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