1 package junit.framework; 2 3 public class ComparisonCompactor { 4 5 private static final String ELLIPSIS= "..."; 6 private static final String DELTA_END= "]"; 7 private static final String DELTA_START= "["; 8 9 private int fContextLength; 10 private String fExpected; 11 private String fActual; 12 private int fPrefix; 13 private int fSuffix; 14 ComparisonCompactor(int contextLength, String expected, String actual)15 public ComparisonCompactor(int contextLength, String expected, String actual) { 16 fContextLength= contextLength; 17 fExpected= expected; 18 fActual= actual; 19 } 20 compact(String message)21 public String compact(String message) { 22 if (fExpected == null || fActual == null || areStringsEqual()) 23 return Assert.format(message, fExpected, fActual); 24 25 findCommonPrefix(); 26 findCommonSuffix(); 27 String expected= compactString(fExpected); 28 String actual= compactString(fActual); 29 return Assert.format(message, expected, actual); 30 } 31 compactString(String source)32 private String compactString(String source) { 33 String result= DELTA_START + source.substring(fPrefix, source.length() - fSuffix + 1) + DELTA_END; 34 if (fPrefix > 0) 35 result= computeCommonPrefix() + result; 36 if (fSuffix > 0) 37 result= result + computeCommonSuffix(); 38 return result; 39 } 40 findCommonPrefix()41 private void findCommonPrefix() { 42 fPrefix= 0; 43 int end= Math.min(fExpected.length(), fActual.length()); 44 for (; fPrefix < end; fPrefix++) { 45 if (fExpected.charAt(fPrefix) != fActual.charAt(fPrefix)) 46 break; 47 } 48 } 49 findCommonSuffix()50 private void findCommonSuffix() { 51 int expectedSuffix= fExpected.length() - 1; 52 int actualSuffix= fActual.length() - 1; 53 for (; actualSuffix >= fPrefix && expectedSuffix >= fPrefix; actualSuffix--, expectedSuffix--) { 54 if (fExpected.charAt(expectedSuffix) != fActual.charAt(actualSuffix)) 55 break; 56 } 57 fSuffix= fExpected.length() - expectedSuffix; 58 } 59 computeCommonPrefix()60 private String computeCommonPrefix() { 61 return (fPrefix > fContextLength ? ELLIPSIS : "") + fExpected.substring(Math.max(0, fPrefix - fContextLength), fPrefix); 62 } 63 computeCommonSuffix()64 private String computeCommonSuffix() { 65 int end= Math.min(fExpected.length() - fSuffix + 1 + fContextLength, fExpected.length()); 66 return fExpected.substring(fExpected.length() - fSuffix + 1, end) + (fExpected.length() - fSuffix + 1 < fExpected.length() - fContextLength ? ELLIPSIS : ""); 67 } 68 areStringsEqual()69 private boolean areStringsEqual() { 70 return fExpected.equals(fActual); 71 } 72 } 73