From 65d6d1101c84ddd6fdfa4ef00db5da0385a57805 Mon Sep 17 00:00:00 2001
From: Gary Gregory <garydgregory@gmail.com>
Date: Mon, 11 Mar 2024 16:04:00 -0400
Subject: [PATCH] Allocate a string look ahead buffer in
 CSVFormat.printWithEscapes(CharSequence, Appendable)

As opposed to one for each character read.
---
 src/main/java/org/apache/commons/csv/CSVFormat.java | 10 ++++++----
 .../apache/commons/csv/ExtendedBufferedReader.java  | 13 -------------
 2 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/src/main/java/org/apache/commons/csv/CSVFormat.java b/src/main/java/org/apache/commons/csv/CSVFormat.java
index 9ab21d5a..c8e566f9 100644
--- a/src/main/java/org/apache/commons/csv/CSVFormat.java
+++ b/src/main/java/org/apache/commons/csv/CSVFormat.java
@@ -2191,15 +2191,17 @@ public final class CSVFormat implements Serializable {
         int pos = 0;
         @SuppressWarnings("resource") // Temp reader on input reader.
         final ExtendedBufferedReader bufferedReader = new ExtendedBufferedReader(reader);
-        final char[] delim = getDelimiterCharArray();
-        final int delimLength = delim.length;
+        final char[] delimArray = getDelimiterCharArray();
+        final int delimLength = delimArray.length;
         final char escape = getEscapeChar();
         final StringBuilder builder = new StringBuilder(IOUtils.DEFAULT_BUFFER_SIZE);
         int c;
+        final char[] lookAheadBuffer = new char[delimLength - 1];
         while (EOF != (c = bufferedReader.read())) {
             builder.append((char) c);
-            final boolean isDelimiterStart = isDelimiter((char) c, builder.toString() + new String(bufferedReader.lookAhead(delimLength - 1)), pos, delim,
-                    delimLength);
+            Arrays.fill(lookAheadBuffer, (char) 0);
+            final String test = builder.toString() + new String(bufferedReader.lookAhead(lookAheadBuffer));
+            final boolean isDelimiterStart = isDelimiter((char) c, test, pos, delimArray, delimLength);
             final boolean isCr = c == CR;
             final boolean isLf = c == LF;
             if (isCr || isLf || c == escape || isDelimiterStart) {
diff --git a/src/main/java/org/apache/commons/csv/ExtendedBufferedReader.java b/src/main/java/org/apache/commons/csv/ExtendedBufferedReader.java
index e193c487..7b833ede 100644
--- a/src/main/java/org/apache/commons/csv/ExtendedBufferedReader.java
+++ b/src/main/java/org/apache/commons/csv/ExtendedBufferedReader.java
@@ -139,19 +139,6 @@ final class ExtendedBufferedReader extends BufferedReader {
         return buf;
     }
 
-    /**
-     * Returns the next n characters in the current reader without consuming them. The next call to {@link #read()} will still return the next value. This
-     * doesn't affect line number or last character.
-     *
-     * @param n the number characters look ahead.
-     * @return the next n characters.
-     * @throws IOException If an I/O error occurs
-     */
-    char[] lookAhead(final int n) throws IOException {
-        final char[] buf = new char[n];
-        return lookAhead(buf);
-    }
-
     @Override
     public int read() throws IOException {
         final int current = super.read();