Use QSyntaxHighlighter for completion.

This is a more "Qt" way of highlighting syntax, and works around the
problems of #4199 without resorting to complicated html escaping.

The tests are more straightforward with less mocking, but do involve
testing a private class.

qutebrowser/app.py

@@ -59,7 +59,6 @@ except ImportError:
 
 import qutebrowser
 import qutebrowser.resources
-from qutebrowser.completion import completiondelegate
 from qutebrowser.completion.models import miscmodels
 from qutebrowser.commands import cmdutils, runners, cmdexc
 from qutebrowser.config import config, websettings, configfiles, configinit
@@ -452,9 +451,6 @@ def _init_modules(args, crash_handler):
                                pre_text='Error initializing SQL')
         sys.exit(usertypes.Exit.err_init)
 
-    log.init.debug("Initializing completion...")
-    completiondelegate.init()
-
     log.init.debug("Initializing command history...")
     cmdhistory.init()
 

qutebrowser/completion/completiondelegate.py

@@ -28,13 +28,27 @@ import html
 from PyQt5.QtWidgets import QStyle, QStyleOptionViewItem, QStyledItemDelegate
 from PyQt5.QtCore import QRectF, QSize, Qt
 from PyQt5.QtGui import (QIcon, QPalette, QTextDocument, QTextOption,
-                         QAbstractTextDocumentLayout)
+                         QAbstractTextDocumentLayout, QSyntaxHighlighter,
+                         QTextCharFormat)
 
 from qutebrowser.config import config
-from qutebrowser.utils import qtutils, jinja
+from qutebrowser.utils import qtutils
 
 
-_cached_stylesheet = None
+class _Highlighter(QSyntaxHighlighter):
+
+    def __init__(self, doc, pattern, color):
+        super().__init__(doc)
+        self._format = QTextCharFormat()
+        self._format.setForeground(color)
+        self._pattern = pattern
+
+    def highlightBlock(self, text):
+        """Override highlightBlock for custom highlighting."""
+        for match in re.finditer(self._pattern, text):
+            start, end = match.span()
+            length = end - start
+            self.setFormat(start, length, self._format)
 
 
 class CompletionItemDelegate(QStyledItemDelegate):
@@ -194,27 +208,15 @@ class CompletionItemDelegate(QStyledItemDelegate):
         self._doc.setDefaultTextOption(text_option)
         self._doc.setDocumentMargin(2)
 
-        assert _cached_stylesheet is not None
-        self._doc.setDefaultStyleSheet(_cached_stylesheet)
-
         if index.parent().isValid():
             view = self.parent()
             pattern = view.pattern
             columns_to_filter = index.model().columns_to_filter(index)
+            self._doc.setPlainText(self._opt.text)
             if index.column() in columns_to_filter and pattern:
-                pat = '({})'.format(re.escape(pattern).replace(r'\ ', r'|'))
-                parts = re.split(pat, self._opt.text, flags=re.IGNORECASE)
-                fmt = '<span class="highlight">{}</span>'
-                escape = lambda s: html.escape(s, quote=False)
-                highlight = lambda s: fmt.format(escape(s))
-                # matches are at every odd index
-                text = ''.join([
-                    highlight(s) if i % 2 == 1 else escape(s)
-                    for i, s in enumerate(parts)
-                ])
-                self._doc.setHtml(text)
-            else:
-                self._doc.setPlainText(self._opt.text)
+                pat = re.escape(pattern).replace(r'\ ', r'|')
+                _Highlighter(self._doc, pat,
+                             config.val.colors.completion.match.fg)
         else:
             self._doc.setHtml(
                 '<span style="font: {};">{}</span>'.format(
@@ -289,24 +291,3 @@ class CompletionItemDelegate(QStyledItemDelegate):
         self._draw_focus_rect()
 
         self._painter.restore()
-
-
-@config.change_filter('colors.completion.match.fg', function=True)
-def _update_stylesheet():
-    """Update the cached stylesheet."""
-    stylesheet = """
-        .highlight {
-            color: {{ conf.colors.completion.match.fg }};
-        }
-    """
-    with jinja.environment.no_autoescape():
-        template = jinja.environment.from_string(stylesheet)
-
-    global _cached_stylesheet
-    _cached_stylesheet = template.render(conf=config.val)
-
-
-def init():
-    """Initialize the cached stylesheet."""
-    _update_stylesheet()
-    config.instance.changed.connect(_update_stylesheet)

