From 8b381ad3e731d9aa2e5002479b473738d39d0a41 Mon Sep 17 00:00:00 2001
From: Denis Defreyne <denis.defreyne@stoneship.org>
Date: Sun, 16 Apr 2017 13:08:57 +0200
Subject: [PATCH 1/7] Refactor: Add action seq convenience methods to
 RecordingExecutor

---
 lib/nanoc/rule_dsl/action_sequence_calculator.rb | 12 +++---------
 lib/nanoc/rule_dsl/recording_executor.rb         | 12 ++++++++++++
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/lib/nanoc/rule_dsl/action_sequence_calculator.rb b/lib/nanoc/rule_dsl/action_sequence_calculator.rb
index 8f90b9cdca..b5fae8b68f 100644
--- a/lib/nanoc/rule_dsl/action_sequence_calculator.rb
+++ b/lib/nanoc/rule_dsl/action_sequence_calculator.rb
@@ -68,15 +68,9 @@ def new_action_sequence_for_rep(rep)
 
       executor.snapshot(:raw)
       rule.apply_to(rep, executor: executor, site: @site, view_context: view_context)
-      if action_sequence.any_layouts?
-        executor.snapshot(:post)
-      end
-      unless action_sequence.snapshot_actions.any? { |sa| sa.snapshot_names.include?(:last) }
-        executor.snapshot(:last)
-      end
-      unless action_sequence.snapshot_actions.any? { |sa| sa.snapshot_names.include?(:pre) }
-        executor.snapshot(:pre)
-      end
+      executor.snapshot(:post) if executor.any_layouts?
+      executor.snapshot(:last) unless executor.last_snapshot?
+      executor.snapshot(:pre) unless executor.pre_snapshot?
 
       copy_paths_from_routing_rules(compact_snapshots(action_sequence), rep: rep)
     end
diff --git a/lib/nanoc/rule_dsl/recording_executor.rb b/lib/nanoc/rule_dsl/recording_executor.rb
index 12d50f29a0..a2622a0617 100644
--- a/lib/nanoc/rule_dsl/recording_executor.rb
+++ b/lib/nanoc/rule_dsl/recording_executor.rb
@@ -29,6 +29,18 @@ def snapshot(snapshot_name, path: nil)
         @action_sequence.add_snapshot(snapshot_name, path && path.to_s)
         nil
       end
+
+      def any_layouts?
+        @action_sequence.any_layouts?
+      end
+
+      def last_snapshot?
+        @action_sequence.snapshot_actions.any? { |sa| sa.snapshot_names.include?(:last) }
+      end
+
+      def pre_snapshot?
+        @action_sequence.snapshot_actions.any? { |sa| sa.snapshot_names.include?(:pre) }
+      end
     end
   end
 end

From 10bb99e1be6febd3c432b0dd40c00cbf89f38ad0 Mon Sep 17 00:00:00 2001
From: Denis Defreyne <denis.defreyne@stoneship.org>
Date: Sun, 16 Apr 2017 13:16:53 +0200
Subject: [PATCH 2/7] Pass item rep, not action seq, to recording executor

---
 lib/nanoc/rule_dsl/action_sequence_calculator.rb |  5 ++---
 lib/nanoc/rule_dsl/recording_executor.rb         | 10 ++++++++--
 spec/nanoc/rule_dsl/recording_executor_spec.rb   |  7 ++++---
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/lib/nanoc/rule_dsl/action_sequence_calculator.rb b/lib/nanoc/rule_dsl/action_sequence_calculator.rb
index b5fae8b68f..ef6d239854 100644
--- a/lib/nanoc/rule_dsl/action_sequence_calculator.rb
+++ b/lib/nanoc/rule_dsl/action_sequence_calculator.rb
@@ -58,8 +58,7 @@ def new_action_sequence_for_rep(rep)
       dependency_tracker = Nanoc::Int::DependencyTracker::Null.new
       view_context = @site.compiler.compilation_context.create_view_context(dependency_tracker)
 
-      action_sequence = Nanoc::Int::ActionSequence.new(rep)
-      executor = Nanoc::RuleDSL::RecordingExecutor.new(action_sequence)
+      executor = Nanoc::RuleDSL::RecordingExecutor.new(rep)
       rule = @rules_collection.compilation_rule_for(rep)
 
       unless rule
@@ -72,7 +71,7 @@ def new_action_sequence_for_rep(rep)
       executor.snapshot(:last) unless executor.last_snapshot?
       executor.snapshot(:pre) unless executor.pre_snapshot?
 
