NAME
    Apache::LogFormat::Compiler - Compile LogFormat to perl-code

SYNOPSIS
      use Apache::LogFormat::Compiler;

      my $log_handler = Apache::LogFormat::Compiler->new("combined");
      my $log = $log_handler->log_line(
          $env,
          $res,
          $length,
          $reqtime,
          $time
      );

DESCRIPTION
    Compile LogFormat to perl-code. For faster generating access_log line.

METHOD
    new($fmt:String)
        Takes a format string (or a preset template "combined" or "custom")
        to specify the log format. This middleware implements a subset of
        Apache's LogFormat templates
        <http://httpd.apache.org/docs/2.0/mod/mod_log_config.html>:

           %%    a percent sign
           %h    REMOTE_ADDR from the PSGI environment, or -
           %l    remote logname not implemented (currently always -)
           %u    REMOTE_USER from the PSGI environment, or -
           %t    [local timestamp, in default format]
           %r    REQUEST_METHOD, REQUEST_URI and SERVER_PROTOCOL from the PSGI environment
           %s    the HTTP status code of the response
           %b    content length of the response
           %T    custom field for handling times in subclasses
           %D    custom field for handling sub-second times in subclasses
           %v    SERVER_NAME from the PSGI environment, or -
           %V    HTTP_HOST or SERVER_NAME from the PSGI environment, or -
           %p    SERVER_PORT from the PSGI environment
           %P    the worker's process id
           %m    REQUEST_METHOD from the PSGI environment
           %U    PATH_INFO from the PSGI environment
           %q    QUERY_STRING from the PSGI environment
           %H    SERVER_PROTOCOL from the PSGI environment

        Some of these format fields are only supported by middleware that
        subclasses "AccessLog".

        In addition, custom values can be referenced, using "%{name}", with
        one of the mandatory modifier flags "i", "o" or "t":

           %{variable-name}i    HTTP_VARIABLE_NAME value from the PSGI environment
           %{header-name}o      header-name header in the response
           %{time-format]t      localtime in the specified strftime format

    log_line($env:HashRef,$res:ArrayRef,$length:Integer,$reqtime:Integer,$ti
    me:Integer): $log:String
        Generates log line.

          $env      PSGI-style $env
          $res      PSGI-style $res
          $length   Content-Length
          $reqtime  the time taken to serve request in microseconds 
          $time     time the request was received

        Sample psgi

          use Plack::Builder;
          use Time::HiRes;
          use Apache::LogFormat::Compiler;

          my $log_handler = Apache::LogFormat::Compiler->new(
              '%h %l %u %t "%r" %>s %b "%{Referer}i" "%{User-agent}i" %D'
          );
          my $compile_log_app = builder {
              enable sub {
                  my $app = shift;
                  sub {
                      my $env = shift;
                      my $t0 = [gettimeofday];
                      my $res = $app->();
                      my $reqtime = int(Time::HiRes::tv_interval($t0) * 1_000_000);
                      $env->{psgi.error}->print($log_handler->log_line(
                          $env,$res,6,$reqtime, $t0->[0]));
                  }
              };
              $app
          };

ADD CUSTOM FORMAT STRING
    Apache::LogFormat::Compiler allows to add custom format string

      my $log_handler = Apache::LogFormat::Compiler->new(
          '%z %{HTTP_X_FORWARDED_FOR|REMOTE_ADDR}Z',
          char_handlers => +{
              'z' => sub {
                  my ($env,$req) = @_;
                  return $env->{HTTP_X_FORWARDED_FOR};
              }
          },
          block_handlers => +{
              'Z' => sub {
                  my ($block,$env,$req) = @_;
                  # block eq 'HTTP_X_FORWARDED_FOR|REMOTE_ADDR'
                  my ($main, $alt) = split('\|', $args);
                  return exists $env->{$main} ? $env->{$main} : $env->{$alt};
              }
          },
      );

    Any single letter can be used other than Apache::LogFormat::Compiler
    used. Your sub is called with two or three arguments the content inside
    the "{}" from the format (block_handlers only), PSGI environment ($env),
    and ArrayRef of the response. It should return the string to be logged

AUTHOR
    Masahiro Nagano <kazeburo@gmail.com>

SEE ALSO
    Plack::Middleware::AccessLog,
    <http://httpd.apache.org/docs/2.2/mod/mod_log_config.html>

LICENSE
    Copyright (C) Masahiro Nagano

    This library is free software; you can redistribute it and/or modify it
    under the same terms as Perl itself.