From 429a98e6d5120b5e3241662836bbfdcc73bac832 Mon Sep 17 00:00:00 2001
From: "glen@roar" <glen@accur8software.com>
Date: Sun, 23 May 2021 17:31:53 -0400
Subject: [PATCH] added fs2.text.linesWithEndings

---
 core/shared/src/main/scala/fs2/text.scala     | 59 +++++++++++++++++++
 .../shared/src/test/scala/fs2/TextSuite.scala | 47 ++++++++++++++-
 2 files changed, 105 insertions(+), 1 deletion(-)

diff --git a/core/shared/src/main/scala/fs2/text.scala b/core/shared/src/main/scala/fs2/text.scala
index 7ad15714fd..430c713857 100644
--- a/core/shared/src/main/scala/fs2/text.scala
+++ b/core/shared/src/main/scala/fs2/text.scala
@@ -184,6 +184,65 @@ object text {
   def utf8EncodeC[F[_]]: Pipe[F, String, Chunk[Byte]] =
     encodeC(utf8Charset)
 
+  sealed abstract class LineEnding(val value: String)
+  object LineEnding {
+//    case object CR extends LineEnding("\r")  looking at the existing code this won't be produced so leaving it out for now
+    case object LF extends LineEnding("\n")
+    case object CRLF extends LineEnding("\r\n")
+    case object EOF extends LineEnding("")
+  }
+
+  /** Transforms a stream of `String` such that each emitted `String` is a line from the input. */
+  def linesWithEndings[F[_]]: Pipe[F, String, (String,LineEnding)] = {
+    import LineEnding._
+    def fillBuffers(
+        stringBuilder: StringBuilder,
+        linesBuffer: ArrayBuffer[(String,LineEnding)],
+        string: String
+    ): Unit = {
+      val l = stringBuilder.length
+      var i =
+        if (l > 0 && stringBuilder(l - 1) == '\r' && string.nonEmpty && string(0) == '\n') {
+          stringBuilder.deleteCharAt(l - 1)
+          linesBuffer += (stringBuilder.result() -> CRLF)
+          stringBuilder.clear()
+          1
+        } else 0
+
+      while (i < string.size) {
+        string(i) match {
+          case '\n' =>
+            linesBuffer += (stringBuilder.result() -> LF)
+            stringBuilder.clear()
+          case '\r' if i + 1 < string.size && string(i + 1) == '\n' =>
+            linesBuffer += (stringBuilder.result() -> CRLF)
+            stringBuilder.clear()
+            i += 1
+          case other =>
+            stringBuilder.append(other)
+        }
+        i += 1
+      }
+    }
+
+    def go(
+        stream: Stream[F, String],
+        stringBuilder: StringBuilder,
+        first: Boolean
+    ): Pull[F, (String, LineEnding), Unit] =
+      stream.pull.uncons.flatMap {
+        case None => if (first) Pull.done else Pull.output1(stringBuilder.result() -> LineEnding.EOF)
+        case Some((chunk, stream)) =>
+          val linesBuffer = ArrayBuffer.empty[(String,LineEnding)]
+          chunk.foreach { string =>
+            fillBuffers(stringBuilder, linesBuffer, string)
+          }
+          Pull.output(Chunk.buffer(linesBuffer)) >> go(stream, stringBuilder, first = false)
+      }
+
+    s => Stream.suspend(go(s, new StringBuilder(), first = true).stream)
+  }
+
   /** Transforms a stream of `String` such that each emitted `String` is a line from the input. */
   def lines[F[_]]: Pipe[F, String, String] = {
     def fillBuffers(
diff --git a/core/shared/src/test/scala/fs2/TextSuite.scala b/core/shared/src/test/scala/fs2/TextSuite.scala
index 063fc8718c..f72d82aebf 100644
--- a/core/shared/src/test/scala/fs2/TextSuite.scala
+++ b/core/shared/src/test/scala/fs2/TextSuite.scala
@@ -266,7 +266,7 @@ class TextSuite extends Fs2Suite {
       }
     }
 
-    property("grouped in 3 characater chunks") {
+    property("grouped in 3 character chunks") {
       forAll { (lines0: Stream[Pure, String]) =>
         val lines = lines0.map(escapeCrLf)
         val s = lines.intersperse("\r\n").toList.mkString.grouped(3).toList
@@ -280,6 +280,51 @@ class TextSuite extends Fs2Suite {
     }
   }
 
+  group("linesWithEndings") {
+    def escapeCrLf(s: String): String =
+      s.replaceAll("\r\n", "<CRLF>").replaceAll("\n", "<LF>").replaceAll("\r", "<CR>")
+
+    def expected(ending: LineEnding, originalLines: Stream[Pure, String]): List[(String,LineEnding)] = {
+      val v = originalLines.toVector
+      (v.dropRight(1).map(_ -> ending) ++ v.takeRight(1).map(_ -> LineEnding.EOF)).toList
+    }
+
+    property("newlines appear in between chunks") {
+      forAll { (lines0: Stream[Pure, String]) =>
+        val lines = lines0.map(escapeCrLf)
+        def assertEnding(ending: LineEnding): Unit = {
+          assertEquals(lines.intersperse(ending.value).through(text.linesWithEndings).toList, expected(ending, lines))
+        }
+        assertEnding(LineEnding.CRLF)
+        assertEnding(LineEnding.LF)
+      }
+    }
+
+    property("single string") {
+      forAll { (lines0: Stream[Pure, String]) =>
+        val lines = lines0.map(escapeCrLf)
+        if (lines.toList.nonEmpty) {
+          val s = lines.intersperse("\r\n").toList.mkString
+          assertEquals(Stream.emit(s).through(text.linesWithEndings).toList, expected(LineEnding.CRLF, lines))
+        }
+      }
+    }
+
+    property("grouped in 3 character chunks") {
+      forAll { (lines0: Stream[Pure, String]) =>
+        val lines = lines0.map(escapeCrLf)
+        val s = lines.intersperse("\r\n").toList.mkString.grouped(3).toList
+        if (s.isEmpty)
+          assertEquals(Stream.emits(s).through(text.linesWithEndings).toList, Nil)
+        else {
+          val expectedLines = expected(LineEnding.CRLF, lines)
+          assertEquals(Stream.emits(s).through(text.linesWithEndings).toList, expectedLines)
+          assertEquals(Stream.emits(s).unchunk.through(text.linesWithEndings).toList, expectedLines)
+        }
+      }
+    }
+  }
+
   property("base64Encode") {
     forAll { (bs: List[Array[Byte]]) =>
       assertEquals(