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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.squareup.okhttp.internal.http;
     18 
     19 final class HeaderParser {
     20 
     21   public interface CacheControlHandler {
     22     void handle(String directive, String parameter);
     23   }
     24 
     25   /** Parse a comma-separated list of cache control header values. */
     26   public static void parseCacheControl(String value, CacheControlHandler handler) {
     27     int pos = 0;
     28     while (pos < value.length()) {
     29       int tokenStart = pos;
     30       pos = skipUntil(value, pos, "=,");
     31       String directive = value.substring(tokenStart, pos).trim();
     32 
     33       if (pos == value.length() || value.charAt(pos) == ',') {
     34         pos++; // consume ',' (if necessary)
     35         handler.handle(directive, null);
     36         continue;
     37       }
     38 
     39       pos++; // consume '='
     40       pos = skipWhitespace(value, pos);
     41 
     42       String parameter;
     43 
     44       // quoted string
     45       if (pos < value.length() && value.charAt(pos) == '\"') {
     46         pos++; // consume '"' open quote
     47         int parameterStart = pos;
     48         pos = skipUntil(value, pos, "\"");
     49         parameter = value.substring(parameterStart, pos);
     50         pos++; // consume '"' close quote (if necessary)
     51 
     52         // unquoted string
     53       } else {
     54         int parameterStart = pos;
     55         pos = skipUntil(value, pos, ",");
     56         parameter = value.substring(parameterStart, pos).trim();
     57       }
     58 
     59       handler.handle(directive, parameter);
     60     }
     61   }
     62 
     63   /**
     64    * Returns the next index in {@code input} at or after {@code pos} that
     65    * contains a character from {@code characters}. Returns the input length if
     66    * none of the requested characters can be found.
     67    */
     68   public static int skipUntil(String input, int pos, String characters) {
     69     for (; pos < input.length(); pos++) {
     70       if (characters.indexOf(input.charAt(pos)) != -1) {
     71         break;
     72       }
     73     }
     74     return pos;
     75   }
     76 
     77   /**
     78    * Returns the next non-whitespace character in {@code input} that is white
     79    * space. Result is undefined if input contains newline characters.
     80    */
     81   public static int skipWhitespace(String input, int pos) {
     82     for (; pos < input.length(); pos++) {
     83       char c = input.charAt(pos);
     84       if (c != ' ' && c != '\t') {
     85         break;
     86       }
     87     }
     88     return pos;
     89   }
     90 
     91   /**
     92    * Returns {@code value} as a positive integer, or 0 if it is negative, or
     93    * -1 if it cannot be parsed.
     94    */
     95   public static int parseSeconds(String value) {
     96     try {
     97       long seconds = Long.parseLong(value);
     98       if (seconds > Integer.MAX_VALUE) {
     99         return Integer.MAX_VALUE;
    100       } else if (seconds < 0) {
    101         return 0;
    102       } else {
    103         return (int) seconds;
    104       }
    105     } catch (NumberFormatException e) {
    106       return -1;
    107     }
    108   }
    109 
    110   private HeaderParser() {
    111   }
    112 }
    113