内存中的微型表格
Table, but you can sort it as your wish.
背景故事
本 crate 源于一个真实的需求：表格排序。
这个需求最先起于 uutils/procps 中 top 的排序需求。在最初的实现中我只考虑了单列排序，但随着时间的发展，procps-ng 突然开始了快速发展：他们引入了进程的树状视图。
在这个时候情况没有变得更糟糕，毕竟只是单独写个算法的事儿，不是很难。直到后来，我意识到了危机：ps 命令支持多键排序！
这是什么意思呢？我们使用一个切实的例子来进行展示，避免不好理解。
使用 ps 命令得到的例子
笔者的测试环境为 Debian Testing，为 2026-10-02 的滚动版本。
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❯ ps -eo uid,user,ppid,pid,stat,comm --sort=uid,-ppid,+pid UID USER PPID PID STAT COMMAND 0 root 12170 562880 S systemd-userwor 0 root 12170 563355 S systemd-userwor 0 root 12170 563522 S systemd-userwor 0 root 2655 2663 Ss fusermount3 0 root 1290 1339 Ssl+ Xorg 0 root 1290 1857 S sddm-helper 0 root 2 3 S pool_workqueue_release 0 root 2 4 I< kworker/R-rcu_gp 0 root 2 5 I< kworker/R-sync_wq 0 root 2 6 I< kworker/R-kvfree_rcu_reclaim 0 root 2 7 I< kworker/R-slub_flushwq 0 root 2 8 I< kworker/R-netns 0 root 2 10 I< kworker/0:0H-kblockd 0 root 2 13 I< kworker/R-mm_percpu_wq 0 root 2 15 S ksoftirqd/0 0 root 2 16 I rcu_preempt 0 root 2 17 S rcub/1 0 root 2 18 S rcu_exp_par_gp_kthread_worker/1 0 root 2 19 S rcu_exp_gp_kthread_worker 0 root 2 20 S migration/0 0 root 2 21 S kprobe-optimizer 0 root 2 22 S idle_inject/0 0 root 2 23 S cpuhp/0 0 root 2 24 S cpuhp/1 0 root 2 25 S idle_inject/1 0 root 2 26 S migration/1 0 root 2 27 S ksoftirqd/1 0 root 2 29 I< kworker/1:0H-kblockd 0 root 2 30 S cpuhp/2 0 root 2 31 S idle_inject/2 0 root 2 32 S migration/2 0 root 2 33 S ksoftirqd/2 0 root 2 35 I< kworker/2:0H-kblockd 0 root 2 36 S cpuhp/3 0 root 2 37 S idle_inject/3 0 root 2 38 S migration/3 0 root 2 39 S ksoftirqd/3 0 root 2 41 I< kworker/3:0H-kblockd 0 root 2 42 S cpuhp/4 0 root 2 43 S idle_inject/4 0 root 2 44 S migration/4 0 root 2 45 S ksoftirqd/4 0 root 2 47 I< kworker/4:0H-kblockd 0 root 2 48 S cpuhp/5 0 root 2 49 S idle_inject/5 0 root 2 50 S migration/5 0 root 2 51 S ksoftirqd/5 0 root 2 53 I< kworker/5:0H-kblockd 0 root 2 54 S cpuhp/6 0 root 2 55 S idle_inject/6 0 root 2 56 S migration/6 0 root 2 57 S ksoftirqd/6 0 root 2 59 I< kworker/6:0H-kblockd 0 root 2 60 S cpuhp/7 0 root 2 61 S idle_inject/7 0 root 2 62 S migration/7 0 root 2 63 S ksoftirqd/7 0 root 2 65 I< kworker/7:0H-kblockd 0 root 2 66 S cpuhp/8 0 root 2 67 S idle_inject/8 0 root 2 68 S migration/8 0 root 2 69 S ksoftirqd/8 0 root 2 71 I< kworker/8:0H-kblockd 0 root 2 72 S cpuhp/9 0 root 2 73 S idle_inject/9 0 root 2 74 S migration/9 0 root 2 75 S ksoftirqd/9 0 root 2 77 I< kworker/9:0H-kblockd 0 root 2 78 S cpuhp/10 0 root 2 79 S idle_inject/10 0 root 2 80 S migration/10 0 root 2 81 S ksoftirqd/10 0 root 2 83 I< kworker/10:0H-kblockd 0 root 2 84 S cpuhp/11 0 root 2 85 S idle_inject/11 0 root 2 86 S migration/11 0 root 2 87 S ksoftirqd/11 0 root 2 89 I< kworker/11:0H-kblockd 0 root 2 90 S cpuhp/12 0 root 2 91 S idle_inject/12 0 root 2 92 S migration/12 0 root 2 93 S ksoftirqd/12 0 root 2 95 I< kworker/12:0H-kblockd 0 root 2 96 S cpuhp/13 0 root 2 97 S idle_inject/13 0 root 2 98 S migration/13 0 root 2 99 S ksoftirqd/13 0 root 2 101 I< kworker/13:0H-kblockd 0 root 2 102 S cpuhp/14 0 root 2 103 S idle_inject/14 0 root 2 104 S migration/14 0 root 2 105 S ksoftirqd/14 0 root 2 107 I< kworker/14:0H-kblockd 0 root 2 108 S cpuhp/15 0 root 2 109 S idle_inject/15 0 root 2 110 S migration/15 0 root 2 111 S ksoftirqd/15 0 root 2 113 I< kworker/15:0H-kblockd 0 root 2 114 S cpuhp/16 0 root 2 115 S idle_inject/16 0 root 2 116 S migration/16 0 root 2 117 S ksoftirqd/16 0 root 2 119 I< kworker/16:0H-kblockd 0 root 2 120 S rcub/2 0 root 2 121 S rcu_exp_par_gp_kthread_worker/2 0 root 2 122 S cpuhp/17 0 root 2 123 S idle_inject/17 0 root 2 124 S migration/17 0 root 2 125 S ksoftirqd/17 0 root 2 127 I< kworker/17:0H-kblockd 0 root 2 128 S cpuhp/18 0 root 2 129 S idle_inject/18 0 root 2 130 S migration/18 0 root 2 131 S ksoftirqd/18 0 root 2 133 I< kworker/18:0H-kblockd 0 root 2 134 S cpuhp/19 0 root 2 135 S idle_inject/19 0 root 2 136 S migration/19 0 root 2 137 S ksoftirqd/19 0 root 2 139 I< kworker/19:0H-kblockd 0 root 2 140 S cpuhp/20 0 root 2 141 S idle_inject/20 0 root 2 142 S migration/20 0 root 2 143 S ksoftirqd/20 0 root 2 145 I< kworker/20:0H-kblockd 0 root 2 146 S cpuhp/21 0 root 2 147 S idle_inject/21 0 root 2 148 S migration/21 0 root 2 149 S ksoftirqd/21 