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📄 pattern matching.mht

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</FONT></PRE></FONT></TD></TR></TBODY></TABLE></DIV>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN315>Speeding Up Interpolated =
Matches</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>while</FONT> <FONT =
color=3D#00ffff>(</FONT>$line =3D &lt;&gt;<FONT color=3D#00ffff>)</FONT> =
<FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ffa500>if</FONT> <FONT color=3D#00ffff>(</FONT>$line =
=3D~ /$pattern/o<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
        <FONT color=3D#bebebe># do something
</FONT>    <FONT color=3D#00ffff>}</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
# <FONT size=3D-1><A =
href=3D"http://pleac.sourceforge.net/include/perl/ch06/popgrep1">download=
 the following standalone program</A></FONT>
#!/usr/bin/perl
# popgrep1 - grep for abbreviations of places that say "pop"
# version 1: slow but obvious way
</FONT><FONT color=3D#cdad00>@popstates</FONT> =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT>CO ON MI WI =
MN<FONT color=3D#00ffff>);</FONT>
<FONT color=3D#ff7f50>LINE:</FONT> <FONT color=3D#ffa500>while</FONT> =
<FONT color=3D#00ffff>(</FONT><FONT color=3D#ff7f50>defined</FONT><FONT =
color=3D#00ffff>(</FONT>$line =3D &lt;&gt;<FONT =
color=3D#00ffff>))</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ffa500>for</FONT> <FONT color=3D#9ac0cd>$state</FONT> =
<FONT color=3D#00ffff>(</FONT><FONT =
color=3D#cdad00>@popstates</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
        <FONT color=3D#ffa500>if</FONT> <FONT =
color=3D#00ffff>(</FONT>$line =3D~ /\b$state\b/<FONT =
color=3D#00ffff>)</FONT> <FONT color=3D#00ffff>{</FONT>
            <FONT color=3D#ff7f50>print</FONT><FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#ffa500>next</FONT> <FONT =
color=3D#ff7f50>LINE</FONT><FONT color=3D#00ffff>;</FONT>
       <FONT color=3D#00ffff>}</FONT>
    <FONT color=3D#00ffff>}</FONT>
<FONT color=3D#00ffff>}</FONT>

<FONT color=3D#bebebe>#-----------------------------
# <FONT size=3D-1><A =
href=3D"http://pleac.sourceforge.net/include/perl/ch06/popgrep2">download=
 the following standalone program</A></FONT>
#!/usr/bin/perl
# popgrep2 - grep for abbreviations of places that say "pop"
# version 2: eval strings; fast but hard to quote
</FONT><FONT color=3D#cdad00>@popstates</FONT> =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT>CO ON MI WI =
MN<FONT color=3D#00ffff>);</FONT>
$code =3D <FONT color=3D#00cd00>'while (defined($line =3D &lt;&gt;)) =
{'</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>for</FONT> <FONT color=3D#9ac0cd>$state</FONT> =
<FONT color=3D#00ffff>(</FONT><FONT =
color=3D#cdad00>@popstates</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    $code .=3D <FONT color=3D#00cd00>"\tif (\$line =3D~ /\\b$state\\b/) =
{ print \$line; next; }\n"</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#00ffff>}</FONT>
$code .=3D <FONT color=3D#00cd00>'}'</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#ff7f50>print</FONT> <FONT color=3D#00cd00>"CODE =
IS\n----\n$code\n----\n"</FONT> <FONT color=3D#ffa500>if</FONT> <FONT =
color=3D#cdcd00>0</FONT><FONT color=3D#00ffff>;</FONT>  <FONT =
color=3D#bebebe># turn on to debug
</FONT><FONT color=3D#ffa500>eval</FONT> $code<FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>die</FONT> <FONT color=3D#ffa500>if</FONT> $@<FONT =
color=3D#00ffff>;</FONT>

