Class: Compo::UrlFinder

Inherits:
Object
  • Object
show all
Defined in:
lib/compo/url_finder.rb

Overview

An ‘UrlFinder’ finds an object in a composite tree via its URL

It is a method object that implements only the finding of a specific URL. UrlFinders are not thread-safe.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(root, url, missing_proc: nil) ⇒ UrlFinder

Initialises a UrlFinder

Examples:

Initialises an UrlFinder with default missing resource handling.

UrlFinder.new(composite, 'a/b/c')

Initialises an UrlFinder returning a default value.

UrlFinder.new(composite, 'a/b/c', missing_proc=->(_) { :default })

Parameters:

  • root (Composite) —

    A composite object serving as the root of the search tree, and the URL.

  • url (String) —

    A partial URL that follows this model object’s URL to form the URL of the resource to locate. Can be nil, in which case this object is returned.

  • missing_proc (Proc) (defaults to: nil) —

    A proc to call, with the requested URL, if the resource could not be found. If nil (the default), this raises a string exception.



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# File 'lib/compo/url_finder.rb', line 25

def initialize(root, url, missing_proc: nil)
  @root         = root
  @url          = url
  @missing_proc = missing_proc || method(:default_missing_proc)

  reset
end

Class Method Details

.find(*args) {|resource, args| ... } ⇒ Object

Finds the model object at a URL, given a model root

Examples:

Finds a URL with default missing resource handling.

UrlFinder.find(composite, 'a/b/c') { |item| p item }

Parameters:

  • root (Composite) —

    A composite object serving as the root of the search tree, and the URL.

  • url (String) —

    A partial URL that follows this model object’s URL to form the URL of the resource to locate. Can be nil, in which case this object is returned.

  • missing_proc (Proc) —

    A proc to call, with the requested URL, if the resource could not be found. If nil (the default), this raises a string exception.

Yield Parameters:

  • resource (ModelObject) —

    The resource found.

  • args (Array) —

    The splat from above.

Returns:

  • (Object) —

    The return value of the block.



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# File 'lib/compo/url_finder.rb', line 44

def self.find(*args, &block)
  new(*args).run(&block)
end

Instance Method Details

#run {|resource, args| ... } ⇒ Object

Attempts to find a child resource with the given partial URL

If the resource is found, it will be yielded to the attached block; otherwise, an exception will be raised.

Examples:

Runs an UrlFinder, returning the item unchanged.

finder.run { |item| item }
#=> item

Yield Parameters:

  • resource (ModelObject) —

    The resource found.

  • args (Array) —

    The splat from above.

Returns:

  • (Object) —

    The return value of the block.



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# File 'lib/compo/url_finder.rb', line 62

def run
  # We're traversing down the URL by repeatedly splitting it into its
  # head (part before the next /) and tail (part after).  While we still
  # have a tail, then the URL still needs walking down.
  reset
  descend until hit_end_of_url?
  yield @resource
end