c++ - 如何使用 QRegExp 解析 pacmd 列表输出并查找接收器索引和名称？

Question

通常从终端我使用命令:

pacmd list-sinks|awk '/index:/ {print $0} /name:/ {print $0};'

这给了我这样的输出:

    index: 0
    name: <alsa_output.pci-0000_01_00.1.hdmi-stereo>
    index: 1
    name: <alsa_output.pci-0000_00_1b.0.analog-stereo>
  * index: 2
    name: <alsa_output.usb-0d8c_C-Media_USB_Audio_Device-00-Device.iec958-stereo>

但显然在 Qt 中，当使用 QProcess 命令时，使用 awk 进行解析不起作用，它只是不进行任何解析all 并生成您期望从命令 pacmd list-sinks 获得的全部输出。整个输出如下:

Welcome to PulseAudio! Use "help" for usage information.
>>> 3 sink(s) available.
    index: 0
    name: <alsa_output.pci-0000_01_00.1.hdmi-stereo>
    driver: <module-alsa-card.c>
    flags: HARDWARE DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
    state: SUSPENDED
    suspend cause: IDLE 
    priority: 9050
    volume: 0:  45% 1:  45%
            0: -20,78 dB 1: -20,78 dB
            balance 0,00
    base volume: 100%
                 0,00 dB
    volume steps: 65537
    muted: no
    current latency: 0,00 ms
    max request: 0 KiB
    max rewind: 0 KiB
    monitor source: 0
    sample spec: s16le 2ch 44100Hz
    channel map: front-left,front-right
                 Stereo
    used by: 0
    linked by: 0
    configured latency: 0,00 ms; range is 0,50 .. 371,52 ms
    card: 0 <alsa_card.pci-0000_01_00.1>
    module: 5
    properties:
        alsa.resolution_bits = "16"
        device.api = "alsa"
        device.class = "sound"
        alsa.class = "generic"
        alsa.subclass = "generic-mix"
        alsa.name = "HDMI 0"
        alsa.id = "HDMI 0"
        alsa.subdevice = "0"
        alsa.subdevice_name = "subdevice #0"
        alsa.device = "3"
        alsa.card = "1"
        alsa.card_name = "HDA NVidia"
        alsa.long_card_name = "HDA NVidia at 0xf7080000 irq 17"
        alsa.driver_name = "snd_hda_intel"
        device.bus_path = "pci-0000:01:00.1"
        sysfs.path = "/devices/pci0000:00/0000:00:01.0/0000:01:00.1/sound/card1"
        device.bus = "pci"
        device.vendor.id = "10de"
        device.vendor.name = "NVIDIA Corporation"
        device.product.id = "0e1b"
        device.product.name = "GK107 HDMI Audio Controller"
        device.string = "hdmi:1"
        device.buffering.buffer_size = "65536"
        device.buffering.fragment_size = "32768"
        device.access_mode = "mmap+timer"
        device.profile.name = "hdmi-stereo"
        device.profile.description = "Digital Stereo (HDMI)"
        device.description = "GK107 HDMI Audio Controller Digital Stereo (HDMI)"
        alsa.mixer_name = "Nvidia GPU 42 HDMI/DP"
        alsa.components = "HDA:10de0042,104383f3,00100100"
        module-udev-detect.discovered = "1"
        device.icon_name = "audio-card-pci"
    ports:
        hdmi-output-0: HDMI / DisplayPort (priority 5900, latency offset 0 usec, available: no)
            properties:
                device.icon_name = "video-display"
    active port: <hdmi-output-0>
    index: 1
    name: <alsa_output.pci-0000_00_1b.0.analog-stereo>
    driver: <module-alsa-card.c>
    flags: HARDWARE HW_MUTE_CTRL HW_VOLUME_CTRL DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
    state: SUSPENDED
    suspend cause: IDLE 
    priority: 9959
    volume: 0:  27% 1:  27%
            0: -34,20 dB 1: -34,20 dB
            balance 0,00
    base volume: 100%
                 0,00 dB
    volume steps: 65537
    muted: no
    current latency: 0,00 ms
    max request: 0 KiB
    max rewind: 0 KiB
    monitor source: 1
    sample spec: s16le 2ch 48000Hz
    channel map: front-left,front-right
                 Stereo
    used by: 0
    linked by: 0
    configured latency: 0,00 ms; range is 0,50 .. 341,33 ms
    card: 1 <alsa_card.pci-0000_00_1b.0>
    module: 6
    properties:
        alsa.resolution_bits = "16"
        device.api = "alsa"
        device.class = "sound"
        alsa.class = "generic"
        alsa.subclass = "generic-mix"
        alsa.name = "ALC269VB Analog"
        alsa.id = "ALC269VB Analog"
        alsa.subdevice = "0"
        alsa.subdevice_name = "subdevice #0"
        alsa.device = "0"
        alsa.card = "0"
        alsa.card_name = "HDA Intel PCH"
        alsa.long_card_name = "HDA Intel PCH at 0xf7330000 irq 38"
        alsa.driver_name = "snd_hda_intel"
        device.bus_path = "pci-0000:00:1b.0"
        sysfs.path = "/devices/pci0000:00/0000:00:1b.0/sound/card0"
        device.bus = "pci"
        device.vendor.id = "8086"
        device.vendor.name = "Intel Corporation"
        device.product.id = "1e20"
        device.product.name = "7 Series/C210 Series Chipset Family High Definition Audio Controller"
        device.form_factor = "internal"
        device.string = "front:0"
        device.buffering.buffer_size = "65536"
        device.buffering.fragment_size = "32768"
        device.access_mode = "mmap+timer"
        device.profile.name = "analog-stereo"
        device.profile.description = "Analog Stereo"
        device.description = "Built-in Audio Analog Stereo"
        alsa.mixer_name = "Realtek ALC269VB"
        alsa.components = "HDA:10ec0269,1028052c,00100100"
        module-udev-detect.discovered = "1"
        device.icon_name = "audio-card-pci"
    ports:
        analog-output: Analog Output (priority 9900, latency offset 0 usec, available: unknown)
            properties:

