src/java.base/share/classes/java/util/Scanner.java

rev 13685 : 8149656: Examine usages of sun.misc.LRUCache
Reviewed-by:

*** 36,47 ****
  import java.util.function.Consumer;
  import java.util.regex.*;
  import java.util.stream.Stream;
  import java.util.stream.StreamSupport;
  
- import sun.misc.LRUCache;
- 
  /**
   * A simple text scanner which can parse primitive types and strings using
   * regular expressions.
   *
   * <p>A {@code Scanner} breaks its input into tokens using a
--- 36,45 ----
*** 364,382 ****
  
      // The locale used by this scanner
      private Locale locale = null;
  
      // A cache of the last few recently used Patterns
!     private LRUCache<String,Pattern> patternCache =
!     new LRUCache<String,Pattern>(7) {
!         protected Pattern create(String s) {
!             return Pattern.compile(s);
!         }
!         protected boolean hasName(Pattern p, String s) {
!             return p.pattern().equals(s);
!         }
!     };
  
      // A holder of the last IOException encountered
      private IOException lastException;
  
      // Number of times this scanner's state has been modified.
--- 362,372 ----
  
      // The locale used by this scanner
      private Locale locale = null;
  
      // A cache of the last few recently used Patterns
!     private PatternLRUCache patternCache = new PatternLRUCache(7);
  
      // A holder of the last IOException encountered
      private IOException lastException;
  
      // Number of times this scanner's state has been modified.
*** 2836,2841 ****
--- 2826,2877 ----
                  else
                      return false; // reached end of input
              }
          }
      }
+ 
+     /** Utility class for small LRU caches. */
+     private static class PatternLRUCache {
+ 
+         private Pattern[] oa = null;
+         private final int size;
+ 
+         PatternLRUCache(int size) {
+             this.size = size;
+         }
+ 
+         boolean hasName(Pattern p, String s) {
+             return p.pattern().equals(s);
+         }
+ 
+         void moveToFront(Object[] oa, int i) {
+             Object ob = oa[i];
+             for (int j = i; j > 0; j--)
+                 oa[j] = oa[j - 1];
+             oa[0] = ob;
+         }
+ 
+         Pattern forName(String name) {
+             if (oa == null) {
+                 Pattern[] temp = new Pattern[size];
+                 oa = temp;
+             } else {
+                 for (int i = 0; i < oa.length; i++) {
+                     Pattern ob = oa[i];
+                     if (ob == null)
+                         continue;
+                     if (hasName(ob, name)) {
+                         if (i > 0)
+                             moveToFront(oa, i);
+                         return ob;
+                     }
+                 }
+             }
+ 
+             // Create a new object
+             Pattern ob = Pattern.compile(name);
+             oa[oa.length - 1] = ob;
+             moveToFront(oa, oa.length - 1);
+             return ob;
+         }
+     }
  }