<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>while</FONT> <FONT =
color=3D#00ffff>(</FONT><FONT color=3D#ff7f50>defined</FONT><FONT =
color=3D#00ffff>(</FONT>$line =3D &lt;&gt;<FONT =
color=3D#00ffff>))</FONT> <FONT color=3D#00ffff>{</FONT>
     <FONT color=3D#ffa500>if</FONT> <FONT color=3D#00ffff>(</FONT>$line =
=3D~ /\bCO\b/<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT> <FONT color=3D#ff7f50>print</FONT> $line<FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#ffa500>next</FONT><FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#00ffff>}</FONT>
     <FONT color=3D#ffa500>if</FONT> <FONT color=3D#00ffff>(</FONT>$line =
=3D~ /\bON\b/<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT> <FONT color=3D#ff7f50>print</FONT> $line<FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#ffa500>next</FONT><FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#00ffff>}</FONT>
     <FONT color=3D#ffa500>if</FONT> <FONT color=3D#00ffff>(</FONT>$line =
=3D~ /\bMI\b/<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT> <FONT color=3D#ff7f50>print</FONT> $line<FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#ffa500>next</FONT><FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#00ffff>}</FONT>
     <FONT color=3D#ffa500>if</FONT> <FONT color=3D#00ffff>(</FONT>$line =
=3D~ /\bWI\b/<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT> <FONT color=3D#ff7f50>print</FONT> $line<FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#ffa500>next</FONT><FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#00ffff>}</FONT>
     <FONT color=3D#ffa500>if</FONT> <FONT color=3D#00ffff>(</FONT>$line =
=3D~ /\bMN\b/<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT> <FONT color=3D#ff7f50>print</FONT> $line<FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#ffa500>next</FONT><FONT =
color=3D#00ffff>;</FONT> <FONT color=3D#00ffff>}</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
# <FONT size=3D-1><A =
href=3D"http://pleac.sourceforge.net/include/perl/ch06/popgrep3">download=
 the following standalone program</A></FONT>
#!/usr/bin/perl
# popgrep3 - grep for abbreviations of places that say "pop"
# version 3: use build_match_func algorithm
</FONT><FONT color=3D#cdad00>@popstates</FONT> =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT>CO ON MI WI =
MN<FONT color=3D#00ffff>);</FONT>
    $expr =3D <FONT color=3D#98fb98>join</FONT><FONT =
color=3D#00ffff>(</FONT><FONT color=3D#00cd00>'||'</FONT>, <FONT =
color=3D#ff7f50>map</FONT> <FONT color=3D#00ffff>{</FONT> <FONT =
color=3D#00cd00>"m/\\b\</FONT><FONT =
color=3D#cdad00>$popstates</FONT><FONT color=3D#00cd00>[$_]\\b/o"</FONT> =
<FONT color=3D#00ffff>}</FONT> <FONT color=3D#cdcd00>0</FONT>..<FONT =
color=3D#cdad00>$#popstates</FONT><FONT color=3D#00ffff>);</FONT>
$match_any =3D <FONT color=3D#ffa500>eval</FONT> <FONT =
color=3D#00cd00>"sub { $expr }"</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>die</FONT> <FONT color=3D#ffa500>if</FONT> $@<FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>while</FONT> <FONT =
color=3D#00ffff>(</FONT>&lt;&gt;<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>print</FONT> <FONT color=3D#ffa500>if</FONT> =
&amp;$match_any<FONT color=3D#00ffff>;</FONT>
<FONT color=3D#00ffff>}</FONT>

