Ctrl+w handler (#32)

* Start the ctrl+w implementation

* Fix an invalid free in the ctrl+l implementation

* Finish implementing ctrl + w

* Only print keys when they miss if KEYS_VERBOSE is YES

* Add ctrl+w and ctrl+l to the README under line editing

README.md

@@ -83,6 +83,8 @@ In YaSh, one can...
  * ctrl + right arrow to go to the next space
  * ctrl + left arrow  to go to the previous space
  * ctrl + delete to remove the word to the right of the cursor
+ * ctrl + w to remove the word to the left of the cursor
+ * ctrl + l to run the clear command
  * use arrow keys to move through history
 
 History:

src/shell-readline.cpp

@@ -273,11 +273,72 @@ bool read_line::handle_ctrl_l(std::string & _line)
   if (!write_with_error(1, line.c_str(), line.size())) {
   }
   /* write back spaces for m_buff.len() */
-  std::unique_ptr<char> bspace(new char[m_buff.size()]);
+  auto bspace = std::make_unique<char[]>(m_buff.size());
   memset(bspace.get(), '\b', m_buff.size());
   return !write_with_error(1, bspace.get(), m_buff.size());
 }
 
+/**
+ * @brief Handle ctrl + w
+ *
+ * Ctrl + w removes the word to the left of the cursor
+ *
+ * @param _line The line to be mutated
+ * @return false unless bad thigns happen
+ */
+bool read_line::handle_ctrl_w(std::string & _line)
+{
+  if (!_line.size()) {
+    /* this is a decidedly shorter type of no-op */
+    return false;
+  }
+  /* first, reverse iterate to the last ' ' in the string */
+  auto it = _line.end();
+  for (; *it != ' ' && it != _line.begin(); --it) {
+    /* don't push, since we're removing this */
+  }
+  /* wipe all to the right */
+  auto b_spaces = std::make_unique<char[]>(m_buff.size());
+  auto spaces = std::make_unique<char[]>(m_buff.size());
+  ::memset(b_spaces.get(), '\b', m_buff.size());
+  ::memset(spaces.get(), ' ', m_buff.size());
+  if (!write_with_error(1, spaces.get(), m_buff.size())) {
+    return true;
+  } else if (!write_with_error(1, b_spaces.get(), m_buff.size())) {
+    return true;
+  }
+  const size_t diff = _line.end() - it;
+  auto b_spaces2 = std::make_unique<char[]>(diff);
+  auto spaces2 = std::make_unique<char[]>(diff);
+  ::memset(b_spaces2.get(), '\b', diff);
+  ::memset(spaces2.get(), ' ', diff);
+  /* wipe the printed argument */
+  if (!write_with_error(1, b_spaces2.get(), diff)) {
+    return true;
+  } else if (!write_with_error(1, spaces2.get(), diff)) {
+    return true;
+  } else if (!write_with_error(1, b_spaces2.get(), diff)) {
+    return true;
+  }
+  /* remove the argument from _line */
+  _line.erase(it, _line.end());
+  /* now we print out the rest of the string and backtrack */
+  char * s = spaces.get();
+  auto buff = m_buff;
+  for (; buff.size(); buff.pop()) {
+    *(s++) = buff.top();
+  }
+  if (!_line.size()) {
+    /* this is a special case like 'asdf ' + ctrl + w */
+    return !(write_with_error(1, " ") &&
+             write_with_error(1, spaces.get(), m_buff.size()) &&
+             write_with_error(1, b_spaces.get(), m_buff.size()) &&
+             write_with_error(1, "\b"));
+  }
+  return !(write_with_error(1, spaces.get(), m_buff.size()) &&
+           write_with_error(1, b_spaces.get(), m_buff.size()));
+}
+
 /**
  * @brief Handle ctrl + d
  *

src/shell-readline.hpp

@@ -73,6 +73,7 @@ class read_line
   bool handle_ctrl_d(std::string & _line);
   bool handle_ctrl_e(std::string & _line);
   bool handle_ctrl_l(std::string & _line);
+  bool handle_ctrl_w(std::string & _line);
   bool handle_ctrl_k();
   bool handle_ctrl_del();
   bool handle_ctrl_arrow(std::string & _line);
@@ -141,6 +142,8 @@ class read_line
         continue;
       } else if (input == 12 && !handle_ctrl_l(_line)) {
         continue;
+      } else if (input == 23 && !handle_ctrl_w(_line)) {
+        continue;
       } else if (input == 9 && !handle_tab(_line)) {
         continue;
       } else if (input == 27) {
@@ -159,11 +162,13 @@ class read_line
         if (ch1 == 91 && ch2 == 66 && !handle_down_arrow(_line)) {continue;}
         if (ch1 == 91 && ch2 == 67 && !handle_right_arrow(_line)) {continue;}
         if (ch1 == 91 && ch2 == 68 && !handle_left_arrow(_line)) {continue;}
+      } else if (!strcmp(getenv("KEY_VERBOSE"), "YES")) {
+        std::cerr << "unknown input '" << static_cast<int>(input) << "'" << std::endl;
       }
     }
 
     if (_line.size()) {
-      std::string _file = tilde_expand("~/.cache/yash_history");
+      const std::string _file = tilde_expand("~/.cache/yash_history");
       int history_fd = open(_file.c_str(), O_CREAT | O_APPEND | O_WRONLY, 0600);
       if (!write_with_error(history_fd, _line.c_str(), _line.size())) {
         return;