0 root 2 151 I< kworker/21:0H-kblockd 0 root 2 152 S cpuhp/22 0 root 2 153 S idle_inject/22 0 root 2 154 S migration/22 0 root 2 155 S ksoftirqd/22 0 root 2 157 I< kworker/22:0H-kblockd 0 root 2 158 S cpuhp/23 0 root 2 159 S idle_inject/23 0 root 2 160 S migration/23 0 root 2 161 S ksoftirqd/23 0 root 2 163 I< kworker/23:0H-kblockd 0 root 2 164 S cpuhp/24 0 root 2 165 S idle_inject/24 0 root 2 166 S migration/24 0 root 2 167 S ksoftirqd/24 0 root 2 169 I< kworker/24:0H-kblockd 0 root 2 170 S cpuhp/25 0 root 2 171 S idle_inject/25 0 root 2 172 S migration/25 0 root 2 173 S ksoftirqd/25 0 root 2 175 I< kworker/25:0H-kblockd 0 root 2 176 S cpuhp/26 0 root 2 177 S idle_inject/26 0 root 2 178 S migration/26 0 root 2 179 S ksoftirqd/26 0 root 2 181 I< kworker/26:0H-kblockd 0 root 2 182 S cpuhp/27 0 root 2 183 S idle_inject/27 0 root 2 184 S migration/27 0 root 2 185 S ksoftirqd/27 0 root 2 187 I< kworker/27:0H-kblockd 0 root 2 188 S cpuhp/28 0 root 2 189 S idle_inject/28 0 root 2 190 S migration/28 0 root 2 191 S ksoftirqd/28 0 root 2 193 I< kworker/28:0H-kblockd 0 root 2 194 S cpuhp/29 0 root 2 195 S idle_inject/29 0 root 2 196 S migration/29 0 root 2 197 S ksoftirqd/29 0 root 2 199 I< kworker/29:0H-kblockd 0 root 2 200 S cpuhp/30 0 root 2 201 S idle_inject/30 0 root 2 202 S migration/30 0 root 2 203 S ksoftirqd/30 0 root 2 205 I< kworker/30:0H-kblockd 0 root 2 206 S cpuhp/31 0 root 2 207 S idle_inject/31 0 root 2 208 S migration/31 0 root 2 209 S ksoftirqd/31 0 root 2 211 I< kworker/31:0H-kblockd 0 root 2 214 S kdevtmpfs 0 root 2 215 I< kworker/R-inet_frag_wq 0 root 2 216 I rcu_tasks_kthread 0 root 2 217 I rcu_tasks_rude_kthread 0 root 2 218 S kauditd 0 root 2 219 S khungtaskd 0 root 2 220 S oom_reaper 0 root 2 223 I< kworker/R-writeback 0 root 2 224 S kcompactd0 0 root 2 225 SN ksmd 0 root 2 226 SN khugepaged 0 root 2 227 I< kworker/R-kblockd 0 root 2 228 I< kworker/R-blkcg_punt_bio 0 root 2 229 I< kworker/R-kintegrityd 0 root 2 231 S irq/9-acpi 0 root 2 234 I< kworker/R-tpm_dev_wq 0 root 2 235 I< kworker/R-ata_sff 0 root 2 236 I< kworker/R-edac-poller 0 root 2 237 I< kworker/R-devfreq_wq 0 root 2 238 S watchdogd 0 root 2 240 I< kworker/R-quota_events_unbound 0 root 2 243 S irq/27-AMD-Vi 0 root 2 248 S kswapd0 0 root 2 249 I< kworker/R-kthrotld 0 root 2 251 S irq/32-pciehp 0 root 2 252 S irq/36-pciehp 0 root 2 253 I< kworker/R-acpi_thermal_pm 0 root 2 255 I< kworker/R-mld 0 root 2 256 I< kworker/R-ipv6_addrconf 0 root 2 257 I< kworker/R-kstrp 0 root 2 279 I< kworker/R-zswap-shrink 0 root 2 285 S irq/28-ACPI:Event 0 root 2 286 S irq/29-ACPI:Event 0 root 2 287 S irq/30-ACPI:Event 0 root 2 288 S irq/31-ACPI:Event 0 root 2 409 S irq/74-ASUF1204:00 0 root 2 410 I< kworker/R-nvme-wq 0 root 2 411 I< kworker/R-nvme-reset-wq 0 root 2 412 I< kworker/R-nvme-delete-wq 0 root 2 413 I< kworker/R-nvme-auth-wq 0 root 2 423 S nv_queue 0 root 2 424 S nv_mem_pool_scrubber_queue 0 root 2 425 S nv_mem_pool_scrubber_queue 0 root 2 426 S nv_mem_pool_scrubber_queue 0 root 2 427 S nv_queue 0 root 2 428 S nv_open_q 0 root 2 429 S nvidia-modeset/kthread_q 0 root 2 430 S nvidia-modeset/deferred_close_kthread_q 0 root 2 432 S irq/96-nvidia 0 root 2 433 S nvidia 0 root 2 434 S nv_queue 0 root 2 435 I< kworker/R-USBC000:00-con1 0 root 2 436 I< kworker/R-amdgpu-reset-dev 0 root 2 437 I< kworker/R-ttm 0 root 2 438 I< kworker/R-amdgpu_dm_hpd_rx_offload_wq 0 root 2 439 I< kworker/R-amdgpu_dm_hpd_rx_offload_wq 0 root 2 440 I< kworker/R-amdgpu_dm_hpd_rx_offload_wq 0 root 2 441 I< kworker/R-amdgpu_dm_hpd_rx_offload_wq 0 root 2 442 I< kworker/R-amdgpu_dm_hpd_rx_offload_wq 0 root 2 443 I< kworker/R-dm_vblank_control_workqueue 0 root 2 444 S card2-crtc0 0 root 2 445 S card2-crtc1 0 root 2 446 S card2-crtc2 0 root 2 447 S card2-crtc3 0 root 2 448 I< kworker/R-gfx_0.0.0 0 root 2 449 I< kworker/R-gfx_0.1.0 0 root 2 450 I< kworker/R-comp_1.0.0 0 root 2 451 I< kworker/R-comp_1.1.0 0 root 2 452 I< kworker/R-comp_1.2.0 0 root 2 453 I< kworker/R-comp_1.3.0 0 root 2 454 I< kworker/R-comp_1.0.1 0 root 2 455 I< kworker/R-comp_1.1.1 0 root 2 456 I< kworker/R-comp_1.2.1 0 root 2 457 I< kworker/R-comp_1.3.1 0 root 2 458 I< kworker/R-sdma0 0 root 2 459 I< kworker/R-vcn_dec_0 0 root 2 460 I< kworker/R-vcn_enc_0.0 0 root 2 461 