LibGUI+HackStudio: Move syntax highlighting from HackStudio to LibGUI

This patch introduces the GUI::SyntaxHighlighter class, which can be
attached to a GUI::TextEditor to provide syntax highlighting.

The C++ syntax highlighting from HackStudio becomes a new class called
GUI::CppSyntaxHighlighter. This will make it possible to get C++ syntax
highlighting in any app that uses a GUI::TextEditor. :^)

Sidenote: It does feel a bit weird having a C++ lexer in a GUI toolkit
library, and we'll probably end up moving this out to a separate place
as this functionality grows larger.

DevTools/HackStudio/Editor.cpp

@@ -25,7 +25,6 @@
  */
 
 #include "Editor.h"
-#include "CppLexer.h"
 #include "EditorWrapper.h"
 #include <AK/FileSystemPath.h>
 #include <LibCore/DirIterator.h>
@@ -197,98 +196,3 @@ void Editor::mousemove_event(GUI::MouseEvent& event)
     }
     GUI::Application::the().hide_tooltip();
 }
-
-void Editor::highlight_matching_token_pair()
-{
-    enum class Direction {
-        Forward,
-        Backward,
-    };
-
-    auto find_span_of_type = [&](int i, CppToken::Type type, CppToken::Type not_type, Direction direction) {
-        int nesting_level = 0;
-        bool forward = direction == Direction::Forward;
-        for (forward ? ++i : --i; forward ? (i < document().spans().size()) : (i >= 0); forward ? ++i : --i) {
-            auto& span = document().spans().at(i);
-            auto span_token_type = (CppToken::Type)((uintptr_t)span.data);
-            if (span_token_type == not_type) {
-                ++nesting_level;
-            } else if (span_token_type == type) {
-                if (nesting_level-- <= 0)
-                    return i;
-            }
-        }
-        return -1;
-    };
-
-    auto make_buddies = [&](int index0, int index1) {
-        auto& buddy0 = const_cast<GUI::TextDocumentSpan&>(document().spans()[index0]);
-        auto& buddy1 = const_cast<GUI::TextDocumentSpan&>(document().spans()[index1]);
-        m_has_brace_buddies = true;
-        m_brace_buddies[0].index = index0;
-        m_brace_buddies[1].index = index1;
-        m_brace_buddies[0].span_backup = buddy0;
-        m_brace_buddies[1].span_backup = buddy1;
-        buddy0.background_color = Color::DarkCyan;
-        buddy1.background_color = Color::DarkCyan;
-        buddy0.color = Color::White;
-        buddy1.color = Color::White;
-        update();
-    };
-
-    struct MatchingTokenPair {
-        CppToken::Type open;
-        CppToken::Type close;
-    };
-
-    MatchingTokenPair pairs[] = {
-        { CppToken::Type::LeftCurly, CppToken::Type::RightCurly },
-        { CppToken::Type::LeftParen, CppToken::Type::RightParen },
-        { CppToken::Type::LeftBracket, CppToken::Type::RightBracket },
-    };
-
-    for (int i = 0; i < document().spans().size(); ++i) {
-        auto& span = const_cast<GUI::TextDocumentSpan&>(document().spans().at(i));
-        auto token_type = (CppToken::Type)((uintptr_t)span.data);
-
-        for (auto& pair : pairs) {
-            if (token_type == pair.open && span.range.start() == cursor()) {
-                auto buddy = find_span_of_type(i, pair.close, pair.open, Direction::Forward);
-                if (buddy != -1)
-                    make_buddies(i, buddy);
-                return;
-            }
-        }
-
-        auto right_of_end = span.range.end();
-        right_of_end.set_column(right_of_end.column() + 1);
-
-        for (auto& pair : pairs) {
-            if (token_type == pair.close && right_of_end == cursor()) {
-                auto buddy = find_span_of_type(i, pair.open, pair.close, Direction::Backward);
-                if (buddy != -1)
-                    make_buddies(i, buddy);
-                return;
-            }
-        }
-    }
-}
-
-void Editor::cursor_did_change()
-{
-    if (m_has_brace_buddies) {
-        if (m_brace_buddies[0].index >= 0 && m_brace_buddies[0].index < document().spans().size())
-            document().set_span_at_index(m_brace_buddies[0].index, m_brace_buddies[0].span_backup);
-        if (m_brace_buddies[1].index >= 0 && m_brace_buddies[1].index < document().spans().size())
-            document().set_span_at_index(m_brace_buddies[1].index, m_brace_buddies[1].span_backup);
-        m_has_brace_buddies = false;
-        update();
-    }
-    highlight_matching_token_pair();
-}
-
-void Editor::notify_did_rehighlight()
-{
-    m_has_brace_buddies = false;
-    highlight_matching_token_pair();
-}