        analog-output-speaker: Speakers (priority 10000, latency offset 0 usec, available: no)
            properties:
                device.icon_name = "audio-speakers"
        analog-output-headphones: Headphones (priority 9000, latency offset 0 usec, available: yes)
            properties:
                device.icon_name = "audio-headphones"
    active port: <analog-output-headphones>
  * index: 2
    name: <alsa_output.usb-0d8c_C-Media_USB_Audio_Device-00-Device.iec958-stereo>
    driver: <module-alsa-card.c>
    flags: HARDWARE DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
    state: RUNNING
    suspend cause: 
    priority: 9048
    volume: 0:  45% 1:  45%
            0: -20,78 dB 1: -20,78 dB
            balance 0,00
    base volume: 100%
                 0,00 dB
    volume steps: 65537
    muted: no
    current latency: 31,29 ms
    max request: 4 KiB
    max rewind: 344 KiB
    monitor source: 4
    sample spec: s16le 2ch 48000Hz
    channel map: front-left,front-right
                 Stereo
    used by: 1
    linked by: 1
    configured latency: 26,00 ms; range is 26,00 .. 1837,50 ms
    card: 3 <alsa_card.usb-0d8c_C-Media_USB_Audio_Device-00-Device>
    module: 22
    properties:
        alsa.resolution_bits = "16"
        device.api = "alsa"
        device.class = "sound"
        alsa.class = "generic"
        alsa.subclass = "generic-mix"
        alsa.name = "USB Audio"
        alsa.id = "USB Audio"
        alsa.subdevice = "0"
        alsa.subdevice_name = "subdevice #0"
        alsa.device = "0"
        alsa.card = "2"
        alsa.card_name = "C-Media USB Audio Device"
        alsa.long_card_name = "C-Media USB Audio Device at usb-0000:00:14.0-1, full speed"
        alsa.driver_name = "snd_usb_audio"
        device.bus_path = "pci-0000:00:14.0-usb-0:1:1.0"
        sysfs.path = "/devices/pci0000:00/0000:00:14.0/usb1/1-1/1-1:1.0/sound/card2"
        udev.id = "usb-0d8c_C-Media_USB_Audio_Device-00-Device"
        device.bus = "usb"
        device.vendor.id = "0d8c"
        device.vendor.name = "C-Media Electronics, Inc."
        device.product.id = "000c"
        device.product.name = "Audio Adapter"
        device.serial = "0d8c_C-Media_USB_Audio_Device"
        device.string = "iec958:2"
        device.buffering.buffer_size = "352800"
        device.buffering.fragment_size = "176400"
        device.access_mode = "mmap+timer"
        device.profile.name = "iec958-stereo"
        device.profile.description = "Digital Stereo (IEC958)"
        device.description = "Audio Adapter Digital Stereo (IEC958)"
        alsa.mixer_name = "USB Mixer"
        alsa.components = "USB0d8c:000c"
        module-udev-detect.discovered = "1"
        device.icon_name = "audio-card-usb"
    ports:
        iec958-stereo-output: Digital Output (S/PDIF) (priority 0, latency offset 0 usec, available: unknown)
            properties:

