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      1 /*
      2  * Copyright (C) 2010 Google Inc.
      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.google.clearsilver.jsilver.data;
     18 
     19 
     20 /**
     21  * Static methods for converting stuff in a ClearSilver compatible way.
     22  */
     23 public class TypeConverter {
     24   private TypeConverter() {}
     25 
     26   private static final String ZERO = "0";
     27   private static final String ONE = "1";
     28 
     29   /**
     30    * Determines if the given data node exists in a ClearSilver compatible way.
     31    */
     32   public static boolean exists(Data data) {
     33     return data != null && data.getValue() != null;
     34   }
     35 
     36   /**
     37    * Helper method to safely convert an arbitrary data instance (including null) into a valid
     38    * (non-null) string representation.
     39    */
     40   public static String asString(Data data) {
     41     // Non-existent variables become the empty string
     42     // (the data instance will return null to us)
     43     String value = data != null ? data.getValue() : null;
     44     return value != null ? value : "";
     45   }
     46 
     47   /**
     48    * Parses a non-null string in a ClearSilver compatible way.
     49    *
     50    * The is the underlying parsing function which can fail for badly formatted strings. It is really
     51    * important that anyone doing parsing of strings calls this function (rather than doing it
     52    * themselves).
     53    *
     54    * This is an area where JSilver and ClearSilver have some notable differences. ClearSilver relies
     55    * on the template compiler to parse strings in the template and a different parser at runtime for
     56    * HDF values. JSilver uses the same code for both cases.
     57    *
     58    * In ClearSilver HDF: Numbers are parsed sequentially and partial results are returned when an
     59    * invalid character is reached. This means that {@code "123abc"} parses to {@code 123}.
     60    *
     61    * Additionally, ClearSilver doesn't do hex in HDF values, so {@code "a.b=0x123"} will just
     62    * resolve to {@code 0}.
     63    *
     64    * In ClearSilver templates: Hex is supported, including negative values.
     65    *
     66    * In JSilver: A string must be a complete, valid numeric value for parsing. This means {@code
     67    * "123abc"} is invalid and will default to {@code 0}.
     68    *
     69    * In JSilver: Positive hex values are supported for both HDF and templates but negative values
     70    * aren't. This means a template containing something like "<?cs if:foo == -0xff ?>" will parse
     71    * correctly but fail to render.
     72    *
     73    * @throws NumberFormatException is the string is badly formatted
     74    */
     75   public static int parseNumber(String value) throws NumberFormatException {
     76     // NOTE: This is likely to be one of the areas we will want to optimize
     77     // for speed eventually.
     78     if (value.startsWith("0x") || value.startsWith("0X")) {
     79       return Integer.parseInt(value.substring(2), 16);
     80     } else {
     81       return Integer.parseInt(value);
     82     }
     83   }
     84 
     85   /**
     86    * Parses and returns the given string as an integer in a ClearSilver compatible way.
     87    */
     88   public static int asNumber(String value) {
     89     if (value == null || value.isEmpty()) {
     90       return 0;
     91     }
     92     // fast detection for common constants to avoid parsing common values
     93     // TODO: Maybe push this down into parseNumber ??
     94     if (value.equals(ONE)) {
     95       return 1;
     96     }
     97     if (value.equals(ZERO)) {
     98       return 0;
     99     }
    100     try {
    101       return parseNumber(value);
    102     } catch (NumberFormatException e) {
    103       return 0;
    104     }
    105   }
    106 
    107   /**
    108    * Helper method to safely convert an arbitrary data instance (including null) into a valid
    109    * integer representation.
    110    */
    111   public static int asNumber(Data data) {
    112     // Non-existent variables become zero
    113     return data != null ? data.getIntValue() : 0;
    114   }
    115 
    116   /**
    117    * Parses and returns the given string as a boolean in a ClearSilver compatible way.
    118    */
    119   public static boolean asBoolean(String value) {
    120     if (value == null || value.isEmpty()) {
    121       return false;
    122     }
    123     // fast detection for common constants to avoid parsing common values
    124     if (value.equals(ONE)) {
    125       return true;
    126     }
    127     if (value.equals(ZERO)) {
    128       return false;
    129     }
    130 
    131     // fast detection of any string not starting with '0'
    132     if (value.charAt(0) != '0') {
    133       return true;
    134     }
    135 
    136     try {
    137       return parseNumber(value) != 0;
    138     } catch (NumberFormatException e) {
    139       // Unlike number parsing, we return a positive value when the
    140       // string is badly formatted (it's what clearsilver does).
    141       return true;
    142     }
    143   }
    144 
    145   /**
    146    * Helper method to safely convert an arbitrary data instance (including null) into a valid
    147    * boolean representation.
    148    */
    149   public static boolean asBoolean(Data data) {
    150     // Non-existent variables become false
    151     return data != null ? data.getBooleanValue() : false;
    152   }
    153 }
    154