Edit Book: Spell check dialog: Add a button to undo the last spelling change

src/calibre/ebooks/oeb/polish/spell.py

@@ -221,7 +221,7 @@ def replace(text, original_word, new_word, lang):
         text = text[:idx] + new_word + text[idx+len(original_word):]
     return text, bool(indices)
 
-def replace_word(container, new_word, locations, locale):
+def replace_word(container, new_word, locations, locale, undo_cache=None):
     changed = set()
     for loc in locations:
         node = loc.location_node
@@ -231,16 +231,26 @@ def replace_word(container, new_word, locations, locale):
         else:
             text = getattr(node, attr)
         replacement = loc.elided_prefix + new_word
-        text, replaced = replace(text, loc.original_word, replacement, locale.langcode)
+        rtext, replaced = replace(text, loc.original_word, replacement, locale.langcode)
         if replaced:
+            if undo_cache is not None:
+                undo_cache[(loc.file_name, node, is_attr, attr)] = text
             if is_attr:
-                node.set(attr, text)
+                node.set(attr, rtext)
             else:
-                setattr(node, attr, text)
+                setattr(node, attr, rtext)
             container.replace(loc.file_name, node.getroottree().getroot())
             changed.add(loc.file_name)
     return changed
 
+def undo_replace_word(container, undo_cache):
+    changed = set()
+    for (file_name, node, is_attr, attr), text in undo_cache.iteritems():
+        node.set(attr, text) if is_attr else setattr(node, attr, text)
+        container.replace(file_name, node.getroottree().getroot())
+        changed.add(file_name)
+    return changed
+
 if __name__ == '__main__':
     import pprint
     from calibre.gui2.tweak_book import set_book_locale, dictionaries

src/calibre/gui2/tweak_book/spell.py

@@ -20,7 +20,7 @@ from PyQt5.Qt import (
     QT_VERSION_STR)
 
 from calibre.constants import __appname__, plugins
-from calibre.ebooks.oeb.polish.spell import replace_word, get_all_words, merge_locations, get_checkable_file_names
+from calibre.ebooks.oeb.polish.spell import replace_word, get_all_words, merge_locations, get_checkable_file_names, undo_replace_word
 from calibre.gui2 import choose_files, error_dialog
 from calibre.gui2.complete2 import LineEdit
 from calibre.gui2.languages import LanguagesEdit
@@ -883,6 +883,7 @@ class SpellCheck(Dialog):
         Dialog.__init__(self, _('Check spelling'), 'spell-check', parent)
         self.work_finished.connect(self.work_done, type=Qt.QueuedConnection)
         self.setAttribute(Qt.WA_DeleteOnClose, False)
+        self.undo_cache = {}
 
     def setup_ui(self):
         self.state_name = 'spell-check-table-state-' + QT_VERSION_STR.partition('.')[0]
@@ -899,6 +900,10 @@ class SpellCheck(Dialog):
         b.setToolTip('<p>' + _('Re-scan the book for words, useful if you have edited the book since opening this dialog'))
         b.setIcon(QIcon(I('view-refresh.png')))
         b.clicked.connect(partial(self.refresh, change_request=None))
+        b = self.bb.addButton(_('&Undo last change'), self.bb.ActionRole)
+        b.setToolTip('<p>' + _('Undo the last spell check word replacement, if any'))
+        b.setIcon(QIcon(I('edit-undo.png')))
+        b.clicked.connect(self.undo_last_change)
 
         self.progress = p = QWidget(self)
         s.addWidget(p)
@@ -1110,7 +1115,8 @@ class SpellCheck(Dialog):
         self.change_requested.emit(w, new_word)
 
     def do_change_word(self, w, new_word):
-        changed_files = replace_word(current_container(), new_word, self.words_model.words[w], w[1])
+        self.undo_cache.clear()
+        changed_files = replace_word(current_container(), new_word, self.words_model.words[w], w[1], undo_cache=self.undo_cache)
         if changed_files:
             self.word_replaced.emit(changed_files)
             w = self.words_model.replace_word(w, new_word)
@@ -1118,6 +1124,16 @@ class SpellCheck(Dialog):
             if row > -1:
                 self.words_view.highlight_row(row)
 
+    def undo_last_change(self):
+        if not self.undo_cache:
+            return error_dialog(self, _('No changed word'), _(
+                'There is no spelling replacement to undo'), show=True)
+        changed_files = undo_replace_word(current_container(), self.undo_cache)
+        self.undo_cache.clear()
+        if changed_files:
+            self.word_replaced.emit(changed_files)
+            self.refresh()
+
     def toggle_ignore(self):
         current = self.words_view.currentIndex()
         if current.isValid():