From 5e45d6844289b772c9538e398eb1b779568e1124 Mon Sep 17 00:00:00 2001
From: FalseHonesty <thefalsehonesty@gmail.com>
Date: Sat, 23 May 2020 18:41:34 -0400
Subject: [PATCH] LibGUI: Use word breaks to intelligently navigate a
 TextEditor

Previously, holding Control while using the left/right arrow keys
to navigate through a TextEditor would only be helpful if the document
had spans. Now, if there are no spans, it will navigate to the
next "word break", defined to be the threshold where text changes
from alphanumeric to non-alphanumeric, or vice versa.
---
 Libraries/LibGUI/TextEditor.cpp | 55 +++++++++++++++++----------------
 1 file changed, 28 insertions(+), 27 deletions(-)

diff --git a/Libraries/LibGUI/TextEditor.cpp b/Libraries/LibGUI/TextEditor.cpp
index 884297e4f99..37404397c62 100644
--- a/Libraries/LibGUI/TextEditor.cpp
+++ b/Libraries/LibGUI/TextEditor.cpp
@@ -209,23 +209,10 @@ void TextEditor::doubleclick_event(MouseEvent& event)
 
     auto start = text_position_at(event.position());
     auto end = start;
-    auto& line = this->line(start.line());
-    auto clicked_on_alphanumeric = isalnum(line.codepoints()[start.column()]);
 
     if (!document().has_spans()) {
-        while (start.column() > 0) {
-            auto next_codepoint = line.codepoints()[start.column() - 1];
-            if ((clicked_on_alphanumeric && !isalnum(next_codepoint)) || (!clicked_on_alphanumeric && isalnum(next_codepoint)))
-                break;
-            start.set_column(start.column() - 1);
-        }
-
-        while (end.column() < line.length()) {
-            auto next_codepoint = line.codepoints()[end.column()];
-            if ((clicked_on_alphanumeric && !isalnum(next_codepoint)) || (!clicked_on_alphanumeric && isalnum(next_codepoint)))
-                break;
-            end.set_column(end.column() + 1);
-        }
+        start = document().first_word_break_before(start);
+        end = document().first_word_break_after(end);
     } else {
         for (auto& span : document().spans()) {
             if (!span.range.contains(start))
@@ -725,12 +712,19 @@ void TextEditor::keydown_event(KeyEvent& event)
         return;
     }
     if (event.key() == KeyCode::Key_Left) {
-        if (event.ctrl() && document().has_spans()) {
-            // FIXME: Do something nice when the document has no spans.
-            auto span = document().first_non_skippable_span_before(m_cursor);
-            TextPosition new_cursor = !span.has_value()
-                ? TextPosition(0, 0)
-                : span.value().range.start();
+        if (event.ctrl()) {
+            TextPosition new_cursor;
+            if (document().has_spans()) {
+                auto span = document().first_non_skippable_span_before(m_cursor);
+                if (span.has_value()) {
+                    new_cursor = span.value().range.start();
+                } else {
+                    // No remaining spans, just use word break calculation
+                    new_cursor = document().first_word_break_before(m_cursor);
+                }
+            } else {
+                new_cursor = document().first_word_break_before(m_cursor);
+            }
             toggle_selection_if_needed_for_event(event);
             set_cursor(new_cursor);
             if (event.shift() && m_selection.start().is_valid()) {
@@ -760,12 +754,19 @@ void TextEditor::keydown_event(KeyEvent& event)
         return;
     }
     if (event.key() == KeyCode::Key_Right) {
-        if (event.ctrl() && document().has_spans()) {
-            // FIXME: Do something nice when the document has no spans.
-            auto span = document().first_non_skippable_span_after(m_cursor);
-            TextPosition new_cursor = !span.has_value()
-                ? document().spans().last().range.end()
-                : span.value().range.start();
+        if (event.ctrl()) {
+            TextPosition new_cursor;
+            if (document().has_spans()) {
+                auto span = document().first_non_skippable_span_after(m_cursor);
+                if (span.has_value()) {
+                    new_cursor = span.value().range.start();
+                } else {
+                    // No remaining spans, just use word break calculation
+                    new_cursor = document().first_word_break_after(m_cursor);
+                }
+            } else {
+                new_cursor = document().first_word_break_after(m_cursor);
+            }
             toggle_selection_if_needed_for_event(event);
             set_cursor(new_cursor);
             if (event.shift() && m_selection.start().is_valid()) {