/* *  gnu/regexp/RESyntax.java *  Copyright (C) 1998-2001 Wes Biggs * *  This library is free software; you can redistribute it and/or modify *  it under the terms of the GNU Lesser General Public License as published *  by the Free Software Foundation; either version 2.1 of the License, or *  (at your option) any later version. * *  This library is distributed in the hope that it will be useful, *  but WITHOUT ANY WARRANTY; without even the implied warranty of *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the *  GNU Lesser General Public License for more details. * *  You should have received a copy of the GNU Lesser General Public License *  along with this program; if not, write to the Free Software *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */package gnu.regexp;import java.io.Serializable;import java.util.BitSet;/** * An RESyntax specifies the way a regular expression will be compiled. * This class provides a number of predefined useful constants for * emulating popular regular expression syntaxes.  Additionally the * user may construct his or her own syntax, using any combination of the * syntax bit constants.  The syntax is an optional argument to any of the * matching methods on class RE. * * @author <A HREF="mailto:wes@cacas.org">Wes Biggs</A> */public final class RESyntax implements Serializable {    static final String DEFAULT_LINE_SEPARATOR = System.getProperty("line.separator");    private static final String SYNTAX_IS_FINAL = RE.getLocalizedMessage("syntax.final");    private BitSet bits;    // true for the constant defined syntaxes    private boolean isFinal = false;    private String lineSeparator = DEFAULT_LINE_SEPARATOR;  // Values for constants are bit indexes  /**   * Syntax bit. Backslash is an escape character in lists.   */  public static final int RE_BACKSLASH_ESCAPE_IN_LISTS =  0;  /**   * Syntax bit. Use \? instead of ? and \+ instead of +.   */  public static final int RE_BK_PLUS_QM                =  1;  /**   * Syntax bit. POSIX character classes ([:...:]) in lists are allowed.   */  public static final int RE_CHAR_CLASSES              =  2;  /**   * Syntax bit. ^ and $ are special everywhere.   * <B>Not implemented.</B>   */  public static final int RE_CONTEXT_INDEP_ANCHORS     =  3;   /**   * Syntax bit. Repetition operators are only special in valid positions.   * <B>Not implemented.</B>   */  public static final int RE_CONTEXT_INDEP_OPS         =  4;   /**   * Syntax bit. Repetition and alternation operators are invalid   * at start and end of pattern and other places.    * <B>Not implemented</B>.   */  public static final int RE_CONTEXT_INVALID_OPS       =  5;   /**   * Syntax bit. Match-any-character operator (.) matches a newline.   */  public static final int RE_DOT_NEWLINE               =  6;  /**   * Syntax bit. Match-any-character operator (.) does not match a null.   */  public static final int RE_DOT_NOT_NULL              =  7;  /**   * Syntax bit. Intervals ({x}, {x,}, {x,y}) are allowed.   */  public static final int RE_INTERVALS                 =  8;  /**   * Syntax bit. No alternation (|), match one-or-more (+), or    * match zero-or-one (?) operators.   */  public static final int RE_LIMITED_OPS               =  9;  /**   * Syntax bit. Newline is an alternation operator.   */  public static final int RE_NEWLINE_ALT               = 10; // impl.  /**   * Syntax bit. Intervals use { } instead of \{ \}   */  public static final int RE_NO_BK_BRACES              = 11;   /**   * Syntax bit. Grouping uses ( ) instead of \( \).   */  public static final int RE_NO_BK_PARENS              = 12;  /**   * Syntax bit. Backreferences not allowed.   */  public static final int RE_NO_BK_REFS                = 13;  /**   * Syntax bit. Alternation uses | instead of \|   */  public static final int RE_NO_BK_VBAR                = 14;  /**   * Syntax bit. <B>Not implemented</B>.   */  public static final int RE_NO_EMPTY_RANGES           = 15;  /**   * Syntax bit. An unmatched right parenthesis (')' or '\)', depending   * on RE_NO_BK_PARENS) will throw an exception when compiling.   */  public static final int RE_UNMATCHED_RIGHT_PAREN_ORD = 16;  /**   * Syntax bit. <B>Not implemented.</B>   */  public static final int RE_HAT_LISTS_NOT_NEWLINE     = 17;  /**   * Syntax bit.  Stingy matching is allowed (+?, *?, ??, {x,y}?).   */  public static final int RE_STINGY_OPS                = 18;  /**   * Syntax bit. Allow character class escapes (\d, \D, \s, \S, \w, \W).   */  public static final int RE_CHAR_CLASS_ESCAPES        = 19;  /**   * Syntax bit. Allow use of (?:xxx) grouping (subexpression is not saved).   */  public static final int RE_PURE_GROUPING             = 20;  /**   * Syntax bit. Allow use of (?=xxx) and (?!xxx) apply the subexpression   * to the text following the current position without consuming that text.   */  public static final int RE_LOOKAHEAD                 = 21;  /**   * Syntax bit. Allow beginning- and end-of-string anchors (\A, \Z).   */  public static final int RE_STRING_ANCHORS            = 22;  /**   * Syntax bit. Allow embedded comments, (?#comment), as in Perl5.   */  public static final int RE_COMMENTS                  = 23;  /**   * Syntax bit. Allow character class escapes within lists, as in Perl5.   */  public static final int RE_CHAR_CLASS_ESC_IN_LISTS   = 24;  private static final int BIT_TOTAL                   = 25;  /**   * Predefined syntax.   * Emulates regular expression support in the awk utility.   */  public static final RESyntax RE_SYNTAX_AWK;  /**   * Predefined syntax.   * Emulates regular expression support in the ed utility.   */  public static final RESyntax RE_SYNTAX_ED;  /**   * Predefined syntax.   * Emulates regular expression support in the egrep utility.   */  public static final RESyntax RE_SYNTAX_EGREP;  /**   * Predefined syntax.   * Emulates regular expression support in the GNU Emacs editor.   */  public static final RESyntax RE_SYNTAX_EMACS;  /**   * Predefined syntax.   * Emulates regular expression support in the grep utility.   */  public static final RESyntax RE_SYNTAX_GREP;  /**   * Predefined syntax.   * Emulates regular expression support in the POSIX awk specification.   */  public static final RESyntax RE_SYNTAX_POSIX_AWK;  /**   * Predefined syntax.   * Emulates POSIX basic regular expression support.   */  public static final RESyntax RE_SYNTAX_POSIX_BASIC;  /**   * Predefined syntax.   * Emulates regular expression support in the POSIX egrep specification.   */  public static final RESyntax RE_SYNTAX_POSIX_EGREP;  /**   * Predefined syntax.   * Emulates POSIX extended regular expression support.   */  public static final RESyntax RE_SYNTAX_POSIX_EXTENDED;  /**   * Predefined syntax.   * Emulates POSIX basic minimal regular expressions.   */  public static final RESyntax RE_SYNTAX_POSIX_MINIMAL_BASIC;  /**   * Predefined syntax.   * Emulates POSIX extended minimal regular expressions.   */  public static final RESyntax RE_SYNTAX_POSIX_MINIMAL_EXTENDED;  /**   * Predefined syntax.   * Emulates regular expression support in the sed utility.   */  public static final RESyntax RE_SYNTAX_SED;  /**   * Predefined syntax.   * Emulates regular expression support in Larry Wall's perl, version 4,   */  public static final RESyntax RE_SYNTAX_PERL4;  /**   * Predefined syntax.   * Emulates regular expression support in Larry Wall's perl, version 4,   * using single line mode (/s modifier).   */  public static final RESyntax RE_SYNTAX_PERL4_S; // single line mode (/s)  /**   * Predefined syntax.   * Emulates regular expression support in Larry Wall's perl, version 5.   */  public static final RESyntax RE_SYNTAX_PERL5;    /**   * Predefined syntax.   * Emulates regular expression support in Larry Wall's perl, version 5,   * using single line mode (/s modifier).   */  public static final RESyntax RE_SYNTAX_PERL5_S;    static {      // Define syntaxes            RE_SYNTAX_EMACS = new RESyntax().makeFinal();            RESyntax RE_SYNTAX_POSIX_COMMON = new RESyntax()	  .set(RE_CHAR_CLASSES)	  .set(RE_DOT_NEWLINE)	  .set(RE_DOT_NOT_NULL)	  .set(RE_INTERVALS)	  .set(RE_NO_EMPTY_RANGES)	  .makeFinal();            RE_SYNTAX_POSIX_BASIC = new RESyntax(RE_SYNTAX_POSIX_COMMON)	  .set(RE_BK_PLUS_QM)	  .makeFinal();            RE_SYNTAX_POSIX_EXTENDED = new RESyntax(RE_SYNTAX_POSIX_COMMON)	  .set(RE_CONTEXT_INDEP_ANCHORS)	  .set(RE_CONTEXT_INDEP_OPS)	  .set(RE_NO_BK_BRACES)	  .set(RE_NO_BK_PARENS)	  .set(RE_NO_BK_VBAR)	  .set(RE_UNMATCHED_RIGHT_PAREN_ORD)	  .makeFinal();      RE_SYNTAX_AWK = new RESyntax()	  .set(RE_BACKSLASH_ESCAPE_IN_LISTS)	  .set(RE_DOT_NOT_NULL)	  .set(RE_NO_BK_PARENS)	  .set(RE_NO_BK_REFS)	  .set(RE_NO_BK_VBAR)	  .set(RE_NO_EMPTY_RANGES)	  .set(RE_UNMATCHED_RIGHT_PAREN_ORD)	  .makeFinal();            RE_SYNTAX_POSIX_AWK = new RESyntax(RE_SYNTAX_POSIX_EXTENDED)	  .set(RE_BACKSLASH_ESCAPE_IN_LISTS)	  .makeFinal();            RE_SYNTAX_GREP = new RESyntax()	  .set(RE_BK_PLUS_QM)	  .set(RE_CHAR_CLASSES)	  .set(RE_HAT_LISTS_NOT_NEWLINE)	  .set(RE_INTERVALS)	  .set(RE_NEWLINE_ALT)	  .makeFinal();            RE_SYNTAX_EGREP = new RESyntax()	  .set(RE_CHAR_CLASSES)	  .set(RE_CONTEXT_INDEP_ANCHORS)	  .set(RE_CONTEXT_INDEP_OPS)	  .set(RE_HAT_LISTS_NOT_NEWLINE)	  .set(RE_NEWLINE_ALT)	  .set(RE_NO_BK_PARENS)	  .set(RE_NO_BK_VBAR)	  .makeFinal();          RE_SYNTAX_POSIX_EGREP = new RESyntax(RE_SYNTAX_EGREP)	  .set(RE_INTERVALS)	  .set(RE_NO_BK_BRACES)	  .makeFinal();          /* P1003.2/D11.2, section 4.20.7.1, lines 5078ff.  */          RE_SYNTAX_ED = new RESyntax(RE_SYNTAX_POSIX_BASIC)	  .makeFinal();          RE_SYNTAX_SED = new RESyntax(RE_SYNTAX_POSIX_BASIC)	  .makeFinal();            RE_SYNTAX_POSIX_MINIMAL_BASIC = new RESyntax(RE_SYNTAX_POSIX_COMMON)	  .set(RE_LIMITED_OPS)	  .makeFinal();            /* Differs from RE_SYNTAX_POSIX_EXTENDED in that RE_CONTEXT_INVALID_OPS	 replaces RE_CONTEXT_INDEP_OPS and RE_NO_BK_REFS is added. */            RE_SYNTAX_POSIX_MINIMAL_EXTENDED = new RESyntax(RE_SYNTAX_POSIX_COMMON)	  .set(RE_CONTEXT_INDEP_ANCHORS)	  .set(RE_CONTEXT_INVALID_OPS)	  .set(RE_NO_BK_BRACES)	  .set(RE_NO_BK_PARENS)	  .set(RE_NO_BK_REFS)	  .set(RE_NO_BK_VBAR)	  .set(RE_UNMATCHED_RIGHT_PAREN_ORD)	  .makeFinal();            /* There is no official Perl spec, but here's a "best guess" */            RE_SYNTAX_PERL4 = new RESyntax()	  .set(RE_BACKSLASH_ESCAPE_IN_LISTS)	  .set(RE_CONTEXT_INDEP_ANCHORS)	  .set(RE_CONTEXT_INDEP_OPS)          // except for '{', apparently	  .set(RE_INTERVALS)	  .set(RE_NO_BK_BRACES)	  .set(RE_NO_BK_PARENS)	  .set(RE_NO_BK_VBAR)	  .set(RE_NO_EMPTY_RANGES)	  .set(RE_CHAR_CLASS_ESCAPES)    // \d,\D,\w,\W,\s,\S	  .makeFinal();            RE_SYNTAX_PERL4_S = new RESyntax(RE_SYNTAX_PERL4)	  .set(RE_DOT_NEWLINE)	  .makeFinal();            RE_SYNTAX_PERL5 = new RESyntax(RE_SYNTAX_PERL4)	  .set(RE_PURE_GROUPING)          // (?:)	  .set(RE_STINGY_OPS)             // *?,??,+?,{}?	  .set(RE_LOOKAHEAD)              // (?=)(?!)	  .set(RE_STRING_ANCHORS)         // \A,\Z	  .set(RE_CHAR_CLASS_ESC_IN_LISTS)// \d,\D,\w,\W,\s,\S within []	  .set(RE_COMMENTS)              // (?#)	  .makeFinal();            RE_SYNTAX_PERL5_S = new RESyntax(RE_SYNTAX_PERL5)	  .set(RE_DOT_NEWLINE)	  .makeFinal();  }  /**   * Construct a new syntax object with all bits turned off.   * This is equivalent to RE_SYNTAX_EMACS.   */  public RESyntax() {    bits = new BitSet(BIT_TOTAL);  }    /**     * Called internally when constructing predefined syntaxes     * so their interpretation cannot vary.  Conceivably useful     * for your syntaxes as well.  Causes IllegalAccessError to     * be thrown if any attempt to modify the syntax is made.     *     * @return this object for convenient chaining     */    public RESyntax makeFinal() {	isFinal = true;	return this;    }  /**   * Construct a new syntax object with all bits set the same    * as the other syntax.   */  public RESyntax(RESyntax other) {    bits = (BitSet) other.bits.clone();  }  /**   * Check if a given bit is set in this syntax.   */  public boolean get(int index) {    return bits.get(index);  }  /**   * Set a given bit in this syntax.    *   * @param index the constant (RESyntax.RE_xxx) bit to set.   * @return a reference to this object for easy chaining.   */  public RESyntax set(int index) {      if (isFinal) throw new IllegalAccessError(SYNTAX_IS_FINAL);    bits.set(index);    return this;  }  /**   * Clear a given bit in this syntax.    *   * @param index the constant (RESyntax.RE_xxx) bit to clear.   * @return a reference to this object for easy chaining.   */  public RESyntax clear(int index) {      if (isFinal) throw new IllegalAccessError(SYNTAX_IS_FINAL);      bits.clear(index);      return this;  }    /**     * Changes the line separator string for regular expressions     * created using this RESyntax.  The default separator is the     * value returned by the system property "line.separator", which     * should be correct when reading platform-specific files from a     * filesystem.  However, many programs may collect input from     * sources where the line separator is differently specified (for     * example, in the applet environment, the text box widget     * interprets line breaks as single-character newlines,     * regardless of the host platform.     *     * Note that setting the line separator to a character or     * characters that have specific meaning within the current syntax     * can cause unexpected chronosynclastic infundibula.     *     * @return this object for convenient chaining      */    public RESyntax setLineSeparator(String aSeparator) {	if (isFinal) throw new IllegalAccessError(SYNTAX_IS_FINAL);	lineSeparator = aSeparator;	return this;    }    /**     * Returns the currently active line separator string.  The default     * is the platform-dependent system property "line.separator".     */    public String getLineSeparator() {	return lineSeparator;    }}