-      copy_paths_from_routing_rules(compact_snapshots(action_sequence), rep: rep)
+      copy_paths_from_routing_rules(compact_snapshots(executor.action_sequence), rep: rep)
     end
 
     # @param [Nanoc::Int::Layout] layout
diff --git a/lib/nanoc/rule_dsl/recording_executor.rb b/lib/nanoc/rule_dsl/recording_executor.rb
index a2622a0617..3b4591340d 100644
--- a/lib/nanoc/rule_dsl/recording_executor.rb
+++ b/lib/nanoc/rule_dsl/recording_executor.rb
@@ -3,8 +3,11 @@ module RuleDSL
     class RecordingExecutor
       include Nanoc::Int::ContractsSupport
 
-      def initialize(action_sequence)
-        @action_sequence = action_sequence
+      attr_reader :action_sequence
+
+      contract Nanoc::Int::ItemRep => C::Any
+      def initialize(rep)
+        @action_sequence = Nanoc::Int::ActionSequence.new(rep)
       end
 
       def filter(filter_name, filter_args = {})
@@ -30,14 +33,17 @@ def snapshot(snapshot_name, path: nil)
         nil
       end
 
+      contract C::None => C::Bool
       def any_layouts?
         @action_sequence.any_layouts?
       end
 
+      contract C::None => C::Bool
       def last_snapshot?
         @action_sequence.snapshot_actions.any? { |sa| sa.snapshot_names.include?(:last) }
       end
 
+      contract C::None => C::Bool
       def pre_snapshot?
         @action_sequence.snapshot_actions.any? { |sa| sa.snapshot_names.include?(:pre) }
       end
diff --git a/spec/nanoc/rule_dsl/recording_executor_spec.rb b/spec/nanoc/rule_dsl/recording_executor_spec.rb
index c3df35c400..f53b02d39e 100644
--- a/spec/nanoc/rule_dsl/recording_executor_spec.rb
+++ b/spec/nanoc/rule_dsl/recording_executor_spec.rb
@@ -1,8 +1,9 @@
 describe Nanoc::RuleDSL::RecordingExecutor do
-  let(:executor) { described_class.new(action_sequence) }
+  let(:executor) { described_class.new(rep) }
 
-  let(:action_sequence) { Nanoc::Int::ActionSequence.new(rep) }
-  let(:rep) { double(:rep) }
+  let(:action_sequence) { executor.action_sequence }
+  let(:item) { Nanoc::Int::Item.new('stuff', {}, '/foo.md') }
+  let(:rep) { Nanoc::Int::ItemRep.new(item, :default) }
 
   describe '#filter' do
     it 'records filter call without arguments' do

From 7848ecde0430c23b8d41e862ef67d95779ccf91b Mon Sep 17 00:00:00 2001
From: Denis Defreyne <denis.defreyne@stoneship.org>
Date: Sun, 16 Apr 2017 13:23:04 +0200
Subject: [PATCH 3/7] Precompute action seq properties

---
 lib/nanoc/base/entities/action_sequence.rb |  5 -----
 lib/nanoc/rule_dsl/recording_executor.rb   | 20 ++++++++++++++++----
 2 files changed, 16 insertions(+), 9 deletions(-)

diff --git a/lib/nanoc/base/entities/action_sequence.rb b/lib/nanoc/base/entities/action_sequence.rb
index 77d1325e1d..4a080eaca5 100644
--- a/lib/nanoc/base/entities/action_sequence.rb
+++ b/lib/nanoc/base/entities/action_sequence.rb
@@ -45,11 +45,6 @@ def snapshot_actions
       @actions.select { |a| a.is_a?(Nanoc::Int::ProcessingActions::Snapshot) }
     end
 