<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>sub</FONT> <FONT color=3D#00ffff>{</FONT>
      <FONT color=3D#ff7f50>m</FONT>/\b<FONT =
color=3D#cdad00>$popstates</FONT><FONT color=3D#00ffff>[</FONT><FONT =
color=3D#cdcd00>0</FONT><FONT color=3D#00ffff>]</FONT>\b/o || <FONT =
color=3D#ff7f50>m</FONT>/\b<FONT color=3D#cdad00>$popstates</FONT><FONT =
color=3D#00ffff>[</FONT><FONT color=3D#cdcd00>1</FONT><FONT =
color=3D#00ffff>]</FONT>\b/o ||
      <FONT color=3D#ff7f50>m</FONT>/\b<FONT =
color=3D#cdad00>$popstates</FONT><FONT color=3D#00ffff>[</FONT><FONT =
color=3D#cdcd00>2</FONT><FONT color=3D#00ffff>]</FONT>\b/o || <FONT =
color=3D#ff7f50>m</FONT>/\b<FONT color=3D#cdad00>$popstates</FONT><FONT =
color=3D#00ffff>[</FONT><FONT color=3D#cdcd00>3</FONT><FONT =
color=3D#00ffff>]</FONT>\b/o ||
      <FONT color=3D#ff7f50>m</FONT>/\b<FONT =
color=3D#cdad00>$popstates</FONT><FONT color=3D#00ffff>[</FONT><FONT =
color=3D#cdcd00>4</FONT><FONT color=3D#00ffff>]</FONT>\b/o
  <FONT color=3D#00ffff>}</FONT>
<FONT color=3D#bebebe>#-----------------------------
# <FONT size=3D-1><A =
href=3D"http://pleac.sourceforge.net/include/perl/ch06/grepauth">download=
 the following standalone program</A></FONT>
#!/usr/bin/perl
# grepauth - print lines that mention both Tom and Nat
</FONT>
$multimatch =3D build_match_all<FONT color=3D#00ffff>(</FONT><FONT =
color=3D#ff7f50>q</FONT>/Tom/, <FONT color=3D#ff7f50>q</FONT>/Nat/<FONT =
color=3D#00ffff>);</FONT>
<FONT color=3D#ffa500>while</FONT> <FONT =
color=3D#00ffff>(</FONT>&lt;&gt;<FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>print</FONT> <FONT color=3D#ffa500>if</FONT> =
&amp;$multimatch<FONT color=3D#00ffff>;</FONT>
<FONT color=3D#00ffff>}</FONT>
<FONT color=3D#ffa500>exit</FONT><FONT color=3D#00ffff>;</FONT>

<FONT color=3D#ffa500>sub</FONT> <FONT =
color=3D#b2dfee>build_match_any</FONT> <FONT color=3D#00ffff>{</FONT> =
build_match_func<FONT color=3D#00ffff>(</FONT><FONT =
color=3D#00cd00>'||'</FONT>, <FONT color=3D#cdad00>@_</FONT><FONT =
color=3D#00ffff>)</FONT> <FONT color=3D#00ffff>}</FONT>
<FONT color=3D#ffa500>sub</FONT> <FONT =
color=3D#b2dfee>build_match_all</FONT> <FONT color=3D#00ffff>{</FONT> =
build_match_func<FONT color=3D#00ffff>(</FONT><FONT =
color=3D#00cd00>'&amp;&amp;'</FONT>, <FONT =
color=3D#cdad00>@_</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>}</FONT>
<FONT color=3D#ffa500>sub</FONT> <FONT =
color=3D#b2dfee>build_match_func</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ffa500>my</FONT> <FONT =
color=3D#9ac0cd>$condition</FONT> =3D <FONT =
color=3D#ff7f50>shift</FONT><FONT color=3D#00ffff>;</FONT>
    <FONT color=3D#ffa500>my</FONT> <FONT =
color=3D#cdad00>@pattern</FONT> =3D <FONT color=3D#cdad00>@_</FONT><FONT =
color=3D#00ffff>;</FONT>  <FONT color=3D#bebebe># must be lexical =
variable, not dynamic one
</FONT>    <FONT color=3D#ffa500>my</FONT> <FONT =
color=3D#9ac0cd>$expr</FONT> =3D <FONT color=3D#98fb98>join</FONT> =
$condition =3D&gt; <FONT color=3D#ff7f50>map</FONT> <FONT =
color=3D#00ffff>{</FONT> <FONT color=3D#00cd00>"m/\</FONT><FONT =
color=3D#cdad00>$pattern</FONT><FONT color=3D#00cd00>[$_]/o"</FONT> =
<FONT color=3D#00ffff>}</FONT> <FONT color=3D#00ffff>(</FONT><FONT =
color=3D#cdcd00>0</FONT>..<FONT color=3D#cdad00>$#pattern</FONT><FONT =
color=3D#00ffff>);</FONT>
    <FONT color=3D#ffa500>my</FONT> <FONT =
color=3D#9ac0cd>$match_func</FONT> =3D <FONT color=3D#ffa500>eval</FONT> =
<FONT color=3D#00cd00>"sub { local \$_ =3D shift if \</FONT><FONT =
color=3D#cdad00>@_</FONT><FONT color=3D#00cd00>; $expr }"</FONT><FONT =
color=3D#00ffff>;</FONT>
    <FONT color=3D#ffa500>die</FONT> <FONT color=3D#ffa500>if</FONT> =
$@<FONT color=3D#00ffff>;</FONT>  <FONT color=3D#bebebe># propagate $@; =
this shouldn't happen!
</FONT>    <FONT color=3D#ffa500>return</FONT> $match_func<FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#00ffff>}</FONT>

