fix(dde-apps): return empty list when firstNItems count <= 0

[MyLeeJiEun]

问题描述

dde-shell 的 applets/dde-apps/itemspage.cpp 方法 ItemsPage::firstNItems(int count) 存在语义缺陷：count = 0（及任意 count <= 0）时返回首项而非空列表，违反 firstNItems(0) 应返回空的直觉契约。

缺陷根因

循环内先 result.append(item) 再判 result.count() >= count：

• count = 0 时：第一次迭代 append("a") → result.count() 变 1 → 1 >= 0 为 true → 返回 ["a"]（首项），而非预期的空列表。
• 同理 count < 0（如 -1）也返回首项（1 >= -1 为 true）。

修复内容

在 QStringList result; 之后、循环之前新增早返逻辑，对 count <= 0 直接返回空列表：

QStringList ItemsPage::firstNItems(int count)
{
    QStringList result;
    if (count <= 0)
        return result;

    for (const QStringList & pageItems : std::as_const(m_pages)) {
        for (const QString & item : pageItems) {
            result.append(item);
            if (result.count() >= count) {
                return result;
            }
        }
    }

    return result;
}

不采用「先判后 append」方案——会改变 count 恰好为页边界时的返回项数（少取一项），引入回归。

修复效果

• firstNItems(0) → [] ✅（修复前返回首项）
• firstNItems(-1) → [] ✅（修复前返回首项）
• firstNItems(2/3/10) 等正数行为完全不变 ✅（无回归）

影响范围

• 仅改 applets/dde-apps/itemspage.cpp 一处，2 行新增。
• count > 0 路径逻辑一字未改，无回归风险。
• 全仓库（C++ / QML）检索 firstNItems 调用点为 0，方法仅声明未使用，生产路径无触发风险，属 API 契约级修复。
• 不涉及 DBus 接口、Wayland 协议、DTK 控件、DConfig 配置，无需同步修改其他仓库。

审核

• 标准-代码审核bot：✅ Approved（已确认早返逻辑正确、count > 0 路径无回归、无副作用、代码风格与既有写法一致）。

Ref: DDE-144

Summary by Sourcery

Ensure firstNItems honors empty-result semantics for non-positive item counts.

Bug Fixes:

• Return an empty list from ItemsPage::firstNItems when the requested count is zero or negative, while preserving positive-count behavior.

Chores:

• Update copyright years for the affected source files.

[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: MyLeeJiEun

The full list of commands accepted by this bot can be found here.

Details

Needs approval from an approver in each of these files:

• debian/deepin/OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Fixes the firstNItems contract for count <= 0 by returning an empty QStringList before iteration, while preserving behavior for all positive counts.

File-Level Changes

Change	Details	Files
Add an early return for non-positive requested counts so the method returns an empty list without entering the item-collection loop.	Handle zero and negative counts as empty-result requests. Leave the existing positive-count iteration and boundary behavior unchanged.	applets/dde-apps/itemspage.cpp

---

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[deepin-ci-robot]

Hi @MyLeeJiEun. Thanks for your PR.

I'm waiting for a linuxdeepin member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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