-    contract C::None => C::Bool
-    def any_layouts?
-      @actions.any? { |a| a.is_a?(Nanoc::Int::ProcessingActions::Layout) }
-    end
-
     contract C::None => Array
     def paths
       snapshot_actions.map { |a| [a.snapshot_names, a.paths] }
diff --git a/lib/nanoc/rule_dsl/recording_executor.rb b/lib/nanoc/rule_dsl/recording_executor.rb
index 3b4591340d..c6f564104e 100644
--- a/lib/nanoc/rule_dsl/recording_executor.rb
+++ b/lib/nanoc/rule_dsl/recording_executor.rb
@@ -8,6 +8,10 @@ class RecordingExecutor
       contract Nanoc::Int::ItemRep => C::Any
       def initialize(rep)
         @action_sequence = Nanoc::Int::ActionSequence.new(rep)
+
+        @any_layouts = false
+        @last_snapshot = false
+        @pre_snapshot = false
       end
 
       def filter(filter_name, filter_args = {})
@@ -19,33 +23,41 @@ def layout(layout_identifier, extra_filter_args = {})
           raise ArgumentError.new('The layout passed to #layout must be a string')
         end
 
-        unless @action_sequence.any_layouts?
+        unless any_layouts?
+          @pre_snapshot = true
           @action_sequence.add_snapshot(:pre, nil)
         end
 
         @action_sequence.add_layout(layout_identifier, extra_filter_args)
+        @any_layouts = true
       end
 
       Pathlike = C::Maybe[C::Or[String, Nanoc::Identifier]]
       contract Symbol, C::KeywordArgs[path: C::Optional[Pathlike]] => nil
       def snapshot(snapshot_name, path: nil)
         @action_sequence.add_snapshot(snapshot_name, path && path.to_s)
+        case snapshot_name
+        when :last
+          @last_snapshot = true
+        when :pre
+          @pre_snapshot = true
+        end
         nil
       end
 
       contract C::None => C::Bool
       def any_layouts?
-        @action_sequence.any_layouts?
+        @any_layouts
       end
 
       contract C::None => C::Bool
       def last_snapshot?
-        @action_sequence.snapshot_actions.any? { |sa| sa.snapshot_names.include?(:last) }
+        @last_snapshot
       end
 
       contract C::None => C::Bool
       def pre_snapshot?
-        @action_sequence.snapshot_actions.any? { |sa| sa.snapshot_names.include?(:pre) }
+        @pre_snapshot
       end
     end
   end

From 556ca1f319455549eb8cf2ff0d633232a87d18df Mon Sep 17 00:00:00 2001
From: Denis Defreyne <denis.defreyne@stoneship.org>
Date: Sun, 16 Apr 2017 13:41:14 +0200
Subject: [PATCH 4/7] Refactor: Add ActionSequenceBuilder (delegates for now)

---
 lib/nanoc/base/entities/action_sequence.rb    |  6 ++++
 lib/nanoc/base/services.rb                    |  1 +
 .../base/services/action_sequence_builder.rb  | 33 +++++++++++++++++++
 lib/nanoc/rule_dsl/recording_executor.rb      | 16 +++++----
 4 files changed, 50 insertions(+), 6 deletions(-)
 create mode 100644 lib/nanoc/base/services/action_sequence_builder.rb

diff --git a/lib/nanoc/base/entities/action_sequence.rb b/lib/nanoc/base/entities/action_sequence.rb
index 4a080eaca5..39b319d97d 100644
--- a/lib/nanoc/base/entities/action_sequence.rb
+++ b/lib/nanoc/base/entities/action_sequence.rb
@@ -11,6 +11,12 @@ def initialize(item_rep, actions: [])
       @actions = actions
     end
 
