Update #0 - First Release

sources/main/java/com/google/common/escape/CharEscaperBuilder.java

@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2006 The Guava Authors
+ *
+ * Licensed 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 com.google.common.escape;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import com.google.common.annotations.Beta;
+import com.google.common.annotations.GwtCompatible;
+
+/**
+ * Simple helper class to build a "sparse" array of objects based on the indexes
+ * that were added to it. The array will be from 0 to the maximum index given.
+ * All non-set indexes will contain null (so it's not really a sparse array,
+ * just a pseudo sparse array). The builder can also return a CharEscaper based
+ * on the generated array.
+ *
+ * @author Sven Mawson
+ * @since 15.0
+ */
+@Beta
+@GwtCompatible
+public final class CharEscaperBuilder {
+	/**
+	 * Simple decorator that turns an array of replacement char[]s into a
+	 * CharEscaper, this results in a very fast escape method.
+	 */
+	private static class CharArrayDecorator extends CharEscaper {
+		private final char[][] replacements;
+		private final int replaceLength;
+
+		CharArrayDecorator(char[][] replacements) {
+			this.replacements = replacements;
+			this.replaceLength = replacements.length;
+		}
+
+		/*
+		 * Overriding escape method to be slightly faster for this decorator. We test
+		 * the replacements array directly, saving a method call.
+		 */
+		@Override
+		public String escape(String s) {
+			int slen = s.length();
+			for (int index = 0; index < slen; index++) {
+				char c = s.charAt(index);
+				if (c < replacements.length && replacements[c] != null) {
+					return escapeSlow(s, index);
+				}
+			}
+			return s;
+		}
+
+		@Override
+		protected char[] escape(char c) {
+			return c < replaceLength ? replacements[c] : null;
+		}
+	}
+
+	// Replacement mappings.
+	private final Map<Character, String> map;
+
+	// The highest index we've seen so far.
+	private int max = -1;
+
+	/**
+	 * Construct a new sparse array builder.
+	 */
+	public CharEscaperBuilder() {
+		this.map = new HashMap<Character, String>();
+	}
+
+	/**
+	 * Add a new mapping from an index to an object to the escaping.
+	 */
+	public CharEscaperBuilder addEscape(char c, String r) {
+		map.put(c, checkNotNull(r));
+		if (c > max) {
+			max = c;
+		}
+		return this;
+	}
+
+	/**
+	 * Add multiple mappings at once for a particular index.
+	 */
+	public CharEscaperBuilder addEscapes(char[] cs, String r) {
+		checkNotNull(r);
+		for (char c : cs) {
+			addEscape(c, r);
+		}
+		return this;
+	}
+
+	/**
+	 * Convert this builder into an array of char[]s where the maximum index is the
+	 * value of the highest character that has been seen. The array will be sparse
+	 * in the sense that any unseen index will default to null.
+	 *
+	 * @return a "sparse" array that holds the replacement mappings.
+	 */
+	public char[][] toArray() {
+		char[][] result = new char[max + 1][];
+		for (Map.Entry<Character, String> entry : map.entrySet()) {
+			result[entry.getKey()] = entry.getValue().toCharArray();
+		}
+		return result;
+	}
+
+	/**
+	 * Convert this builder into a char escaper which is just a decorator around the
+	 * underlying array of replacement char[]s.
+	 *
+	 * @return an escaper that escapes based on the underlying array.
+	 */
+	public Escaper toEscaper() {
+		return new CharArrayDecorator(toArray());
+	}
+}