LibLine: Refactor suggestion handling and display logic out

Libraries/LibLine/SuggestionManager.h

@@ -0,0 +1,145 @@
+/*
+ * 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.
+ */
+
+#pragma once
+#include <AK/Forward.h>
+#include <AK/String.h>
+#include <AK/Utf32View.h>
+#include <AK/Utf8View.h>
+#include <LibLine/Style.h>
+#include <stdlib.h>
+
+namespace Line {
+
+// FIXME: These objects are pretty heavy since they store two copies of text
+//        somehow get rid of one
+struct CompletionSuggestion {
+    // intentionally not explicit (allows suggesting bare strings)
+    CompletionSuggestion(const String& completion)
+        : CompletionSuggestion(completion, "", {})
+    {
+    }
+
+    CompletionSuggestion(const StringView& completion, const StringView& trailing_trivia)
+        : CompletionSuggestion(completion, trailing_trivia, {})
+    {
+    }
+
+    CompletionSuggestion(const StringView& completion, const StringView& trailing_trivia, Style style);
+
+    bool operator==(const CompletionSuggestion& suggestion) const
+    {
+        return suggestion.text == text;
+    }
+
+    Vector<u32> text;
+    Vector<u32> trailing_trivia;
+    Style style;
+    size_t start_index { 0 };
+
+    Utf32View text_view;
+    Utf32View trivia_view;
+    String text_string;
+};
+
+class SuggestionManager {
+    friend class Editor;
+
+public:
+    void set_suggestions(Vector<CompletionSuggestion>&& suggestions);
+    void set_current_suggestion_initiation_index(size_t index);
+
+    size_t count() const { return m_suggestions.size(); }
+    size_t display_length() const { return m_last_shown_suggestion_display_length; }
+    size_t index() const { return m_last_displayed_suggestion_index; }
+    size_t next_index() const { return m_next_suggestion_index; }
+
+    size_t for_each_suggestion(Function<IterationDecision(const CompletionSuggestion&, size_t)>) const;
+
+    enum CompletionMode {
+        DontComplete,
+        CompletePrefix,
+        ShowSuggestions,
+        CycleSuggestions,
+    };
+
+    class CompletionAttemptResult {
+    public:
+        CompletionMode new_completion_mode;
+
+        ssize_t new_cursor_offset { 0 };
+
+        struct {
+            size_t start;
+            size_t end;
+        } offset_region_to_remove { 0, 0 }; // The region to remove as defined by [start, end) translated by (old_cursor + new_cursor_offset)
+
+        Vector<Utf32View> insert {};
+
+        Optional<Style> style_to_apply {};
+    };
+
+    CompletionAttemptResult attempt_completion(CompletionMode, size_t initiation_start_index);
+
+    void next();
+    void previous();
+    void set_suggestion_variants(size_t static_offset, size_t invariant_offset, size_t suggestion_index) const
+    {
+        m_next_suggestion_index = suggestion_index;
+        m_next_suggestion_static_offset = static_offset;
+        m_next_suggestion_invariant_offset = invariant_offset;
+    }
+
+    const CompletionSuggestion& suggest();
+    const CompletionSuggestion& current_suggestion() const { return m_last_shown_suggestion; }
+    bool is_current_suggestion_complete() const { return m_last_shown_suggestion_was_complete; }
+
+    void reset()
+    {
+        m_last_shown_suggestion = String::empty();
+        m_last_shown_suggestion_display_length = 0;
+        m_suggestions.clear();
+        m_last_displayed_suggestion_index = 0;
+    }
+
+private:
+    SuggestionManager()
+    {
+    }
+
+    Vector<CompletionSuggestion> m_suggestions;
+    CompletionSuggestion m_last_shown_suggestion { String::empty() };
+    size_t m_last_shown_suggestion_display_length { 0 };
+    bool m_last_shown_suggestion_was_complete { false };
+    mutable size_t m_next_suggestion_index { 0 };
+    mutable size_t m_next_suggestion_invariant_offset { 0 };
+    mutable size_t m_next_suggestion_static_offset { 0 };
+    size_t m_largest_common_suggestion_prefix_length { 0 };
+    size_t m_last_displayed_suggestion_index { 0 };
+    size_t m_selected_suggestion_index { 0 };
+};
+
+}