+    def self.build(rep)
+      builder = Nanoc::Int::ActionSequenceBuilder.new(rep)
+      yield(builder)
+      builder.action_sequence
+    end
+
     contract C::None => Numeric
     def size
       @actions.size
diff --git a/lib/nanoc/base/services.rb b/lib/nanoc/base/services.rb
index b6edfd46d7..732ec3bf63 100644
--- a/lib/nanoc/base/services.rb
+++ b/lib/nanoc/base/services.rb
@@ -1,4 +1,5 @@
 require_relative 'services/action_provider'
+require_relative 'services/action_sequence_builder'
 require_relative 'services/checksummer'
 require_relative 'services/compilation_context'
 require_relative 'services/compiler'
diff --git a/lib/nanoc/base/services/action_sequence_builder.rb b/lib/nanoc/base/services/action_sequence_builder.rb
new file mode 100644
index 0000000000..9794934dc1
--- /dev/null
+++ b/lib/nanoc/base/services/action_sequence_builder.rb
@@ -0,0 +1,33 @@
+module Nanoc::Int
+  class ActionSequenceBuilder
+    include Nanoc::Int::ContractsSupport
+
+    def initialize(rep)
+      @rep = rep
+      @action_sequence = Nanoc::Int::ActionSequence.new(rep)
+    end
+
+    contract Symbol, Hash => self
+    def add_filter(filter_name, params)
+      @action_sequence.add_filter(filter_name, params)
+      self
+    end
+
+    contract String, C::Maybe[Hash] => self
+    def add_layout(layout_identifier, params)
+      @action_sequence.add_layout(layout_identifier, params)
+      self
+    end
+
+    contract Symbol, C::Maybe[String] => self
+    def add_snapshot(snapshot_name, path)
+      @action_sequence.add_snapshot(snapshot_name, path)
+      self
+    end
+
+    contract C::None => Nanoc::Int::ActionSequence
+    def action_sequence
+      @action_sequence
+    end
+  end
+end
diff --git a/lib/nanoc/rule_dsl/recording_executor.rb b/lib/nanoc/rule_dsl/recording_executor.rb
index c6f564104e..24b8503180 100644
--- a/lib/nanoc/rule_dsl/recording_executor.rb
+++ b/lib/nanoc/rule_dsl/recording_executor.rb
@@ -3,11 +3,10 @@ module RuleDSL
     class RecordingExecutor
       include Nanoc::Int::ContractsSupport
 
-      attr_reader :action_sequence
-
       contract Nanoc::Int::ItemRep => C::Any
       def initialize(rep)
         @action_sequence = Nanoc::Int::ActionSequence.new(rep)
+        @action_sequence_builder = Nanoc::Int::ActionSequenceBuilder.new(rep)
 
         @any_layouts = false
         @last_snapshot = false
@@ -15,7 +14,7 @@ def initialize(rep)
       end
 
       def filter(filter_name, filter_args = {})
-        @action_sequence.add_filter(filter_name, filter_args)
+        @action_sequence_builder.add_filter(filter_name, filter_args)
       end
 
       def layout(layout_identifier, extra_filter_args = {})
@@ -25,17 +24,17 @@ def layout(layout_identifier, extra_filter_args = {})
 
         unless any_layouts?
           @pre_snapshot = true
-          @action_sequence.add_snapshot(:pre, nil)
+          @action_sequence_builder.add_snapshot(:pre, nil)
         end
 
-        @action_sequence.add_layout(layout_identifier, extra_filter_args)
+        @action_sequence_builder.add_layout(layout_identifier, extra_filter_args)
         @any_layouts = true
       end
 
       Pathlike = C::Maybe[C::Or[String, Nanoc::Identifier]]
       contract Symbol, C::KeywordArgs[path: C::Optional[Pathlike]] => nil
       def snapshot(snapshot_name, path: nil)
-        @action_sequence.add_snapshot(snapshot_name, path && path.to_s)
+        @action_sequence_builder.add_snapshot(snapshot_name, path && path.to_s)
         case snapshot_name
         when :last
           @last_snapshot = true
@@ -45,6 +44,11 @@ def snapshot(snapshot_name, path: nil)
         nil
       end
 
+      contract C::None => Nanoc::Int::ActionSequence
+      def action_sequence
+        @action_sequence_builder.action_sequence
+      end
+
       contract C::None => C::Bool
       def any_layouts?
         @any_layouts

From eeb30005a2a29f9b34d0625f7f5d25b9565e9346 Mon Sep 17 00:00:00 2001
From: Denis Defreyne <denis.defreyne@stoneship.org>
Date: Sun, 16 Apr 2017 13:54:30 +0200
Subject: [PATCH 5/7] Refactor: Use ActionSequenceBuilder in ActionSequence
 spec

---
 .../rule_dsl/action_sequence_calculator.rb    |   4 +-
 .../base/entities/action_sequence_spec.rb     | 211 +++++++++++-------
 spec/nanoc/base/services/executor_spec.rb     |   4 +-
 .../services/outdatedness_checker_spec.rb     |  46 ++--
 .../base/services/outdatedness_rules_spec.rb  |  28 +--
 .../action_sequence_calculator_spec.rb        |  28 +--
 6 files changed, 188 insertions(+), 133 deletions(-)

diff --git a/lib/nanoc/rule_dsl/action_sequence_calculator.rb b/lib/nanoc/rule_dsl/action_sequence_calculator.rb
index ef6d239854..1d56f23685 100644
--- a/lib/nanoc/rule_dsl/action_sequence_calculator.rb
+++ b/lib/nanoc/rule_dsl/action_sequence_calculator.rb
@@ -84,8 +84,8 @@ def new_action_sequence_for_layout(layout)
         raise NoActionSequenceForLayoutException.new(layout)
       end
 