I< kworker/R-vcn_enc_0.1 0 root 2 462 I< kworker/R-jpeg_dec 0 root 2 490 I< kworker/R-btrfs-worker 0 root 2 491 I< kworker/R-btrfs-delalloc 0 root 2 492 I< kworker/R-btrfs-flush_delalloc 0 root 2 493 I< kworker/R-btrfs-cache 0 root 2 494 I< kworker/R-btrfs-fixup 0 root 2 495 I< kworker/R-btrfs-endio 0 root 2 496 I< kworker/R-btrfs-endio-meta 0 root 2 497 I< kworker/R-btrfs-rmw 0 root 2 498 I< kworker/R-btrfs-endio-write 0 root 2 499 I< kworker/R-btrfs-freespace-write 0 root 2 500 I< kworker/R-btrfs-delayed-meta 0 root 2 501 I< kworker/R-btrfs-qgroup-rescan 0 root 2 502 S btrfs-cleaner 0 root 2 503 S btrfs-transaction 0 root 2 513 I< kworker/12:1H-kblockd 0 root 2 519 I< kworker/2:1H-xfs-log/nvme1n1p3 0 root 2 520 I< kworker/3:1H-xfs-log/nvme1n1p3 0 root 2 521 I< kworker/0:1H-kblockd 0 root 2 523 I< kworker/13:1H-kblockd 0 root 2 524 I< kworker/28:1H-kblockd 0 root 2 525 I< kworker/18:1H-kblockd 0 root 2 528 I< kworker/19:1H-xfs-log/nvme1n1p3 0 root 2 534 I< kworker/14:1H-xfs-log/nvme1n1p3 0 root 2 542 I< kworker/6:1H-kblockd 0 root 2 545 I< kworker/8:1H-kblockd 0 root 2 554 I< kworker/1:1H-xfs-log/nvme1n1p3 0 root 2 563 I< kworker/4:1H-kblockd 0 root 2 578 I< kworker/10:1H-kblockd 0 root 2 591 I< kworker/16:1H-kblockd 0 root 2 598 I< kworker/7:1H-kblockd 0 root 2 623 I< kworker/20:1H-kblockd 0 root 2 635 I< kworker/5:1H-kblockd 0 root 2 636 I< kworker/22:1H-kblockd 0 root 2 637 I< kworker/23:1H-kblockd 0 root 2 638 I< kworker/17:1H-xfs-log/nvme1n1p3 0 root 2 653 I< kworker/9:1H-xfs-log/nvme1n1p3 0 root 2 657 I< kworker/29:1H-kblockd 0 root 2 659 I< kworker/15:1H-kblockd 0 root 2 765 I< kworker/11:1H-xfs-log/nvme1n1p3 0 root 2 768 S UVM global queue 0 root 2 769 S UVM deferred release queue 0 root 2 770 S UVM Tools Event Queue 0 root 2 785 I< kworker/R-cfg80211 0 root 2 799 I< kworker/21:1H-kblockd 0 root 2 836 I< kworker/26:1H-xfs-log/nvme1n1p3 0 root 2 844 S jbd2/nvme1n1p1-8 0 root 2 845 I< kworker/R-ext4-rsv-conversion 0 root 2 852 S irq/102-iwlwifi:default_queue 0 root 2 853 S irq/103-iwlwifi:queue_1 0 root 2 854 S irq/104-iwlwifi:queue_2 0 root 2 855 S irq/105-iwlwifi:queue_3 0 root 2 856 S irq/106-iwlwifi:queue_4 0 root 2 857 S irq/107-iwlwifi:queue_5 0 root 2 858 S irq/108-iwlwifi:queue_6 0 root 2 859 S irq/109-iwlwifi:queue_7 0 root 2 860 S irq/110-iwlwifi:queue_8 0 root 2 861 S irq/111-iwlwifi:queue_9 0 root 2 862 S irq/112-iwlwifi:queue_10 0 root 2 863 S irq/113-iwlwifi:queue_11 0 root 2 864 S irq/114-iwlwifi:queue_12 0 root 2 865 S irq/115-iwlwifi:queue_13 0 root 2 866 S irq/116-iwlwifi:queue_14 0 root 2 867 S irq/117-iwlwifi:exception 0 root 2 869 I< kworker/R-xfsalloc 0 root 2 870 I< kworker/R-xfs_mru_cache 0 root 2 871 I< kworker/R-xfs-buf/nvme1n1p3 0 root 2 872 I< kworker/R-xfs-conv/nvme1n1p3 0 root 2 873 I< kworker/R-xfs-reclaim/nvme1n1p3 0 root 2 874 I< kworker/R-xfs-blockgc/nvme1n1p3 0 root 2 875 I< kworker/R-xfs-inodegc/nvme1n1p3 0 root 2 876 I< kworker/R-xfs-log/nvme1n1p3 0 root 2 877 I< kworker/R-xfs-cil/nvme1n1p3 0 root 2 878 S xfsaild/nvme1n1p3 0 root 2 879 I< kworker/24:1H-xfs-log/nvme1n1p3 0 root 2 881 I< kworker/R-led_workqueue 0 root 2 883 S irq/98-cs35l41 IRQ1 Controller 0 root 2 886 S irq/98-cs35l41 IRQ1 Controller 0 root 2 930 I< kworker/30:1H-xfs-log/nvme1n1p3 0 root 2 1019 I< kworker/25:1H-kblockd 0 root 2 1113 I< kworker/31:1H-kblockd 0 root 2 1180 I< kworker/27:1H-kblockd 0 root 2 1411 S nvidia-drm/timeline-e2 0 root 2 1511 S< krfcommd 0 root 2 2001 S nvidia-drm/timeline-113 0 root 2 2004 S nvidia-drm/timeline-126 0 root 2 2007 S nvidia-drm/timeline-127 0 root 2 2010 S nvidia-drm/timeline-128 0 root 2 2011 S nvidia-drm/timeline-129 0 root 2 2012 S nvidia-drm/timeline-12a 0 root 2 2013 S nvidia-drm/timeline-12b 0 root 2 2014 S nvidia-drm/timeline-12c 0 root 2 2015 S nvidia-drm/timeline-12d 0 root 2 153714 I kworker/31:186-mm_percpu_wq 0 root 2 368865 I kworker/29:2-events_freezable 0 root 2 375105 I kworker/25:2-events 0 root 2 401948 I kworker/11:7-mm_percpu_wq 0 root 2 436295 I kworker/27:0-mm_percpu_wq 0 root 2 463598 I kworker/25:0-mm_percpu_wq 0 root 2 469844 I< kworker/u131:2-hci0 0 root 2 472491 I kworker/3:1-mm_percpu_wq 0 root 2 485578 I kworker/24:1-mm_percpu_wq 0 root 2 490980 I kworker/14:2-mm_percpu_wq 0 root 2 494431 I