tests/unit/completion/test_completiondelegate.py

@@ -19,82 +19,33 @@
 from unittest import mock
 
 import pytest
-from PyQt5.QtCore import QModelIndex, QObject
-from PyQt5.QtGui import QPainter
+from PyQt5.QtCore import Qt
+from PyQt5.QtGui import QTextDocument
 
 from qutebrowser.completion import completiondelegate
 
 
-@pytest.fixture
-def painter():
-    return mock.Mock(spec=QPainter)
-
-
-def _qt_mock(klass, mocker):
-    m = mocker.patch.object(completiondelegate, klass, autospec=True)
-    return m
-
-
-@pytest.fixture
-def mock_style_option(mocker):
-    return _qt_mock('QStyleOptionViewItem', mocker)
-
-
-@pytest.fixture
-def mock_text_document(mocker):
-    return _qt_mock('QTextDocument', mocker)
-
-
-@pytest.fixture
-def view():
-    class FakeView(QObject):
-        def __init__(self):
-            super().__init__()
-            self.pattern = None
-
-    return FakeView()
-
-
-@pytest.fixture
-def delegate(mock_style_option, mock_text_document, config_stub, mocker, view):
-    _qt_mock('QStyle', mocker)
-    _qt_mock('QTextOption', mocker)
-    _qt_mock('QAbstractTextDocumentLayout', mocker)
-    completiondelegate._cached_stylesheet = ''
-    delegate = completiondelegate.CompletionItemDelegate(parent=view)
-    delegate.initStyleOption = mock.Mock()
-    return delegate
-
-
-@pytest.mark.parametrize('pat,txt_in,txt_out', [
-    # { and } represent the open/close html tags for highlighting
-    ('foo', 'foo', '{foo}'),
-    ('foo', 'foobar', '{foo}bar'),
-    ('foo', 'barfoo', 'bar{foo}'),
-    ('foo', 'barfoobaz', 'bar{foo}baz'),
-    ('foo', 'barfoobazfoo', 'bar{foo}baz{foo}'),
-    ('foo', 'foofoo', '{foo}{foo}'),
-    ('a b', 'cadb', 'c{a}d{b}'),
-    ('foo', '<foo>', '&lt;{foo}&gt;'),
-    ('<a>', "<a>bc", '{&lt;a&gt;}bc'),
+@pytest.mark.parametrize('pat,txt,segments', [
+    ('foo', 'foo', [(0, 3)]),
+    ('foo', 'foobar', [(0, 3)]),
+    ('foo', 'barfoo', [(3, 3)]),
+    ('foo', 'barfoobaz', [(3, 3)]),
+    ('foo', 'barfoobazfoo', [(3, 3), (9, 3)]),
+    ('foo', 'foofoo', [(0, 3), (3, 3)]),
+    ('a|b', 'cadb', [(1, 1), (3, 1)]),
+    ('foo', '<foo>', [(1, 3)]),
+    ('<a>', "<a>bc", [(0, 3)]),
 
     # https://github.com/qutebrowser/qutebrowser/issues/4199
-    ('foo', "'foo'", "'{foo}'"),
-    ('x', "'x'", "'{x}'"),
-    ('lt', "<lt", "&lt;{lt}"),
+    ('foo', "'foo'", [(1, 3)]),
+    ('x', "'x'", [(1, 1)]),
+    ('lt', "<lt", [(1, 2)]),
 ])
-def test_paint(delegate, painter, view, mock_style_option, mock_text_document,
-               pat, txt_in, txt_out):
-    view.pattern = pat
-    mock_style_option().text = txt_in
-    index = mock.Mock(spec=QModelIndex)
-    index.column.return_value = 0
-    index.model.return_value.columns_to_filter.return_value = [0]
-    opt = mock_style_option()
-    delegate.paint(painter, opt, index)
-    expected = txt_out.replace(
-        '{', '<span class="highlight">'
-    ).replace(
-        '}', '</span>'
-    )
-    mock_text_document().setHtml.assert_called_once_with(expected)
+def test_highlight(pat, txt, segments):
+    doc = QTextDocument(txt)
+    highlighter = completiondelegate._Highlighter(doc, pat, Qt.red)
+    highlighter.setFormat = mock.Mock()
+    highlighter.highlightBlock(txt)
+    highlighter.setFormat.assert_has_calls([
+        mock.call(s[0], s[1], mock.ANY) for s in segments
+    ])