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/*
* Copyright (C) 2015 The Android Open Source Project
*
* 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 com.android.voicemailomtp.mail;
import java.util.HashMap;
import java.util.Map;
/**
* A utility class for creating and modifying Strings that are tagged and packed together.
*
* Uses non-printable (control chars) for internal delimiters; Intended for regular displayable
* strings only, so please use base64 or other encoding if you need to hide any binary data here.
*
* Binary compatible with Address.pack() format, which should migrate to use this code.
*/
public class PackedString {
/**
* Packing format is:
* element : [ value ] or [ value TAG-DELIMITER tag ]
* packed-string : [ element ] [ ELEMENT-DELIMITER [ element ] ]*
*/
private static final char DELIMITER_ELEMENT = '\1';
private static final char DELIMITER_TAG = '\2';
private String mString;
private HashMap<String, String> mExploded;
private static final HashMap<String, String> EMPTY_MAP = new HashMap<String, String>();
/**
* Create a packed string using an already-packed string (e.g. from database)
* @param string packed string
*/
public PackedString(String string) {
mString = string;
mExploded = null;
}
/**
* Get the value referred to by a given tag. If the tag does not exist, return null.
* @param tag identifier of string of interest
* @return returns value, or null if no string is found
*/
public String get(String tag) {
if (mExploded == null) {
mExploded = explode(mString);
}
return mExploded.get(tag);
}
/**
* Return a map of all of the values referred to by a given tag. This is a shallow
* copy, don't edit the values.
* @return a map of the values in the packed string
*/
public Map<String, String> unpack() {
if (mExploded == null) {
mExploded = explode(mString);
}
return new HashMap<String,String>(mExploded);
}
/**
* Read out all values into a map.
*/
private static HashMap<String, String> explode(String packed) {
if (packed == null || packed.length() == 0) {
return EMPTY_MAP;
}
HashMap<String, String> map = new HashMap<String, String>();
int length = packed.length();
int elementStartIndex = 0;
int elementEndIndex = 0;
int tagEndIndex = packed.indexOf(DELIMITER_TAG);
while (elementStartIndex < length) {
elementEndIndex = packed.indexOf(DELIMITER_ELEMENT, elementStartIndex);
if (elementEndIndex == -1) {
elementEndIndex = length;
}
String tag;
String value;
if (tagEndIndex == -1 || elementEndIndex <= tagEndIndex) {
// in this case the DELIMITER_PERSONAL is in a future pair (or not found)
// so synthesize a positional tag for the value, and don't update tagEndIndex
value = packed.substring(elementStartIndex, elementEndIndex);
tag = Integer.toString(map.size());
} else {
value = packed.substring(elementStartIndex, tagEndIndex);
tag = packed.substring(tagEndIndex + 1, elementEndIndex);
// scan forward for next tag, if any
tagEndIndex = packed.indexOf(DELIMITER_TAG, elementEndIndex + 1);
}
map.put(tag, value);
elementStartIndex = elementEndIndex + 1;
}
return map;
}
/**
* Builder class for creating PackedString values. Can also be used for editing existing
* PackedString representations.
*/
static public class Builder {
HashMap<String, String> mMap;
/**
* Create a builder that's empty (for filling)
*/
public Builder() {
mMap = new HashMap<String, String>();
}
/**
* Create a builder using the values of an existing PackedString (for editing).
*/
public Builder(String packed) {
mMap = explode(packed);
}
/**
* Add a tagged value
* @param tag identifier of string of interest
* @param value the value to record in this position. null to delete entry.
*/
public void put(String tag, String value) {
if (value == null) {
mMap.remove(tag);
} else {
mMap.put(tag, value);
}
}
/**
* Get the value referred to by a given tag. If the tag does not exist, return null.
* @param tag identifier of string of interest
* @return returns value, or null if no string is found
*/
public String get(String tag) {
return mMap.get(tag);
}
/**
* Pack the values and return a single, encoded string
*/
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
for (Map.Entry<String,String> entry : mMap.entrySet()) {
if (sb.length() > 0) {
sb.append(DELIMITER_ELEMENT);
}
sb.append(entry.getValue());
sb.append(DELIMITER_TAG);
sb.append(entry.getKey());
}
return sb.toString();
}
}
}
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