kworker/22:3-mm_percpu_wq 0 root 2 494458 I kworker/17:7-events 0 root 2 498549 I kworker/24:0 0 root 2 500460 I kworker/28:0-mm_percpu_wq 0 root 2 505935 I kworker/15:0-events 0 root 2 517522 I kworker/26:0-mm_percpu_wq 0 root 2 520369 I kworker/20:0-memcg 0 root 2 525051 I kworker/28:1-xfs-conv/nvme1n1p3 0 root 2 527607 I kworker/9:1-xfs-conv/nvme1n1p3 0 root 2 532255 I kworker/6:0-mm_percpu_wq 0 root 2 532561 I kworker/2:5-mm_percpu_wq 0 root 2 532678 I kworker/13:8-mm_percpu_wq 0 root 2 534213 I kworker/19:0-cgroup_free 0 root 2 534657 I< kworker/u131:0-hci0 0 root 2 540265 I kworker/23:0-mm_percpu_wq 0 root 2 540863 I kworker/u130:17-events_unbound 0 root 2 541036 I kworker/16:1-events 0 root 2 541489 I kworker/12:2 0 root 2 541693 I kworker/0:0-events 0 root 2 541961 I kworker/5:1-mm_percpu_wq 0 root 2 542165 I kworker/8:1-mm_percpu_wq 0 root 2 542596 I kworker/7:2 0 root 2 542890 I kworker/u129:7-events_unbound 0 root 2 543460 I kworker/1:2-mm_percpu_wq 0 root 2 543475 I< kworker/u132:12-ttm 0 root 2 546114 I kworker/18:2-mm_percpu_wq 0 root 2 548148 I kworker/27:1-events 0 root 2 548394 I kworker/29:0 0 root 2 549551 I kworker/16:0-events 0 root 2 552452 I kworker/19:2-mm_percpu_wq 0 root 2 552545 I kworker/26:2-events 0 root 2 553146 I kworker/7:1-mm_percpu_wq 0 root 2 554148 I kworker/31:1-cgroup_free 0 root 2 555918 I kworker/12:1-mm_percpu_wq 0 root 2 556018 I kworker/0:2 0 root 2 556444 I kworker/10:0-mm_percpu_wq 0 root 2 556500 I kworker/u128:0-sdma0 0 root 2 557204 I kworker/1:1 0 root 2 557271 I kworker/21:2-xfs-conv/nvme1n1p3 0 root 2 557276 I kworker/21:8-events 0 root 2 557386 I kworker/23:1 0 root 2 557454 I kworker/13:1 0 root 2 557604 I kworker/20:1-mm_percpu_wq 0 root 2 557727 I< kworker/u133:0-rb_allocator 0 root 2 558130 I kworker/5:0-xfs-conv/nvme1n1p3 0 root 2 558233 I kworker/u130:1-btrfs-endio-write 0 root 2 558361 I kworker/4:0-mm_percpu_wq 0 root 2 558452 I< kworker/u132:1-ttm 0 root 2 558502 I kworker/17:1-mm_percpu_wq 0 root 2 558899 I kworker/11:1 0 root 2 559279 I kworker/15:1-xfs-conv/nvme1n1p3 0 root 2 559388 I kworker/6:2-mm_percpu_wq 0 root 2 560059 I kworker/u129:0-btrfs-endio-write 0 root 2 560092 I kworker/8:2 0 root 2 560593 I kworker/18:1 0 root 2 560603 I kworker/2:1 0 root 2 560631 I kworker/30:1-mm_percpu_wq 0 root 2 560634 I kworker/30:5 0 root 2 560635 I kworker/9:3-mm_percpu_wq 0 root 2 560975 I< kworker/u133:6-ttm 0 root 2 561094 I kworker/u130:6-btrfs-endio-write 0 root 2 561275 I kworker/u128:2-sdma0 0 root 2 561564 I kworker/10:2 0 root 2 561615 I kworker/u129:4-btrfs-endio-write 0 root 2 561912 I kworker/u129:5-btrfs-endio-write 0 root 2 561917 I kworker/22:0 0 root 2 562171 I kworker/14:0 0 root 2 562320 I kworker/4:1 0 root 2 562593 I< kworker/u132:0-rb_allocator 0 root 2 562615 I kworker/u130:0-btrfs-endio-write 0 root 2 562625 I kworker/25:3 0 root 2 562662 I kworker/3:0-mm_percpu_wq 0 root 2 562734 I kworker/5:2 0 root 2 562759 I kworker/u130:2-btrfs-endio 0 root 2 562760 I kworker/u130:3-events_unbound 0 root 2 562779 I kworker/10:1 0 root 2 563267 I< kworker/u131:1 0 root 2 563341 I kworker/u129:1-flush-btrfs-1 0 root 2 563343 I< kworker/u133:1 0 root 2 563359 I kworker/u128:1-gfx_0.1.0 0 root 2 563515 I< kworker/u132:2-rb_allocator 0 root 2 563543 I kworker/31:0 0 root 2 563576 I kworker/u129:2-btrfs-endio 0 root 2 563577 I kworker/u129:3-btrfs-endio-write 0 root 2 563578 I kworker/u129:6-btrfs-endio-meta 0 root 2 563579 I kworker/u129:8-btrfs-endio-write 0 root 2 563580 I kworker/u129:9-writeback 0 root 1 1004 S<sl auditd 0 root 1 1012 Ssl accounts-daemon 0 root 1 1026 Ss cron 0 root 1 1038 Ssl nvidia-powerd 0 root 1 1057 Ss smartd 0 root 1 1059 Ssl switcheroo-cont 0 root 1 1063 Ss systemd-logind 0 root 1 1064 Ssl udisksd 0 root 1 1120 Ssl lxcfs 0 root 1 1170 Ssl NetworkManager 0 root 1 1175 Ss wpa_supplicant 0 root 1 1198 Ssl ModemManager 0 root 1 1269 Ss lxc-monitord 0 root 1 1281 Ssl tuned 0 root 1 1290 Ssl sddm 0 root 1 1293 Ssl asusd 0 root 1 1386 Ssl tuned-ppd 0 root 1 1391 Ssl upowerd 0 root 1 10670 Ss systemd-journal 0 root 1 11078 Ss systemd-udevd 0 root 1 12170 Ss systemd-userdbd 0 root 1 12662 Ss bluetoothd 0 root 1 42686 Ssl fwupd 0 root 1 270970 Ssl cupsd 0 root 0 1 Ss systemd 0 root 0 2 S kthreadd 