1 /*
   2  * Copyright (c) 2005, 2019, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package javax.lang.model;
  27 
  28 import java.util.Collections;
  29 import java.util.Set;
  30 import java.util.HashSet;
  31 
  32 /**
  33  * Source versions of the Java™ programming language.
  34  *
  35  * See the appropriate edition of
  36  * <cite>The Java&trade; Language Specification</cite>
  37  * for information about a particular source version.
  38  *
  39  * <p>Note that additional source version constants will be added to
  40  * model future releases of the language.
  41  *
  42  * @author Joseph D. Darcy
  43  * @author Scott Seligman
  44  * @author Peter von der Ah&eacute;
  45  * @since 1.6
  46  */
  47 public enum SourceVersion {
  48     /*
  49      * Summary of language evolution
  50      * 1.1: nested classes
  51      * 1.2: strictfp
  52      * 1.3: no changes
  53      * 1.4: assert
  54      * 1.5: annotations, generics, autoboxing, var-args...
  55      * 1.6: no changes
  56      * 1.7: diamond syntax, try-with-resources, etc.
  57      * 1.8: lambda expressions and default methods
  58      *   9: modules, small cleanups to 1.7 and 1.8 changes
  59      *  10: local-variable type inference (var)
  60      *  11: local-variable syntax for lambda parameters
  61      *  12: no changes (switch expressions in preview)
  62      *  13: TBD
  63      */
  64 
  65     /**
  66      * The original version.
  67      *
  68      * The language described in
  69      * <cite>The Java&trade; Language Specification, First Edition</cite>.
  70      */
  71     RELEASE_0,
  72 
  73     /**
  74      * The version recognized by the Java Platform 1.1.
  75      *
  76      * The language is {@code RELEASE_0} augmented with nested classes as described in the 1.1 update to
  77      * <cite>The Java&trade; Language Specification, First Edition</cite>.
  78      */
  79     RELEASE_1,
  80 
  81     /**
  82      * The version recognized by the Java 2 Platform, Standard Edition,
  83      * v 1.2.
  84      *
  85      * The language described in
  86      * <cite>The Java&trade; Language Specification,
  87      * Second Edition</cite>, which includes the {@code
  88      * strictfp} modifier.
  89      */
  90     RELEASE_2,
  91 
  92     /**
  93      * The version recognized by the Java 2 Platform, Standard Edition,
  94      * v 1.3.
  95      *
  96      * No major changes from {@code RELEASE_2}.
  97      */
  98     RELEASE_3,
  99 
 100     /**
 101      * The version recognized by the Java 2 Platform, Standard Edition,
 102      * v 1.4.
 103      *
 104      * Added a simple assertion facility.
 105      */
 106     RELEASE_4,
 107 
 108     /**
 109      * The version recognized by the Java 2 Platform, Standard
 110      * Edition 5.0.
 111      *
 112      * The language described in
 113      * <cite>The Java&trade; Language Specification,
 114      * Third Edition</cite>.  First release to support
 115      * generics, annotations, autoboxing, var-args, enhanced {@code
 116      * for} loop, and hexadecimal floating-point literals.
 117      */
 118     RELEASE_5,
 119 
 120     /**
 121      * The version recognized by the Java Platform, Standard Edition
 122      * 6.
 123      *
 124      * No major changes from {@code RELEASE_5}.
 125      */
 126     RELEASE_6,
 127 
 128     /**
 129      * The version recognized by the Java Platform, Standard Edition
 130      * 7.
 131      *
 132      * Additions in this release include, diamond syntax for
 133      * constructors, {@code try}-with-resources, strings in switch,
 134      * binary literals, and multi-catch.
 135      * @since 1.7
 136      */
 137     RELEASE_7,
 138 
 139     /**
 140      * The version recognized by the Java Platform, Standard Edition
 141      * 8.
 142      *
 143      * Additions in this release include lambda expressions and default methods.
 144      * @since 1.8
 145      */
 146     RELEASE_8,
 147 
 148     /**
 149      * The version recognized by the Java Platform, Standard Edition
 150      * 9.
 151      *
 152      * Additions in this release include modules and removal of a
 153      * single underscore from the set of legal identifier names.
 154      *
 155      * @since 9
 156      */
 157      RELEASE_9,
 158 
 159     /**
 160      * The version recognized by the Java Platform, Standard Edition
 161      * 10.
 162      *
 163      * Additions in this release include local-variable type inference
 164      * ({@code var}).
