1 files changed, 155 insertions, 0 deletions
diff --git a/Userland/Libraries/LibGUI/SyntaxHighlighter.cpp b/Userland/Libraries/LibGUI/SyntaxHighlighter.cpp
new file mode 100644
index 0000000000..032adc65d7
--- /dev/null
+++ b/Userland/Libraries/LibGUI/SyntaxHighlighter.cpp
@@ -0,0 +1,155 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibGUI/SyntaxHighlighter.h>
+#include <LibGUI/TextEditor.h>
+
+namespace GUI {
+
+SyntaxHighlighter::~SyntaxHighlighter()
+{
+}
+
+void SyntaxHighlighter::highlight_matching_token_pair()
+{
+    ASSERT(m_editor);
+    auto& document = m_editor->document();
+
+    enum class Direction {
+        Forward,
+        Backward,
+    };
+
+    auto find_span_of_type = [&](auto i, void* type, void* not_type, Direction direction) -> Optional<size_t> {
+        size_t nesting_level = 0;
+        bool forward = direction == Direction::Forward;
+
+        if (forward) {
+            ++i;
+            if (i >= document.spans().size())
+                return {};
+        } else {
+            if (i == 0)
+                return {};
+            --i;
+        }
+
+        for (;;) {
+            auto& span = document.spans().at(i);
+            auto span_token_type = span.data;
+            if (token_types_equal(span_token_type, not_type)) {
+                ++nesting_level;
+            } else if (token_types_equal(span_token_type, type)) {
+                if (nesting_level-- <= 0)
+                    return i;
+            }
+
+            if (forward) {
+                ++i;
+                if (i >= document.spans().size())
+                    return {};
+            } else {
+                if (i == 0)
+                    return {};
+                --i;
+            }
+        }
+
+        return {};
+    };
+
+    auto make_buddies = [&](int index0, int index1) {
+        auto& buddy0 = document.spans()[index0];
+        auto& buddy1 = 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.attributes.background_color = Color::DarkCyan;
+        buddy1.attributes.background_color = Color::DarkCyan;
+        buddy0.attributes.color = Color::White;
+        buddy1.attributes.color = Color::White;
+        m_editor->update();
+    };
+
+    auto pairs = matching_token_pairs();
+
+    for (size_t i = 0; i < document.spans().size(); ++i) {
+        auto& span = const_cast<GUI::TextDocumentSpan&>(document.spans().at(i));
+        auto token_type = span.data;
+
+        for (auto& pair : pairs) {
+            if (token_types_equal(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.has_value())
+                    make_buddies(i, buddy.value());
+                return;
+            }
+        }
+
+        auto right_of_end = span.range.end();
+        right_of_end.set_column(right_of_end.column() + 1);
+
+        for (auto& pair : pairs) {
+            if (token_types_equal(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.has_value())
+                    make_buddies(i, buddy.value());
+                return;
+            }
+        }
+    }
+}
+
+void SyntaxHighlighter::attach(TextEditor& editor)
+{
+    ASSERT(!m_editor);
+    m_editor = editor;
+}
+
+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 < static_cast<int>(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 < static_cast<int>(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();
+}
+
+}