438 lines
11 KiB
Go
438 lines
11 KiB
Go
package remap
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/*
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Map returns a map[string][]<match bytes> for regexes with named capture groups matched in bytes b.
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Note that this supports non-unique group names; [regexp.Regexp] allows for patterns with multiple groups
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using the same group name (though your IDE might complain; I know GoLand does).
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Each match for each group is in a slice keyed under that group name, with that slice
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ordered by the indexing done by the regex match itself.
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In summary, the parameters are as follows:
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# inclNoMatch
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If true, then attempt to return a non-nil matches (as long as b isn't nil).
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Group keys will be populated and explicitly defined as nil.
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For example, if a pattern
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^(?P<g1>foo)(?P<g1>bar)(?P<g2>baz)$
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is provided but b does not match then matches will be:
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map[string][][]byte{
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"g1": nil,
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"g2": nil,
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}
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# inclNoMatchStrict
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If true (and inclNoMatch is true), instead of a single nil the group's values will be
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a slice of nil values explicitly matching the number of times the group name is specified
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in the pattern.
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For example, if a pattern:
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^(?P<g1>foo)(?P<g1>bar)(?P<g2>baz)$
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is provided but b does not match then matches will be:
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map[string][][]byte{
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"g1": [][]byte{
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nil,
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nil,
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},
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"g2": [][]byte{
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nil,
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},
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}
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# mustMatch
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If true, matches will be nil if the entirety of b does not match the pattern (and thus
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no capture groups matched) (overrides inclNoMatch) -- explicitly:
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matches == nil
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Otherwise if false (and assuming inclNoMatch is false), matches will be:
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map[string][][]byte{}{}
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# Condition Tree
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In detail, matches and/or its values may be nil or empty under the following condition tree:
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IF b is nil:
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THEN matches will always be nil
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ELSE:
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IF all of b does not match pattern
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IF mustMuch is true
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THEN matches == nil
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ELSE
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THEN matches == map[string][][]byte{} (non-nil but empty)
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ELSE IF pattern has no named capture groups
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IF inclNoMatch is true
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THEN matches == map[string][][]byte{} (non-nil but empty)
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ELSE
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THEN matches == nil
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ELSE
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IF there are no named group matches
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IF inclNoMatch is true
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THEN matches is non-nil; matches[<group name>, ...] is/are defined but nil (_, ok = matches[<group name>]; ok == true)
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ELSE
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THEN matches == nil
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ELSE
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IF <group name> does not have a match
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IF inclNoMatch is true
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IF inclNoMatchStrict is true
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THEN matches[<group name>] is defined and non-nil, but populated with placeholder nils
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(matches[<group name>] == [][]byte{nil[, nil...]})
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ELSE
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THEN matches[<group name>] is guaranteed defined but may be nil (_, ok = matches[<group name>]; ok == true)
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ELSE
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THEN matches[<group name>] is not defined (_, ok = matches[<group name>]; ok == false)
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ELSE
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matches[<group name>] == []{<match>[, <match>...]}
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*/
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func (r *ReMap) Map(b []byte, inclNoMatch, inclNoMatchStrict, mustMatch bool) (matches map[string][][]byte) {
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var ok bool
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var mIdx int
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var match []byte
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var grpNm string
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var names []string
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var matchBytes [][]byte
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var tmpMap map[string][][]byte = make(map[string][][]byte)
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if b == nil {
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return
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}
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names = r.Regexp.SubexpNames()
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matchBytes = r.Regexp.FindSubmatch(b)
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if matchBytes == nil {
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// b does not match pattern
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if !mustMatch {
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matches = make(map[string][][]byte)
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}
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return
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}
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if names == nil || len(names) == 0 || len(names) == 1 {
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/*
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no named capture groups;
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technically only the last condition would be the case.
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*/
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if inclNoMatch {
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matches = make(map[string][][]byte)
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}
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return
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}
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names = names[1:]
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if len(matchBytes) == 0 || len(matchBytes) == 1 {
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/*
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no submatches whatsoever.
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*technically* I don't think this condition can actually be reached.
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This is more of a safe-return before we re-slice.