 165      *
 166      * @since 10
 167      */
 168      RELEASE_10,
 169 
 170     /**
 171      * The version recognized by the Java Platform, Standard Edition
 172      * 11.
 173      *
 174      * Additions in this release include local-variable syntax for
 175      * lambda parameters.
 176      *
 177      * @since 11
 178      */
 179      RELEASE_11,
 180 
 181     /**
 182      * The version recognized by the Java Platform, Standard Edition
 183      * 12.
 184      *
 185      * @since 12
 186      */
 187      RELEASE_12,
 188 
 189     /**
 190      * The version recognized by the Java Platform, Standard Edition
 191      * 13.
 192      *
 193      * @since 13
 194      */
 195      RELEASE_13;
 196 
 197     // Note that when adding constants for newer releases, the
 198     // behavior of latest() and latestSupported() must be updated too.
 199 
 200     /**
 201      * Returns the latest source version that can be modeled.
 202      *
 203      * @return the latest source version that can be modeled
 204      */
 205     public static SourceVersion latest() {
 206         return RELEASE_13;
 207     }
 208 
 209     private static final SourceVersion latestSupported = getLatestSupported();
 210 
 211     /*
 212      * The integer version to enum constant mapping implemented by
 213      * this method assumes the JEP 322: "Time-Based Release
 214      * Versioning" scheme is in effect. This scheme began in JDK
 215      * 10. If the JDK versioning scheme is revised, this method may
 216      * need to be updated accordingly.
 217      */
 218     private static SourceVersion getLatestSupported() {
 219         int intVersion = Runtime.version().feature();
 220         return (intVersion >= 11) ?
 221             valueOf("RELEASE_" + Math.min(13, intVersion)):
 222             RELEASE_10;
 223     }
 224 
 225     /**
 226      * Returns the latest source version fully supported by the
 227      * current execution environment.  {@code RELEASE_9} or later must
 228      * be returned.
 229      *
 230      * @apiNote This method is included alongside {@link latest} to
 231      * allow identification of situations where the language model API
 232      * is running on a platform version different than the latest
 233      * version modeled by the API. One way that sort of situation can
 234      * occur is if an IDE or similar tool is using the API to model
 235      * source version <i>N</i> while running on platform version
 236      * (<i>N</i>&nbsp;-&nbsp;1). Running in this configuration is
 237      * supported by the API. Running an API on platform versions
 238      * earlier than (<i>N</i>&nbsp;-&nbsp;1) or later than <i>N</i>
 239      * may or may not work as an implementation detail. If an
 240      * annotation processor was generating code to run under the
 241      * current execution environment, the processor should only use
 242      * platform features up to the {@code latestSupported} release,
 243      * which may be earlier than the {@code latest} release.
 244      *
 245      * @return the latest source version that is fully supported
 246      */
 247     public static SourceVersion latestSupported() {
 248         return latestSupported;
 249     }
 250 
 251     /**
 252      * Returns whether or not {@code name} is a syntactically valid
 253      * identifier (simple name) or keyword in the latest source
 254      * version.  The method returns {@code true} if the name consists
 255      * of an initial character for which {@link
 256      * Character#isJavaIdentifierStart(int)} returns {@code true},
 257      * followed only by characters for which {@link
 258      * Character#isJavaIdentifierPart(int)} returns {@code true}.
 259      * This pattern matches regular identifiers, keywords, restricted
 260      * keywords, and the literals {@code "true"}, {@code "false"},
 261      * {@code "null"}, and {@code "var"}.
 262      *
 263      * The method returns {@code false} for all other strings.
 264      *
 265      * @param name the string to check
 266      * @return {@code true} if this string is a
 267      * syntactically valid identifier or keyword, {@code false}
 268      * otherwise.
 269      */
 270     public static boolean isIdentifier(CharSequence name) {
 271         String id = name.toString();
 272 
 273         if (id.length() == 0) {
 274             return false;
 275         }
 276         int cp = id.codePointAt(0);
 277         if (!Character.isJavaIdentifierStart(cp)) {
 278             return false;
 279         }
 280         for (int i = Character.charCount(cp);
 281                 i < id.length();
 282                 i += Character.charCount(cp)) {
 283             cp = id.codePointAt(i);
 284             if (!Character.isJavaIdentifierPart(cp)) {
 285                 return false;
 286             }
 287         }
 288         return true;
 289     }
 290 
 291     /**
 292      * Returns whether or not {@code name} is a syntactically valid
 293      * qualified name in the latest source version.  Unlike {@link
 294      * #isIdentifier isIdentifier}, this method returns {@code false}
 295      * for keywords, boolean literals, and the null literal.
