LibLine: Add internal function to erase consecutive spaces under cursor

Userland/Libraries/LibLine/Editor.cpp

@@ -172,6 +172,7 @@ void Editor::set_default_keybinds()
     // ^[^H: alt-backspace: backward delete word
     register_key_input_callback(Key { '\b', Key::Alt }, EDITOR_INTERNAL_FUNCTION(erase_alnum_word_backwards));
     register_key_input_callback(Key { 'd', Key::Alt }, EDITOR_INTERNAL_FUNCTION(erase_alnum_word_forwards));
+    register_key_input_callback(Key { '\\', Key::Alt }, EDITOR_INTERNAL_FUNCTION(erase_spaces));
     register_key_input_callback(Key { 'c', Key::Alt }, EDITOR_INTERNAL_FUNCTION(capitalize_word));
     register_key_input_callback(Key { 'l', Key::Alt }, EDITOR_INTERNAL_FUNCTION(lowercase_word));
     register_key_input_callback(Key { 'u', Key::Alt }, EDITOR_INTERNAL_FUNCTION(uppercase_word));

Userland/Libraries/LibLine/Editor.h

@@ -127,6 +127,7 @@ struct Configuration {
     M(insert_last_erased)                      \
     M(erase_alnum_word_backwards)              \
     M(erase_alnum_word_forwards)               \
+    M(erase_spaces)                            \
     M(capitalize_word)                         \
     M(lowercase_word)                          \
     M(uppercase_word)                          \

Userland/Libraries/LibLine/InternalFunctions.cpp

@@ -579,6 +579,23 @@ void Editor::erase_alnum_word_forwards()
     }
 }
 
+void Editor::erase_spaces()
+{
+    while (m_cursor < m_buffer.size()) {
+        if (is_ascii_space(m_buffer[m_cursor]))
+            erase_character_forwards();
+        else
+            break;
+    }
+
+    while (m_cursor > 0) {
+        if (is_ascii_space(m_buffer[m_cursor - 1]))
+            erase_character_backwards();
+        else
+            break;
+    }
+}
+
 void Editor::case_change_word(Editor::CaseChangeOp change_op)
 {
     // A word here is contiguous alnums. `foo=bar baz` is three words.