checker.pm

UNIX下perl实现代码

#############################################################################
# Pod/Checker.pm -- check pod documents for syntax errors
#
# Copyright (C) 1994-2000 by Bradford Appleton. All rights reserved.
# This file is part of "PodParser". PodParser is free software;
# you can redistribute it and/or modify it under the same terms
# as Perl itself.
#############################################################################

package Pod::Checker;

use vars qw($VERSION);
$VERSION = 1.2;  ## Current version of this package
require  5.005;    ## requires this Perl version or later

use Pod::ParseUtils; ## for hyperlinks and lists

=head1 NAME

Pod::Checker, podchecker() - check pod documents for syntax errors

=head1 SYNOPSIS

  use Pod::Checker;

  $syntax_okay = podchecker($filepath, $outputpath, %options);

  my $checker = new Pod::Checker %options;
  $checker->parse_from_file($filepath, \*STDERR);

=head1 OPTIONS/ARGUMENTS

C<$filepath> is the input POD to read and C<$outputpath> is
where to write POD syntax error messages. Either argument may be a scalar
indicating a file-path, or else a reference to an open filehandle.
If unspecified, the input-file it defaults to C<\*STDIN>, and
the output-file defaults to C<\*STDERR>.

=head2 podchecker()

This function can take a hash of options:

=over 4

=item B<-warnings> =E<gt> I<val>

Turn warnings on/off. I<val> is usually 1 for on, but higher values
trigger additional warnings. See L<"Warnings">.

=back

=head1 DESCRIPTION

B<podchecker> will perform syntax checking of Perl5 POD format documentation.

I<NOTE THAT THIS MODULE IS CURRENTLY IN THE BETA STAGE!>

It is hoped that curious/ambitious user will help flesh out and add the
additional features they wish to see in B<Pod::Checker> and B<podchecker>
and verify that the checks are consistent with L<perlpod>.

The following checks are currently preformed:

=over 4

=item *

Unknown '=xxxx' commands, unknown 'XE<lt>...E<gt>' interior-sequences,
and unterminated interior sequences.

=item *

Check for proper balancing of C<=begin> and C<=end>. The contents of such
a block are generally ignored, i.e. no syntax checks are performed.

=item *

Check for proper nesting and balancing of C<=over>, C<=item> and C<=back>.

=item *

Check for same nested interior-sequences (e.g. 
C<LE<lt>...LE<lt>...E<gt>...E<gt>>).

=item *

Check for malformed or nonexisting entities C<EE<lt>...E<gt>>.

=item *

Check for correct syntax of hyperlinks C<LE<lt>...E<gt>>. See L<perlpod>
for details.

=item *

Check for unresolved document-internal links. This check may also reveal
misspelled links that seem to be internal links but should be links
to something else.

=back

=head1 DIAGNOSTICS

=head2 Errors

=over 4

=item * empty =headn

A heading (C<=head1> or C<=head2>) without any text? That ain't no
heading!

=item * =over on line I<N> without closing =back

The C<=over> command does not have a corresponding C<=back> before the
next heading (C<=head1> or C<=head2>) or the end of the file.

=item * =item without previous =over

=item * =back without previous =over

An C<=item> or C<=back> command has been found outside a
C<=over>/C<=back> block.

=item * No argument for =begin

A C<=begin> command was found that is not followed by the formatter
specification.

=item * =end without =begin

A standalone C<=end> command was found.

=item * Nested =begin's

There were at least two consecutive C<=begin> commands without
the corresponding C<=end>. Only one C<=begin> may be active at
a time.

=item * =for without formatter specification

There is no specification of the formatter after the C<=for> command.

=item * unresolved internal link I<NAME>

The given link to I<NAME> does not have a matching node in the current
POD. This also happend when a single word node name is not enclosed in
C<"">.

=item * Unknown command "I<CMD>"

An invalid POD command has been found. Valid are C<=head1>, C<=head2>,
C<=over>, C<=item>, C<=back>, C<=begin>, C<=end>, C<=for>, C<=pod>,
C<=cut>

=item * Unknown interior-sequence "I<SEQ>"

An invalid markup command has been encountered. Valid are:
C<BE<lt>E<gt>>, C<CE<lt>E<gt>>, C<EE<lt>E<gt>>, C<FE<lt>E<gt>>, 
C<IE<lt>E<gt>>, C<LE<lt>E<gt>>, C<SE<lt>E<gt>>, C<XE<lt>E<gt>>, 
C<ZE<lt>E<gt>>

=item * nested commands I<CMD>E<lt>...I<CMD>E<lt>...E<gt>...E<gt>

Two nested identical markup commands have been found. Generally this
does not make sense.

=item * garbled entity I<STRING>

The I<STRING> found cannot be interpreted as a character entity.

=item * Entity number out of range

An entity specified by number (dec, hex, oct) is out of range (1-255).

=item * malformed link LE<lt>E<gt>

The link found cannot be parsed because it does not conform to the
syntax described in L<perlpod>.

=item * nonempty ZE<lt>E<gt>

The C<ZE<lt>E<gt>> sequence is supposed to be empty.

=item * empty XE<lt>E<gt>

The index entry specified contains nothing but whitespace.

=item * Spurious text after =pod / =cut

The commands C<=pod> and C<=cut> do not take any arguments.

