Adding upstream version 2.5.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

analysis/lang/pl/stempel/diff.go

@@ -0,0 +1,64 @@
+//  Copyright (c) 2018 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package stempel
+
+// Diff transforms the dest rune slice following the rules described
+// in the diff command rune slice.
+func Diff(dest, diff []rune) []rune {
+	if len(diff) == 0 {
+		return dest
+	}
+
+	pos := len(dest) - 1
+	if pos < 0 {
+		return dest
+	}
+
+	for i := 0; i < len(diff)/2; i++ {
+		cmd := diff[2*i]
+		param := diff[2*i+1]
+		parNum := int(param - 'a' + 1)
+		switch cmd {
+		case '-':
+			pos = pos - parNum + 1
+		case 'R':
+			if pos < 0 || pos >= len(dest) {
+				// out of bounds, just return
+				return dest
+			}
+			dest[pos] = param
+		case 'D':
+			o := pos
+			pos -= parNum - 1
+			if pos < 0 || pos >= len(dest) {
+				// out of bounds, just return
+				return dest
+			}
+			dest = append(dest[:pos], dest[o+1:]...)
+		case 'I':
+			pos++
+			if pos < 0 || pos > len(dest) {
+				// out of bounds, just return
+				return dest
+			}
+
+			dest = append(dest, 0)
+			copy(dest[pos+1:], dest[pos:])
+			dest[pos] = param
+		}
+		pos--
+	}
+	return dest
+}