DevTools/HackStudio/Editor.h

@@ -41,29 +41,17 @@ public:
     EditorWrapper& wrapper();
     const EditorWrapper& wrapper() const;
 
-    void notify_did_rehighlight();
-
 private:
     virtual void focusin_event(Core::Event&) override;
     virtual void focusout_event(Core::Event&) override;
     virtual void paint_event(GUI::PaintEvent&) override;
     virtual void mousemove_event(GUI::MouseEvent&) override;
-    virtual void cursor_did_change() override;
 
     void show_documentation_tooltip_if_available(const String&, const Gfx::Point& screen_location);
-    void highlight_matching_token_pair();
 
     explicit Editor(GUI::Widget* parent);
 
     RefPtr<GUI::Window> m_documentation_tooltip_window;
     RefPtr<HtmlView> m_documentation_html_view;
     String m_last_parsed_token;
-
-    struct BuddySpan {
-        int index { -1 };
-        GUI::TextDocumentSpan span_backup;
-    };
-
-    bool m_has_brace_buddies { false };
-    BuddySpan m_brace_buddies[2];
 };

DevTools/HackStudio/Makefile

@@ -6,7 +6,6 @@ OBJS = \
     ProcessStateWidget.o \
     FormEditorWidget.o \
     FormWidget.o \
-    CppLexer.o \
     Editor.o \
     EditorWrapper.o \
     Locator.o \

DevTools/HackStudio/main.cpp

@@ -24,7 +24,6 @@
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "CppLexer.h"
 #include "CursorTool.h"
 #include "Editor.h"
 #include "EditorWrapper.h"
@@ -44,6 +43,7 @@
 #include <LibGUI/Application.h>
 #include <LibGUI/BoxLayout.h>
 #include <LibGUI/Button.h>
+#include <LibGUI/CppSyntaxHighlighter.h>
 #include <LibGUI/FilePicker.h>
 #include <LibGUI/InputBox.h>
 #include <LibGUI/Label.h>
@@ -548,70 +548,13 @@ void run(TerminalWrapper& wrapper)
     wrapper.run_command("make run");
 }
 
-struct TextStyle {
-    Color color;
-    const Gfx::Font* font { nullptr };
-};
-
-static TextStyle style_for_token_type(CppToken::Type type)
-{
-    switch (type) {
-    case CppToken::Type::Keyword:
-        return { Color::Black, &Gfx::Font::default_bold_fixed_width_font() };
-    case CppToken::Type::KnownType:
-        return { Color::from_rgb(0x929200), &Gfx::Font::default_bold_fixed_width_font() };
-    case CppToken::Type::Identifier:
-        return { Color::from_rgb(0x000092) };
-    case CppToken::Type::DoubleQuotedString:
-    case CppToken::Type::SingleQuotedString:
-    case CppToken::Type::Number:
-        return { Color::from_rgb(0x920000) };
-    case CppToken::Type::PreprocessorStatement:
-        return { Color::from_rgb(0x009292) };
-    case CppToken::Type::Comment:
-        return { Color::from_rgb(0x009200) };
-    default:
-        return { Color::Black };
-    }
-}
-
-static void rehighlight()
-{
-    auto text = current_editor().text();
-    CppLexer lexer(text);
-    auto tokens = lexer.lex();
-
-    Vector<GUI::TextDocumentSpan> spans;
-    for (auto& token : tokens) {
-#ifdef DEBUG_SYNTAX_HIGHLIGHTING
-        dbg() << token.to_string() << " @ " << token.m_start.line << ":" << token.m_start.column << " - " << token.m_end.line << ":" << token.m_end.column;
-#endif
-        GUI::TextDocumentSpan span;
-        span.range.set_start({ token.m_start.line, token.m_start.column });
-        span.range.set_end({ token.m_end.line, token.m_end.column });
-        auto style = style_for_token_type(token.m_type);
-        span.color = style.color;
-        span.font = style.font;
-        span.is_skippable = token.m_type == CppToken::Type::Whitespace;
-        span.data = (void*)token.m_type;
-        spans.append(span);
-    }
-    current_editor().document().set_spans(spans);
-    static_cast<Editor&>(current_editor()).notify_did_rehighlight();
-    current_editor().update();
-}
-
 void open_file(const String& filename)
 {
     auto file = g_project->get_file(filename);
     current_editor().set_document(const_cast<GUI::TextDocument&>(file->document()));
 
