[C++] std::string manipulation: whitespace, "newline escapes '\'" and comments #
- by rubenvb
Kind of looking for affirmation here. I have some hand-written code, which I'm not shy to say I'm proud of, which reads a file, removes leading whitespace, processes newline escapes '\' and removes comments starting with #. It also removes all empty lines (also whitespace-only ones). Any thoughts/recommendations? I could probably replace some std::cout's with std::runtime_errors... but that's not a priority here :)
const int RecipeReader::readRecipe()
{
ifstream is_recipe(s_buffer.c_str());
if (!is_recipe)
cout << "unable to open file" << endl;
while (getline(is_recipe, s_buffer))
{
// whitespace+comment
removeLeadingWhitespace(s_buffer);
processComment(s_buffer);
// newline escapes + append all subsequent lines with '\'
processNewlineEscapes(s_buffer, is_recipe);
// store the real text line
if (!s_buffer.empty())
v_s_recipe.push_back(s_buffer);
s_buffer.clear();
}
is_recipe.close();
return 0;
}
void RecipeReader::processNewlineEscapes(string &s_string, ifstream &is_stream)
{
string s_temp;
size_t sz_index = s_string.find_first_of("\\");
while (sz_index <= s_string.length())
{
if (getline(is_stream,s_temp))
{
removeLeadingWhitespace(s_temp);
processComment(s_temp);
s_string = s_string.substr(0,sz_index-1) + " " + s_temp;
}
else
cout << "Error: newline escape '\' found at EOF" << endl;
sz_index = s_string.find_first_of("\\");
}
}
void RecipeReader::processComment(string &s_string)
{
size_t sz_index = s_string.find_first_of("#");
s_string = s_string.substr(0,sz_index);
}
void RecipeReader::removeLeadingWhitespace(string &s_string)
{
const size_t sz_length = s_string.size();
size_t sz_index = s_string.find_first_not_of(" \t");
if (sz_index <= sz_length)
s_string = s_string.substr(sz_index);
else if ((sz_index > sz_length) && (sz_length != 0)) // "empty" lines with only whitespace
s_string.clear();
}
Some extra info: the first s_buffer passed to the ifstream contains the filename, std::string s_buffer is a class data member, so is std::vector v_s_recipe. Any comment is welcome :)
