【发布时间】：2017-10-21 18:48:32
【问题描述】：
我正在尝试编写一些正则表达式来根据条件插入画框字符，但我不断收到预期的编译错误子模式名称。
这是我的代码：
int match_pkg_details(char **pkgdetail, char *pkginfo)
{
PCRE2_SPTR pattern = (PCRE2_SPTR)"^(?!Name|Architecture|URL|Licenses|"\
"Installed Size|Packager|Build Date|"\
"Install Date|Install Script|Validated By| *$).*$";
*pkgdetail = malloc(4096); // FIXME malloc in initializer
char *worker = *pkgdetail;
size_t pattern_length = strlen((char *)pattern);
int errornumber;
PCRE2_SIZE erroroffset;
pcre2_code *regex = pcre2_compile(
pattern,
pattern_length,
PCRE2_MULTILINE,
&errornumber,
&erroroffset,
NULL);
if (regex == NULL)
{
PCRE2_UCHAR buffer[256];
pcre2_get_error_message(errornumber, buffer, sizeof(buffer));
printf("PCRE2 compilation failed at offset %d: %s\n", (int)erroroffset,
buffer);
return 1;
}
PCRE2_SPTR replacement = (PCRE2_SPTR)"(?(?=^Install Reason) a | ((?=(\\w) b | ((?=(\\s) c )))))";
// if starts with Install Reason replace with bottom line arrow }}}
size_t replacement_length = strlen((char*)replacement);
pcre2_code *replacement_regex = pcre2_compile(
replacement,
replacement_length,
PCRE2_EXTENDED,
&errornumber,
&erroroffset,
NULL);
if (replacement_regex == NULL)
{
PCRE2_UCHAR buffer[256];
pcre2_get_error_message(errornumber, buffer, sizeof(buffer));
printf("PCRE2 compilation failed at offset %d: %s\n", (int)erroroffset,
buffer);
return 1;
}
pcre2_match_data *match_data =
pcre2_match_data_create_from_pattern(regex, NULL);
PCRE2_SPTR subject = (PCRE2_SPTR)pkginfo;
size_t length = strlen((char *)subject);
PCRE2_SIZE *ovector = pcre2_get_ovector_pointer(match_data);
ovector[1] = 0;
int rc;
PCRE2_SIZE offset = 0;
uint32_t options = PCRE2_NOTEMPTY_ATSTART | PCRE2_ANCHORED;
while (offset < length - 1 && (rc =
pcre2_match(regex, subject, length, offset, options, match_data, NULL)))
{
offset = ovector[1];
options = 0;
if (rc == PCRE2_ERROR_NOMATCH)
{
ovector[1] = offset + 1;
continue;
}
for (int i = 0; i < rc; i++)
{
PCRE2_SIZE worker_len = strlen(worker);
PCRE2_UCHAR output[4096];
PCRE2_SIZE outlen;
int rs = pcre2_substitute(
replacement_regex,
subject,
length,
offset,
PCRE2_SUBSTITUTE_EXTENDED,
NULL,
NULL,
(PCRE2_SPTR)"@",
1,
output,
&outlen);
PCRE2_SPTR substring_start = subject + ovector[2*i];
size_t substring_length = ovector[2*i+1] - ovector[2*i];
snprintf(worker, 4096, "%.*s\n", (int)substring_length, (char*)substring_start);
worker += (int)substring_length + 1;
}
}
pcre2_match_data_free(match_data);
pcre2_code_free(regex);
return 0;
}
我要匹配的字符串：
Name : cinnamon
Version : 3.4.6-1
Description : Linux desktop which provides advanced innovative features and
a traditional user experience
Architecture : x86_64
URL : https://github.com/linuxmint/Cinnamon
Licenses : GPL2
Groups : None
Provides : None
Depends On : accountsservice caribou cinnamon-settings-daemon
cinnamon-session cinnamon-translations cjs clutter-gtk
gnome-backgrounds gnome-themes-standard gstreamer
libgnome-keyring libkeybinder3 librsvg muffin
python2-cairo python-dbus python2-dbus python2-pillow
