Class Nanoc3::Filter
In: lib/nanoc3/base/filter.rb
Parent: Context

Nanoc3::Filter is responsible for filtering items. It is the superclass for all textual filters.

A filter instance should only be used once. Filters should not be reused since they store state.

When creating a filter with a hash containing assigned variables, those variables will be made available in the `@assigns` instance variable and the {assigns} method. The assigns itself will also be available as instance variables and instance methods.

@example Accessing assigns in different ways

  filter = SomeFilter.new({ :foo => 'bar' })
  filter.instance_eval { @assigns[:foo] }
    # => 'bar'
  filter.instance_eval { assigns[:foo] }
    # => 'bar'
  filter.instance_eval { @foo }
    # => 'bar'
  filter.instance_eval { foo }
    # => 'bar'

@abstract Subclass and override {run} to implement a custom filter.

Methods

Constants

TMP_BINARY_ITEMS_DIR = 'tmp/binary_items'   The path to the directory where temporary binary items are stored

Attributes

assigns  [R]  A hash containing variables that will be made available during filtering.

@return [Hash]

Public Class methods

@return [Boolean] True if this filter can be applied to binary item

  representations, false otherwise

Creates a new filter that has access to the given assigns.

@param [Hash] hash A hash containing variables that should be made

  available during filtering.

@return [Boolean] True if this filter results in a binary item

  representation, false otherwise

Sets the new type for the filter. The type can be `:binary` (default) or `:text`. The given argument can either be a symbol indicating both “from” and “to” types, or a hash where the only key is the “from” type and the only value is the “to” type.

@example Specifying a text-to-text filter

    type :text

@example Specifying a text-to-binary filter

    type :text => :binary

@param [Symbol, Hash] arg The new type of this filter

@return [void]

Public Instance methods

Returns the filename associated with the item that is being filtered.

  It is in the format `item <identifier> (rep <name>)`.

@return [String] The filename

Returns a filename that is used to write data to. This method is only

  used on binary items. When running a binary filter on a file, the
  resulting file must end up in the location returned by this method.

@return [String] The output filename

Runs the filter on the given content or filename.

@abstract

@param [String] content_or_filename The unprocessed content that should

  be filtered (if the item is a textual item) or the path to the file
  that should be filtered (if the item is a binary item)

@param [Hash] params A hash containing parameters. Filter subclasses can

  use these parameters to allow modifying the filter's behaviour.

@return [String, void] If the filter output binary content, the return

  value is undefined; if the filter outputs textual content, the return
  value will be the filtered content.

[Validate]