Added overloads to the config_reader's methods to allow it to load directly from

a file name given as a string in addition to taking istream objects.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%404085

dlib/config_reader/config_reader_kernel_1.h

@@ -7,6 +7,7 @@
 #include <string>
 #include <iostream>
 #include <sstream>
+#include <fstream>
 #include "../algs.h"
 #include "../stl_checked/std_vector_c.h"
 
@@ -65,6 +66,22 @@ namespace dlib
             const bool redefinition;
         };
 
+        class file_not_found : public dlib::error 
+        {
+            friend class config_reader_kernel_1;
+            file_not_found(
+                const std::string& file_name_
+            ) : 
+                dlib::error(ECONFIG_READER, "Error in config_reader, unable to open file " + file_name_),
+                file_name(file_name_)
+            {}
+
+            ~file_not_found() throw() {}
+
+        public:
+            const std::string file_name;
+        };
+
         class config_reader_access_error : public dlib::error
         {
         public:
@@ -91,6 +108,10 @@ namespace dlib
             const std::string key_name;
         };
 
+        config_reader_kernel_1(
+            const std::string& config_file 
+        );
+
         config_reader_kernel_1(
             std::istream& in
         );
@@ -105,6 +126,10 @@ namespace dlib
             std::istream& in
         );
 
+        void load_from (
+            const std::string& config_file
+        );
+
         bool is_key_defined (
             const std::string& key
         ) const;
@@ -263,6 +288,26 @@ namespace dlib
         }
     }
 
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename map_string_string,
+        typename map_string_void,
+        typename tokenizer
+        >
+    void config_reader_kernel_1<map_string_string,map_string_void,tokenizer>::
+    load_from(
+        const std::string& config_file
+    )
+    {
+        clear();
+        std::ifstream fin(config_file.c_str());
+        if (!fin)
+            throw file_not_found(config_file);
+
+        load_from(fin);
+    }
+
 // ----------------------------------------------------------------------------------------
 
     template <
@@ -278,6 +323,21 @@ namespace dlib
         load_from(in);
     }
 
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename map_string_string,
+        typename map_string_void,
+        typename tokenizer
+        >
+    config_reader_kernel_1<map_string_string,map_string_void,tokenizer>::
+    config_reader_kernel_1(
+        const std::string& config_file
+    )
+    {
+        load_from(config_file);
+    }
+
 // ----------------------------------------------------------------------------------------
 
     template <

dlib/config_reader/config_reader_kernel_abstract.h

@@ -109,6 +109,22 @@ namespace dlib
             const bool redefinition;
         };
 
+        class file_not_found : public dlib::error 
+        {
+            /*!
+                GENERAL
+                    This exception is thrown if the config file can't be opened for
+                    some reason.  The type member of this exception will be set
+                    to ECONFIG_READER.
+
+                INTERPRETING THIS EXCEPTION
+                    - file_name == the name of the config file which we failed to open
+            !*/
+        public:
+            const std::string file_name;
+        };
+
+
         class config_reader_access_error : public dlib::error
         {
             /*!
@@ -154,10 +170,32 @@ namespace dlib
                 - reads the config file to parse from the given input stream,
                   parses it and loads this object up with all the sub blocks and
                   key/value pairs it finds.
+                - before the load is performed, the previous state of the config file
+                  reader is erased.  So after the load the config file reader will contain
+                  only information from the given config file.
+                - This object will represent the top most block of the config file.
+            throws
+                - std::bad_alloc
+                - config_reader_error
+        !*/
+
+        config_reader(
+            const std::string& config_file 
+        );
+        /*!
+            ensures 
+                - #*this is properly initialized
+                - parses the config file named by the config_file string.  Specifically, 
+                  parses it and loads this object up with all the sub blocks and
+                  key/value pairs it finds in the file.
+                - before the load is performed, the previous state of the config file
+                  reader is erased.  So after the load the config file reader will contain
+                  only information from the given config file.
                 - This object will represent the top most block of the config file.
             throws
                 - std::bad_alloc
                 - config_reader_error
+                - file_not_found
         !*/
 
         virtual ~config_reader(
@@ -186,6 +224,9 @@ namespace dlib
                 - reads the config file to parse from the given input stream,
                   parses it and loads this object up with all the sub blocks and
                   key/value pairs it finds.
+                - before the load is performed, the previous state of the config file
+                  reader is erased.  So after the load the config file reader will contain
+                  only information from the given config file.
                 - *this will represent the top most block of the config file contained
                   in the input stream in.
             throws
@@ -197,6 +238,30 @@ namespace dlib
                     revert to its initial value.
         !*/
 
+        void load_from (
+            const std::string& config_file
+        );
+        /*!
+            ensures 
+                - parses the config file named by the config_file string.  Specifically, 
+                  parses it and loads this object up with all the sub blocks and
+                  key/value pairs it finds in the file.  
+                - before the load is performed, the previous state of the config file
+                  reader is erased.  So after the load the config file reader will contain
+                  only information from the given config file.
+                - This object will represent the top most block of the config file.
+            throws
+                - std::bad_alloc 
+                    If this exception is thrown then *this is unusable 
+                    until clear() is called and succeeds
+                - config_reader_error
+                    If this exception is thrown then this object will
+                    revert to its initial value.
+                - file_not_found
+                    If this exception is thrown then this object will
+                    revert to its initial value.
+        !*/
+
         bool is_key_defined (
             const std::string& key_name
         ) const;