copy from adp-gmbh.ch

Author: ReneNyffenegger

.gitignore

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+*.swp

Chameleon.cpp

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+/* 
+   Chameleon.cpp
+
+   Copyright (C) 2002-2004 René Nyffenegger
+
+   This source code is provided 'as-is', without any express or implied
+   warranty. In no event will the author be held liable for any damages
+   arising from the use of this software.
+
+   Permission is granted to anyone to use this software for any purpose,
+   including commercial applications, and to alter it and redistribute it
+   freely, subject to the following restrictions:
+
+   1. The origin of this source code must not be misrepresented; you must not
+      claim that you wrote the original source code. If you use this source code
+      in a product, an acknowledgment in the product documentation would be
+      appreciated but is not required.
+
+   2. Altered source versions must be plainly marked as such, and must not be
+      misrepresented as being the original source code.
+
+   3. This notice may not be removed or altered from any source distribution.
+
+   René Nyffenegger rene.nyffenegger@adp-gmbh.ch
+*/
+
+#include <string>
+#include <sstream>
+
+#include "Chameleon.h"
+
+Chameleon::Chameleon(std::string const& value) {
+  value_=value;
+}
+
+#include <iostream>
+
+Chameleon::Chameleon(const char* c) {
+  value_=c;
+}
+
+Chameleon::Chameleon(double d) {
+  std::stringstream s;
+  s<<d;
+  value_=s.str();
+}
+
+Chameleon::Chameleon(Chameleon const& other) {
+  value_=other.value_;
+}
+
+Chameleon& Chameleon::operator=(Chameleon const& other) {
+  value_=other.value_;
+  return *this;
+}
+
+Chameleon& Chameleon::operator=(double i) {
+  std::stringstream s;
+  s << i;
+  value_ = s.str();
+  return *this;
+}
+
+Chameleon& Chameleon::operator=(std::string const& s) {
+  value_=s;
+  return *this;
+}
+
+Chameleon::operator std::string() const {
+  return value_;
+}
+
+Chameleon::operator double() const {
+  return atof(value_.c_str());
+}

Chameleon.h

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+/* 
+   Chameleon.h
+
+   Copyright (C) 2002-2004 René Nyffenegger
+
+   This source code is provided 'as-is', without any express or implied
+   warranty. In no event will the author be held liable for any damages
+   arising from the use of this software.
+
+   Permission is granted to anyone to use this software for any purpose,
+   including commercial applications, and to alter it and redistribute it
+   freely, subject to the following restrictions:
+
+   1. The origin of this source code must not be misrepresented; you must not
+      claim that you wrote the original source code. If you use this source code
+      in a product, an acknowledgment in the product documentation would be
+      appreciated but is not required.
+
+   2. Altered source versions must be plainly marked as such, and must not be
+      misrepresented as being the original source code.
+
+   3. This notice may not be removed or altered from any source distribution.
+
+   René Nyffenegger rene.nyffenegger@adp-gmbh.ch
+*/
+
+#ifndef CHAMELEON_H__
+#define CHAMELEON_H__
+
+#include <string>
+
+class Chameleon {
+public:
+  Chameleon() {};
+  explicit Chameleon(const std::string&);
+  explicit Chameleon(double);
+  explicit Chameleon(const char*);
+
+  Chameleon(const Chameleon&);
+  Chameleon& operator=(Chameleon const&);
+
+  Chameleon& operator=(double);
+  Chameleon& operator=(std::string const&);
+
+public:
+  operator std::string() const;
+  operator double     () const;
+private:
+  std::string value_;
+};
+
+#endif

ConfigFile.cpp

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+#include "ConfigFile.h"
+
+#include <fstream>
+
+std::string trim(std::string const& source, char const* delims = " \t\r\n") {
+  std::string result(source);
+  std::string::size_type index = result.find_last_not_of(delims);
+  if(index != std::string::npos)
+    result.erase(++index);
+
+  index = result.find_first_not_of(delims);
+  if(index != std::string::npos)
+    result.erase(0, index);
+  else
+    result.erase();
+  return result;
+}
+
+ConfigFile::ConfigFile(std::string const& configFile) {
+  std::ifstream file(configFile.c_str());
+
+  std::string line;
+  std::string name;
+  std::string value;
+  std::string inSection;
+  int posEqual;
+  while (std::getline(file,line)) {
+
+    if (! line.length()) continue;
+
+    if (line[0] == '#') continue;
+    if (line[0] == ';') continue;
+
+    if (line[0] == '[') {
+      inSection=trim(line.substr(1,line.find(']')-1));
+      continue;
+    }
+
+    posEqual=line.find('=');
+    name  = trim(line.substr(0,posEqual));
+    value = trim(line.substr(posEqual+1));
+
+    content_[inSection+'/'+name]=Chameleon(value);
+  }
+}
+
+Chameleon const& ConfigFile::Value(std::string const& section, std::string const& entry) const {
+
+  std::map<std::string,Chameleon>::const_iterator ci = content_.find(section + '/' + entry);
+
+  if (ci == content_.end()) throw "does not exist";
+
+  return ci->second;
+}
+
+Chameleon const& ConfigFile::Value(std::string const& section, std::string const& entry, double value) {
+  try {
+    return Value(section, entry);
+  } catch(const char *) {
+    return content_.insert(std::make_pair(section+'/'+entry, Chameleon(value))).first->second;
+  }
+}
+
+Chameleon const& ConfigFile::Value(std::string const& section, std::string const& entry, std::string const& value) {
+  try {
+    return Value(section, entry);
+  } catch(const char *) {
+    return content_.insert(std::make_pair(section+'/'+entry, Chameleon(value))).first->second;
+  }
+}

ConfigFile.h

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+#ifndef __CONFIG_FILE_H__
+#define __CONFIG_FILE_H__
+
+#include <string>
+#include <map>
+
+#include "Chameleon.h"
+
+class ConfigFile {
+  std::map<std::string,Chameleon> content_;
+
+public:
+  ConfigFile(std::string const& configFile);
+
+  Chameleon const& Value(std::string const& section, std::string const& entry) const;
+
+  Chameleon const& Value(std::string const& section, std::string const& entry, double value);
+  Chameleon const& Value(std::string const& section, std::string const& entry, std::string const& value);
+};
+
+#endif

test/config.txt

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+[section_1]
+foo  = bar
+water= h2o
+
+[section_2]
+foo  = foo
+water= wet
+four = 4.2

test/read-config.txt.cpp

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+//
+//  g++ ../ConfigFile.cpp ../Chameleon.cpp read-config.txt.cpp -o read-config.txt
+//
+
+#include "../ConfigFile.h"
+
+#include <iostream>
+
+int main() {
+  ConfigFile cf("config.txt");
+
+  std::string foo;
+  std::string water;
+  double      four;
+
+  foo   = cf.Value("section_1","foo"  );
+  water = cf.Value("section_2","water");
+  four  = cf.Value("section_2","four" );
+
+  std::cout << foo   << std::endl;
+  std::cout << water << std::endl;
+  std::cout << four  << std::endl;
+
+  return 0;
+}