App-Buffer.cppm

// This project is licensed under the GPL-3.0 License. See the LICENSE file for details, or check out <gnu.org>.
// Copyright (C) 2026 mxreal64

export module delta.app:buffer;
import delta.types;
import std;

export class DocumentBuffer {
private:
    std::string text_ = "";

public:
    DocumentBuffer() noexcept = default;

    //  Standard types must be explicitly namespace qualified under named modules
    void insert_str(std::size_t index, const std::string& str) noexcept {
        if (index <= text_.size()) {
            text_.insert(index, str);
        }
    }

    void erase_range(std::size_t index, std::size_t length) noexcept {
        if (index + length <= text_.size()) {
            text_.erase(index, length);
        }
    }

    void inject_style(selection_span& sel, char marker) noexcept {
        if (sel.start != sel.end) {
            std::string before = text_.substr(0, sel.start);
            std::string middle = text_.substr(sel.start, sel.end - sel.start);
            std::string after  = text_.substr(sel.end);
            
            text_ = before + marker + middle + marker + after;
            sel.start += 2;
            sel.end += 2;
        } else {
            text_.insert(sel.start, std::string(1, marker));
            sel.start++;
            sel.end = sel.start;
        }
    }

    [[nodiscard]] const std::string& get_raw() const noexcept { return text_; }
    [[nodiscard]] std::size_t size() const noexcept { return text_.size(); }
    [[nodiscard]] char operator[](std::size_t idx) const noexcept { return text_[idx]; }
};