Rewrite FlowedMessageUtils.deflow()
This new version should use a lot less allocations.
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cketti
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2 changed files with 99 additions and 122 deletions
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@ -1,120 +1,83 @@
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package com.fsck.k9.mail.internet;
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package com.fsck.k9.mail.internet
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/**
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* Adapted from the Apache James project, see
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* https://james.apache.org/mailet/base/apidocs/org/apache/mailet/base/FlowedMessageUtils.html
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*
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* <p>Manages texts encoded as <code>text/plain; format=flowed</code>.</p>
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* <p>As a reference see:</p>
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* <ul>
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* <li><a href='http://www.rfc-editor.org/rfc/rfc2646.txt'>RFC2646</a></li>
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* <li><a href='http://www.rfc-editor.org/rfc/rfc3676.txt'>RFC3676</a> (new method with DelSP support).
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* </ul>
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* <h4>Note</h4>
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* <ul>
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* <li>In order to decode, the input text must belong to a mail with headers similar to:
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* Content-Type: text/plain; charset="CHARSET"; [delsp="yes|no"; ]format="flowed"
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* (the quotes around CHARSET are not mandatory).
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* Furthermore the header Content-Transfer-Encoding MUST NOT BE Quoted-Printable
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* (see RFC3676 paragraph 4.2).(In fact this happens often for non 7bit messages).
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* </li>
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* </ul>
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* Decodes text encoded as `text/plain; format=flowed` (RFC 3676).
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*/
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public final class FlowedMessageUtils {
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private static final char RFC2646_SPACE = ' ';
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private static final char RFC2646_QUOTE = '>';
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private static final String RFC2646_SIGNATURE = "-- ";
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private static final String RFC2646_CRLF = "\r\n";
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object FlowedMessageUtils {
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private const val QUOTE = '>'
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private const val SPACE = ' '
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private const val CR = '\r'
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private const val LF = '\n'
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private const val SIGNATURE = "-- "
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private const val CRLF = "\r\n"
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private FlowedMessageUtils() {
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// this class cannot be instantiated
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}
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@JvmStatic
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fun deflow(text: String, delSp: Boolean): String {
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var lineStartIndex = 0
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var lastLineQuoteDepth = 0
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var lastLineFlowed = false
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/**
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* Decodes a text previously wrapped using "format=flowed".
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*/
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public static String deflow(String text, boolean delSp) {
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String[] lines = text.split("\r\n|\n", -1);
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StringBuffer result = null;
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StringBuffer resultLine = new StringBuffer();
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int resultLineQuoteDepth = 0;
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boolean resultLineFlowed = false;
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// One more cycle, to close the last line
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for (int i = 0; i <= lines.length; i++) {
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String line = i < lines.length ? lines[i] : null;
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int actualQuoteDepth = 0;
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return buildString {
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while (lineStartIndex <= text.lastIndex) {
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var quoteDepth = 0
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while (lineStartIndex <= text.lastIndex && text[lineStartIndex] == QUOTE) {
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quoteDepth++
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lineStartIndex++
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}
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if (line != null) {
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if (line.equals(RFC2646_SIGNATURE)) {
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// signature handling (the previous line is not flowed)
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resultLineFlowed = false;
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} else if (line.length() > 0 && line.charAt(0) == RFC2646_QUOTE) {
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// Quote
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actualQuoteDepth = 1;
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while (actualQuoteDepth < line.length() && line.charAt(actualQuoteDepth) == RFC2646_QUOTE) {
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actualQuoteDepth++;
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// Remove space stuffing
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if (lineStartIndex <= text.lastIndex && text[lineStartIndex] == SPACE) {
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lineStartIndex++
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}
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// We support both LF and CRLF line endings. To cover both cases we search for LF.
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val lineFeedIndex = text.indexOf(LF, lineStartIndex)
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val lineBreakFound = lineFeedIndex != -1
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var lineEndIndex = if (lineBreakFound) lineFeedIndex else text.length
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if (lineEndIndex > 0 && text[lineEndIndex - 1] == CR) {
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lineEndIndex--
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}
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if (lastLineFlowed && quoteDepth != lastLineQuoteDepth) {
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append(CRLF)
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lastLineFlowed = false
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}
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val lineIsSignatureMarker = lineEndIndex - lineStartIndex == SIGNATURE.length &&
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text.regionMatches(lineStartIndex, SIGNATURE, 0, SIGNATURE.length)
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var lineFlowed = false
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if (lineIsSignatureMarker) {
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if (lastLineFlowed) {
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append(CRLF)
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lastLineFlowed = false
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}
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// if quote-depth changes wrt the previous line then this is not flowed
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if (resultLineQuoteDepth != actualQuoteDepth) {
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resultLineFlowed = false;
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}
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line = line.substring(actualQuoteDepth);
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} else {
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// if quote-depth changes wrt the first line then this is not flowed
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if (resultLineQuoteDepth > 0) {
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resultLineFlowed = false;
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}
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}
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if (line.length() > 0 && line.charAt(0) == RFC2646_SPACE) {
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// Line space-stuffed
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line = line.substring(1);
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}
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// if the previous was the last then it was not flowed
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} else {
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resultLineFlowed = false;
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}
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// Add the PREVIOUS line.
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// This often will find the flow looking for a space as the last char of the line.
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// With quote changes or signatures it could be the following line to void the flow.
