From c5de85e4329457b4d0b3019e0a8bb89c8132d7f1 Mon Sep 17 00:00:00 2001
From: stepancheg <stepancheg@epfl.ch>
Date: Fri, 6 Jun 2008 18:53:49 +0000
Subject: makeRichChar to, until return RandomAccessSeq.P...

makeRichChar to, until return RandomAccessSeq.Projection (#970)
---
 src/library/scala/RandomAccessSeq.scala  |  8 ++++++++
 src/library/scala/Seq.scala              |  6 +-----
 src/library/scala/runtime/RichChar.scala | 24 ++++++++++++++----------
 test/files/run/runtime-richChar.check    | 10 ++++++++++
 test/files/run/runtime-richChar.scala    | 25 +++++++++++++++++++++++++
 5 files changed, 58 insertions(+), 15 deletions(-)
 create mode 100644 test/files/run/runtime-richChar.check
 create mode 100644 test/files/run/runtime-richChar.scala

diff --git a/src/library/scala/RandomAccessSeq.scala b/src/library/scala/RandomAccessSeq.scala
index 437d7ae8fb..363fc72d85 100644
--- a/src/library/scala/RandomAccessSeq.scala
+++ b/src/library/scala/RandomAccessSeq.scala
@@ -13,6 +13,14 @@ package scala
 import collection.mutable.ArrayBuffer
 
 object RandomAccessSeq {
+
+  /** The empty sequence */
+  val empty : RandomAccessSeq[Nothing] = new RandomAccessSeq[Nothing] {
+    def length = 0
+    def apply(i: Int): Nothing = throw new NoSuchElementException("empty sequence")
+    override def elements = Iterator.empty
+  }
+
   trait Projection[+A] extends Seq.Projection[A] with RandomAccessSeq[A] {
     override def projection = this
     override def force : RandomAccessSeq[A] = toArray
diff --git a/src/library/scala/Seq.scala b/src/library/scala/Seq.scala
index 3b184a1ba5..763a2e8ec2 100644
--- a/src/library/scala/Seq.scala
+++ b/src/library/scala/Seq.scala
@@ -17,11 +17,7 @@ import collection.mutable.ArrayBuffer
 object Seq {
 
   /** The empty sequence */
-  val empty : Seq[Nothing] = new RandomAccessSeq[Nothing] {
-    def length = 0
-    def apply(i: Int): Nothing = throw new NoSuchElementException("empty sequence")
-    override def elements = Iterator.empty
-  }
+  val empty : Seq[Nothing] = RandomAccessSeq.empty
 
   /** This method is called in a pattern match { case Seq(...) => }.
    *
diff --git a/src/library/scala/runtime/RichChar.scala b/src/library/scala/runtime/RichChar.scala
index d06aa62a57..52fe17d751 100644
--- a/src/library/scala/runtime/RichChar.scala
+++ b/src/library/scala/runtime/RichChar.scala
@@ -52,20 +52,24 @@ final class RichChar(x: Char) extends Proxy with Ordered[Char] {
   def toLowerCase: Char = Character.toLowerCase(x)
   def toUpperCase: Char = Character.toUpperCase(x)
 
-  /** Create an Iterator[Char] over the characters from 'x' to 'y' - 1
+  /** Create a <code>RandomAccessSeq.Projection[Char]</code> over the characters from 'x' to 'y' - 1
    */
-  def until(limit: Char): Iterator[Char] = new Iterator[Char] {
-    private var ch = x
-    def hasNext: Boolean = ch < limit
-    def next: Char =
-      if (hasNext) { val j = ch; ch = (ch + 1).toChar; j }
-      else throw new NoSuchElementException("next on empty iterator")
-  }
+  def until(limit: Char): RandomAccessSeq.Projection[Char] =
+    if (limit <= x) RandomAccessSeq.empty.projection
+    else
+      new RandomAccessSeq.Projection[Char] {
+        def length = limit - x
+        def apply(i: Int): Char = {
+          Predef.require(i >= 0 && i < length)
+          (x + i).toChar
+        }
+        override def stringPrefix = "RandomAccessSeq.Projection"
+      }
 
   //def until(y: Char): Iterator[Char] = to(y)
 
-  /** Create an Iterator[Char] over the characters from 'x' to 'y'
+  /** Create a <code>RandomAccessSeq.Projection[Char]</code> over the characters from 'x' to 'y'
    */
-  def to(y: Char): Iterator[Char] = until((y + 1).toChar)
+  def to(y: Char): RandomAccessSeq.Projection[Char] = until((y + 1).toChar)
 
 }
diff --git a/test/files/run/runtime-richChar.check b/test/files/run/runtime-richChar.check
new file mode 100644
index 0000000000..8d7a008585
--- /dev/null
+++ b/test/files/run/runtime-richChar.check
@@ -0,0 +1,10 @@
+'a' to 'c' ok
+'a' until 'c' ok
+'a' to 'b' ok
+'a' until 'b' ok
+'a' to 'a' ok
+'a' until 'a' ok
+'b' to 'a' ok
+'b' until 'a' ok
+'c' to 'a' ok
+'c' until 'a' ok
diff --git a/test/files/run/runtime-richChar.scala b/test/files/run/runtime-richChar.scala
new file mode 100644
index 0000000000..b2c488983d
--- /dev/null
+++ b/test/files/run/runtime-richChar.scala
@@ -0,0 +1,25 @@
+object Test extends Application {
+  def testSeq(name: String, expected: Seq[Char], got: Seq[Char]) {
+    if (expected.toList == got.toList)
+      println(name + " ok")
+    else
+      println(name + " failed: " + expected + " differs from " + got)
+  }
+
+  testSeq("'a' to 'c'", List('a', 'b', 'c'), 'a' to 'c')
+  testSeq("'a' until 'c'", List('a', 'b'), 'a' until 'c')
+
+  testSeq("'a' to 'b'", List('a', 'b'), 'a' to 'b')
+  testSeq("'a' until 'b'", List('a'), 'a' until 'b')
+
+  testSeq("'a' to 'a'", List('a'), 'a' to 'a')
+  testSeq("'a' until 'a'", List(), 'a' until 'a')
+
+  testSeq("'b' to 'a'", List(), 'b' to 'a')
+  testSeq("'b' until 'a'", List(), 'b' until 'a')
+
+  testSeq("'c' to 'a'", List(), 'c' to 'a')
+  testSeq("'c' until 'a'", List(), 'c' until 'a')
+}
+
+// vim: set ts=2 sw=2 et:
-- 
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