python2-pam python2-pexpect python2-pyinotify python2-lxml
cinnamon-control-center cinnamon-screensaver cinnamon-menus
libgnomekbd network-manager-applet nemo polkit-gnome xapps
python2-gobject
Optional Deps : blueberry: Bluetooth support [installed]
gnome-panel: fallback mode
metacity: fallback mode
system-config-printer: printer settings [installed]
Required By : cinnamon-sound-effects
Optional For : None
Conflicts With : None
Replaces : None
Installed Size : 8.31 MiB
Packager : Antonio Rojas <arojas@archlinux.org>
Build Date : Sat 09 Sep 2017 05:38:21 AM CDT
Install Date : Sat 09 Sep 2017 11:37:44 AM CDT
Install Reason : Installed as a dependency for another package
Install Script : No
Validated By : Signature
目前，如果我删除我得到的替换组：
Version : 3.4.6-1
Description : Linux desktop which provides advanced innovative features
and a traditional user experience
Provides : None
Depends On : accountsservice caribou cinnamon-settings-daemon
cinnamon-session cinnamon-translations cjs clutter-gtk gnome-backgrounds
gnome-themes-standard gstreamer libgnome-keyring libkeybinder3 librsvg
muffin python2-cairo python-dbus python2-dbus python2-pillow python2-pam
python2-pexpect python2-pyinotify python2-lxml cinnamon-control-center
cinnamon-screensaver cinnamon-menus libgnomekbd network-manager-applet
nemo polkit-gnome xapps python2-gobject
Optional Deps : blueberry: Bluetooth support [installed]
Required By : cinnamon-sound-effects
Optional For : None
Conflicts With : None
Replaces : None
Install Reason : Installed as a dependency for another package
预期的输出如下所示：
├─ Version : 3.4.6-1
├─ Description : Linux desktop which provides advanced innovative features
│ and a traditional user experience
├─ Provides : None
├─ Depends On : accountsservice caribou cinnamon-settings-daemon
│ cinnamon-session cinnamon-translations cjs clutter-gtk gnome-backgrounds
│ gnome-themes-standard gstreamer libgnome-keyring libkeybinder3 librsvg
│ muffin python2-cairo python-dbus python2-dbus python2-pillow python2-pam
│ python2-pexpect python2-pyinotify python2-lxml cinnamon-control-center
│ cinnamon-screensaver cinnamon-menus libgnomekbd network-manager-applet
│ nemo polkit-gnome xapps python2-gobject
├─ Optional Deps : blueberry: Bluetooth support [installed]
├─ Required By : cinnamon-sound-effects
├─ Optional For : None
├─ Conflicts With : None
├─ Replaces : None
└─ Install Reason : Installed as a dependency for another package
a、b 和 c 仅用于测试目的（我认为我应该将它们替换为命名的捕获组）。一旦我让替换工作正常，我将把regex_compile 部分分解为它自己的方法。如何用pcre2_substitute 替换命名组？
【问题讨论】：
-
(?(^Install Reason)应该是什么？我在regular-expressions.info/refadv.html 的任何条件运算符中都没有看到它 -
我基于 pcre2 文档中的 if then else 语句。 pcre.org/current/doc/html/pcre2pattern.html#SEC21 和
^Install Reason我正在检查它是否是行首的字符。如果它不存在，请检查空格，并且如果没有空格匹配字母。然后我将使用pcre2_substitute替换字符。 -
该页面列出了5种条件。这应该是哪种类型，因为它似乎与它们中的任何一个都不匹配？
-
嗯，很多人混淆了“条件”这个词。有些只是表示常规的“或”是有条件的，或者是可选的子字符串。你想匹配什么文本？如果以后没有帮助，修复当前代码有什么好处？看，您当前的声明中很可能有 2 种类型的拼写错误：1）删除不必要的空格 - 它们是有意义的，2）双反斜杠。
-
您不能只在
condition中添加任何内容，它必须是捕获引用或环视表达式（DEFINE和VERSION是特殊情况）。你是说(?(?=^Install Reason)...|...)吗？