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if (!resultLineFlowed && i > 0) {
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if (resultLineQuoteDepth > 0) {
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resultLine.insert(0, RFC2646_SPACE);
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}
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for (int j = 0; j < resultLineQuoteDepth; j++) {
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resultLine.insert(0, RFC2646_QUOTE);
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}
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if (result == null) {
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result = new StringBuffer();
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} else {
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result.append(RFC2646_CRLF);
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}
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result.append(resultLine.toString());
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resultLine = new StringBuffer();
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resultLineFlowed = false;
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}
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resultLineQuoteDepth = actualQuoteDepth;
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if (line != null) {
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if (!line.equals(RFC2646_SIGNATURE) && line.endsWith("" + RFC2646_SPACE) && i < lines.length - 1) {
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// Line flowed (NOTE: for the split operation the line having i == lines.length is the last that
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// does not end with RFC2646_CRLF)
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} else if (lineEndIndex > lineStartIndex && text[lineEndIndex - 1] == SPACE) {
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lineFlowed = true
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if (delSp) {
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line = line.substring(0, line.length() - 1);
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lineEndIndex--
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}
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resultLineFlowed = true;
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} else {
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resultLineFlowed = false;
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}
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resultLine.append(line);
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if (!lastLineFlowed && quoteDepth > 0) {
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// This is not a continuation line, so prefix the text with quote characters.
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repeat(quoteDepth) {
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append(QUOTE)
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}
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append(SPACE)
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}
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append(text, lineStartIndex, lineEndIndex)
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if (!lineFlowed && lineBreakFound) {
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append(CRLF)
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}
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lineStartIndex = if (lineBreakFound) lineFeedIndex + 1 else text.length
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lastLineQuoteDepth = quoteDepth
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lastLineFlowed = lineFlowed
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}
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}
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return result.toString();
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}
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}
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@ -4,16 +4,13 @@ import com.fsck.k9.mail.crlf
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import com.google.common.truth.Truth.assertThat
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import org.junit.Test
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private const val DEL_SP_NO = false
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private const val DEL_SP_YES = true
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class FlowedMessageUtilsTest {
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@Test
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fun `deflow() with simple text`() {
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val input = "Text that should be \r\n" +
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"displayed on one line"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo("Text that should be displayed on one line")
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}
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@ -27,7 +24,7 @@ class FlowedMessageUtilsTest {
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"Text that should retain\r\n" +
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"its line break."
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo(
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"""
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@ -42,7 +39,7 @@ class FlowedMessageUtilsTest {
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fun `deflow() with nothing to do`() {
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val input = "Line one\r\nLine two\r\n"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo(input)
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}
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@ -56,7 +53,7 @@ class FlowedMessageUtilsTest {
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"Some more text that should be \r\n" +
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"displayed on one line.\r\n"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo(
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"""
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@ -74,7 +71,7 @@ class FlowedMessageUtilsTest {
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val input = "> Quoted text \r\n" +
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"Some other text"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo("> Quoted text \r\nSome other text")
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}
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@ -86,7 +83,7 @@ class FlowedMessageUtilsTest {
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"> is here\r\n" +
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"Some other text"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo(
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"""
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@ -103,7 +100,7 @@ class FlowedMessageUtilsTest {
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"\r\n" +
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"Text"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo(input)
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}
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@ -112,7 +109,7 @@ class FlowedMessageUtilsTest {
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fun `deflow() with delSp=true`() {
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val input = "Text that is wrapped mid wo \r\nrd"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_YES)
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val result = FlowedMessageUtils.deflow(input, delSp = true)
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assertThat(result).isEqualTo("Text that is wrapped mid word")
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}
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@ -122,7 +119,7 @@ class FlowedMessageUtilsTest {
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val input = "> Quoted te \r\n" +
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"> xt"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_YES)
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val result = FlowedMessageUtils.deflow(input, delSp = true)
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assertThat(result).isEqualTo("> Quoted text")
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}
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@ -132,7 +129,7 @@ class FlowedMessageUtilsTest {
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val input = "Text that should be \r\n" +
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" displayed on one line"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo("Text that should be displayed on one line")
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}
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@ -143,7 +140,7 @@ class FlowedMessageUtilsTest {
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" Line 2\r\n" +
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" Line 3\r\n"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo("Line 1\r\nLine 2\r\nLine 3\r\n")
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}
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@ -153,7 +150,7 @@ class FlowedMessageUtilsTest {
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val input = "> Text that should be \r\n" +
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"> displayed on one line"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo("> Text that should be displayed on one line")
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}
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@ -167,7 +164,7 @@ class FlowedMessageUtilsTest {
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"Signature \r\n" +
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"text"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo(
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"""
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@ -188,7 +185,7 @@ class FlowedMessageUtilsTest {
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"> Signature \r\n" +
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"> text"
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val result = FlowedMessageUtils.deflow(input, DEL_SP_NO)
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val result = FlowedMessageUtils.deflow(input, delSp = false)
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assertThat(result).isEqualTo(
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"""
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@ -199,4 +196,21 @@ class FlowedMessageUtilsTest {
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""".trimIndent().crlf()
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)
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}
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@Test
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fun `deflow() with flowed line followed by signature separator`() {
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val input = "Fake flowed line \r\n" +
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"-- \r\n" +
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"Signature"
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val result = FlowedMessageUtils.deflow(input, delSp = true)
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assertThat(result).isEqualTo(
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"""
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Fake flowed line
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--${" "}
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Signature
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""".trimIndent().crlf()
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)
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}
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}
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