Change hash function for HashedStringSegment

xplicit · xplicit · commit c5ffaedbcf53 · 2017-05-31T18:03:09.000+07:00
diff --git a/src/ServiceStack.Text/Json/JsonTypeSerializer.cs b/src/ServiceStack.Text/Json/JsonTypeSerializer.cs
@@ -460,8 +460,17 @@ private static StringSegment UnEscapeJsonString(StringSegment json, ref int inde
             }
             else
             {
-                var strEndPos = json.IndexOfAny(IsSafeJsonChars, index);
-                if (strEndPos == -1) return new StringSegment(buffer, offset + index, jsonLength - index);
+                var i = index + offset;
+                var end = offset + jsonLength;
+
+                while (i < end)
+                {
+                    var c = buffer[i];
+                    if (c == JsonUtils.QuoteChar || c == JsonUtils.EscapeChar)
+                        break;
+                    i++;
+                }
+                if (i == end) return new StringSegment(buffer, offset + index, jsonLength - index);
             }
 
             return Unescape(json);
diff --git a/src/ServiceStack.Text/Support/HashedStringSegment.cs b/src/ServiceStack.Text/Support/HashedStringSegment.cs
@@ -30,29 +30,23 @@ public override bool Equals(object obj)
 
         public static int ComputeHashCode(StringSegment value)
         {
-            return value.Length;
+            var length = value.Length;
+            if (length == 0)
+                return 0;
 
-            //this implementation of case insensitive hash code is temporary commented
-            //because we need to implement fast char.ToUpperInvariant() at first
-/*            int c;
-            int last = value.Offset + value.Length;
-            int i = value.Offset;
-            int hash1 = 5381;
-            int hash2 = hash1;
+            var offset = value.Offset;
+            var hash = 37 * length;
 
-            while (i < last)
+            char c1 = Char.ToUpperInvariant(value.Buffer[offset]);
+            hash += 53 * c1;
+
+            if (length > 1)
             {
-                c = char.ToUpperInvariant(value.Buffer[i]);
-                hash1 = ((hash1 << 5) + hash1) ^ c;
-                if ((i += 5) >= last)
-                    break;
-                c = char.ToUpperInvariant(value.Buffer[i]);
-                hash2 = ((hash2 << 5) + hash2) ^ c;
-                i += 5;
+                char c2 = Char.ToUpperInvariant(value.Buffer[offset + length - 1]);
+                hash += 37 * c2;
             }
 
-            return hash1 + (hash2 * 1566083941);
-*/
+            return hash;
         }
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -460,8 +460,17 @@ private static StringSegment UnEscapeJsonString(StringSegment json, ref int inde`
`460`	`460`	`}`
`461`	`461`	`else`
`462`	`462`	`{`
`463`		`- var strEndPos = json.IndexOfAny(IsSafeJsonChars, index);`
`464`		`- if (strEndPos == -1) return new StringSegment(buffer, offset + index, jsonLength - index);`
	`463`	`+ var i = index + offset;`
	`464`	`+ var end = offset + jsonLength;`
	`465`	`+`
	`466`	`+ while (i < end)`
	`467`	`+ {`
	`468`	`+ var c = buffer[i];`
	`469`	`+ if (c == JsonUtils.QuoteChar \|\| c == JsonUtils.EscapeChar)`
	`470`	`+ break;`
	`471`	`+ i++;`
	`472`	`+ }`
	`473`	`+ if (i == end) return new StringSegment(buffer, offset + index, jsonLength - index);`
`465`	`474`	`}`
`466`	`475`
`467`	`476`	`return Unescape(json);`