Question

我刚问了一个关于如何check if the current line is blank or not in Perl的问题。

适用于当前行，但如何检查 next 行是否为空？

要解析的文本文件:(我需要解析文本文件并创建一个新的XML文件）

constant fixup GemEstabCommDelay = <U2 20>
    vid = 6
    name = "ESTABLISHCOMMUNICATIONSTIMEOUT"
    units = "s"
    min = <U2 0>
    max = <U2 1800>
    default = <U2 20>


constant fixup private GemConstantFileName = <A "C:\\TMP\\CONST.LOG">
    vid = 4
    name = ""  units = ""


constant fixup private GemAlarmFileName = <A "C:\\TMP\\ALARM.LOG">
    vid = 0
    name = ""
    units = ""

我想要下面的输出。

<EquipmentConstants>
<ECID logicalName="GemEstabCommDelay " valueType="U2" value="20" vid="6" name="ESTABLISHCOMMUNICATIONSTIMEOUT" units="s" min="0" max="1800" default="20"></ECID>
<ECID logicalName="GemConstantFileName" valueType="A" value="C:\\TMP\\CONST.LOG" vid="4" name="" units=""></ECID>
<ECID logicalName="GemAlarmFileName" valueType="A" value="C:\\TMP\\ALARM.LOG" vid="0" name="" units=""></ECID>
</EquipmentConstants>

Answer 1

让perl为你做。将句柄放在paragraph mode：

中

$/ = "";  # paragraph mode
while (<>) {
    ...
}

现在在循环的每次迭代中，$_将包含整个记录，其中每条记录由两个或多个换行符分隔。

看到它的实际效果：

#! /usr/bin/perl

use warnings;
use strict;

use 5.10.0;  # for named capture buffers and %+

my $equipconst = qr/
  ^
  constant \s+ fixup \s+ (?:private \s+)?
  (?<logicalName>.+?)  # non-greedy to right-trim whitespace
  \s+ = \s+
  < (?<valueType>\S+) \s+ (?<value>\S+) >
/x;

my $equipattr = qr/
    \s*
    (?<name>\S+)
    \s* = \s*
    (?<value>.+?)  # must be non-greedy!
/x;

# read from DATA rather than standard input/named arguments
# (used for demo purposes only)
*ARGV = *DATA;

print "<EquipmentConstants>\n";

$/ = "";
while (<>) {
  if (/$equipconst/g) {
    my @attrs = map [ $_ => $+{$_} ] =>
                qw/ logicalName valueType value /;

    # \G picks up where the last //g stopped
    while (/\G $equipattr (?=\s*$|$equipattr)/gx) {
      my($name,$value) = @+{ qw/ name value / };

      # discard tag, e.g., <U2 1800> becomes 1800
      $value =~ s/<.+ (.+)>/$1/;
      push @attrs => [ $name => $value ];
    }

    my $attrs = join " ",
                map {
                  # strip quotes if present
                  $_->[1] =~ s/^"(.*)"$/$1/;
                  qq{$_->[0]="$_->[1]"};
                }
                @attrs;

    print "<ECID $attrs></ECID>\n";
  }
}

print "</EquipmentConstants>\n";

__DATA__
constant fixup GemEstabCommDelay = <U2 20>
    vid = 6
    name = "ESTABLISHCOMMUNICATIONSTIMEOUT"
    units = "s"
    min = <U2 0>
    max = <U2 1800>
    default = <U2 20>


constant fixup private GemConstantFileName = <A "C:\\TMP\\CONST.LOG">
    vid = 4
    name = ""  units = ""


constant fixup private GemAlarmFileName = <A "C:\\TMP\\ALARM.LOG">
    vid = 0
    name = ""
    units = ""

输出：

<EquipmentConstants>
<ECID logicalName="GemEstabCommDelay" valueType="U2" value="20" vid="6" name="ESTABLISHCOMMUNICATIONSTIMEOUT" units="s" min="0" max="1800" default="20"></ECID>
<ECID logicalName="GemConstantFileName" valueType="A" value="C:\\TMP\\CONST.LOG" vid="4" name="" units=""></ECID>
<ECID logicalName="GemAlarmFileName" valueType="A" value="C:\\TMP\\ALARM.LOG" vid="0" name="" units=""></ECID>
</EquipmentConstants>

请注意，它与您的规范略有不同：第一个logicalName属性不包含空格。

Answer 2

使用单独的变量来存储当前行和下一行：

$_ = <>;
while ($next_line = <>) {
    if ($next_line !~ /\S/) {
        # do something with $_ when next line is blank
    } else {
        # do something else with $_ when next line is not blank
    }
    $_ = $next_line;
}
# $_ now contains last line of file -- you may want to do something with it here

Answer 3

我不确定你想要什么，但我想你想要在每个块的最后显示具有“units = xxx”的块。如果没有，请清楚描述您的输出

$/ = "\n\n"; #set record separator
while (<>) {
    chomp;
    @F = split(/\n/, $_);
    if ($F[-1] =~ /units/) {
        print $_ ."\n";
    }
}

输出

$ perl test.pl file

constant fixup private GemConstantFileName = <A "C:\\TMP\\CONST.LOG">
    vid = 4
    name = ""  units = ""

constant fixup private GemAlarmFileName = <A "C:\\TMP\\ALARM.LOG">
    vid = 0
    name = ""
    units = ""

Answer 4

use strict;
my @lines=<>; # slurp-in the whole file

for (my $i=0; $i<@lines-1; $i++) {
  print "line " .  ($i + 1) . " : next line is blank\n" if $lines[$i+1] =~ /^\s*$/;
}

Answer 5

如果您不关心内存使用情况，或者您正在阅读的文件相对较小，您只需将其全部读入数组即可。

@lines = <>;

for ($i = 0; $i < @lines; $i++)
{
    print "Current line blank" if ( "" eq @lines[$i]);
    print "Next line blank"    if ( "" eq @lines[$i + 1]);
}

如何检查Perl中的下一行是否为空？

5 个答案: