Update #0 - First Release

sources/main/java/com/google/common/base/CaseFormat.java

@@ -0,0 +1,228 @@
+/*
+ * 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.base;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import java.io.Serializable;
+
+import javax.annotation.Nullable;
+
+import com.google.common.annotations.Beta;
+import com.google.common.annotations.GwtCompatible;
+
+/**
+ * Utility class for converting between various ASCII case formats. Behavior is
+ * undefined for non-ASCII input.
+ *
+ * @author Mike Bostock
+ * @since 1.0
+ */
+@GwtCompatible
+public enum CaseFormat {
+	/**
+	 * Hyphenated variable naming convention, e.g., "lower-hyphen".
+	 */
+	LOWER_HYPHEN(CharMatcher.is('-'), "-") {
+		@Override
+		String normalizeWord(String word) {
+			return Ascii.toLowerCase(word);
+		}
+
+		@Override
+		String convert(CaseFormat format, String s) {
+			if (format == LOWER_UNDERSCORE) {
+				return s.replace('-', '_');
+			}
+			if (format == UPPER_UNDERSCORE) {
+				return Ascii.toUpperCase(s.replace('-', '_'));
+			}
+			return super.convert(format, s);
+		}
+	},
+
+	/**
+	 * C++ variable naming convention, e.g., "lower_underscore".
+	 */
+	LOWER_UNDERSCORE(CharMatcher.is('_'), "_") {
+		@Override
+		String normalizeWord(String word) {
+			return Ascii.toLowerCase(word);
+		}
+
+		@Override
+		String convert(CaseFormat format, String s) {
+			if (format == LOWER_HYPHEN) {
+				return s.replace('_', '-');
+			}
+			if (format == UPPER_UNDERSCORE) {
+				return Ascii.toUpperCase(s);
+			}
+			return super.convert(format, s);
+		}
+	},
+
+	/**
+	 * Java variable naming convention, e.g., "lowerCamel".
+	 */
+	LOWER_CAMEL(CharMatcher.inRange('A', 'Z'), "") {
+		@Override
+		String normalizeWord(String word) {
+			return firstCharOnlyToUpper(word);
+		}
+	},
+
+	/**
+	 * Java and C++ class naming convention, e.g., "UpperCamel".
+	 */
+	UPPER_CAMEL(CharMatcher.inRange('A', 'Z'), "") {
+		@Override
+		String normalizeWord(String word) {
+			return firstCharOnlyToUpper(word);
+		}
+	},
+
+	/**
+	 * Java and C++ constant naming convention, e.g., "UPPER_UNDERSCORE".
+	 */
+	UPPER_UNDERSCORE(CharMatcher.is('_'), "_") {
+		@Override
+		String normalizeWord(String word) {
+			return Ascii.toUpperCase(word);
+		}
+
+		@Override
+		String convert(CaseFormat format, String s) {
+			if (format == LOWER_HYPHEN) {
+				return Ascii.toLowerCase(s.replace('_', '-'));
+			}
+			if (format == LOWER_UNDERSCORE) {
+				return Ascii.toLowerCase(s);
+			}
+			return super.convert(format, s);
+		}
+	};
+
+	private final CharMatcher wordBoundary;
+	private final String wordSeparator;
+
+	CaseFormat(CharMatcher wordBoundary, String wordSeparator) {
+		this.wordBoundary = wordBoundary;
+		this.wordSeparator = wordSeparator;
+	}
+
+	/**
+	 * Converts the specified {@code String str} from this format to the specified
+	 * {@code format}. A "best effort" approach is taken; if {@code str} does not
+	 * conform to the assumed format, then the behavior of this method is undefined
+	 * but we make a reasonable effort at converting anyway.
+	 */
+	public final String to(CaseFormat format, String str) {
+		checkNotNull(format);
+		checkNotNull(str);
+		return (format == this) ? str : convert(format, str);
+	}
+
+	/**
+	 * Enum values can override for performance reasons.
+	 */
+	String convert(CaseFormat format, String s) {
+		// deal with camel conversion
+		StringBuilder out = null;
+		int i = 0;
+		int j = -1;
+		while ((j = wordBoundary.indexIn(s, ++j)) != -1) {
+			if (i == 0) {
+				// include some extra space for separators
+				out = new StringBuilder(s.length() + 4 * wordSeparator.length());
+				out.append(format.normalizeFirstWord(s.substring(i, j)));
+			} else {
+				out.append(format.normalizeWord(s.substring(i, j)));
+			}
+			out.append(format.wordSeparator);
+			i = j + wordSeparator.length();
+		}
+		return (i == 0) ? format.normalizeFirstWord(s) : out.append(format.normalizeWord(s.substring(i))).toString();
+	}
+
+	/**
+	 * Returns a {@code Converter} that converts strings from this format to
+	 * {@code targetFormat}.
+	 *
+	 * @since 16.0
+	 */
+	@Beta
+	public Converter<String, String> converterTo(CaseFormat targetFormat) {
+		return new StringConverter(this, targetFormat);
+	}
+
+	private static final class StringConverter extends Converter<String, String> implements Serializable {
+
+		private final CaseFormat sourceFormat;
+		private final CaseFormat targetFormat;
+
+		StringConverter(CaseFormat sourceFormat, CaseFormat targetFormat) {
+			this.sourceFormat = checkNotNull(sourceFormat);
+			this.targetFormat = checkNotNull(targetFormat);
+		}
+
+		@Override
+		protected String doForward(String s) {
+			// TODO(kevinb): remove null boilerplate (convert() will do it automatically)
+			return s == null ? null : sourceFormat.to(targetFormat, s);
+		}
+
+		@Override
+		protected String doBackward(String s) {
+			// TODO(kevinb): remove null boilerplate (convert() will do it automatically)
+			return s == null ? null : targetFormat.to(sourceFormat, s);
+		}
+
+		@Override
+		public boolean equals(@Nullable Object object) {
+			if (object instanceof StringConverter) {
+				StringConverter that = (StringConverter) object;
+				return sourceFormat.equals(that.sourceFormat) && targetFormat.equals(that.targetFormat);
+			}
+			return false;
+		}
+
+		@Override
+		public int hashCode() {
+			return sourceFormat.hashCode() ^ targetFormat.hashCode();
+		}
+
+		@Override
+		public String toString() {
+			return sourceFormat + ".converterTo(" + targetFormat + ")";
+		}
+
+		private static final long serialVersionUID = 0L;
+	}
+
+	abstract String normalizeWord(String word);
+
+	private String normalizeFirstWord(String word) {
+		return (this == LOWER_CAMEL) ? Ascii.toLowerCase(word) : normalizeWord(word);
+	}
+
+	private static String firstCharOnlyToUpper(String word) {
+		return (word.isEmpty()) ? word
+				: new StringBuilder(word.length()).append(Ascii.toUpperCase(word.charAt(0)))
+						.append(Ascii.toLowerCase(word.substring(1))).toString();
+	}
+}