我正在尝试编写一些正则表达式来插入基于条件的框图字符，但我不断得到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;
}
我正在匹配的字符串：
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，如果我删除替换组，我会：
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
预期输出如下：
├─ 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（我想我应该用命名的捕获组替换它们）。一旦我让替换工作正常，我将打破regex_compile部分的自己的方法。如何使用pcre2_substitute替换命名组？
答案 0 :(得分：1)
你试图在错误的地方做你的逻辑。您需要在替换模式中处理它，而不是在正则表达式模式中处理它。
首先，让我们编写一个模式来识别字符串的不同部分：
^(?:
(?<remove>(?:
Name|Architecture|URL|Licenses|
Installed[ ]Size|Packager|Build[ ]Date|
Install[ ]Date|Install[ ]Script|Validated[ ]By
)\s*:[^\n]*\n)
|(?<last>(?=Install[ ]Reason\s*:))
|(?<field>(?=\S))
|(?<cont>(?=\s))
)
使用mx选项（PCRE2_MULTILINE | PCRE2_EXTENDED），但我们在C代码中确实不需要PCRE2_EXTENDED。
这将识别字符串的某些部分，并在结果中填充一个命名的捕获组：
remove要删除的部分last field cont表示值继续（没有字段标签的行）接下来，我们必须用不同的字符串替换每个部分：
remove =＆gt; （空字符串） last =＆gt; └─（我将在下面的程序中使用\-）field =＆gt; ├─（我将在下面的程序中使用+-）cont =＆gt; │（我将在下面的程序中使用|）我们可以让PCRE通过PCRE2_SUBSTITUTE_EXTENDED（docs）处理该问题：
设置
PCRE2_SUBSTITUTE_EXTENDED的第二个效果是为群组替换增加更多灵活性。语法类似于Bash使用的语法：${<n>:-<string>} ${<n>:+<string1>:<string2>}和以前一样，
的便捷简写<n>可以是组号或名称。第一种形式指定默认值。如果设置了组<n>，则插入其值;如果不是，则展开<string>并插入结果。第二种形式指定分别设置或取消设置组<n>时展开和插入的字符串。第一种形式只是${<n>:+${<n>}:<string>}
因此，使用该语法，我们的替换字符串如下所示：
${remove:+:${last:+\\- :${field:++- :${cont:+| :}}}}
这是一个完整的演示：
#include <stdio.h>
#define PCRE2_CODE_UNIT_WIDTH 8
#include <pcre2.h>
PCRE2_SPTR input =
"Name : cinnamon\n"
"Version : 3.4.6-1\n"
"Description : Linux desktop which provides advanced innovative features and\n"
" a traditional user experience\n"
"Architecture : x86_64\n"
"URL : https://github.com/linuxmint/Cinnamon\n"
"Licenses : GPL2\n"
"Groups : None\n"
"Provides : None\n"
"Depends On : accountsservice caribou cinnamon-settings-daemon\n"
" cinnamon-session cinnamon-translations cjs clutter-gtk\n"
" gnome-backgrounds gnome-themes-standard gstreamer \n"
" libgnome-keyring libkeybinder3 librsvg muffin \n"
" python2-cairo python-dbus python2-dbus python2-pillow\n"
" python2-pam python2-pexpect python2-pyinotify python2-lxml\n"
" cinnamon-control-center cinnamon-screensaver cinnamon-menus\n"
" libgnomekbd network-manager-applet nemo polkit-gnome xapps\n"
" python2-gobject\n"
"Optional Deps : blueberry: Bluetooth support [installed]\n"
" gnome-panel: fallback mode\n"
" metacity: fallback mode\n"
" system-config-printer: printer settings [installed]\n"
"Required By : cinnamon-sound-effects\n"
"Optional For : None\n"
"Conflicts With : None\n"
"Replaces : None\n"
"Installed Size : 8.31 MiB\n"
"Packager : Antonio Rojas <arojas@archlinux.org>\n"
"Build Date : Sat 09 Sep 2017 05:38:21 AM CDT\n"
"Install Date : Sat 09 Sep 2017 11:37:44 AM CDT\n"
"Install Reason : Installed as a dependency for another package\n"
"Install Script : No\n"
"Validated By : Signature\n";
PCRE2_SPTR pattern =
"^(?:"
"(?<remove>(?:"
"Name|Architecture|URL|Licenses|"
"Installed Size|Packager|Build Date|"
"Install Date|Install Script|Validated By"
")\\s*:[^\n]*\n)"
"|(?<last>(?=Install Reason\\s*:))"
"|(?<field>(?=\\S))"
"|(?<cont>(?=\\s))"
")";
PCRE2_SPTR replacement =
"${remove:+:${last:+\\\\- :${field:++- :${cont:+| :}}}}";
static void print_error(int code)
{
PCRE2_UCHAR message[256];
if (pcre2_get_error_message(code, &message, sizeof(message) / sizeof(PCRE2_UCHAR)))
puts(message);
}
int main()
{
pcre2_code *re;
pcre2_match_context *match_context;
int result, error;
PCRE2_SIZE erroffset, outlength;
PCRE2_UCHAR* outbuf;
re = pcre2_compile(pattern, PCRE2_ZERO_TERMINATED, PCRE2_MULTILINE, &error, &erroffset, 0);
if (!re)
{
print_error(error);
return 1;
}
match_context = pcre2_match_context_create(0);
outlength = 0;
result = pcre2_substitute(
re,
input,
PCRE2_ZERO_TERMINATED,
0,
PCRE2_SUBSTITUTE_GLOBAL | PCRE2_SUBSTITUTE_OVERFLOW_LENGTH | PCRE2_SUBSTITUTE_EXTENDED,
0,
match_context,
replacement,
PCRE2_ZERO_TERMINATED,
0,
&outlength
);
if (result != PCRE2_ERROR_NOMEMORY)
{
print_error(result);
return ;
}
outbuf = malloc(outlength * sizeof(PCRE2_UCHAR));
result = pcre2_substitute(
re,
input,
PCRE2_ZERO_TERMINATED,
0,
PCRE2_SUBSTITUTE_GLOBAL | PCRE2_SUBSTITUTE_EXTENDED,
0,
match_context,
replacement,
PCRE2_ZERO_TERMINATED,
outbuf,
&outlength
);
if (result < 0)
{
print_error(result);
return;
}
puts(outbuf);
free(outbuf);
pcre2_match_context_free(match_context);
pcre2_code_free(re);
return 0;
}
输出结果为：
+- Version : 3.4.6-1
+- Description : Linux desktop which provides advanced innovative features and
| a traditional user experience
+- 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
\- Install Reason : Installed as a dependency for another package
我想我应该提一下，在你的情况下，手动执行字符串操作肯定会更容易，而不是通过正则表达式模式。