1000 krysztal 561650 561670 Ssl markdown-oxide 1000 krysztal 561650 561740 S inotifywait 1000 krysztal 561650 563639 Rs ps 1000 krysztal 561649 561650 Ssl nvim 1000 krysztal 558710 561649 S+ nvim 1000 krysztal 558694 558710 Ss zsh 1000 krysztal 553315 553365 Sl Socket Process 1000 krysztal 553315 553388 Sl Isolated Web Co 1000 krysztal 553315 553395 Sl RDD Process 1000 krysztal 553315 553754 Sl WebExtensions 1000 krysztal 553315 553817 Sl Utility Process 1000 krysztal 553315 553845 Sl Web Content 1000 krysztal 553315 553851 Sl Web Content 1000 krysztal 553315 553858 Sl Web Content 1000 krysztal 553155 553315 S forkserver 1000 krysztal 551616 551619 Sl Socket Process 1000 krysztal 551616 551647 Sl Privileged Cont 1000 krysztal 551616 551655 Sl RDD Process 1000 krysztal 551616 551696 Sl Web Content 1000 krysztal 551616 551791 Sl WebExtensions 1000 krysztal 551616 551926 Sl Utility Process 1000 krysztal 551616 554178 Sl Isolated Web Co 1000 krysztal 551616 554257 Sl Isolated Web Co 1000 krysztal 551616 554327 Sl Isolated Web Co 1000 krysztal 551616 554330 Sl Isolated Web Co 1000 krysztal 551616 554335 Sl Isolated Web Co 1000 krysztal 551616 554487 Sl Isolated Web Co 1000 krysztal 551616 555863 Sl Isolated Web Co 1000 krysztal 551616 557336 Sl Isolated Web Co 1000 krysztal 551616 559250 Sl Isolated Web Co 1000 krysztal 551616 559343 Sl Isolated Web Co 1000 krysztal 551616 559445 Sl Isolated Web Co 1000 krysztal 551616 559531 Sl Isolated Web Co 1000 krysztal 551616 559758 Sl Isolated Web Co 1000 krysztal 551616 560163 Sl Web Content 1000 krysztal 551616 560826 Sl Web Content 1000 krysztal 551616 561398 Sl Web Content 1000 krysztal 551520 551616 S forkserver 1000 krysztal 551519 551520 Sl zen 1000 krysztal 551515 551516 Sl xdg-dbus-proxy 1000 krysztal 551509 551519 S bwrap 1000 krysztal 533009 533201 S rust-analyzer-p 1000 krysztal 526803 526806 Sl MainThread 1000 krysztal 526573 526611 Sl mcp-grafana 1000 krysztal 526570 526803 S sh 1000 krysztal 526141 526570 Ssl npm exec @mozil 1000 krysztal 526141 526572 Ssl dart:dartdev_ao 1000 krysztal 526141 526573 Ssl uv 1000 krysztal 526122 526123 Sl+ fzf 1000 krysztal 526073 526122 Ss+ sh 1000 krysztal 526073 526141 Ssl+ pi 1000 krysztal 526073 533009 Ssl rust-analyzer 1000 krysztal 526073 533358 Ssl markdown-oxide 1000 krysztal 526073 533699 Ssl MainThread 1000 krysztal 526072 526073 Ssl nvim 1000 krysztal 472708 526072 S+ nvim 1000 krysztal 472690 472708 Ss zsh 1000 krysztal 437792 437793 Sl glycin-image-rs 1000 krysztal 437784 437792 S bwrap 1000 krysztal 372180 372181 Sl+ fzf 1000 krysztal 333796 333999 S rust-analyzer-p 1000 krysztal 332503 332504 S Discord 1000 krysztal 332486 332553 Sl Discord 1000 krysztal 332479 332486 S Discord 1000 krysztal 332479 332488 Z zypak-sandbox <defunct> 1000 krysztal 332479 332559 Sl Discord 1000 krysztal 332479 332648 Sl Discord 1000 krysztal 332479 332751 Sl Discord 1000 krysztal 332479 437777 Sl flatpak-spawn 1000 krysztal 332474 332475 S socat 1000 krysztal 332474 332479 Sl Discord 1000 krysztal 332473 332474 S com.discordapp. 1000 krysztal 332473 332490 S cat 1000 krysztal 332473 332491 S cat 1000 krysztal 332473 332503 S bwrap 1000 krysztal 332473 332525 Sl chrome_crashpad 1000 krysztal 332469 332470 Sl xdg-dbus-proxy 1000 krysztal 332460 332473 S bwrap 1000 krysztal 331320 331321 Sl MainThread 1000 krysztal 331237 331272 Sl mcp-grafana 1000 krysztal 331233 331320 S sh 1000 krysztal 330998 331233 Ssl npm exec @mozil 1000 krysztal 330998 331234 Ssl dart:dartdev_ao 1000 krysztal 330998 331237 Ssl uv 1000 krysztal 330939 330998 Ssl+ pi 1000 krysztal 330939 333796 Ssl rust-analyzer 1000 krysztal 330939 372180 Ss+ sh 1000 krysztal 330938 330939 Ssl nvim 1000 krysztal 330672 330938 S+ nvim 1000 krysztal 330653 330672 Ss zsh 1000 krysztal 164616 164618 Ss+ zsh 1000 krysztal 89645 89646 Sl+ fzf 1000 krysztal 36976 36979 SLl scdaemon 1000 krysztal 36038 36371 Sl qq 1000 krysztal 36038 561535 Sl qq 1000 krysztal 36036 36038 S qq 1000 krysztal 36035 36067 Sl qq 1000 krysztal 36031 36035 S qq 1000 krysztal 36031 36036 S qq 1000 krysztal 36031 36074 Sl qq 1000 krysztal 36031 36455 Sl qq 1000 krysztal 21961 22176 S rust-analyzer-p 1000 krysztal 21640 21641 Sl MainThread 1000 krysztal 21568 21640 S sh 1000 krysztal 21369 21568 Ssl npm exec @mozil 1000 krysztal 21369 21569 Ssl dart:dartdev_ao 1000 krysztal 21234 21369 Ssl+ pi 1000 krysztal 21234 21961 Ssl rust-analyzer 1000 krysztal 21234 38268 Ssl markdown-oxide 1000 krysztal 21234 89645 Ss+ sh 1000 krysztal 20025 20043 Z sd_espeak-ng-mb <defunct> 1000 krysztal 20025 20045 S sd_espeak-ng 1000 krysztal 20025 20060 Sl sd_dummy 1000 krysztal 20025 20063 S sd_espeak-ng 1000 krysztal 18965 18977 Sl esbuild 1000 krysztal 18954 18965 Sl MainThread 1000 krysztal 18261 332493 Ss bwrap 1000 krysztal 18261 437784 Ss bwrap 1000 krysztal 18145 18146 Sl Telegram 1000 krysztal 18141 18142 Sl xdg-dbus-proxy 1000 krysztal 18135 18145 S bwrap 1000 krysztal 12854 332647 S p11-kit-remote 1000 krysztal 2768 2860 Sl bitwarden-app 1000 krysztal 2767 2768 S bitwarden-app 1000 krysztal 2749 2829 Sl bitwarden-app 1000 krysztal 2734 2749 S bitwarden-app 1000 krysztal 2734 2751 Z zypak-sandbox <defunct> 1000 krysztal 2734 2835 Sl bitwarden-app 1000 krysztal 2733 2734 SLl bitwarden-app 1000 krysztal 2733 2753 S cat 1000 krysztal 2733 2754 S cat 1000 krysztal 2733 2767 S bwrap 1000 krysztal 2729 2730 Sl xdg-dbus-proxy 1000 krysztal 2600 2733 S bwrap 1000 krysztal 2094 2145 S dbus-daemon 1000 krysztal 1991 2059 S fcitx5-wayland- 1000 krysztal 1991 2064 Sl Xwayland 1000 krysztal 1977 1991 Sl kwin_wayland 1000 krysztal 1975 39293 S ssh-agent 1000 krysztal 1882 1885 S (sd-pam) 1000 krysztal 1882 1912 Ss dbus-daemon 1000 krysztal 1882 1913 S<sl pipewire 1000 krysztal 1882 1916 Ss mpris-proxy 1000 krysztal 1882 1917 S<Lsl wireplumber 1000 krysztal 1882 1918 Ssl pipewire 1000 krysztal 1882 1919 S<Lsl pipewire-pulse 1000 krysztal 1882 1975 Ssl gcr-ssh-agent 1000 krysztal 1882 1977 Ssl kwin_wayland_wr 1000 krysztal 1882 1978 Ss ssh-agent 1000 krysztal 1882 2053 Ssl knighttimed 1000 krysztal 1882 2062 Sl fcitx5 1000 krysztal 1882 2094 Ssl at-spi-bus-laun 1000 krysztal 1882 2133 Ssl ksmserver 1000 krysztal 1882 2135 Ssl kded6 1000 krysztal 1882 2181 Ssl plasmashell 1000 krysztal 1882 2184 Sl at-spi2-registr 1000 krysztal 1882 2197 Ssl dconf-service 1000 krysztal 1882 2200 Ssl kwalletmanager5 1000 krysztal 1882 2229 Ssl kactivitymanage 1000 krysztal 1882 2244 SLl kwalletd6 1000 krysztal 1882 2247 Ssl gmenudbusmenupr 1000 krysztal 1882 2248 Ssl kaccess 1000 krysztal 1882 2249 Ssl polkit-kde-auth 1000 krysztal 1882 2253 Ssl org_kde_powerde 1000 krysztal 1882 2256 Ssl xembedsniproxy 1000 krysztal 1882 2324 S xsettingsd 1000 krysztal 1882 2332 Ssl obexd 1000 krysztal 1882 2473 Sl kdeconnectd 1000 krysztal 1882 2600 Ss bwrap 1000 krysztal 1882 2602 Ssl jetbrains-toolb 1000 krysztal 1882 2621 Ssl xdg-desktop-por 1000 krysztal 1882 2624 Ssl DiscoverNotifie 1000 krysztal 1882 2628 Ssl kalendarac 1000 krysztal 1882 2643 Ssl xdg-permission- 1000 krysztal 1882 2655 Ssl xdg-document-po 1000 krysztal 1882 2667 Ssl xdg-desktop-por 1000 krysztal 1882 2706 Ssl xdg-desktop-por 1000 krysztal 1882 2729 S bwrap 1000 krysztal 1882 2755 Ss bwrap 1000 krysztal 1882 3092 Sl jetbrainsd 1000 krysztal 1882 12849 Ssl flatpak-session 1000 krysztal 1882 12854 Ss p11-kit-server 1000 krysztal 1882 18069 Ssl krunner 1000 krysztal 1882 18135 S bwrap 1000 krysztal 1882 18141 S bwrap 1000 krysztal 1882 18261 Ssl flatpak-portal 1000 krysztal 1882 18954 Ssl MainThread 1000 krysztal 1882 20025 Ssl speech-dispatch 1000 krysztal 1882 21234 Ssl nvim 1000 krysztal 1882 36031 Ssl qq 1000 krysztal 1882 36052 Sl chrome_crashpad 1000 krysztal 1882 36974 Ss keyboxd 1000 krysztal 1882 36976 SLsl gpg-agent 1000 krysztal 1882 83210 S catatonit 1000 krysztal 1882 108333 Sl java 1000 krysztal 1882 164613 Ss pasta.avx2 1000 krysztal 1882 164616 Ss conmon 1000 krysztal 1882 330653 Ssl alacritty 1000 krysztal 1882 332460 Ss bwrap 1000 krysztal 1882 332469 S bwrap 1000 krysztal 1882 472690 Ssl alacritty 1000 krysztal 1882 551509 Ss bwrap 1000 krysztal 1882 551515 S bwrap 1000 krysztal 1882 553155 Sl firefox-bin 1000 krysztal 1882 553160 Sl crashhelper 1000 krysztal 1882 558694 Ssl alacritty 1000 krysztal 1857 1939 Ssl+ startplasma-way 1000 krysztal 1 1882 Ss systemd 1000 krysztal 1 1933 SLl ksecretd是否还记得我们定义了 --sort=uid,-ppid,+pid 参数？此时我们来确定他的语义：
uid：按uid升序。无前缀等价于+，默认方向就是”数值/字典升序”-ppid：主键并列时，按ppid降序。-只反转它紧邻的这一个键，不影响其他键+pid：前两个键都并列时，按pid升序(+写了和没写一样，纯显式）
什么你说不好理解，真拿你没办法，人再笨还学不会 SQL 吗？
-- 假设在 output 表SELECT *FROM outputORDER BY uid ASC, ppid DESC, pid ASC借用 SQL/Rust 来进行理解
在刚刚我写了一条 SQL，那么借助这个 SQL 来进行理解：对 uid 进行排序，然后基于 uid 的排序结果对 ppid 进行降序，最后在前者的结果上按照 pid 进行升序，并且始终不违背前者的排序结果。
行吧，那我还是写个 Rust 风格伪代码吧：
fn cmp_rows(a: &Row, b: &Row) -> Ordering { a.uid.cmp(&b.uid) // 主键 .then_with(|| b.ppid.cmp(&a.ppid)) // 平局才求值(惰性),降序 .then_with(|| a.pid.cmp(&b.pid)) // 再平局才求值}
rows.sort_by(cmp_rows);这样就能看懂了，实质上这是一刻逐级精细化的决策树！ 
使用 SQLite 来帮助我们验证一下
接下来我们使用 SQLite 复刻一下我们的猜想，这段代码请 AI 大人帮我写就好了。
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#!/usr/bin/env -S uv run --script# /// script# requires-python = ">=3.11"# ///"""对照实验:Rust 风格比较器 vs SQLite ORDER BY。
复刻 `ps --sort=uid,-ppid,+pid`(等价 SQL:ORDER BY uid ASC, ppid DESC, pid ASC)。零依赖,sqlite3 是标准库。运行:uv run ps_multisort_demo.py"""
import functoolsimport sqlite3
# 摘自真实 `ps -eo uid,ppid,pid,comm` 输出,平局结构是刻意的:# uid 大量并列 → ppid 并列 → 最后靠 pid 决胜ROWS = [ {"uid": 0, "ppid": 12170, "pid": 557285, "comm": "systemd-userwor"}, {"uid": 0, "ppid": 12170, "pid": 558099, "comm": "systemd-userwor"}, {"uid": 0, "ppid": 12170, "pid": 558405, "comm": "systemd-userwor"}, {"uid": 0, "ppid": 2655, "pid": 2663, "comm": "fusermount3"}, {"uid": 0, "ppid": 1290, "pid": 1857, "comm": "sddm-helper"}, {"uid": 0, "ppid": 1290, "pid": 1339, "comm": "Xorg"}, {"uid": 0, "ppid": 2, "pid": 15, "comm": "ksoftirqd/0"}, {"uid": 0, "ppid": 2, "pid": 3, "comm": "pool_workqueue"}, {"uid": 0, "ppid": 2, "pid": 16, "comm": "rcu_preempt"}, {"uid": 0, "ppid": 2, "pid": 4, "comm": "kworker/R-rcu_gp"}, {"uid": 1000, "ppid": 1882, "pid": 553155, "comm": "firefox-bin"}, {"uid": 1000, "ppid": 1882, "pid": 3092, "comm": "jetbrainsd"}, {"uid": 1000, "ppid": 1882, "pid": 108333, "comm": "java"}, {"uid": 1000, "ppid": 1882, "pid": 12849, "comm": "flatpak-session"}, {"uid": 1000, "ppid": 1882, "pid": 21234, "comm": "nvim"}, {"uid": 1000, "ppid": 1, "pid": 1933, "comm": "ksecretd"}, {"uid": 1000, "ppid": 1, "pid": 1882, "comm": "systemd"}, {"uid": 1000, "ppid": 1857, "pid": 1939, "comm": "startplasma-way"},]
FIELDS = ("uid", "ppid", "pid", "comm")
def sort_like_rust(rows): # 与文章中的 Rust 代码逐行对应: # a.uid.cmp(&b.uid) // 主键 # .then_with(|| b.ppid.cmp(&a.ppid)) // 平局才比较,降序 # .then_with(|| a.pid.cmp(&b.pid)) // 再平局才比较 def cmp_rows(a, b): if a["uid"] != b["uid"]: return -1 if a["uid"] < b["uid"] else 1 if a["ppid"] != b["ppid"]: return -1 if b["ppid"] < a["ppid"] else 1 return (a["pid"] > b["pid"]) - (a["pid"] < b["pid"])
return sorted(rows, key=functools.cmp_to_key(cmp_rows))
def sort_by_sqlite(rows): con = sqlite3.connect(":memory:") con.execute(f"CREATE TABLE p ({', '.join(FIELDS)})") con.executemany( f"INSERT INTO p VALUES ({', '.join('?' * len(FIELDS))})", ([row[f] for f in FIELDS] for row in rows), ) rows_out = con.execute("SELECT * FROM p ORDER BY uid ASC, ppid DESC, pid ASC") return [dict(zip(FIELDS, t)) for t in rows_out]
def main(): rust_side, sqlite_side = sort_like_rust(ROWS), sort_by_sqlite(ROWS) assert rust_side == sqlite_side, "两种方法结果不一致!"
print("排序规格 : --sort=uid,-ppid,+pid") print("等价 SQL : ORDER BY uid ASC, ppid DESC, pid ASC") print(f"数据 : 内置示例({len(ROWS)} 行,两种方法结果一致)\n")
print(f"{'UID':>6} {'PPID':>6} {'PID':>7} COMMAND") prev = None for row in rust_side: if prev is not None and row["uid"] != prev: # 主键跨组时分一行 print(" " + "-" * 38) prev = row["uid"] print(f"{row['uid']:>6} {row['ppid']:>6} {row['pid']:>7} {row['comm']}")
if __name__ == "__main__": main()然后可以使用各种工具来检查它是否符合我们的预期，很明显是符合我们的观测的。
实现
道理就先说到这里，显然非常麻烦的是我们要怎么实现这些东西？然后又怎么使得其更加通用？
试想一下：我们以行为储存，以列为行为基准，基于列的数据进行操作得到行的顺序，那么实际上我们是设计了非常小的一款数据库。
兜兜转转，回到了 SQLite 的怀抱。不过我们需要继续限定一下：我们做的不是储存，而是一个小型的查询引擎
参照
自参与 uutils/procps 以来，在没有引入 TUI 界面的时候我都是直接使用了 prettytable-rs 这个库，十分感谢开发者们的付出。
在本轮的调研中我深入查看了这些库
prettytable-rs: 我们最原始的 Table 引擎- tabled：另外一款很流行的输出 Table 的库
非常感谢他们的付出！
行模式
在查看 tabled 的时候我看到了一个很聪明的写法：使用 Tabled 这个派生宏来自动将字段转换成行模式：
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use tabled::Tabled;
#[derive(Tabled)]struct Language<'a> { name: &'a str, designed_by: &'a str, invented_year: usize,}有了行模式，我们相当于免费获得了如下内容：
- 表头：始终可以获得表头的布局
- 输入验证：始终有机会验证输入是否合法，因为我们可以将字段布局展平成为元组作为输入的类型
- 借用
std生态的排序：只要类型实现了PartialOrd这个trait就可以参与排序
那么接下来的考虑便出现了：如何储存异构内容？比如一个 (u8, u16, u32, String) 的行类型我应该怎么储存？
