C++ Cookbook

4.22. Autocorrect Text as a Buffer Changes

Problem

You have a class that represents some kind of text field or document, and as text is appended to it, you want to correct automatically misspelled words the way Microsoft Word’s Autocorrect feature does.

Solution

Using a map, defined in <map>, strings, and a variety of standard library features, you can implement this with relatively little code. Example 4-31 shows how to do it.

Example 4-31. Autocorrect text

#include <iostream> #include <string> #include <cctype> #include <map> using namespace std; typedef map<string, string> StrStrMap; // Class for holding text fields class TextAutoField { public: TextAutoField(StrStrMap* const p) : pDict_(p) {} ~TextAutoField() {} void append(char c); void getText(string& s) {s = buf_;} private: TextAutoField(); string buf_; StrStrMap* const pDict_; }; // Append with autocorrect void TextAutoField::append(char c) { if ((isspace(c) || ispunct(c)) && // Only do the auto- buf_.length() > 0 && // correct when ws or !isspace(buf_[buf_.length() - 1])) { // punct is entered string::size_type i = buf_.find_last_of(" \f\n\r\t\v"); i = (i == string::npos) ? 0 : ++i; string tmp = buf_.substr(i, buf_.length() - i); StrStrMap::const_iterator p = pDict_->find(tmp); if (p != pDict_->end()) { // Found it, so erase buf_.erase(i, buf_.length() - i); // and replace buf_ += p->second; } } buf_ += c; } int main() { // Set up the map StrStrMap dict; TextAutoField txt(&dict); dict["taht"] = "that"; dict["right"] = "wrong"; ...