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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.http.server;
/**
* Simple encoding scheme to remove space, linefeed, control characters and
* anything outside ISO 646.irv:1991 from strings. The scheme is supposed to be
* human readable and debugging friendly. Opening and closing curly braces are
* used as quoting characters, the output is by definition US-ASCII only
* characters.
*
* @author Steinar Knutsen
*/
final class Encoder {
/**
* ISO 646.irv:1991 safe quoting into a StringBuilder instance.
*
* @param input the string to encode
* @param output the destination buffer
* @return the destination buffer given as input
*/
public static StringBuilder encode(String input, StringBuilder output) {
for (int i = 0; i < input.length(); i = input.offsetByCodePoints(i, 1)) {
int c = input.codePointAt(i);
if (c <= '~') {
if (c <= ' ') {
encode(c, output);
} else {
switch (c) {
case '{':
case '}':
encode(c, output);
break;
default:
output.append((char) c);
}
}
} else {
encode(c, output);
}
}
return output;
}
/**
* ISO 646.irv:1991 safe unquoting into a StringBuilder instance.
*
* @param input the string to decode
* @param output the destination buffer
* @return the destination buffer given as input
* @throws IllegalArgumentException if the input string contains unexpected or invalid data
*/
public static StringBuilder decode(String input, StringBuilder output) {
for (int i = 0; i < input.length(); i = input.offsetByCodePoints(i, 1)) {
int c = input.codePointAt(i);
if (c > '~')
throw new IllegalArgumentException("Input contained character above printable ASCII at position " + i);
if (c == '{')
i = decode(input, i, output);
else
output.append((char) c);
}
return output;
}
private static int decode(String input, int offset, StringBuilder output) {
char c = 0;
int end = offset;
int start = offset + 1;
int codePoint;
while ('}' != c) {
if (++end >= input.length()) {
throw new IllegalArgumentException("Unterminated quoted character or empty quoting.");
}
c = input.charAt(end);
}
try {
codePoint = Integer.parseInt(input.substring(start, end), 16);
} catch (NumberFormatException e) {
throw new IllegalArgumentException("Unexpected quoted data: [" + input.substring(start, end) + "]", e);
}
if (Character.charCount(codePoint) > 1) {
try {
output.append(Character.toChars(codePoint));
} catch (IllegalArgumentException e) {
throw new IllegalArgumentException("Unexpected quoted data: [" + input.substring(start, end) + "]", e);
}
} else {
output.append((char) codePoint);
}
return end;
}
private static void encode(int c, StringBuilder output) {
output.append("{").append(Integer.toHexString(c)).append("}");
}
}
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