行储存
在 Rust 中，我们可以使用 &dyn Trait 的方式动态派发类型，但显然我们还需要定义如何获取其中的数据、如何解析等等等行为。这是非常复杂的且完全不符合人体工程学的，所以我们应该有更好的选择。
我的希望是可以利用类型在编译期进行检查，而非在运行时动态检查杂七杂八的东西。而对于一行的数据，且其为异构，我们可以让行就是一个普通的结构体，再用派生宏把字段布局展平成编译期元数据。
NOTE
enum？不不不，是结构体与派生宏这个组合。
使用宏，我们可以轻松做到类似静态反射一样的事情。
不过我们依然需要定义支持的类型，但这方面的事情是在编译期为编译期服务
考虑到为编译器服务，我们还是需要定义一组列类型来标记行布局。别忘了，我们至关重要的 Option 也是其中一员：
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#[derive(Clone, Copy, Debug, PartialEq, Eq)]#[rustfmt::skip]pub enum ColumnKind { F64, F32, I128, I16, I32, I64, I8, ISize, U128, U16, U32, U64, U8, USize, String, Bool, /// A nullable column: the kind of the inner, non-`Option` type. Optional(&'static ColumnKind),}于是行定义可以收束成一个 trait：表头与列类型都是编译期常量，再配一个按列下标取用单元格的方法。配套的 ColumnType 约束了合法的单元格类型（Sized + 'static + Clone，并带一个 const KIND 指回对应的 ColumnKind），Option<T> 则经 blanket impl 自动成为可空列：
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pub trait NamedRow: Sized { const KINDS: &'static [ColumnKind]; // 列类型，字段序 const NAMES: &'static [&'static str]; // 表头，字段序 fn cell_as<T: ColumnType>(&self, index: usize) -> Option<&T>;}对于如下的结构体，只要派生一次就免费获得了行定义：
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#[derive(NamedRow)]struct Language { name: String, designed_by: String, invented_year: usize,}注意到，我们用了某种方式自动获取到了 KINDS 与 NAMES，这便是行定义，专门用于定义行类型且为自动派生（当然也可以手写 impl，毫无问题）。派生宏还顺手生成了 From<元组> 的桥接，于是元组字面量依然能作为构造一行的语法糖喂给 push，但元组自身不实现任何 trait。
NOTE
这些只是思维模式，具体实现需要看具体代码
在这个设计之上，我们的行储存就变成了这样的类型：Vec<Language>，还获得编译期的灵活性，可以遍历 Language::KINDS 在运行时做一些事情。看起来很符合直觉，且非常安全的类型化了。
随后我们再想办法看看表头在 Table 一侧怎么处理。
表头
表头其实就是非常简单的做法了：默认表头已经由派生宏写进了 NamedRow::NAMES，是编译期常量；而 Table 内部则用 Vec<String> 储存一份，为自定义表头留出余地。出于偷懒的目的，直接存 String 就行。
依旧是之前的结构体，其默认表头如下所示
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struct Language { name: String, designed_by: String, invented_year: usize,}
// 派生宏生成的 impl 里：const NAMES: &'static [&'static str] = &["name", "designed_by", "invented_year"];表储存
好了，现在我们得到了如下的东西：
- 行类型定义：实现了
NamedRow的结构体 - 表头定义：默认是
R::NAMES，Table内部存Vec<String> - 储存方式：按照行储存，使用
Vec即可
那我们顺理成章就可以得到类型定义：
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pub struct Table<R: NamedRow> { names: Vec<String>, rows: Vec<R>,}其中泛型 R 的定义为行类型，唯一的约束就是实现 NamedRow。
读与写
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impl<R: NamedRow> Table<R> { pub fn new(names: impl IntoIterator<Item = impl Into<String>>) -> Self; pub fn push(&mut self, row: impl Into<R>); pub fn get_as<T: ColumnType>(&self, row: usize, column: usize) -> Option<&T>; pub fn kinds(&self) -> &'static [ColumnKind]; // 其余皆为常规容器访问器}new接受自定义表头，为ps -o uid=HDR式的需求保留；日常构造走零参数的Default，表头就是R::NAMES。push接受impl Into<R>，类型与元数检查全在编译期，所以签名里连Result都不需要。get_as其实没有任何转换：只是self.row(row)?.cell_as(column)，按列下标借用后downcast_ref到T- 返回
None意味着下标越界或T与该列静态类型不符。因为拿错类型是调用方的问题，不是运行时的失败模式。
- 返回
排序
好了，地基打完，终于可以回到核心问题本身。比较器链的语义前面已经验证过，剩下的麻烦只有一个：如何在运行时用列名 + 方向的键列表把这棵决策树搭起来？
回想起我们先前的决定：我们引入了泛型，那么我们也可以约束一下泛型参数必须要实现 PartialOrd，这样我们就把这个操作留给了类型层，可以被类型系统在编译期处理干净。
不过有个例外：浮点类型没有实现 PartialOrd，给了个 total_cmp。基于这个考虑，我想可能只能折中一下约束必须要实现一个 cmp 函数。
给 ColumnType 加一个必需的 cmp（浮点用 total_cmp 就行），这样下来通过派生宏生成 cmp_cell 时连字段类型都不需要知道是什么：
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pub trait ColumnType { fn cmp(a: &Self, b: &Self) -> Ordering;}
pub trait NamedRow: Sized { // ... fn cmp_cell(&self, other: &Self, index: usize) -> Option<Ordering>;}Table 一侧只需要有结构化的键和一个稳定排序：
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pub enum SortDirection { Ascending, Descending }
impl<R: NamedRow> Table<R> { pub fn sort(&mut self, keys: impl IntoIterator<Item = (impl AsRef<str>, SortDirection)>) -> Option<()>;}NOTE
--sort=uid,-ppid,+pid 这种小 DSL 的解析？不不不，那不是我们这个 crate 该做的事，用户会自己找到出路。
投影
至于选中留下什么列，那就更简单了：一个只读视图，构造时把投影坐标到表坐标的翻译一次绑死，之后 get_as 直接用投影本地的下标：
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impl<R: NamedRow> Table<R> { pub fn project(&self, names: impl IntoIterator<Item = impl AsRef<str>>) -> Option<Projection<'_, R>>;}sort(&mut self) 和 Projection<'_, R> 的借用天然互斥，借用检查器会强制我们先排序后投影。这样下来 ps -o pid --sort=ppid 的形态就这么成立了。
最后我们得到了什么？
很显然的，我们得到了一个还算可以的 Table 容器，支持很标准的增删查改，还有最重要的：
- 细化决策树：
sort输入Vec<(String, SortDirection)>键列表，使用稳定排序 - 选中留下什么列，去掉什么列：
project给出只读投影
并且根据上面的需求，我们始终可以为单元格引入一个 Cell 类型来对其进行配置
NOTE
还是那句话，要看具体代码是怎么实现的，上面只是提供了我的思路
代码开源在了 sortable 中