external_libraries/yaml-cpp-0.3.0/util/api.cpp

   1 // a sketch of what the new API might look like
   2
   3 #include "yaml-cpp/yaml.h"
   4 #include <iostream>
   5
   6 int main()
   7 {
   8         {
   9                 // test.yaml
  10                 // - foo
  11                 // - primes: [2, 3, 5, 7, 11]
  12                 //   odds: [1, 3, 5, 7, 9, 11]
  13                 // - [x, y]
  14
  15                 // move-like semantics
  16                 YAML::Value root = YAML::Parse("test.yaml");
  17
  18                 std::cout << root[0].as<std::string>(); // "foo"
  19                 std::cout << str(root[0]); // "foo", shorthand?
  20                 std::cout << root[1]["primes"][3].as<int>(); // "7"
  21                 std::cout << root[1]["odds"][6].as<int>(); // throws?
  22
  23                 root[2].push_back(5);
  24                 root[3] = "Hello, World";
  25                 root[0].reset();
  26                 root[0]["key"] = "value";
  27
  28                 std::cout << root;
  29                 // # not sure about formatting
  30                 // - {key: value}
  31                 // - primes: [2, 3, 5, 7, 11]
  32                 //   odds: [1, 3, 5, 7, 9, 11]
  33                 // - [x, y, 5]
  34                 // - Hello, World
  35         }
  36
  37         {
  38                 // for all copy-like commands, think of python's "name/value" semantics
  39                 YAML::Value root = "Hello";  // Hello
  40                 root = YAML::Sequence();     // []
  41                 root[0] = 0;                 // [0]
  42                 root[2] = "two";             // [0, ~, two]  # forces root[1] to be initialized to null
  43
  44                 YAML::Value other = root;    // both point to the same thing
  45                 other[0] = 5;                // now root[0] is 0 also
  46                 other.push_back(root);       // &1 [5, ~, two, *1]
  47                 other[3][0] = 0;             // &1 [0, ~, two, *1]   # since it's a true alias
  48                 other.push_back(Copy(root)); // &1 [0, ~, two, *1, &2 [0, ~, two, *2]]
  49                 other[4][0] = 5;             // &1 [0, ~, two, *1, &2 [5, ~, two, *2]]  # they're really different
  50         }
  51
  52         {
  53                 YAML::Value node;            // ~
  54                 node[0] = 1;                 // [1]  # auto-construct a sequence
  55                 node["key"] = 5;             // {0: 1, key: 5}  # auto-turn it into a map
  56                 node.push_back(10);          // error, can't turn a map into a sequence
  57                 node.erase("key");           // {0: 1}  # still a map, even if we remove the key that caused the problem
  58                 node = "Hello";              // Hello  # assignment overwrites everything, so it's now just a plain scalar
  59         }
  60
  61         {
  62                 YAML::Value map;             // ~
  63                 map[3] = 1;                  // {3: 1}  # auto-constructs a map, *not* a sequence
  64
  65                 YAML::Value seq;             // ~
  66                 seq = YAML::Sequence();      // []
  67                 seq[3] = 1;                  // [~, ~, ~, 1]
  68         }
  69
  70         {
  71                 YAML::Value node;            // ~
  72                 node[0] = node;              // &1 [*1]  # fun stuff
  73         }
  74
  75         {
  76                 YAML::Value node;
  77                 YAML::Value subnode = node["key"]; // 'subnode' is not instantiated ('node' is still null)
  78                 subnode = "value";           // {key: value}  # now it is
  79                 YAML::Value subnode2 = node["key2"];
  80                 node["key3"] = subnode2;     // subnode2 is still not instantiated, but node["key3"] is "pseudo" aliased to it
  81                 subnode2 = "monkey";         // {key: value, key2: &1 monkey, key3: *1}  # bam! it instantiates both
  82         }
  83
  84         {
  85                 YAML::Value seq = YAML::Sequence();
  86                 seq[0] = "zero";             // [zero]
  87                 seq[1] = seq[0];             // [&1 zero, *1]
  88                 seq[0] = seq[1];             // [&1 zero, *1]  # no-op (they both alias the same thing, so setting them equal is nothing)
  89                 Is(seq[0], seq[1]);          // true
  90                 seq[1] = "one";              // [&1 one, *1]
  91                 UnAlias(seq[1]);             // [one, one]
  92                 Is(seq[0], seq[1]);          // false
  93         }
  94
  95         {
  96                 YAML::Value root;
  97                 root.push_back("zero");
  98                 root.push_back("one");
  99                 root.push_back("two");
 100                 YAML::Value two = root[2];
 101                 root = "scalar";             // 'two' is still "two", even though 'root' is "scalar" (the sequence effectively no longer exists)
 102
 103                 // Note: in all likelihood, the memory for nodes "zero" and "one" is still allocated. How can it go away? Weak pointers?
 104         }
 105
 106         {
 107                 YAML::Value root;            // ~
 108                 root[0] = root;              // &1 [*1]
 109                 root[0] = 5;                 // [5]
 110         }
 111
 112         {
 113                 YAML::Value root;
 114                 YAML::Value key;
 115                 key["key"] = "value";
 116                 root[key] = key;             // &1 {key: value}: *1
 117         }
 118
 119         {
 120                 YAML::Value root;
 121                 root[0] = "hi";
 122                 root[1][0] = "bye";
 123                 root[1][1] = root;           // &1 [hi, [bye, *1]]  # root
 124                 YAML::Value sub = root[1];   // &1 [bye, [hi, *1]]  # sub
 125                 root = "gone";               // [bye, gone]  # sub
 126         }
 127
 128         return 0;
 129 }