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java/org/apache/tomcat/util/buf/Ascii.java

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+/*
+ *  Licensed to the Apache Software Foundation (ASF) under one or more
+ *  contributor license agreements.  See the NOTICE file distributed with
+ *  this work for additional information regarding copyright ownership.
+ *  The ASF licenses this file to You under the Apache License, Version 2.0
+ *  (the "License"); you may not use this file except in compliance with
+ *  the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.apache.tomcat.util.buf;
+
+/**
+ * This class implements some basic ASCII character handling functions.
+ *
+ * @author dac@eng.sun.com
+ * @author James Todd [gonzo@eng.sun.com]
+ */
+public final class Ascii {
+    /*
+     * Character translation tables.
+     */
+    private static final byte[] toLower = new byte[256];
+
+    /*
+     * Character type tables.
+     */
+    private static final boolean[] isDigit = new boolean[256];
+
+    private static final long OVERFLOW_LIMIT = Long.MAX_VALUE / 10;
+
+    /*
+     * Initialize character translation and type tables.
+     */
+    static {
+        for (int i = 0; i < 256; i++) {
+            toLower[i] = (byte)i;
+        }
+
+        for (int lc = 'a'; lc <= 'z'; lc++) {
+            int uc = lc + 'A' - 'a';
+
+            toLower[uc] = (byte)lc;
+        }
+
+        for (int d = '0'; d <= '9'; d++) {
+            isDigit[d] = true;
+        }
+    }
+
+    /**
+     * Returns the lower case equivalent of the specified ASCII character.
+     * @param c The char
+     * @return the lower case equivalent char
+     */
+    public static int toLower(int c) {
+        return toLower[c & 0xff] & 0xff;
+    }
+
+    /**
+     * @return <code>true</code> if the specified ASCII character is a digit.
+     * @param c The char
+     */
+    private static boolean isDigit(int c) {
+        return isDigit[c & 0xff];
+    }
+
+    /**
+     * Parses an unsigned long from the specified subarray of bytes.
+     * @param b the bytes to parse
+     * @param off the start offset of the bytes
+     * @param len the length of the bytes
+     * @return the long value
+     * @exception NumberFormatException if the long format was invalid
+     */
+    public static long parseLong(byte[] b, int off, int len)
+        throws NumberFormatException
+    {
+        int c;
+
+        if (b == null || len <= 0 || !isDigit(c = b[off++])) {
+            throw new NumberFormatException();
+        }
+
+        long n = c - '0';
+        while (--len > 0) {
+            if (isDigit(c = b[off++]) &&
+                    (n < OVERFLOW_LIMIT || (n == OVERFLOW_LIMIT && (c - '0') < 8))) {
+                n = n * 10 + c - '0';
+            } else {
+                throw new NumberFormatException();
+            }
+        }
+
+        return n;
+    }
+}