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See the License for the * 011// * specific language governing permissions and limitations under the License. * 012// *************************************************************************************************************************** 013package org.apache.juneau.http; 014 015import static org.apache.juneau.http.Constants.*; 016import static org.apache.juneau.internal.StringUtils.*; 017 018import java.util.*; 019 020import org.apache.http.*; 021import org.apache.http.message.*; 022import org.apache.juneau.annotation.*; 023import org.apache.juneau.collections.*; 024import org.apache.juneau.internal.*; 025 026/** 027 * A parsed <c>Accept-Encoding</c> or similar header value. 028 * 029 * <p> 030 * The returned ranges are sorted such that the most acceptable value is available at ordinal position 031 * <js>'0'</js>, and the least acceptable at position n-1. 032 * 033 * <h5 class='topic'>RFC2616 Specification</h5> 034 * 035 * The Accept-Encoding request-header field is similar to Accept, but restricts the content-codings (section 3.5) that 036 * are acceptable in the response. 037 * 038 * <p class='bcode w800'> 039 * Accept-Encoding = "Accept-Encoding" ":" 040 * 1#( codings [ ";" "q" "=" qvalue ] ) 041 * codings = ( content-coding | "*" ) 042 * </p> 043 * 044 * <p> 045 * Examples of its use are: 046 * <p class='bcode w800'> 047 * Accept-Encoding: compress, gzip 048 * Accept-Encoding: 049 * Accept-Encoding: * 050 * Accept-Encoding: compress;q=0.5, gzip;q=1.0 051 * Accept-Encoding: gzip;q=1.0, identity; q=0.5, *;q=0 052 * </p> 053 */ 054@BeanIgnore 055public class StringRanges { 056 057 private static final StringRanges DEFAULT = new StringRanges(""); 058 private static final Cache<String,StringRanges> CACHE = new Cache<>(NOCACHE, CACHE_MAX_SIZE); 059 060 private final StringRange[] ranges; 061 private final String string; 062 063 /** 064 * Returns a parsed string range header value. 065 * 066 * @param value The raw string range header value. 067 * @return A parsed string range header value. 068 */ 069 public static StringRanges of(String value) { 070 if (value == null || value.length() == 0) 071 return DEFAULT; 072 073 StringRanges mr = CACHE.get(value); 074 if (mr == null) 075 mr = CACHE.put(value, new StringRanges(value)); 076 return mr; 077 } 078 079 /** 080 * Constructor. 081 * 082 * @param value The string range header value. 083 */ 084 public StringRanges(String value) { 085 this(parse(value)); 086 } 087 088 /** 089 * Constructor. 090 * 091 * @param e The parsed string range header value. 092 */ 093 public StringRanges(HeaderElement[] e) { 094 095 List<StringRange> l = AList.of(); 096 for (HeaderElement e2 : e) 097 l.add(new StringRange(e2)); 098 099 l.sort(RANGE_COMPARATOR); 100 ranges = l.toArray(new StringRange[l.size()]); 101 102 this.string = ranges.length == 1 ? ranges[0].toString() : StringUtils.join(l, ','); 103 } 104 105 /** 106 * Compares two StringRanges for equality. 107 * 108 * <p> 109 * The values are first compared according to <c>qValue</c> values. 110 * Should those values be equal, the <c>type</c> is then lexicographically compared (case-insensitive) in 111 * ascending order, with the <js>"*"</js> type demoted last in that order. 112 */ 113 private static final Comparator<StringRange> RANGE_COMPARATOR = new Comparator<StringRange>() { 114 @Override 115 public int compare(StringRange o1, StringRange o2) { 116 // Compare q-values. 117 int qCompare = Float.compare(o2.getQValue(), o1.getQValue()); 118 if (qCompare != 0) 119 return qCompare; 120 121 // Compare media-types. 122 // Note that '*' comes alphabetically before letters, so just do a reverse-alphabetical comparison. 123 int i = o2.toString().compareTo(o1.toString()); 124 return i; 125 } 126 }; 127 128 /** 129 * Given a list of media types, returns the best match for this string range header. 130 * 131 * <p> 132 * Note that fuzzy matching is allowed on the media types where the string range header may 133 * contain additional subtype parts. 134 * <br>For example, given identical q-values and an string range value of <js>"text/json+activity"</js>, 135 * the media type <js>"text/json"</js> will match if <js>"text/json+activity"</js> or <js>"text/activity+json"</js> 136 * isn't found. 137 * <br>The purpose for this is to allow serializers to match when artifacts such as <c>id</c> properties are 138 * present in the header. 139 * 140 * <p> 141 * See {@doc https://www.w3.org/TR/activitypub/#retrieving-objects ActivityPub / Retrieving Objects} 142 * 143 * @param names The names to match against. 144 * @return The index into the array of the best match, or <c>-1</c> if no suitable matches could be found. 145 */ 146 public int match(List<String> names) { 147 if (string.isEmpty()) 148 return -1; 149 150 int matchQuant = 0, matchIndex = -1; 151 float q = 0f; 152 153 // Media ranges are ordered by 'q'. 154 // So we only need to search until we've found a match. 155 for (StringRange mr : ranges) { 156 float q2 = mr.getQValue(); 157 158 if (q2 < q || q2 == 0) 159 break; 160 161 for (int i = 0; i < names.size(); i++) { 162 String mt = names.get(i); 163 int matchQuant2 = mr.match(mt); 164 165 if (matchQuant2 > matchQuant) { 166 matchIndex = i; 167 matchQuant = matchQuant2; 168 q = q2; 169 } 170 } 171 } 172 173 return matchIndex; 174 } 175 176 /** 177 * Returns the {@link MediaRange} at the specified index. 178 * 179 * @param index The index position of the media range. 180 * @return The {@link MediaRange} at the specified index or <jk>null</jk> if the index is out of range. 181 */ 182 public StringRange getRange(int index) { 183 if (index < 0 || index >= ranges.length) 184 return null; 185 return ranges[index]; 186 } 187 188 /** 189 * Returns the string ranges that make up this object. 190 * 191 * @return The string ranges that make up this object. 192 */ 193 public List<StringRange> getRanges() { 194 return Collections.unmodifiableList(Arrays.asList(ranges)); 195 } 196 197 private static HeaderElement[] parse(String value) { 198 return BasicHeaderValueParser.parseElements(emptyIfNull(trim(value)), null); 199 } 200 201 @Override /* Object */ 202 public String toString() { 203 return string; 204 } 205}