=item * Spurious character(s) after =back

The C<=back> command does not take any arguments.

=back

=head2 Warnings

These may not necessarily cause trouble, but indicate mediocre style.

=over 4

=item * multiple occurence of link target I<name>

The POD file has some C<=item> and/or C<=head> commands that have
the same text. Potential hyperlinks to such a text cannot be unique then.

=item * line containing nothing but whitespace in paragraph

There is some whitespace on a seemingly empty line. POD is very sensitive
to such things, so this is flagged. B<vi> users switch on the B<list>
option to avoid this problem.

=begin _disabled_

=item * file does not start with =head

The file starts with a different POD directive than head.
This is most probably something you do not want.

=end _disabled_

=item * previous =item has no contents

There is a list C<=item> right above the flagged line that has no
text contents. You probably want to delete empty items.

=item * preceding non-item paragraph(s)

A list introduced by C<=over> starts with a text or verbatim paragraph,
but continues with C<=item>s. Move the non-item paragraph out of the
C<=over>/C<=back> block.

=item * =item type mismatch (I<one> vs. I<two>)

A list started with e.g. a bulletted C<=item> and continued with a
numbered one. This is obviously inconsistent. For most translators the
type of the I<first> C<=item> determines the type of the list.

=item * I<N> unescaped C<E<lt>E<gt>> in paragraph

Angle brackets not written as C<E<lt>ltE<gt>> and C<E<lt>gtE<gt>>
can potentially cause errors as they could be misinterpreted as
markup commands. This is only printed when the -warnings level is
greater than 1.

=item * Unknown entity

A character entity was found that does not belong to the standard
ISO set or the POD specials C<verbar> and C<sol>.

=item * No items in =over

The list opened with C<=over> does not contain any items.

=item * No argument for =item

C<=item> without any parameters is deprecated. It should either be followed
by C<*> to indicate an unordered list, by a number (optionally followed
by a dot) to indicate an ordered (numbered) list or simple text for a
definition list.

=item * empty section in previous paragraph

The previous section (introduced by a C<=head> command) does not contain
any text. This usually indicates that something is missing. Note: A 
C<=head1> followed immediately by C<=head2> does not trigger this warning.

=item * Verbatim paragraph in NAME section

The NAME section (C<=head1 NAME>) should consist of a single paragraph
with the script/module name, followed by a dash `-' and a very short
description of what the thing is good for.

=back

=head2 Hyperlinks

There are some warnings wrt. malformed hyperlinks.

=over 4

=item * ignoring leading/trailing whitespace in link

There is whitespace at the beginning or the end of the contents of 
LE<lt>...E<gt>.

=item * (section) in '$page' deprecated

There is a section detected in the page name of LE<lt>...E<gt>, e.g.
C<LE<gt>passwd(2)E<gt>>. POD hyperlinks may point to POD documents only.
Please write C<CE<lt>passwd(2)E<gt>> instead. Some formatters are able
to expand this to appropriate code. For links to (builtin) functions,
please say C<LE<lt>perlfunc/mkdirE<gt>>, without ().

=item * alternative text/node '%s' contains non-escaped | or /

The characters C<|> and C</> are special in the LE<lt>...E<gt> context.
Although the hyperlink parser does its best to determine which "/" is
text and which is a delimiter in case of doubt, one ought to escape
these literal characters like this:

  /     E<sol>
  |     E<verbar>

=back

=head1 RETURN VALUE

B<podchecker> returns the number of POD syntax errors found or -1 if
there were no POD commands at all found in the file.

=head1 EXAMPLES

I<[T.B.D.]>

=head1 INTERFACE

While checking, this module collects document properties, e.g. the nodes
for hyperlinks (C<=headX>, C<=item>) and index entries (C<XE<lt>E<gt>>).
POD translators can use this feature to syntax-check and get the nodes in
a first pass before actually starting to convert. This is expensive in terms
of execution time, but allows for very robust conversions.

=cut

#############################################################################

use strict;
#use diagnostics;
use Carp;
use Exporter;
use Pod::Parser;

use vars qw(@ISA @EXPORT);
@ISA = qw(Pod::Parser);
@EXPORT = qw(&podchecker);

use vars qw(%VALID_COMMANDS %VALID_SEQUENCES);

my %VALID_COMMANDS = (
    'pod'    =>  1,
    'cut'    =>  1,
    'head1'  =>  1,
    'head2'  =>  1,
    'over'   =>  1,
    'back'   =>  1,
    'item'   =>  1,
    'for'    =>  1,
    'begin'  =>  1,
    'end'    =>  1,
);

my %VALID_SEQUENCES = (
    'I'  =>  1,
    'B'  =>  1,
    'S'  =>  1,
    'C'  =>  1,
    'L'  =>  1,
    'F'  =>  1,
    'X'  =>  1,
    'Z'  =>  1,
    'E'  =>  1,
);

# stolen from HTML::Entities
my %ENTITIES = (
 # Some normal chars that have special meaning in SGML context
 amp    => '&',  # ampersand 
'gt'    => '>',  # greater than
'lt'    => '<',  # less than
 quot   => '"',  # double quote

 # PUBLIC ISO 8879-1986//ENTITIES Added Latin 1//EN//HTML
 AElig	=> '