Add sample code

sample/CMakeLists.txt

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+
+add_executable(sample sample.cpp)
+target_link_libraries(sample xcdat)

sample/sample.cpp

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+#include <iostream>
+#include <xcdat.hpp>
+
+int main() {
+  std::vector<std::string> keys_buf = {
+    "Aoba", "Yun", "Hajime", "Hihumi", "Kou", "Rin",
+    "Hazuki", "Umiko", "Nene", "Nenecchi"
+  };
+
+  // Convert to the input format
+  std::vector<std::string_view> keys(keys_buf.size());
+  for (size_t i = 0; i < keys.size(); ++i) {
+    keys[i] = std::string_view{keys_buf[i]};
+  }
+
+  // Input data must be sorted.
+  std::sort(std::begin(keys), std::end(keys));
+
+  // Dictionary class
+  using Trie = xcdat::Trie<true>;
+
+  try {
+    // Builds a dictionary from the keys
+    Trie trie = xcdat::TrieBuilder::build<true>(keys); // move
+
+    // Writes the dictionary to a file.
+    std::ofstream ofs{"sample.bin"};
+    trie.write(ofs);
+  } catch (const xcdat::TrieBuilder::Exception& ex) {
+    // Abort if something went wrong...
+    std::cerr << ex.what() << std::endl;
+    return 1;
+  }
+
+  // Creates an empty dictionary
+  Trie trie;
+  {
+    // Reads the dictionary to the file.
+    std::ifstream ifs{"sample.bin"};
+    trie = Trie{ifs}; // move
+  }
+
+  std::cout << "Performing basic operations..." << std::endl;
+  {
+    // lookup() obtains the unique ID for a given key
+    xcdat::id_type key_id = trie.lookup("Rin");
+    // access() decodes the key from a given ID
+    std::cout << key_id << " : " << trie.access(key_id) << std::endl;
+
+    // Given an unregistered key, lookup() returns NOT_FOUND.
+    if (trie.lookup("Hotaru") == Trie::NOT_FOUND) {
+      std::cout << "? : " << "Hotaru" << std::endl;
+    }
+  }
+
+  std::cout << "Performing a common prefix operation..." << std::endl;
+  {
+    // Common prefix operation is implemented using PrefixIterator, created by
+    // make_prefix_iterator().
+    Trie::PrefixIterator it = trie.make_prefix_iterator("Nenecchi");
+
+    // next() continues to obtain the next key until false is returned.
+    while (it.next()) {
+      std::cout << it.id() << " : " << it.key() << std::endl;
+    }
+  }
+
+  std::cout << "Performing a predictive operation..." << std::endl;
+  {
+    // Predictive operation is implemented using PredictiveIterator, created by
+    // make_predictive_iterator().
+    Trie::PredictiveIterator it = trie.make_predictive_iterator("Ha");
+
+    // next() continues to obtain the next key until false is returned in
+    // lexicographical order.
+    while (it.next()) {
+      std::cout << it.id() << " : " << it.key() << std::endl;
+    }
+  }
+
+  std::cout << "Enumerating all registered keys..." << std::endl;
+  {
+    // PredictiveIterator for an empty string provides enumeration of all
+    // registered keys in lexicographical order.
+    Trie::PredictiveIterator it = trie.make_predictive_iterator("");
+    while (it.next()) {
+      std::cout << it.id() << " : " << it.key() << std::endl;
+    }
+  }
+
+  return 0;
+}