 296      *
 297      * This method returns {@code true} for <i>restricted
 298      * keywords</i> and {@code "var"}.
 299      *
 300      * @param name the string to check
 301      * @return {@code true} if this string is a
 302      * syntactically valid name, {@code false} otherwise.
 303      * @jls 3.9 Keywords
 304      * @jls 6.2 Names and Identifiers
 305      */
 306     public static boolean isName(CharSequence name) {
 307         return isName(name, latest());
 308     }
 309 
 310     /**
 311      * Returns whether or not {@code name} is a syntactically valid
 312      * qualified name in the given source version.  Unlike {@link
 313      * #isIdentifier isIdentifier}, this method returns {@code false}
 314      * for keywords, boolean literals, and the null literal.
 315      *
 316      * This method returns {@code true} for <i>restricted
 317      * keywords</i> and {@code "var"}.
 318      *
 319      * @param name the string to check
 320      * @param version the version to use
 321      * @return {@code true} if this string is a
 322      * syntactically valid name, {@code false} otherwise.
 323      * @jls 3.9 Keywords
 324      * @jls 6.2 Names and Identifiers
 325      * @since 9
 326      */
 327     public static boolean isName(CharSequence name, SourceVersion version) {
 328         String id = name.toString();
 329 
 330         for(String s : id.split("\\.", -1)) {
 331             if (!isIdentifier(s) || isKeyword(s, version))
 332                 return false;
 333         }
 334         return true;
 335     }
 336 
 337     /**
 338      * Returns whether or not {@code s} is a keyword, boolean literal,
 339      * or null literal in the latest source version.
 340      * This method returns {@code false} for <i>restricted
 341      * keywords</i> and {@code "var"}.
 342      *
 343      * @param s the string to check
 344      * @return {@code true} if {@code s} is a keyword, or boolean
 345      * literal, or null literal, {@code false} otherwise.
 346      * @jls 3.9 Keywords
 347      * @jls 3.10.3 Boolean Literals
 348      * @jls 3.10.7 The Null Literal
 349      */
 350     public static boolean isKeyword(CharSequence s) {
 351         return isKeyword(s, latest());
 352     }
 353 
 354     /**
 355      * Returns whether or not {@code s} is a keyword, boolean literal,
 356      * or null literal in the given source version.
 357      * This method returns {@code false} for <i>restricted
 358      * keywords</i> and {@code "var"}.
 359      *
 360      * @param s the string to check
 361      * @param version the version to use
 362      * @return {@code true} if {@code s} is a keyword, or boolean
 363      * literal, or null literal, {@code false} otherwise.
 364      * @jls 3.9 Keywords
 365      * @jls 3.10.3 Boolean Literals
 366      * @jls 3.10.7 The Null Literal
 367      * @since 9
 368      */
 369     public static boolean isKeyword(CharSequence s, SourceVersion version) {
 370         String id = s.toString();
 371         switch(id) {
 372             // A trip through history
 373         case "strictfp":
 374             return version.compareTo(RELEASE_2) >= 0;
 375 
 376         case "assert":
 377             return version.compareTo(RELEASE_4) >= 0;
 378 
 379         case "enum":
 380             return version.compareTo(RELEASE_5) >= 0;
 381 
 382         case "_":
 383             return version.compareTo(RELEASE_9) >= 0;
 384 
 385             // Keywords common across versions
 386 
 387             // Modifiers
 388         case "public":    case "protected": case "private":
 389         case "abstract":  case "static":    case "final":
 390         case "transient": case "volatile":  case "synchronized":
 391         case "native":
 392 
 393             // Declarations
 394         case "class":     case "interface": case "extends":
 395         case "package":   case "throws":    case "implements":
 396 
 397             // Primitive types and void
 398         case "boolean":   case "byte":      case "char":
 399         case "short":     case "int":       case "long":
 400         case "float":     case "double":
 401         case "void":
 402 
 403             // Control flow
 404         case "if":      case "else":
 405         case "try":     case "catch":    case "finally":
 406         case "do":      case "while":
 407         case "for":     case "continue":
 408         case "switch":  case "case":     case "default":
 409         case "break":   case "throw":    case "return":
 410 
 411             // Other keywords
 412         case  "this":   case "new":      case "super":
 413         case "import":  case "instanceof":
 414 
 415             // Forbidden!
 416         case "goto":        case "const":
 417 
 418             // literals
 419         case "null":         case "true":       case "false":
 420             return true;
 421 
 422         default:
 423             return false;
 424         }
 425     }
 426 }