-    if (filename.ends_with(".cpp") || filename.ends_with(".h")) {
-        current_editor().on_change = [] { rehighlight(); };
-        rehighlight();
-    } else {
-        current_editor().on_change = nullptr;
-    }
+    if (filename.ends_with(".cpp") || filename.ends_with(".h"))
+        current_editor().set_syntax_highlighter(make<GUI::CppSyntaxHighlighter>());
 
     if (filename.ends_with(".frm")) {
         set_edit_mode(EditMode::Form);

Libraries/LibGUI/CppLexer.cpp

@@ -29,6 +29,8 @@
 #include <AK/String.h>
 #include <ctype.h>
 
+namespace GUI {
+
 CppLexer::CppLexer(const StringView& input)
     : m_input(input)
 {
@@ -368,3 +370,5 @@ Vector<CppToken> CppLexer::lex()
     }
     return tokens;
 }
+
+}

Libraries/LibGUI/CppLexer.h

@@ -29,6 +29,8 @@
 #include <AK/StringView.h>
 #include <AK/Vector.h>
 
+namespace GUI {
+
 #define FOR_EACH_TOKEN_TYPE        \
     __TOKEN(Unknown)               \
     __TOKEN(Whitespace)            \
@@ -94,3 +96,5 @@ private:
     CppPosition m_previous_position { 0, 0 };
     CppPosition m_position { 0, 0 };
 };
+
+}

Libraries/LibGUI/CppSyntaxHighlighter.cpp

@@ -0,0 +1,147 @@
+#include <LibGUI/CppLexer.h>
+#include <LibGUI/CppSyntaxHighlighter.h>
+#include <LibGUI/TextEditor.h>
+
+namespace GUI {
+
+struct TextStyle {
+    Color color;
+    const Gfx::Font* font { nullptr };
+};
+
+static TextStyle style_for_token_type(CppToken::Type type)
+{
+    switch (type) {
+    case CppToken::Type::Keyword:
+        return { Color::Black, &Gfx::Font::default_bold_fixed_width_font() };
+    case CppToken::Type::KnownType:
+        return { Color::from_rgb(0x929200), &Gfx::Font::default_bold_fixed_width_font() };
+    case CppToken::Type::Identifier:
+        return { Color::from_rgb(0x000092) };
+    case CppToken::Type::DoubleQuotedString:
+    case CppToken::Type::SingleQuotedString:
+    case CppToken::Type::Number:
+        return { Color::from_rgb(0x920000) };
+    case CppToken::Type::PreprocessorStatement:
+        return { Color::from_rgb(0x009292) };
+    case CppToken::Type::Comment:
+        return { Color::from_rgb(0x009200) };
+    default:
+        return { Color::Black };
+    }
+}
+
+void CppSyntaxHighlighter::rehighlight()
+{
+    ASSERT(m_editor);
+    auto text = m_editor->text();
+    CppLexer lexer(text);
+    auto tokens = lexer.lex();
+
+    Vector<GUI::TextDocumentSpan> spans;
+    for (auto& token : tokens) {
+#ifdef DEBUG_SYNTAX_HIGHLIGHTING
+        dbg() << token.to_string() << " @ " << token.m_start.line << ":" << token.m_start.column << " - " << token.m_end.line << ":" << token.m_end.column;
+#endif
+        GUI::TextDocumentSpan span;
+        span.range.set_start({ token.m_start.line, token.m_start.column });
+        span.range.set_end({ token.m_end.line, token.m_end.column });
+        auto style = style_for_token_type(token.m_type);
+        span.color = style.color;
+        span.font = style.font;
+        span.is_skippable = token.m_type == CppToken::Type::Whitespace;
+        span.data = (void*)token.m_type;
+        spans.append(span);
+    }
+    m_editor->document().set_spans(spans);
+
+    m_has_brace_buddies = false;
+    highlight_matching_token_pair();
+
+    m_editor->update();
+}
+
+void CppSyntaxHighlighter::highlight_matching_token_pair()
+{
+    ASSERT(m_editor);
+    auto& document = m_editor->document();
+
+    enum class Direction {
+        Forward,
+        Backward,
+    };
+
+    auto find_span_of_type = [&](int i, CppToken::Type type, CppToken::Type not_type, Direction direction) {
+        int nesting_level = 0;
+        bool forward = direction == Direction::Forward;
+        for (forward ? ++i : --i; forward ? (i < document.spans().size()) : (i >= 0); forward ? ++i : --i) {
+            auto& span = document.spans().at(i);
+            auto span_token_type = (CppToken::Type)((uintptr_t)span.data);
+            if (span_token_type == not_type) {
+                ++nesting_level;
+            } else if (span_token_type == type) {
+                if (nesting_level-- <= 0)
+                    return i;
+            }
+        }
+        return -1;
+    };
+
+    auto make_buddies = [&](int index0, int index1) {
+        auto& buddy0 = const_cast<GUI::TextDocumentSpan&>(document.spans()[index0]);
+        auto& buddy1 = const_cast<GUI::TextDocumentSpan&>(document.spans()[index1]);
+        m_has_brace_buddies = true;
+        m_brace_buddies[0].index = index0;
+        m_brace_buddies[1].index = index1;
+        m_brace_buddies[0].span_backup = buddy0;
+        m_brace_buddies[1].span_backup = buddy1;
+        buddy0.background_color = Color::DarkCyan;
+        buddy1.background_color = Color::DarkCyan;
+        buddy0.color = Color::White;
+        buddy1.color = Color::White;
+        m_editor->update();
+    };
+
+    struct MatchingTokenPair {
+        CppToken::Type open;
+        CppToken::Type close;
+    };
+
+    MatchingTokenPair pairs[] = {
+        { CppToken::Type::LeftCurly, CppToken::Type::RightCurly },
+        { CppToken::Type::LeftParen, CppToken::Type::RightParen },
+        { CppToken::Type::LeftBracket, CppToken::Type::RightBracket },
+    };
+
+    for (int i = 0; i < document.spans().size(); ++i) {
+        auto& span = const_cast<GUI::TextDocumentSpan&>(document.spans().at(i));
+        auto token_type = (CppToken::Type)((uintptr_t)span.data);
+
+        for (auto& pair : pairs) {
+            if (token_type == pair.open && span.range.start() == m_editor->cursor()) {
+                auto buddy = find_span_of_type(i, pair.close, pair.open, Direction::Forward);
+                if (buddy != -1)
+                    make_buddies(i, buddy);
+                return;
+            }
+        }
+
+        auto right_of_end = span.range.end();
+        right_of_end.set_column(right_of_end.column() + 1);
+
+        for (auto& pair : pairs) {
+            if (token_type == pair.close && right_of_end == m_editor->cursor()) {
+                auto buddy = find_span_of_type(i, pair.open, pair.close, Direction::Backward);
+                if (buddy != -1)
+                    make_buddies(i, buddy);
+                return;
+            }
+        }
+    }
+}
+
+CppSyntaxHighlighter::~CppSyntaxHighlighter()
+{
+}
+
+}