-      Nanoc::Int::ActionSequence.new(layout).tap do |rm|
-        rm.add_filter(res[0], res[1])
+      Nanoc::Int::ActionSequence.build(layout) do |b|
+        b.add_filter(res[0], res[1])
       end
     end
 
diff --git a/spec/nanoc/base/entities/action_sequence_spec.rb b/spec/nanoc/base/entities/action_sequence_spec.rb
index 1eaa72ad27..be89c8cc3c 100644
--- a/spec/nanoc/base/entities/action_sequence_spec.rb
+++ b/spec/nanoc/base/entities/action_sequence_spec.rb
@@ -1,17 +1,26 @@
 describe Nanoc::Int::ActionSequence do
-  let(:action_sequence) { described_class.new(rep) }
-  let(:rep) { double(:rep) }
+  let(:action_sequence) { raise 'override me' }
+
+  let(:item) { Nanoc::Int::Item.new('foo', {}, '/foo.md') }
+  let(:rep) { Nanoc::Int::ItemRep.new(item, :default) }
 
   describe '#size' do
     subject { action_sequence.size }
 
     context 'no actions' do
+      let(:action_sequence) do
+        described_class.build(rep) do |b|
+        end
+      end
+
       it { is_expected.to eql(0) }
     end
 
     context 'some actions' do
-      before do
-        action_sequence.add_filter(:foo, {})
+      let(:action_sequence) do
+        described_class.build(rep) do |b|
+          b.add_filter(:foo, {})
+        end
       end
 
       it { is_expected.to eql(1) }
@@ -23,12 +32,19 @@
     let(:index) { 0 }
 
     context 'no actions' do
+      let(:action_sequence) do
+        described_class.build(rep) do |b|
+        end
+      end
+
       it { is_expected.to be_nil }
     end
 
     context 'some actions' do
-      before do
-        action_sequence.add_filter(:foo, {})
+      let(:action_sequence) do
+        described_class.build(rep) do |b|
+          b.add_filter(:foo, {})
+        end
       end
 
       it { is_expected.to be_a(Nanoc::Int::ProcessingActions::Filter) }
@@ -36,9 +52,13 @@
   end
 
   describe '#add_filter' do
-    example do
-      action_sequence.add_filter(:foo, donkey: 123)
+    let(:action_sequence) do
+      described_class.build(rep) do |b|
+        b.add_filter(:foo, donkey: 123)
+      end
+    end
 
+    example do
       expect(action_sequence.size).to eql(1)
       expect(action_sequence[0]).to be_a(Nanoc::Int::ProcessingActions::Filter)
       expect(action_sequence[0].filter_name).to eql(:foo)
@@ -47,9 +67,13 @@
   end
 
   describe '#add_layout' do
-    example do
-      action_sequence.add_layout('/foo.*', donkey: 123)
+    let(:action_sequence) do
+      described_class.build(rep) do |b|
+        b.add_layout('/foo.*', donkey: 123)
+      end
+    end
 
+    example do
       expect(action_sequence.size).to eql(1)
       expect(action_sequence[0]).to be_a(Nanoc::Int::ProcessingActions::Layout)
       expect(action_sequence[0].layout_identifier).to eql('/foo.*')
@@ -59,9 +83,13 @@
 
   describe '#add_snapshot' do
     context 'snapshot does not yet exist' do
-      example do
-        action_sequence.add_snapshot(:before_layout, '/foo.md')
+      let(:action_sequence) do
+        described_class.build(rep) do |b|
+          b.add_snapshot(:before_layout, '/foo.md')
+        end
+      end
 
