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// SPDX-License-Identifier: GPL-3.0-or-later
package matcher
import "regexp"
// NewRegExpMatcher create new matcher with RegExp format
func NewRegExpMatcher(expr string) (Matcher, error) {
switch expr {
case "", "^", "$":
return TRUE(), nil
case "^$", "$^":
return NewStringMatcher("", true, true)
}
size := len(expr)
chars := []rune(expr)
var startWith, endWith bool
startIdx := 0
endIdx := size - 1
if chars[startIdx] == '^' {
startWith = true
startIdx = 1
}
if chars[endIdx] == '$' {
endWith = true
endIdx--
}
unescapedExpr := make([]rune, 0, endIdx-startIdx+1)
for i := startIdx; i <= endIdx; i++ {
ch := chars[i]
if ch == '\\' {
if i == endIdx { // end with '\' => invalid format
return regexp.Compile(expr)
}
nextCh := chars[i+1]
if !isRegExpMeta(nextCh) { // '\' + mon-meta char => special meaning
return regexp.Compile(expr)
}
unescapedExpr = append(unescapedExpr, nextCh)
i++
} else if isRegExpMeta(ch) {
return regexp.Compile(expr)
} else {
unescapedExpr = append(unescapedExpr, ch)
}
}
return NewStringMatcher(string(unescapedExpr), startWith, endWith)
}
// isRegExpMeta reports whether byte b needs to be escaped by QuoteMeta.
func isRegExpMeta(b rune) bool {
switch b {
case '\\', '.', '+', '*', '?', '(', ')', '|', '[', ']', '{', '}', '^', '$':
return true
default:
return false
}
}
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