fixed bug that if value is null

ch11/README.md

@@ -99,3 +99,4 @@ std::pair<std::map<std::string, std::vector<int>>::iterator, bool> // return
 ## [Exercise 11.27 ~ 11.30](ex11_27_28_29_30.cpp)
 ## [Exercise 11.31](ex11_31.cpp)
 ## [Exercise 11.32](ex11_32.cpp)
+## [Exercise 11.33](ex11_33.cpp)

ch11/ex11_33.cpp

@@ -1,95 +1,48 @@
-//! @Alan
-//!
-//!
-//! Exercise 11.33:
-//! Implement your own version of the word-transformation program.
-//  I used one function to for this exercise. It proved that
-//  less functions are harder to debug. Besides, the comment style shoud be polished.
-//!
+//
+//  ex11_33.cpp
+//  Exercise 11.33
+//
+//  Created by pezy on 12/18/14.
+//  Copyright (c) 2014 pezy. All rights reserved.
+//
+//  Implement your own version of the word-transformation program.
 
-#include <iostream>
-#include <fstream>
 #include <map>
 #include <string>
-#include <algorithm>
-#include <vector>
+#include <fstream> 
+#include <iostream>
 #include <sstream>
 
-//!
-//! \brief wy_word_transformation for ex 11.33
-//! \param rulesFileName    const   string&
-//! \param inputFileName    const   string&
-//!
-void
-wy_word_transformation(const std::string &rulesFileName, const std::string &inputFileName);
-int main()
+using std::string; using std::ifstream;
+
+std::map<string, string> buildMap(ifstream &map_file)
 {
-    wy_word_transformation("rules.txt","original.txt");
-    return 0;
+    std::map<string, string> trans_map;
+    for (string key, value; map_file >> key && getline(map_file, value); )
+        if (value.size() > 1) trans_map[key] = value.substr(1).substr(0, value.find_last_not_of(' '));
+    return trans_map;
 }
 
-
-void
-wy_word_transformation(const std::string &rulesFileName, const std::string &inputFileName)
+const string & transform(const string &s, const std::map<string, string> &m)
 {
-    //! Build rules map
-    std::ifstream fin(rulesFileName);
-    std::string line;
-    std::map<std::string, std::string> rules_map;
-
-    while(std::getline(fin,line))
-    {
-        std::string key, value;
-        key     =   line.substr(0, line.find(' '));
-        //!                             ^^^^^^^^^
-        //! @note
-        //! Suppose the line is
-        //          where r u
-        //!              ^
-        //!         012345
-        //! the statement becomes
-        //          line.substr(0,5)
-        //!                       ^
-        //! which means returnning a new string using 5 characters starting at 0.
-
-        value   =   line.substr(line.find(' ') + 1);
-        //! @note                              ^^^
-        //! the + 1 here increment the index so from the space to next character.
-        //! size_t n is the second parameter whose defualt value is npos. If leave
-        //! it as default, it means "until the end of the string"
+    auto map_it = m.find(s);
+    return map_it == m.cend() ? s : map_it->second;
+}
 
-        //! add the key-value pair into the map.
-        rules_map[key] = value;
+void word_transform(ifstream &map, ifstream &input)
+{
+    auto trans_map = buildMap(map);
+    for (string text; getline(input, text); ) {
+        std::istringstream iss(text);
+        for (string word; iss >> word; )
+            std::cout << transform(word, trans_map) << " ";
+        std::cout << std::endl;
     }
-    fin.close();
-
-
-    //! Read the input file ,transform it and print
-    fin.open(inputFileName);
-    std::string text;
-
-    while(std::getline(fin, text))
-    {
-        std::istringstream stream(text);
-//!     ^^^^^^^^^^^^^^^^^^
-
-        std::string word;
-        while(stream >> word)
-//!           ^^^^^^^^^^^^^^
-//! @attention
-//! std::istringstream is quite a handy way to handle spaces in a string, far more convinient
-//! than generic algorithm or search a space manually.
-
-        {
-            //! obtain the iterator using the key given
-            std::map<std::string, std::string>::const_iterator
-                    it = rules_map.find(word);
+}
 
-            //! check if the give key is found in the map
-            std::cout << (it == rules_map.end() ? word +" " : it->second + " ");
-            //!          ^                                                    ^
-            //! @attention  the parentheses are necessay here.
-        }
-        std::cout <<"\n";
-    }
+int main()
+{
+    ifstream ifs_map("../data/word_transformation.txt"), ifs_content("../data/given_to_transform.txt");
+    if (ifs_map && ifs_content) word_transform(ifs_map, ifs_content);
+    else std::cerr << "can't find the documents." << std::endl;
 }