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1 files changed, 88 insertions, 0 deletions

diff --git a/config-lib/src/main/java/com/yahoo/config/text/StringUtilities.java b/config-lib/src/main/java/com/yahoo/config/text/StringUtilities.java
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+++ b/config-lib/src/main/java/com/yahoo/config/text/StringUtilities.java
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+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.config.text;
+
+import java.nio.charset.Charset;
+import java.io.ByteArrayOutputStream;
+
+/**
+ * Escapes strings into and out of a format where they only contain printable characters.
+ *
+ * Need to duplicate escape / unescape of strings as we have in C++ for java version of system states.
+ *
+ * @author <a href="mailto:humbe@yahoo-inc.com">Haakon Humberset</a>
+ */
+public class StringUtilities {
+    private static Charset UTF8 = Charset.forName("utf8");
+
+    private static byte toHex(int val) { return (byte) (val < 10 ? '0' + val : 'a' + (val - 10)); }
+
+    private static class ReplacementCharacters {
+        public byte needEscape[] = new byte[256];
+        public byte replacement1[] = new byte[256];
+        public byte replacement2[] = new byte[256];
+
+        public ReplacementCharacters() {
+            for (int i=0; i<256; ++i) {
+                if (i >= 32 && i <= 126) {
+                    needEscape[i] = 0;
+                } else if (i > 127) {
+                    needEscape[i] = 0;
+                } else {
+                    needEscape[i] = 3;
+                    replacement1[i] = toHex((i >> 4) & 0xF);
+                    replacement2[i] = toHex(i & 0xF);
+                }
+            }
+            makeSimpleEscape('"', '"');
+            makeSimpleEscape('\\', '\\');
+            makeSimpleEscape('\t', 't');
+            makeSimpleEscape('\n', 'n');
+            makeSimpleEscape('\r', 'r');
+            makeSimpleEscape('\f', 'f');
+        }
+
+        private void makeSimpleEscape(char source, char dest) {
+            needEscape[source] = 1;
+            replacement1[source] = '\\';
+            replacement2[source] = (byte) dest;
+        }
+    }
+
+    private final static ReplacementCharacters replacementCharacters = new ReplacementCharacters();
+
+    public static String escape(String source) { return escape(source, '\0'); }
+
+    /**
+     * Escapes strings into a format with only printable ASCII characters.
+     *
+     * @param source The string to escape
+     * @param delimiter Escape this character too, even if it is printable.
+     * @return The escaped string
+     */
+    public static String escape(String source, char delimiter) {
+        byte bytes[] = source.getBytes(UTF8);
+        ByteArrayOutputStream result = new ByteArrayOutputStream();
+        for (byte b : bytes) {
+            int val = b;
+            if (val < 0) val += 256;
+            if (b == delimiter) {
+                result.write('\\');
+                result.write('x');
+                result.write(toHex((val >> 4) & 0xF));
+                result.write(toHex(val & 0xF));
+            } else if (replacementCharacters.needEscape[val] == 0) {
+                result.write(b);
+            } else {
+                if (replacementCharacters.needEscape[val] == 3) {
+                    result.write('\\');
+                    result.write('x');
+                }
+                result.write(replacementCharacters.replacement1[val]);
+                result.write(replacementCharacters.replacement2[val]);
+            }
+        }
+        return new String(result.toByteArray(), UTF8);
+    }
+
+
+}