Class: EPO::Observer

Inherits:
Welo::Observer
  • Object
show all
Defined in:
lib/epo/core/observer.rb

Overview

An Observer is a object able to look at the filesystem and observe resources in it.

Defined Under Namespace

Classes: Source

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(models = []) ⇒ Observer

Creates a new observer for given models. Will instanciate a new DB.



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# File 'lib/epo/core/observer.rb', line 40

def initialize(models=[])
  super()
  @db = DB.new(models)
  @structures = {}
  register(:observation) do |o|
    event(o.class.resource, o)
  end
end

Instance Attribute Details

#db ⇒ Object

The DB able to tell if a path is understandable or not



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# File 'lib/epo/core/observer.rb', line 25

def db
  @db
end

#models ⇒ Object (readonly)

The list of models understood by this observer



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# File 'lib/epo/core/observer.rb', line 22

def models
  @models
end

#structures ⇒ Object

A cache for the observation structures



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# File 'lib/epo/core/observer.rb', line 28

def structures
  @structures
end

Class Method Details

.for_db(db) ⇒ Object

Creates and return a new observer from a DB. It will take the models from the DB.



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# File 'lib/epo/core/observer.rb', line 32

def self.for_db(db)
  obj = self.new(db.models)
  obj.db = db
  obj
end

Instance Method Details

#get_node_for_path(path, root = nil) ⇒ Object

Returns the node for a db path, or nil if doesnt exist



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# File 'lib/epo/core/observer.rb', line 50

def get_node_for_path(path, root=nil)
  case root
  when Regexp
    path = path.sub(root,'') 
  when String
    re = %r{^#{root}}
    path = path.sub(re,'') 
  when nil
    #ok
  else
    raise ArgumentError, "can only understand string or regexps as roots" 
  end
  db.get_route_silent(path)
end

#read_path_as_resource(path, model) ⇒ Object

Reads the file to path as a resource dumped EPO-style



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# File 'lib/epo/core/observer.rb', line 66

def read_path_as_resource(path, model)
  persp_str = db.persp_and_ext_for_basename(path).first
  persp = model.perspectives.keys.find{|k| k.to_s == persp_str}
  observe_source(Source.new(db, path), structure(model, persp))
end

#read_tree(root) ⇒ Object

Recursively reads the files in the filesystem (with Find). For each path, will try to read_path Currently, there is no pruning, or control possible.



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# File 'lib/epo/core/observer.rb', line 81

def read_tree(root)
  Find.find(root) do |path|
    node = get_node_for_path(path, root) 
    if node 
      if node.content #a model attached to a file in a directory
        if db.understands_filename?(path)
          read_path_as_resource(path, node.content)
        end
      end
    else #the db doesn't understand this branch, we'd rather drop now
      Find.prune
    end
  end
end

#structure(model, persp) ⇒ Object

Handy-cache for mapping (model, persp) pairs to Welo::ObservationStruct



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# File 'lib/epo/core/observer.rb', line 73

def structure(model, persp)
  pair = [model, persp]
  @structures[pair] ||= Welo::ObservationStruct.new_for_resource_in_perspective(model, persp)
end