From 96a6898ce7625d3d4f5e55324a303d615bf9df68 Mon Sep 17 00:00:00 2001
From: Michael McCandless <mikemccand@apache.org>
Date: Tue, 27 Jul 2010 10:56:04 +0000
Subject: [PATCH] LUCENE-2568: fix AutomatonTestUtil.RandomAcceptedString to
 not return invalid (containing code points in the UTF16 surrogates range)
 UTF32

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@979639 13f79535-47bb-0310-9956-ffa450edef68
---
 .../util/automaton/AutomatonTestUtil.java     | 43 ++++++++++++++++---
 1 file changed, 37 insertions(+), 6 deletions(-)

diff --git a/lucene/src/test/org/apache/lucene/util/automaton/AutomatonTestUtil.java b/lucene/src/test/org/apache/lucene/util/automaton/AutomatonTestUtil.java
index a1dd2da5072..9f7087ff78c 100644
--- a/lucene/src/test/org/apache/lucene/util/automaton/AutomatonTestUtil.java
+++ b/lucene/src/test/org/apache/lucene/util/automaton/AutomatonTestUtil.java
@@ -77,12 +77,44 @@ public class AutomatonTestUtil {
     return new String(buffer, 0, end);
   }
   
-  // picks a random int code point that this transition
-  // accepts, avoiding the surrogates range since they are
-  // "defined" in UTF32.  Don't call this on a transition
-  // that only accepts UTF16 surrogate values!!
+  // picks a random int code point, avoiding surrogates;
+  // throws IllegalArgumentException if this transition only
+  // accepts surrogates
   private static int getRandomCodePoint(final Random r, final Transition t) {
-    return t.min+r.nextInt(t.max-t.min+1);
+    final int code;
+    if (t.max < UnicodeUtil.UNI_SUR_HIGH_START ||
+        t.min > UnicodeUtil.UNI_SUR_HIGH_END) {
+      // easy: entire range is before or after surrogates
+      code = t.min+r.nextInt(t.max-t.min+1);
+    } else if (t.min >= UnicodeUtil.UNI_SUR_HIGH_START) {
+      if (t.max > UnicodeUtil.UNI_SUR_LOW_END) {
+        // after surrogates
+        code = 1+UnicodeUtil.UNI_SUR_LOW_END+r.nextInt(t.max-UnicodeUtil.UNI_SUR_LOW_END+1);
+      } else {
+        throw new IllegalArgumentException("transition accepts only surrogates: " + t);
+      }
+    } else if (t.max <= UnicodeUtil.UNI_SUR_LOW_END) {
+      if (t.min < UnicodeUtil.UNI_SUR_HIGH_START) {
+        // before surrogates
+        code = t.min + r.nextInt(UnicodeUtil.UNI_SUR_HIGH_START - t.min);
+      } else {
+        throw new IllegalArgumentException("transition accepts only surrogates: " + t);
+      }
+    } else {
+      // range includes all surrogates
+      int gap1 = UnicodeUtil.UNI_SUR_HIGH_START - t.min;
+      int gap2 = t.max - UnicodeUtil.UNI_SUR_LOW_END;
+      int c = r.nextInt(gap1+gap2);
+      if (c < gap1) {
+        code = t.min + c;
+      } else {
+        code = UnicodeUtil.UNI_SUR_LOW_END + c - gap1 + 1;
+      }
+    }
+
+    assert code >= t.min && code <= t.max && (code < UnicodeUtil.UNI_SUR_HIGH_START || code > UnicodeUtil.UNI_SUR_LOW_END):
+      "code=" + code + " min=" + t.min + " max=" + t.max;
+    return code;
   }
 
   public static class RandomAcceptedStrings {
@@ -206,7 +238,6 @@ public class AutomatonTestUtil {
           } else {
             t = s.transitionsArray[r.nextInt(s.numTransitions)];
           }
-          
           soFar.add(getRandomCodePoint(r, t));
           s = t.to;
         }