<FONT color=3D#bebebe>#-----------------------------
# <FONT size=3D-1><A =
href=3D"http://pleac.sourceforge.net/include/perl/ch06/popgrep4">download=
 the following standalone program</A></FONT>
#!/usr/bin/perl
# popgrep4 - grep for abbreviations of places that say "pop"
# version 4: use Regexp module
</FONT><FONT color=3D#ffa500>use</FONT> <FONT =
color=3D#b2dfee>Regexp</FONT><FONT color=3D#00ffff>;</FONT>
<FONT color=3D#cdad00>@popstates</FONT> =3D <FONT =
color=3D#ff7f50>qw</FONT><FONT color=3D#00ffff>(</FONT>CO ON MI WI =
MN<FONT color=3D#00ffff>);</FONT>
<FONT color=3D#cdad00>@poppats</FONT>   =3D <FONT =
color=3D#ff7f50>map</FONT> <FONT color=3D#00ffff>{</FONT> =
Regexp-&gt;new<FONT color=3D#00ffff>(</FONT> <FONT =
color=3D#00cd00>'\b'</FONT> . $_ . <FONT =
color=3D#00cd00>'\b'</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>}</FONT> <FONT color=3D#cdad00>@popstates</FONT><FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#ffa500>while</FONT> <FONT color=3D#00ffff>(</FONT><FONT =
color=3D#ff7f50>defined</FONT><FONT color=3D#00ffff>(</FONT>$line =3D =
&lt;&gt;<FONT color=3D#00ffff>))</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ffa500>for</FONT> <FONT =
color=3D#9ac0cd>$patobj</FONT> <FONT color=3D#00ffff>(</FONT><FONT =
color=3D#cdad00>@poppats</FONT><FONT color=3D#00ffff>)</FONT> <FONT =
color=3D#00ffff>{</FONT>
        <FONT color=3D#ff7f50>print</FONT> $line <FONT =
color=3D#ffa500>if</FONT> $patobj-&gt;match<FONT =
color=3D#00ffff>(</FONT>$line<FONT color=3D#00ffff>);</FONT>
    <FONT color=3D#00ffff>}</FONT>
<FONT color=3D#00ffff>}</FONT>

<FONT color=3D#bebebe>#-----------------------------
</FONT></PRE></FONT></TD></TR></TBODY></TABLE></DIV>
<DIV class=3DSECT2>
<H2 class=3DSECT2><A name=3DAEN318>Testing for a Valid Pattern</A></H2>
<TABLE width=3D"100%" bgColor=3D#2f4f4f border=3D0>
  <TBODY>
  <TR>
    <TD><PRE class=3DSCREEN><FONT color=3D#f5deb3 size=3D+1><FONT =
color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>do</FONT> <FONT color=3D#00ffff>{</FONT>
    <FONT color=3D#ff7f50>print</FONT> <FONT color=3D#00cd00>"Pattern? =
"</FONT><FONT color=3D#00ffff>;</FONT>
    <FONT color=3D#ff7f50>chomp</FONT><FONT color=3D#00ffff>(</FONT>$pat =
=3D &lt;&gt;<FONT color=3D#00ffff>);</FONT>
    <FONT color=3D#ffa500>eval</FONT> <FONT color=3D#00ffff>{</FONT> =
<FONT color=3D#00cd00>""</FONT> =3D~ /$pat/ <FONT =
color=3D#00ffff>};</FONT>
    <FONT color=3D#98fb98>warn</FONT> <FONT color=3D#00cd00>"INVALID =
PATTERN $@"</FONT> <FONT color=3D#ffa500>if</FONT> $@<FONT =
color=3D#00ffff>;</FONT>
<FONT color=3D#00ffff>}</FONT> <FONT color=3D#ffa500>while</FONT> =
$@<FONT color=3D#00ffff>;</FONT>
<FONT color=3D#bebebe>#-----------------------------
</FONT><FONT color=3D#ffa500>sub</FONT> <FONT =
12345

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