Unified lookup interface for Config and Setting.

To address hyperrealm/libconfig#4, `Config::operator[](const char*)` and
`Setting::lookup(const std::string& key)` have been added.

Note: `operator[]` had to remain as `const char*` to avoid ambiguities
      in some situations.

lib/libconfig.h++

@@ -234,15 +234,12 @@ class LIBCONFIGXX_API Setting
   Setting & operator=(const char *value) throw(SettingTypeException);
   Setting & operator=(const std::string &value) throw(SettingTypeException);
 
-  Setting & operator[](const char *key) const
-    throw(SettingTypeException, SettingNotFoundException);
+  Setting & lookup(const std::string &key) const;
 
-  inline Setting & operator[](const std::string &key) const
-    throw(SettingTypeException, SettingNotFoundException)
-  { return(operator[](key.c_str())); }
+  inline Setting & operator[](const char *key) const
+  { return(lookup(key)); }
 
-  Setting & operator[](int index) const
-    throw(SettingTypeException, SettingNotFoundException);
+  Setting & operator[](int index) const;
 
   bool lookupValue(const char *name, bool &value) const throw();
   bool lookupValue(const char *name, int &value) const throw();
@@ -388,11 +385,10 @@ class LIBCONFIGXX_API Config
   void readFile(const char *filename) throw(FileIOException, ParseException);
   void writeFile(const char *filename) throw(FileIOException);
 
-  inline Setting & lookup(const std::string &path) const
-    throw(SettingNotFoundException)
-  { return(lookup(path.c_str())); }
+  Setting & lookup(const std::string &path) const;
 
-  Setting & lookup(const char *path) const throw(SettingNotFoundException);
+  inline Setting & operator[](const char *path) const
+  { return(lookup(path)); }
 
   inline bool exists(const std::string & path) const throw()
   { return(exists(path.c_str())); }

lib/libconfigcpp.c++

@@ -446,12 +446,11 @@ void Config::writeFile(const char *filename) throw(FileIOException)
 
 // ---------------------------------------------------------------------------
 
-Setting & Config::lookup(const char *path) const
-  throw(SettingNotFoundException)
+Setting & Config::lookup(const std::string &path) const
 {
-  config_setting_t *s = config_lookup(_config, path);
+  config_setting_t *s = config_lookup(_config, path.c_str());
   if(! s)
-    throw SettingNotFoundException(path);
+    throw SettingNotFoundException(path.c_str());
 
   return(Setting::wrapSetting(s));
 }
@@ -834,31 +833,29 @@ Setting & Setting::operator=(const std::string &value)
 
 // ---------------------------------------------------------------------------
 
-Setting & Setting::operator[](int i) const
-  throw(SettingTypeException, SettingNotFoundException)
+Setting & Setting::lookup(const std::string &key) const
 {
-  if((_type != TypeArray) && (_type != TypeGroup) && (_type != TypeList))
-    throw SettingTypeException(*this, i);
+  assertType(TypeGroup);
 
-  config_setting_t *setting = config_setting_get_elem(_setting, i);
+  config_setting_t *setting = config_setting_get_member(_setting, key.c_str());
 
   if(! setting)
-    throw SettingNotFoundException(*this, i);
+    throw SettingNotFoundException(*this, key.c_str());
 
   return(wrapSetting(setting));
 }
 
 // ---------------------------------------------------------------------------
 
-Setting & Setting::operator[](const char *key) const
-  throw(SettingTypeException, SettingNotFoundException)
+Setting & Setting::operator[](int i) const
 {
-  assertType(TypeGroup);
+  if((_type != TypeArray) && (_type != TypeGroup) && (_type != TypeList))
+    throw SettingTypeException(*this, i);
 
-  config_setting_t *setting = config_setting_get_member(_setting, key);
+  config_setting_t *setting = config_setting_get_elem(_setting, i);
 
   if(! setting)
-    throw SettingNotFoundException(*this, key);
+    throw SettingNotFoundException(*this, i);
 
   return(wrapSetting(setting));
 }