blob: cab50ac386463375f1c15c8a077e1629640b3ee1 [file] [log] [blame]
// Copyright (c) 2018, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
// @dart = 2.7
/// Compares [text1] and [text2] line-by-line. If a mismatch is found, a diff
/// of the [windowSize] lines before and after are printed and the mismatch line
/// number is returned. If identical, nothing is printed and `null` is returned.
int checkEqualContentAndShowDiff(String text1, String text2,
{int windowSize: 20,
bool Function(int, List<String>, List<String>) filter}) {
List<String> lines1 = text1.split('\n');
List<String> lines2 = text2.split('\n');
for (int i = 0; i < lines1.length && i < lines2.length; i++) {
if (i >= lines1.length || i >= lines2.length || lines1[i] != lines2[i]) {
if (filter != null && filter(i, lines1, lines2)) {
String line1 = 0 <= i && i < lines1.length ? lines1[i] : null;
String line2 = 0 <= i && i < lines2.length ? lines2[i] : null;
String text = line1 == null ? '<eof>' : line1;
String newText = line2 == null ? '<eof>' : line2;
print('(skipped) - $i ${text}');
print('(skipped) + $i ${newText}');
} else {
List<String> pendingLines = <String>[];
void flushPendingLines() {
if (pendingLines.isNotEmpty) {
print(pendingLines.join('\n'));
pendingLines.clear();
}
}
for (int j = i - windowSize; j < i + windowSize; j++) {
if (j < 0) continue;
String line1 = 0 <= j && j < lines1.length ? lines1[j] : null;
String line2 = 0 <= j && j < lines2.length ? lines2[j] : null;
if (line1 == line2) {
flushPendingLines();
if (line1 != null) {
print(' $j $line1');
}
} else {
String text = line1 == null ? '<eof>' : line1;
String newText = line2 == null ? '<eof>' : line2;
if (text.length > 80 && newText.length > 80) {
flushPendingLines();
print('- $j ${text}');
print('+ $j ${newText}');
assert(text != newText);
StringBuffer diff = new StringBuffer();
diff.write(' $j ');
for (int k = 0; k < text.length && k < newText.length; k++) {
int char1 = k < text.length ? text.codeUnitAt(k) : null;
int char2 = k < newText.length ? newText.codeUnitAt(k) : null;
if (char1 != char2) {
diff.write('^');
} else {
diff.write(' ');
}
}
print(diff);
} else {
print('- $j ${text}');
pendingLines.add('+ $j ${newText}');
}
}
}
flushPendingLines();
return i;
}
}
}
return null;
}