From 42a675f74e4cabe4f44fc91ac200956d55538a20 Mon Sep 17 00:00:00 2001
From: Markus KARG <markus@headcrashing.eu>
Date: Sat, 5 Oct 2024 22:05:07 +0000
Subject: [PATCH] Draft: CharSequence.getChars

---
 .../share/classes/java/io/Reader.java         | 11 +------
 .../share/classes/java/lang/CharSequence.java | 33 +++++++++++++++++++
 .../classes/java/nio/X-Buffer.java.template   | 11 +++++++
 3 files changed, 45 insertions(+), 10 deletions(-)

diff --git a/src/java.base/share/classes/java/io/Reader.java b/src/java.base/share/classes/java/io/Reader.java
index 6cad0c6b57f08..eb61169606bb6 100644
--- a/src/java.base/share/classes/java/io/Reader.java
+++ b/src/java.base/share/classes/java/io/Reader.java
@@ -200,16 +200,7 @@ public int read(char[] cbuf, int off, int len) throws IOException {
                 if (next >= cs.length())
                     return -1;
                 int n = Math.min(cs.length() - next, len);
-                switch (cs) {
-                    case String s -> s.getChars(next, next + n, cbuf, off);
-                    case StringBuilder sb -> sb.getChars(next, next + n, cbuf, off);
-                    case StringBuffer sb -> sb.getChars(next, next + n, cbuf, off);
-                    case CharBuffer cb -> cb.get(next, cbuf, off, n);
-                    default -> {
-                        for (int i = 0; i < n; i++)
-                            cbuf[off + i] = cs.charAt(next + i);
-                    }
-                }
+                cs.getChars(next, next + n, cbuf, off);
                 next += n;
                 return n;
             }
diff --git a/src/java.base/share/classes/java/lang/CharSequence.java b/src/java.base/share/classes/java/lang/CharSequence.java
index 87bc4a5525a85..6a884acd3f2bf 100644
--- a/src/java.base/share/classes/java/lang/CharSequence.java
+++ b/src/java.base/share/classes/java/lang/CharSequence.java
@@ -302,4 +302,37 @@ public static int compare(CharSequence cs1, CharSequence cs2) {
         return cs1.length() - cs2.length();
     }
 
+    /**
+     * Characters are copied from this sequence into the
+     * destination character array {@code dst}. The first character to
+     * be copied is at index {@code srcBegin}; the last character to
+     * be copied is at index {@code srcEnd-1}. The total number of
+     * characters to be copied is {@code srcEnd-srcBegin}. The
+     * characters are copied into the subarray of {@code dst} starting
+     * at index {@code dstBegin} and ending at index
+     * {@code dstbegin + (srcEnd-srcBegin) - 1}.
+     *
+     * @param      srcBegin   start copying at this offset.
+     * @param      srcEnd     stop copying at this offset.
+     * @param      dst        the array to copy the data into.
+     * @param      dstBegin   offset into {@code dst}.
+     * @throws     IndexOutOfBoundsException  if any of the following is true:
+     *             <ul>
+     *             <li>{@code srcBegin} is negative
+     *             <li>{@code dstBegin} is negative
+     *             <li>the {@code srcBegin} argument is greater than
+     *             the {@code srcEnd} argument.
+     *             <li>{@code srcEnd} is greater than
+     *             {@code this.length()}.
+     *             <li>{@code dstBegin+srcEnd-srcBegin} is greater than
+     *             {@code dst.length}
+     *             </ul>
+     */
+    public default void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) {
+        Objects.checkFromToIndex(srcBegin, srcEnd, length());
+        int n = srcEnd - srcBegin;
+        Objects.checkFromToIndex(dstBegin, dstBegin + n, dst.length);
+        for (int i = 0; i < n; i++)
+            dst[dstBegin + i] = charAt(srcBegin + i);
+    }
 }
diff --git a/src/java.base/share/classes/java/nio/X-Buffer.java.template b/src/java.base/share/classes/java/nio/X-Buffer.java.template
index 1b378a2ef4a91..c297b43ac67f9 100644
--- a/src/java.base/share/classes/java/nio/X-Buffer.java.template
+++ b/src/java.base/share/classes/java/nio/X-Buffer.java.template
@@ -2333,4 +2333,15 @@ public abstract sealed class $Type$Buffer
 
 #end[streamableType]
 
+#if[char]
+    @Override
+    public void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) {
+        Objects.checkFromToIndex(srcBegin, srcEnd, limit());
+        int size = srcEnd - srcBegin;
+        Objects.checkFromIndexSize(dstBegin, size, dst.length);
+
+        getArray(srcBegin, dst, dstBegin, size);
+    }
+#end[char]
+
 }