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/*
* Copyright (C) 2008 The Guava Authors
*
* 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.google.thirdparty.publicsuffix;
import com.google.common.annotations.GwtCompatible;
import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Lists;
import java.util.List;
/**
* Parser for a map of reversed domain names stored as a serialized radix tree.
*/
@GwtCompatible
final class TrieParser {
private static final Joiner PREFIX_JOINER = Joiner.on("");
/**
* Parses a serialized trie representation of a map of reversed public suffixes into an immutable
* map of public suffixes.
*/
static ImmutableMap parseTrie(CharSequence encoded) {
ImmutableMap.Builder builder = ImmutableMap.builder();
int encodedLen = encoded.length();
int idx = 0;
while (idx < encodedLen) {
idx +=
doParseTrieToBuilder(
Lists.newLinkedList(), encoded.subSequence(idx, encodedLen), builder);
}
return builder.build();
}
/**
* Parses a trie node and returns the number of characters consumed.
*
* @param stack The prefixes that precede the characters represented by this node. Each entry of
* the stack is in reverse order.
* @param encoded The serialized trie.
* @param builder A map builder to which all entries will be added.
* @return The number of characters consumed from {@code encoded}.
*/
private static int doParseTrieToBuilder(
List stack,
CharSequence encoded,
ImmutableMap.Builder builder) {
int encodedLen = encoded.length();
int idx = 0;
char c = '\0';
// Read all of the characters for this node.
for (; idx < encodedLen; idx++) {
c = encoded.charAt(idx);
if (c == '&' || c == '?' || c == '!' || c == ':' || c == ',') {
break;
}
}
stack.add(0, reverse(encoded.subSequence(0, idx)));
if (c == '!' || c == '?' || c == ':' || c == ',') {
// '!' represents an interior node that represents an ICANN entry in the map.
// '?' represents a leaf node, which represents an ICANN entry in map.
// ':' represents an interior node that represents a private entry in the map
// ',' represents a leaf node, which represents a private entry in the map.
String domain = PREFIX_JOINER.join(stack);
if (domain.length() > 0) {
builder.put(domain, PublicSuffixType.fromCode(c));
}
}
idx++;
if (c != '?' && c != ',') {
while (idx < encodedLen) {
// Read all the children
idx += doParseTrieToBuilder(stack, encoded.subSequence(idx, encodedLen), builder);
if (encoded.charAt(idx) == '?' || encoded.charAt(idx) == ',') {
// An extra '?' or ',' after a child node indicates the end of all children of this node.
idx++;
break;
}
}
}
stack.remove(0);
return idx;
}
private static CharSequence reverse(CharSequence s) {
return new StringBuilder(s).reverse();
}
}