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StringUtils.wrapText will not split surrogate pair. #103

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Merged
merged 1 commit into from
Nov 22, 2020
Merged

StringUtils.wrapText will not split surrogate pair. #103

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16 changes: 13 additions & 3 deletions java-diff-utils/src/main/java/com/github/difflib/text/StringUtils.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,10 +21,10 @@
final class StringUtils {

/**
* Replaces all opening an closing tags with <code>&lt;</code> or <code>&gt;</code>.
* Replaces all opening and closing tags with <code>&lt;</code> or <code>&gt;</code>.
*
* @param str
* @return
* @return str with some HTML meta characters escaped.
*/
public static String htmlEntites(String str) {
return str.replace("<", "&lt;").replace(">", "&gt;");
Expand Down Expand Up @@ -61,7 +61,17 @@ public static String wrapText(String line, int columnWidth) {
StringBuilder b = new StringBuilder(line);

for (int count = 0; length > widthIndex; count++) {
b.insert(widthIndex + delimiter * count, "<br/>");
int breakPoint = widthIndex + delimiter * count;
if (Character.isHighSurrogate(b.charAt(breakPoint - 1)) &&
Character.isLowSurrogate(b.charAt(breakPoint))) {
// Shift a breakpoint that would split a supplemental code-point.
breakPoint += 1;
if (breakPoint == b.length()) {
// Break before instead of after if this is the last code-point.
breakPoint -= 2;
}
}
b.insert(breakPoint, "<br/>");
widthIndex += columnWidth;
}

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2 changes: 2 additions & 0 deletions java-diff-utils/src/test/java/com/github/difflib/text/StringUtilsTest.java
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Expand Up @@ -49,6 +49,8 @@ public void testWrapText_String_int() {
assertEquals("te<br/>st", StringUtils.wrapText("test", 2));
assertEquals("tes<br/>t", StringUtils.wrapText("test", 3));
assertEquals("test", StringUtils.wrapText("test", 10));
assertEquals(".\uD800\uDC01<br/>.", StringUtils.wrapText(".\uD800\uDC01.", 2));
assertEquals("..<br/>\uD800\uDC01", StringUtils.wrapText("..\uD800\uDC01", 3));
}

@Test
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