replacerdata.go

Documentation: github.com/dlclark/regexp2/syntax

     1  package syntax
     2  
     3  import (
     4  	"bytes"
     5  	"errors"
     6  )
     7  
     8  type ReplacerData struct {
     9  	Rep     string
    10  	Strings []string
    11  	Rules   []int
    12  }
    13  
    14  const (
    15  	replaceSpecials     = 4
    16  	replaceLeftPortion  = -1
    17  	replaceRightPortion = -2
    18  	replaceLastGroup    = -3
    19  	replaceWholeString  = -4
    20  )
    21  
    22  //ErrReplacementError is a general error during parsing the replacement text
    23  var ErrReplacementError = errors.New("Replacement pattern error.")
    24  
    25  // NewReplacerData will populate a reusable replacer data struct based on the given replacement string
    26  // and the capture group data from a regexp
    27  func NewReplacerData(rep string, caps map[int]int, capsize int, capnames map[string]int, op RegexOptions) (*ReplacerData, error) {
    28  	p := parser{
    29  		options:  op,
    30  		caps:     caps,
    31  		capsize:  capsize,
    32  		capnames: capnames,
    33  	}
    34  	p.setPattern(rep)
    35  	concat, err := p.scanReplacement()
    36  	if err != nil {
    37  		return nil, err
    38  	}
    39  
    40  	if concat.t != ntConcatenate {
    41  		panic(ErrReplacementError)
    42  	}
    43  
    44  	sb := &bytes.Buffer{}
    45  	var (
    46  		strings []string
    47  		rules   []int
    48  	)
    49  
    50  	for _, child := range concat.children {
    51  		switch child.t {
    52  		case ntMulti:
    53  			child.writeStrToBuf(sb)
    54  
    55  		case ntOne:
    56  			sb.WriteRune(child.ch)
    57  
    58  		case ntRef:
    59  			if sb.Len() > 0 {
    60  				rules = append(rules, len(strings))
    61  				strings = append(strings, sb.String())
    62  				sb.Reset()
    63  			}
    64  			slot := child.m
    65  
    66  			if len(caps) > 0 && slot >= 0 {
    67  				slot = caps[slot]
    68  			}
    69  
    70  			rules = append(rules, -replaceSpecials-1-slot)
    71  
    72  		default:
    73  			panic(ErrReplacementError)
    74  		}
    75  	}
    76  
    77  	if sb.Len() > 0 {
    78  		rules = append(rules, len(strings))
    79  		strings = append(strings, sb.String())
    80  	}
    81  
    82  	return &ReplacerData{
    83  		Rep:     rep,
    84  		Strings: strings,
    85  		Rules:   rules,
    86  	}, nil
    87  }
    88
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