Refactoring: extract exposures.

This one reaches many goals at once:

 - Fixes #56.
 - `exposures` hash table is removed and substituted with
   `root_exposures` array.
 - Due to previous point, tree structure `nested_exposures` based on
   flat hash table with keys like `root_node__node__node` is removed
   because now double exposures don't rewrite previously defined
   so such tree structure is simply incorrect.
   `NestingExposure` with an array of children is introduced instead.
 - Ones who want an old rewriting behavior should manually `unexpose`.
 - Fixes #112.
 - Fixes #149: runtime `options` are now wrapped in an `Options` object.
 - Fixes #150: see new `spec/grape_entity/exposure_spec.rb`.
 - Fixes #152.
 - Fixes #153.
 - Fixes #155.
 - Fixes #156.
 - All exposure configuration and exposing strategies are extracted to
   the separate classes.
 - `key_for`, `name_for` internal methods are removed.
 - Much of the overhead is gone so performance is increased by 20-30%.

Version is bumbed to 0.5.0.

Author: marshall-lee

CHANGELOG.md

@@ -7,10 +7,21 @@
 * [#134](https://github.com/intridea/grape-entity/pull/134): Subclasses no longer affected in all cases by `unexpose` in parent - [@etehtsea](https://github.com/etehtsea).
 * [#135](https://github.com/intridea/grape-entity/pull/135): Added `except` option - [@dan-corneanu](https://github.com/dan-corneanu).
 * [#136](https://github.com/intridea/grape-entity/pull/136): Allow for strings in `only` and `except` options - [@bswinnerton](https://github.com/bswinnerton).
-* [#147](https://github.com/intridea/grape-entity/pull/147): Expose `safe` attributes as `nil` if they cannot be evaluated: [#140](https://github.com/intridea/grape-entity/issues/140).
-* [#147](https://github.com/intridea/grape-entity/pull/147): Fix: private method values were not exposed with `safe` option: [#142](https://github.com/intridea/grape-entity/pull/142).
-* [#147](https://github.com/intridea/grape-entity/pull/147): Remove catching of `NoMethodError` because it can occur deep inside in a method call so this exception does not mean that attribute not exist.
-* [#147](https://github.com/intridea/grape-entity/pull/147): `valid_exposures` is removed.
+* [#147](https://github.com/intridea/grape-entity/pull/147): Expose `safe` attributes as `nil` if they cannot be evaluated: [#140](https://github.com/intridea/grape-entity/issues/140) - [@marshall-lee](https://github.com/marshall-lee).
+* [#147](https://github.com/intridea/grape-entity/pull/147): Fix: private method values were not exposed with `safe` option: [#142](https://github.com/intridea/grape-entity/pull/142) - [@marshall-lee](https://github.com/marshall-lee).
+* [#147](https://github.com/intridea/grape-entity/pull/147): Remove catching of `NoMethodError` because it can occur deep inside in a method call so this exception does not mean that attribute not exist - [@marshall-lee](https://github.com/marshall-lee).
+* [#147](https://github.com/intridea/grape-entity/pull/147): `valid_exposures` is removed - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): `.exposures` is removed and substituted with `.root_exposures` array - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): `.nested_exposures` is removed too - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): `#should_return_attribute?`, `#only_fields` and `#except_fields` are moved to other classes - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): Fix: double exposures with conditions does not rewrite previously defined now: [#56](https://github.com/intridea/grape-entity/issues/56) - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): Fix: nested exposures were flattened in `.documentation`: [#112](https://github.com/intridea/grape-entity/issues/112) - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): Fix: `@only_fields` and `@except_fields` memoization: [#149](https://github.com/intridea/grape-entity/issues/149) - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): Fix: `:unless` condition with `Hash` argument logic: [#150](https://github.com/intridea/grape-entity/issues/150) - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): Nested `unexpose` now raises an exception: [#152](https://github.com/intridea/grape-entity/issues/152) - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): Fix: `@documentation` memoization: [#153](https://github.com/intridea/grape-entity/issues/153) - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): Fix: serializing of deeply nested presenter exposures: [#155](https://github.com/intridea/grape-entity/issues/155) - [@marshall-lee](https://github.com/marshall-lee).
+* [#151](https://github.com/intridea/grape-entity/pull/151): Fix: deep projections (`:only`, `:except`) were unaware of nesting: [#156](https://github.com/intridea/grape-entity/issues/156) - [@marshall-lee](https://github.com/marshall-lee).
 * Your contribution here.
 
