*2]
286 last := index + matches[(c*2)-1]
287
288 for ; index < last; index++ {
289 buf.WriteRune(m.text[index])
290 }
291 }
292
293 func newGroup(name string, text []rune, caps []int, capcount int) Group {
294 g := Group{}
295 g.text = text
296 if capcount > 0 {
297 g.Index = caps[(capcount-1)*2]
298 g.Length = caps[(capcount*2)-1]
299 }
300 g.Name = name
301 g.Captures = make([]Capture, capcount)
302 for i := 0; i < capcount; i++ {
303 g.Captures[i] = Capture{
304 text: text,
305 Index: caps[i*2],
306 Length: caps[i*2+1],
307 }
308 }
309 //log.Printf("newGroup! capcount %v, %+v", capcount, g)
310
311 return g
312 }
313
314 func (m *Match) dump() string {
315 buf := &bytes.Buffer{}
316 buf.WriteRune('\n')
317 if len(m.sparseCaps) > 0 {
318 for k, v := range m.sparseCaps {
319 fmt.Fprintf(buf, "Slot %v -> %v\n", k, v)
320 }
321 }
322
323 for i, g := range m.Groups() {
324 fmt.Fprintf(buf, "Group %v (%v), %v caps:\n", i, g.Name, len(g.Captures))
325
326 for _, c := range g.Captures {
327 fmt.Fprintf(buf, " (%v, %v) %v\n", c.Index, c.Length, c.String())
328 }
329 }
330 /*
331 for i := 0; i < len(m.matchcount); i++ {
332 fmt.Fprintf(buf, "\nGroup %v (%v):\n", i, m.regex.GroupNameFromNumber(i))
333
334 for j := 0; j < m.matchcount[i]; j++ {
335 text := ""
336
337 if m.matches[i][j*2] >= 0 {
338 start := m.matches[i][j*2]
339 text = m.text[start : start+m.matches[i][j*2+1]]
340 }
341
342 fmt.Fprintf(buf, " (%v, %v) %v\n", m.matches[i][j*2], m.matches[i][j*2+1], text)
343 }
344 }
345 */
346 return buf.String()
347 }