RE.java (initialize): Add RETokenLookAhead support.

2004-09-25  Shashank Bapat  <shashankbapat@yahoo.com>
            Mark Wielaard  <mark@klomp.org>

       * gnu/regexp/RE.java (initialize): Add RETokenLookAhead support.
       * gnu/regexp/RETokenLookAhead.java: New file.

       * Makefile.am (ordinary_java_source_files): Add RETokenLookAhead.java.
       * Makefile.in: Regenerated.

Co-Authored-By: Mark Wielaard <mark@klomp.org>

From-SVN: r88106

libjava/gnu/regexp/RE.java

@@ -492,8 +492,25 @@ public class RE extends REToken {
       else if ((unit.ch == '(') && (syntax.get(RESyntax.RE_NO_BK_PARENS) ^ unit.bk)) {
 	boolean pure = false;
 	boolean comment = false;
+        boolean lookAhead = false;
+        boolean negativelh = false;
 	if ((index+1 < pLength) && (pattern[index] == '?')) {
 	  switch (pattern[index+1]) {
+          case '!':
+            if (syntax.get(RESyntax.RE_LOOKAHEAD)) {
+              pure = true;
+              negativelh = true;
+              lookAhead = true;
+              index += 2;
+            }
+            break;
+          case '=':
+            if (syntax.get(RESyntax.RE_LOOKAHEAD)) {
+              pure = true;
+              lookAhead = true;
+              index += 2;
+            }
+            break;
 	  case ':':
 	    if (syntax.get(RESyntax.RE_PURE_GROUPING)) {
 	      pure = true;
@@ -539,10 +556,14 @@ public class RE extends REToken {
 	    numSubs++;
 	  }
 
-	  int useIndex = (pure) ? 0 : nextSub + numSubs;
+	  int useIndex = (pure || lookAhead) ? 0 : nextSub + numSubs;
 	  currentToken = new RE(String.valueOf(pattern,index,endIndex-index).toCharArray(),cflags,syntax,useIndex,nextSub + numSubs);
 	  numSubs += ((RE) currentToken).getNumSubs();
 
+          if (lookAhead) {
+	      currentToken = new RETokenLookAhead(currentToken,negativelh);
+	  }
+
 	  index = nextIndex;
 	} // not a comment
       } // subexpression

libjava/gnu/regexp/RETokenLookAhead.java

@@ -0,0 +1,87 @@
+/* gnu/regexp/RETokenLookAhead.java
+   Copyright (C) 1998-2001, 2004 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath 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
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+02111-1307 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package gnu.regexp;
+
+/**
+ * @since gnu.regexp 1.1.3
+ * @author Shashank Bapat
+ */
+final class RETokenLookAhead extends REToken
+{
+  REToken re;
+  boolean negative;
+
+  RETokenLookAhead(REToken re, boolean negative) throws REException {
+    super(0);
+    this.re = re;
+    this.negative = negative;
+  }
+
+  boolean match(CharIndexed input, REMatch mymatch)
+  {
+    REMatch trymatch = (REMatch)mymatch.clone();
+    REMatch trymatch1 = (REMatch)mymatch.clone();
+    REMatch newMatch = null;
+    if (re.match(input, trymatch)) {
+      if (negative) return false;
+      if (next(input, trymatch1))
+        newMatch = trymatch1;
+    }
+
+    if (newMatch != null) {
+      if (negative) return false;
+      //else
+      mymatch.assignFrom(newMatch);
+      return true;
+    }
+    else { // no match
+      if (negative)
+        return next(input, mymatch);
+      //else
+      return false;
+    }
+  }
+
+    void dump(StringBuffer os) {
+	os.append("(?");
+	os.append(negative ? '!' : '=');
+	re.dumpAll(os);
+	os.append(')');
+    }
+}
+