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*/
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matches = make(map[string][][]byte)
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if inclNoMatch {
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if len(names) >= 1 {
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for _, grpNm = range names {
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matches[grpNm] = nil
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}
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}
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}
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return
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}
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matchBytes = matchBytes[1:]
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for mIdx, match = range matchBytes {
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grpNm = names[mIdx]
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/*
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Thankfully, it's actually a build error if a pattern specifies a named
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capture group with an empty name.
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So we don't need to worry about accounting for that,
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and can just skip over grpNm == "" (which is an *unnamed* capture group).
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*/
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if grpNm == "" {
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continue
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}
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if match == nil {
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// group did not match
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if !inclNoMatch {
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continue
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}
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if _, ok = tmpMap[grpNm]; !ok {
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if !inclNoMatchStrict {
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tmpMap[grpNm] = nil
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} else {
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tmpMap[grpNm] = [][]byte{nil}
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}
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} else {
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if inclNoMatchStrict {
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tmpMap[grpNm] = append(tmpMap[grpNm], nil)
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}
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}
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continue
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}
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if _, ok = tmpMap[grpNm]; !ok {
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tmpMap[grpNm] = make([][]byte, 0)
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}
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tmpMap[grpNm] = append(tmpMap[grpNm], match)
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}
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// This *technically* should be completely handled above.
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if inclNoMatch {
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for _, grpNm = range names {
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if _, ok = tmpMap[grpNm]; !ok {
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tmpMap[grpNm] = nil
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}
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}
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}
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if len(tmpMap) > 0 {
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matches = tmpMap
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}
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return
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}
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/*
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MapString is exactly like ReMap.Map(), but operates on (and returns) strings instead.
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(matches will always be nil if s == “.)
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A small deviation, though; empty strings instead of nils (because duh) will occupy slice placeholders (if `inclNoMatchStrict` is specified).
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This unfortunately *does not provide any indication* if an empty string positively matched the pattern (a "hit") or if it was simply
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not matched at all (a "miss"). If you need definitive determination between the two conditions, it is instead recommended to either
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*not* use inclNoMatchStrict or to use ReMap.Map() instead and convert any non-nil values to strings after.
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Particularly:
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# inclNoMatch
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If true, then attempt to return a non-nil matches (as long as s isn't empty).
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Group keys will be populated and explicitly defined as nil.
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|
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For example, if a pattern
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^(?P<g1>foo)(?P<g1>bar)(?P<g2>baz)$
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|
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is provided but s does not match then matches will be:
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map[string][]string{
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"g1": nil,
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"g2": nil,
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}
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# inclNoMatchStrict
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If true (and inclNoMatch is true), instead of a single nil the group's values will be
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a slice of eempty string values explicitly matching the number of times the group name is specified
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in the pattern.
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For example, if a pattern:
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^(?P<g1>foo)(?P<g1>bar)(?P<g2>baz)$
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is provided but s does not match then matches will be:
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map[string][]string{
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"g1": []string{
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"",
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"",
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},
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"g2": []string{
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"",
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},
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}
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# mustMatch
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If true, matches will be nil if the entirety of s does not match the pattern (and thus
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no capture groups matched) (overrides inclNoMatch) -- explicitly:
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matches == nil
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Otherwise if false (and assuming inclNoMatch is false), matches will be:
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map[string][]string{}{}
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# Condition Tree
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In detail, matches and/or its values may be nil or empty under the following condition tree:
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IF s is empty:
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THEN matches will always be nil
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ELSE:
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IF all of s does not match pattern
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IF mustMuch is true
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THEN matches == nil
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ELSE
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THEN matches == map[string][]string{} (non-nil but empty)
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ELSE IF pattern has no named capture groups
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IF inclNoMatch is true
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THEN matches == map[string][]string{} (non-nil but empty)
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ELSE
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THEN matches == nil
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ELSE
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IF there are no named group matches
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IF inclNoMatch is true
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THEN matches is non-nil; matches[<group name>, ...] is/are defined but nil (_, ok = matches[<group name>]; ok == true)
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ELSE
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THEN matches == nil
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ELSE
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IF <group name> does not have a match
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IF inclNoMatch is true
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IF inclNoMatchStrict is true
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THEN matches[<group name>] is defined and non-nil, but populated with placeholder nils
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(matches[<group name>] == []string{""[, ""...]})
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ELSE
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THEN matches[<group name>] is guaranteed defined but may be nil (_, ok = matches[<group name>]; ok == true)
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ELSE
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THEN matches[<group name>] is not defined (_, ok = matches[<group name>]; ok == false)
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ELSE
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matches[<group name>] == []{<match>[, <match>...]}
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*/
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func (r *ReMap) MapString(s string, inclNoMatch, inclNoMatchStrict, mustMatch bool) (matches map[string][]string) {
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var ok bool
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var endIdx int
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var startIdx int
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var chunkIdx int
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var grpNm string
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var names []string
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var matchStr string
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var idxChunks [][]int
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var matchIndices []int
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var chunkIndices []int // always 2 elements; start pos and end pos
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var tmpMap map[string][]string = make(map[string][]string)
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/*
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OK so this is a bit of a deviation.
