loncom/ConfigFileEdit.pm - diff

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Diff for /loncom/ConfigFileEdit.pm between versions 1.1 and 1.2

-version 1.1, 2003/11/25 12:09:57
+version 1.2, 2003/12/02 12:06:25
  Line 26
  package ConfigFileEdit;
+ use IO::File;
  #
  #   Module to read/edit configuration files.
  #   See the POD at the bottom of the file for more information.
- Line 239  sub DeleteLine {
+ Line 241  sub DeleteLine {
      my $lastidx  = $self->LineCount() - 1;   # Index of last item.
-     my @temp = @$lines;
+     my @temp;
      if(! defined($index->{$key})) {           # bail if no match.
  	return;
      }
      my $itemno   = $index->{$key}; # Index of item to delete.
      if ($itemno != $lastidx) {               # need to slide and reindex.
- 	@$temp[$itemno..($lastidx-1)] =
+ 	@temp = @$lines[0..($itemno-1)];
- 	    @$temp[$itemno+1..$lastidx];
+ 	@temp[$itemno..($lastidx-1)] = @$lines[($itemno+1)..$lastidx];
- 	$#temp = $lastidx - 1;
- 	$self->{KeyToLines} = Index(\@temp, $self->{Indexfield});
      } else {			             # just need to truncate
- 	$#temp = $lastidx-1;		             # the line array...
+ 	@temp = @$lines[0..$lastidx-1];	     # So take the initial slice.
- 	delete($index->{$key});	             # and remove from index hash.
      }
-     $self->{LineArray} = \@temp;
+     $self->{KeyToLines} = Index(\@temp, $self->{Indexfield});
+     $self->{LineArray} = \@temp;             # Replace the lines index.
  }
- Line 294  sub ReplaceLine {
+ Line 297  sub ReplaceLine {
  	}
      }
  }
+ #
+ #   Write the configuration array to a file:
+ #   Parameters:
+ #      $self           - Reference to the object's member data hash.
+ #      $fh              - Name of file to write.
+ sub Write {
+     my $self     = shift;
+     my $fh       = shift;
+     my $lines    = $self->{LineArray};
+     my $length   = @$lines;
+     for (my $i = 0; $i < $length; $i++) {
+ 	print $fh $lines->[$i]."\n";
+     }
+ }
 ;
+ #----------------------------- Documentation --------------------------------------
+ #
+ =pod
+ =head1 NAME
+ ConfigFileEdit - Lookups and edits on a configuration file.
+ =head1 SYNOPSIS
+     use LONCAPA::ConfigFileEdit;
+     use IO::File;
+     my $editor = ConfigFileEdit->new("file.cfg", 0);
+     $editor->Append("new:line:with:config:info");
+     my $line   = $editor->Find("key");
+     my $size   = $editor->LineCount();
+     $editor->DeleteLine("george");
+     $editor->ReplaceLine("new","new:line:with:different:info");
+     my $fh = new IO::File("> modified.cfg", 0);
+     $editor->Write($fh);
+ =head1 DESCRIPTION
+ Configuration files in LonCAPA contain lines of colon separated fields.
+ Configuration files can also contain comments initiated by the hash (#)
+ character that continue to the end of line.  Finally, configuration files
+ can be made more readable by the inclusion of either empty lines or
+ lines entirely made up of whitespace.
+ ConfigFileEdit allows manipulation of configuration files in a way that
+ preserves comments and order.  This differs from LonCAPA's 'normal' mechanism
+ handling configuration files by throwing them up into a hash by key.
+ ConfigFileEdit maintains the original configuration file in an array and
+ creates the index hash as a hash to line numbers in the array.  This allows
+ O(k) time lookups, while preserving file order and comments (comments are
+ lines in the array that have no indices in the associated hash.
+ In addition to line lookup, ConfigFileEdit supports simple editing
+ functions such as delete, append, and replace.  At present, Insertions
+ at arbitrary points in the file are not supported.  The modified
+ file can also be written out.
+ =head1 METHODS
+ =head2 new ( filename, keyfield )
+ Creates  a new ConfigFileEdit object from an existing file.   Where:
+ =over 4
+ =item * filename - The name of the configuration file to open.
+ =item * keyfield - The number of the field for which the index hash is generated.
+     Fields are enumerated from zero.
+ =item * RETURNS: - undef if the file could not be open, otherwise a reference
+     to a hash that contains the object member data.
+ =back
+ =head2 Append ( newline )
+ Appends a new line to the configuration file in memory.  The file that was
+ used to create the object is not modified by this operation.
+ =over 4
+ =item * newline - A new line to append to the end of the configurationfile.
+ =back
+ =head2 LineCount
+ Returns the number of lines in the file.  This count includes the nubmer of
+ comments.
+ =head2 DeleteLine ( key )
+ Deletes the line that matches key.  Note that if there is no matching line,
+ this function is a no-op.
+ =over 4
+ =item * key   - The key to match, the line that is indexed by this key is deleted.
+ =back
+ =head2 ReplaceLine ( key, newcontents  )
+ Replaces the selected line in its entirety.  Note that the config file is re-indexed
+ so it is legal to modify the line's key field.
+ =over 4
+ =item * key    - The key that selects which line is replaced.
+ =item * newcontents - The new contents of the line.
+ =back
+ =head2 Write ( fh )
+ Writes the contents of the configuration file's line array to file.
+ =over 4
+ =item * fh   - A file handle that is open for write on the destination file.
+ =back
+ =head2 Comment ( line )
+ Static member that returns true if the line passed in is a comment or blank line.
+ =head2 Field ( line, index )
+ Static member that returns the value of a particular field on a config file line.
+ =over 4
+ =item * line   - The line that's parsed.
+ =item * index  - The index requested (0 is the first field on the line).
+ =back
+ =head2 Index ( linearray, fieldno )
+ Returns a reference to a hash that indexes a line array by a particular field number.
+ this can be used to produce secondary indices if required by the application (see
+ MEMBER DATA below).
+ =over 4
+ =item * linearray - A reference to an array containing text in configuration file format.
+ =item * fieldno - Number of the field to index (0 is the first field).
+ =item * RETURNS - A reference to a hash from field value to line array element number.
+ =back
+ =head1 MEMBER DATA
+ The following member data can be considered exported.
+ =head2 LineArray
+ The reference to the configuration files line array.
+ =cut
+ __END__

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Removed from v.1.1
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	Added in v.1.2