 0.4.5 (2015-03-10)

lib/grape_entity.rb

@@ -3,3 +3,5 @@
 require 'grape_entity/version'
 require 'grape_entity/entity'
 require 'grape_entity/delegator'
+require 'grape_entity/exposure'
+require 'grape_entity/options'

lib/grape_entity/condition.rb

@@ -0,0 +1,26 @@
+require 'grape_entity/condition/base'
+require 'grape_entity/condition/block_condition'
+require 'grape_entity/condition/hash_condition'
+require 'grape_entity/condition/symbol_condition'
+
+module Grape
+  class Entity
+    module Condition
+      def self.new_if(arg)
+        case arg
+        when Hash then HashCondition.new false, arg
+        when Proc then BlockCondition.new false, &arg
+        when Symbol then SymbolCondition.new false, arg
+        end
+      end
+
+      def self.new_unless(arg)
+        case arg
+        when Hash then HashCondition.new true, arg
+        when Proc then BlockCondition.new true, &arg
+        when Symbol then SymbolCondition.new true, arg
+        end
+      end
+    end
+  end
+end

lib/grape_entity/condition/base.rb

@@ -0,0 +1,35 @@
+module Grape
+  class Entity
+    module Condition
+      class Base
+        def self.new(inverse, *args, &block)
+          super(inverse).tap { |e| e.setup(*args, &block) }
+        end
+
+        def initialize(inverse = false)
+          @inverse = inverse
+        end
+
+        def ==(other)
+          (self.class == other.class) && (self.inversed? == other.inversed?)
+        end
+
+        def inversed?
+          @inverse
+        end
+
+        def met?(entity, options)
+          !@inverse ? if_value(entity, options) : unless_value(entity, options)
+        end
+
+        def if_value(_entity, _options)
+          fail NotImplementedError
+        end
+
+        def unless_value(entity, options)
+          !if_value(entity, options)
+        end
+      end
+    end
+  end
+end

lib/grape_entity/condition/block_condition.rb

@@ -0,0 +1,21 @@
+module Grape
+  class Entity
+    module Condition
+      class BlockCondition < Base
+        attr_reader :block
+
+        def setup(&block)
+          @block = block
+        end
+
+        def ==(other)
+          super && @block == other.block
+        end
+
+        def if_value(entity, options)
+          entity.exec_with_object(options, &@block)
+        end
+      end
+    end
+  end
+end

lib/grape_entity/condition/hash_condition.rb

@@ -0,0 +1,25 @@
+module Grape
+  class Entity
+    module Condition
+      class HashCondition < Base
+        attr_reader :cond_hash
+
+        def setup(cond_hash)
+          @cond_hash = cond_hash
+        end
+
+        def ==(other)
+          super && @cond_hash == other.cond_hash
+        end
+
+        def if_value(_entity, options)
+          @cond_hash.all? { |k, v| options[k.to_sym] == v }
+        end
+
+        def unless_value(_entity, options)
+          @cond_hash.any? { |k, v| options[k.to_sym] != v }
+        end
+      end
+    end
+  end
+end

lib/grape_entity/condition/symbol_condition.rb

@@ -0,0 +1,21 @@
+module Grape
+  class Entity
+    module Condition
+      class SymbolCondition < Base
+        attr_reader :symbol
+
+        def setup(symbol)
+          @symbol = symbol
+        end
+
+        def ==(other)
+          super && @symbol == other.symbol
+        end
+
+        def if_value(_entity, options)
+          options[symbol]
+        end
+      end
+    end
+  end
+end