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It's not as straightforward as above, because there isn't an explicit way
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like above to determine if a patterb was *matched as an empty string* vs.
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*not matched*.
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So instead do roundabout index-y things.
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*/
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if s == "" {
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return
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}
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names = r.Regexp.SubexpNames()
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matchIndices = r.Regexp.FindStringSubmatchIndex(s)
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if matchIndices == nil {
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// s does not match pattern
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if !mustMatch {
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matches = make(map[string][]string)
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}
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return
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}
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if names == nil || len(names) == 0 || len(names) == 1 {
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/*
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no named capture groups;
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technically only the last condition would be the case.
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*/
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if inclNoMatch {
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matches = make(map[string][]string)
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}
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return
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}
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names = names[1:]
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if len(matchIndices) == 0 || len(matchIndices) == 1 {
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/*
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no submatches whatsoever.
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*technically* I don't think this condition can actually be reached.
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This is more of a safe-return before we chunk the indices.
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*/
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matches = make(map[string][]string)
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if inclNoMatch {
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if len(names) >= 1 {
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for _, grpNm = range names {
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matches[grpNm] = nil
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}
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}
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}
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return
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}
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/*
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The reslice starts at 2 because they're in pairs: []int{<start>, <end>, <start>, <end>, ...}
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and the first *pair* is the entire pattern match.
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Thus the len(matchIndices) == 2*len(names).
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Keep in mind that since the first element of names is removed,
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the first pair here is also removed.
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*/
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matchIndices = matchIndices[2:]
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idxChunks = make([][]int, len(names))
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for startIdx = 0; startIdx < len(idxChunks); startIdx += 2 {
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endIdx = startIdx + 2
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grpNm = names[chunkIdx]
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/*
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Thankfully, it's actually a build error if a pattern specifies a named
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capture group with an empty name.
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So we don't need to worry about accounting for that,
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and can just skip over grpNm == "" (which is an *unnamed* capture group).
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*/
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if grpNm == "" {
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continue
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}
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// This technically should never happen.
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if endIdx > len(matchIndices) {
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endIdx = len(matchIndices)
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}
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chunkIndices = matchIndices[startIdx:endIdx]
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if chunkIndices[0] == -1 || chunkIndices[1] == -1 {
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// group did not match
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if !inclNoMatch {
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continue
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}
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if _, ok = tmpMap[grpNm]; !ok {
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if !inclNoMatchStrict {
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tmpMap[grpNm] = nil
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} else {
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tmpMap[grpNm] = []string{""}
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}
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} else {
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if inclNoMatchStrict {
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tmpMap[grpNm] = append(tmpMap[grpNm], "")
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}
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}
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continue
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}
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matchStr = s[chunkIndices[0]:chunkIndices[1]]
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if _, ok = tmpMap[grpNm]; !ok {
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tmpMap[grpNm] = make([]string, 0)
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}
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tmpMap[grpNm] = append(tmpMap[grpNm], matchStr)
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chunkIdx++
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}
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// This *technically* should be completely handled above.
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if inclNoMatch {
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for _, grpNm = range names {
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if _, ok = tmpMap[grpNm]; !ok {
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tmpMap[grpNm] = nil
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}
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}
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}
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if len(tmpMap) > 0 {
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matches = tmpMap
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}
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return
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}
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