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October 31, 2019 12:50
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| using System.Collections.Generic; | |
| using System.Globalization; | |
| // https://stackoverflow.com/a/7048016/3542151 | |
| public class NaturalComparer: IComparer<string> | |
| { | |
| private readonly CultureInfo _culture; | |
| private readonly CompareOptions _compareOptions; | |
| public NaturalComparer(CultureInfo culture = null, CompareOptions? compareOptions = null) | |
| { | |
| _culture = culture ?? CultureInfo.CurrentCulture; | |
| _compareOptions = compareOptions ?? CompareOptions.None; | |
| } | |
| private static int CompareNatural(string strA, string strB, CultureInfo culture, CompareOptions options) | |
| { | |
| if (strA == null && strB == null) return 0; | |
| if (strA == null) return -1; | |
| if (strB == null) return 1; | |
| var cmp = culture.CompareInfo; | |
| var iA = 0; | |
| var iB = 0; | |
| var softResult = 0; | |
| var softResultWeight = 0; | |
| while (iA < strA.Length && iB < strB.Length) | |
| { | |
| var isDigitA = char.IsDigit(strA[iA]); | |
| var isDigitB = char.IsDigit(strB[iB]); | |
| if (isDigitA != isDigitB) | |
| { | |
| return cmp.Compare(strA, iA, strB, iB, options); | |
| } | |
| if (!isDigitA) | |
| { | |
| var jA = iA + 1; | |
| var jB = iB + 1; | |
| while (jA < strA.Length && !char.IsDigit(strA[jA])) jA++; | |
| while (jB < strB.Length && !char.IsDigit(strB[jB])) jB++; | |
| var cmpResult = cmp.Compare(strA, iA, jA - iA, strB, iB, jB - iB, options); | |
| if (cmpResult != 0) | |
| { | |
| // Certain strings may be considered different due to "soft" differences that are | |
| // ignored if more significant differences follow, e.g. a hyphen only affects the | |
| // comparison if no other differences follow | |
| var sectionA = strA.Substring(iA, jA - iA); | |
| var sectionB = strB.Substring(iB, jB - iB); | |
| if (cmp.Compare(sectionA + "1", sectionB + "2", options) == | |
| cmp.Compare(sectionA + "2", sectionB + "1", options)) | |
| { | |
| return cmp.Compare(strA, iA, strB, iB, options); | |
| } | |
| if (softResultWeight < 1) | |
| { | |
| softResult = cmpResult; | |
| softResultWeight = 1; | |
| } | |
| } | |
| iA = jA; | |
| iB = jB; | |
| } | |
| else | |
| { | |
| var zeroA = (char)(strA[iA] - (int)char.GetNumericValue(strA[iA])); | |
| var zeroB = (char)(strB[iB] - (int)char.GetNumericValue(strB[iB])); | |
| var jA = iA; | |
| var jB = iB; | |
| while (jA < strA.Length && strA[jA] == zeroA) jA++; | |
| while (jB < strB.Length && strB[jB] == zeroB) jB++; | |
| var resultIfSameLength = 0; | |
| do | |
| { | |
| isDigitA = jA < strA.Length && char.IsDigit(strA[jA]); | |
| isDigitB = jB < strB.Length && char.IsDigit(strB[jB]); | |
| var numA = isDigitA ? (int)char.GetNumericValue(strA[jA]) : 0; | |
| var numB = isDigitB ? (int)char.GetNumericValue(strB[jB]) : 0; | |
| if (isDigitA && (char)(strA[jA] - numA) != zeroA) isDigitA = false; | |
| if (isDigitB && (char)(strB[jB] - numB) != zeroB) isDigitB = false; | |
| if (isDigitA && isDigitB) | |
| { | |
| if (numA != numB && resultIfSameLength == 0) | |
| { | |
| resultIfSameLength = numA < numB ? -1 : 1; | |
| } | |
| jA++; | |
| jB++; | |
| } | |
| } while (isDigitA && isDigitB); | |
| if (isDigitA != isDigitB) | |
| { | |
| // One number has more digits than the other (ignoring leading zeros) - the longer | |
| // number must be larger | |
| return isDigitA ? 1 : -1; | |
| } | |
| if (resultIfSameLength != 0) | |
| { | |
| // Both numbers are the same length (ignoring leading zeros) and at least one of | |
| // the digits differed - the first difference determines the result | |
| return resultIfSameLength; | |
| } | |
| var lA = jA - iA; | |
| var lB = jB - iB; | |
| if (lA != lB) | |
| { | |
| // Both numbers are equivalent but one has more leading zeros | |
| return lA > lB ? -1 : 1; | |
| } | |
| if (zeroA != zeroB && softResultWeight < 2) | |
| { | |
| softResult = cmp.Compare(strA, iA, 1, strB, iB, 1, options); | |
| softResultWeight = 2; | |
| } | |
| iA = jA; | |
| iB = jB; | |
| } | |
| } | |
| if (iA < strA.Length || iB < strB.Length) | |
| { | |
| return iA < strA.Length ? 1 : -1; | |
| } | |
| if (softResult != 0) | |
| { | |
| return softResult; | |
| } | |
| return 0; | |
| } | |
| public int Compare(string x, string y) => CompareNatural(x, y, _culture, _compareOptions); | |
| } |
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