    active port: <iec958-stereo-output>
>>> 

我想我指挥错了。我使用 awk 命令和解析的代码如下:

QString prog = "pacmd";
QStringList arguments;
QProcess p;
arguments << "list-sinks"<<"|awk '/index:/ {print $0} /name:/ {print $0};'";
QString reply;
p.start(prog, arguments);
if (p.waitForStarted())
{
    p.waitForFinished();
    reply = p.readAllStandardOutput();
    qDebug()<<reply<<endl;
}
else
{
    qDebug()<< "Error using pacmd for getting list of sinks";
}

所以，现在，我尝试在不使用 awk 的情况下解析索引和名称。我能够找到索引，但找不到名称。代码如下:

QString prog = "pacmd";
QStringList arguments;
QProcess p;
arguments << "list-sinks";
QString reply;
p.start(prog, arguments);
if (p.waitForStarted())
{
    p.waitForFinished();
    reply = p.readAllStandardOutput();
    QRegExp rx("index: \\d+|'", Qt::CaseInsensitive);
    QStringList indexList;
    int pos = 0;
    while ((pos = rx.indexIn(reply, pos)) != -1) {
        indexList << rx.capturedTexts();
        pos += rx.matchedLength();
    }
    foreach (QString index, indexList) {
        qDebug()<<index;
    }

    QRegExp rx1("name: \\s*|'", Qt::CaseInsensitive);
    QStringList nameList;
    pos = 0;
    while ((pos = rx1.indexIn(reply, pos)) != -1) {
        nameList << rx1.capturedTexts();
        pos += rx1.matchedLength();
    }
    foreach (QString index, nameList) {
        qDebug()<<index;
    }
}
else
{
    qDebug()<< "Error using pacmd for getting list of sinks";
}

我从代码中得到的输出如下:

"index: 0" 
"index: 1" 
"index: 2" 
"name: " 
"name: " 
"name: " 

如何获取名称以及如下字符串？

name: <alsa_output.pci-0000_01_00.1.hdmi-stereo>

"name:\\s*|'" 不是用于捕获名称的正则表达式的正确模式吗？

谢谢。

Answer 1

首先说明您第一次尝试运行 awk 失败的原因:

管道'|'是 shell 的一个特性(例如 bash)。当您使用 QProcess 运行可执行文件时，这不会在 shell 中运行可执行文件，而是直接运行可执行文件。因此，在您的代码中，pacmd 可执行文件使用命令行参数 list-sinks 和 |awk '/index:/{print $0}/name:/{print $0};'.

要使其工作，您需要首先运行 list-sinks，获取其输出，然后运行 ​​awk 并将其作为输入传递给它，或者如果您取决于特定的 shell，您也可以运行 shell 并将命令行传递给它(在 bash 的情况下，您将传递 -c 和 pacmd list-sinks| awk '/index:/{print $0}/name:/{print $0};' 作为 /bin/bash 的参数)。

关于使用正则表达式解析 name: something，表达式 \s 匹配 whitespace。所以只需将 name:\\s* 更改为 name:\\S* (使用大写的 S)以获得非空白字符.