Libraries/LibGUI/CppSyntaxHighlighter.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <LibGUI/SyntaxHighlighter.h>
+
+namespace GUI {
+
+class CppSyntaxHighlighter final : public SyntaxHighlighter {
+public:
+    CppSyntaxHighlighter() {}
+
+    virtual ~CppSyntaxHighlighter() override;
+    virtual void rehighlight() override;
+    virtual void highlight_matching_token_pair() override;
+};
+
+}

Libraries/LibGUI/Makefile

@@ -14,6 +14,8 @@ OBJS = \
     ColumnsView.o \
     ComboBox.o \
     Command.o \
+    CppLexer.o \
+    CppSyntaxHighlighter.o \
     Desktop.o \
     Dialog.o \
     DragOperation.o \
@@ -49,6 +51,7 @@ OBJS = \
     Splitter.o \
     StackWidget.o \
     StatusBar.o \
+    SyntaxHighlighter.o \
     TabWidget.o \
     TableView.o \
     TextBox.o \

Libraries/LibGUI/SyntaxHighlighter.cpp

@@ -0,0 +1,37 @@
+#include <LibGUI/SyntaxHighlighter.h>
+#include <LibGUI/TextEditor.h>
+
+namespace GUI {
+
+SyntaxHighlighter::~SyntaxHighlighter()
+{
+}
+
+void SyntaxHighlighter::attach(TextEditor& editor)
+{
+    ASSERT(!m_editor);
+    m_editor = editor.make_weak_ptr();
+}
+
+void SyntaxHighlighter::detach()
+{
+    ASSERT(m_editor);
+    m_editor = nullptr;
+}
+
+void SyntaxHighlighter::cursor_did_change()
+{
+    ASSERT(m_editor);
+    auto& document = m_editor->document();
+    if (m_has_brace_buddies) {
+        if (m_brace_buddies[0].index >= 0 && m_brace_buddies[0].index < document.spans().size())
+            document.set_span_at_index(m_brace_buddies[0].index, m_brace_buddies[0].span_backup);
+        if (m_brace_buddies[1].index >= 0 && m_brace_buddies[1].index < document.spans().size())
+            document.set_span_at_index(m_brace_buddies[1].index, m_brace_buddies[1].span_backup);
+        m_has_brace_buddies = false;
+        m_editor->update();
+    }
+    highlight_matching_token_pair();
+}
+
+}

Libraries/LibGUI/SyntaxHighlighter.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <AK/Noncopyable.h>
+#include <AK/WeakPtr.h>
+#include <LibGUI/TextDocument.h>
+
+namespace GUI {
+
+class TextEditor;
+
+class SyntaxHighlighter {
+    AK_MAKE_NONCOPYABLE(SyntaxHighlighter);
+    AK_MAKE_NONMOVABLE(SyntaxHighlighter);
+
+public:
+    virtual ~SyntaxHighlighter();
+
+    virtual void rehighlight() = 0;
+    virtual void highlight_matching_token_pair() = 0;
+
+    void attach(TextEditor& editor);
+    void detach();
+    void cursor_did_change();
+
+protected:
+    SyntaxHighlighter() {}
+
+    WeakPtr<TextEditor> m_editor;
+
+    struct BuddySpan {
+        int index { -1 };
+        GUI::TextDocumentSpan span_backup;
+    };
+
+    bool m_has_brace_buddies { false };
+    BuddySpan m_brace_buddies[2];
+};
+
+}

Libraries/LibGUI/TextEditor.cpp

@@ -27,7 +27,6 @@
 #include <AK/QuickSort.h>
 #include <AK/StringBuilder.h>
 #include <Kernel/KeyCode.h>
-#include <LibGfx/Palette.h>
 #include <LibGUI/Action.h>
 #include <LibGUI/Clipboard.h>
 #include <LibGUI/FontDatabase.h>
@@ -35,8 +34,10 @@
 #include <LibGUI/Menu.h>
 #include <LibGUI/Painter.h>
 #include <LibGUI/ScrollBar.h>
+#include <LibGUI/SyntaxHighlighter.h>
 #include <LibGUI/TextEditor.h>
 #include <LibGUI/Window.h>
+#include <LibGfx/Palette.h>
 #include <ctype.h>
 #include <fcntl.h>
 #include <stdio.h>
@@ -1030,6 +1031,8 @@ void TextEditor::set_cursor(const TextPosition& a_position)
     cursor_did_change();
     if (on_cursor_change)
         on_cursor_change();
+    if (m_highlighter)
+        m_highlighter->cursor_did_change();
 }
 
 void TextEditor::focusin_event(Core::Event&)
@@ -1198,6 +1201,8 @@ void TextEditor::did_change()
                 return;
             if (on_change)
                 on_change();
+            if (m_highlighter)
+                m_highlighter->rehighlight();
             m_has_pending_change_notification = false;
         });
     }
@@ -1476,7 +1481,20 @@ void TextEditor::flush_pending_change_notification_if_needed()
         return;
     if (on_change)
         on_change();
+    if (m_highlighter)
+        m_highlighter->rehighlight();
     m_has_pending_change_notification = false;
 }
 
+void TextEditor::set_syntax_highlighter(OwnPtr<SyntaxHighlighter> highlighter)
+{
+    if (m_highlighter)
+        m_highlighter->detach();
+    m_highlighter = move(highlighter);
+    if (m_highlighter) {
+        m_highlighter->attach(*this);
+        m_highlighter->rehighlight();
+    }
+}
+
 }

Libraries/LibGUI/TextEditor.h

@@ -42,6 +42,7 @@ class Action;
 class Menu;
 class Painter;
 class ScrollBar;
+class SyntaxHighlighter;
 
 class TextEditor
     : public ScrollableWidget
@@ -133,6 +134,8 @@ public:
     void set_cursor(size_t line, size_t column);
     void set_cursor(const TextPosition&);
 
+    void set_syntax_highlighter(OwnPtr<SyntaxHighlighter>);
+
 protected:
     explicit TextEditor(Widget* parent);
     explicit TextEditor(Type, Widget* parent);
@@ -248,6 +251,8 @@ private:
     };
 
     NonnullOwnPtrVector<LineVisualData> m_line_visual_data;
+
+    OwnPtr<SyntaxHighlighter> m_highlighter;
 };
 
 }