+      example do
         expect(action_sequence.size).to eql(1)
         expect(action_sequence[0]).to be_a(Nanoc::Int::ProcessingActions::Snapshot)
         expect(action_sequence[0].snapshot_names).to eql([:before_layout])
@@ -70,22 +98,23 @@
     end
 
     context 'snapshot already exist' do
-      before do
-        action_sequence.add_snapshot(:before_layout, '/bar.md')
-      end
-
       it 'raises' do
-        expect { action_sequence.add_snapshot(:before_layout, '/foo.md') }
-          .to raise_error(Nanoc::Int::Errors::CannotCreateMultipleSnapshotsWithSameName)
+        described_class.build(rep) do |b|
+          b.add_snapshot(:before_layout, '/bar.md')
+          expect { b.add_snapshot(:before_layout, '/foo.md') }
+            .to raise_error(Nanoc::Int::Errors::CannotCreateMultipleSnapshotsWithSameName)
+        end
       end
     end
   end
 
   describe '#each' do
-    before do
-      action_sequence.add_filter(:erb, awesomeness: 'high')
-      action_sequence.add_snapshot(:bar, '/foo.md')
-      action_sequence.add_layout('/default.erb', somelayoutparam: 'yes')
+    let(:action_sequence) do
+      described_class.build(rep) do |b|
+        b.add_filter(:erb, awesomeness: 'high')
+        b.add_snapshot(:bar, '/foo.md')
+        b.add_layout('/default.erb', somelayoutparam: 'yes')
+      end
     end
 
     example do
@@ -96,10 +125,12 @@
   end
 
   describe '#map' do
-    before do
-      action_sequence.add_filter(:erb, awesomeness: 'high')
-      action_sequence.add_snapshot(:bar, '/foo.md')
-      action_sequence.add_layout('/default.erb', somelayoutparam: 'yes')
+    let(:action_sequence) do
+      described_class.build(rep) do |b|
+        b.add_filter(:erb, awesomeness: 'high')
+        b.add_snapshot(:bar, '/foo.md')
+        b.add_layout('/default.erb', somelayoutparam: 'yes')
+      end
     end
 
     example do
@@ -112,10 +143,12 @@
   describe '#serialize' do
     subject { action_sequence.serialize }
 
-    before do
-      action_sequence.add_filter(:erb, awesomeness: 'high')
-      action_sequence.add_snapshot(:bar, '/foo.md')
-      action_sequence.add_layout('/default.erb', somelayoutparam: 'yes')
+    let(:action_sequence) do
+      described_class.build(rep) do |b|
+        b.add_filter(:erb, awesomeness: 'high')
+        b.add_snapshot(:bar, '/foo.md')
+        b.add_layout('/default.erb', somelayoutparam: 'yes')
+      end
     end
 
     example do
@@ -130,8 +163,6 @@
   end
 
   describe '#snapshots_defs' do
-    subject { action_sequence.snapshots_defs }
-
     let(:item) { Nanoc::Int::Item.new('asdf', {}, '/foo.md') }
     let(:rep) { Nanoc::Int::ItemRep.new(item, :default) }
 
@@ -164,42 +195,55 @@ def run(content, params = {}); end
     end
 
     it 'has no snapshot defs by default' do
-      expect(subject).to be_empty
+      action_sequence =
+        described_class.build(rep) do |b|
+        end
+
+      expect(action_sequence.snapshots_defs).to be_empty
     end
 
     context 'textual item' do
       let(:item) { Nanoc::Int::Item.new('asdf', {}, '/foo.md') }
 
       it 'generates initial textual snapshot def' do
-        action_sequence.add_snapshot(:giraffe, nil)
-
-        expect(subject.size).to eq(1)
-        expect(subject[0].name).to eq(:giraffe)
-        expect(subject[0]).not_to be_binary
+        action_sequence =
+          described_class.build(rep) do |b|
+            b.add_snapshot(:giraffe, nil)
+          end
+
+        expect(action_sequence.snapshots_defs.size).to eq(1)
+        expect(action_sequence.snapshots_defs[0].name).to eq(:giraffe)
+        expect(action_sequence.snapshots_defs[0]).not_to be_binary
       end
 
       it 'generated follow-up textual snapshot def if previous filter is textual' do
-        action_sequence.add_snapshot(:giraffe, nil)
-        action_sequence.add_filter(:RuleMemSpec_filter_t2t, arguments: 'irrelevant')
-        action_sequence.add_snapshot(:zebra, nil)
-
-        expect(subject.size).to eq(2)
-        expect(subject[0].name).to eq(:giraffe)
-        expect(subject[0]).not_to be_binary
-        expect(subject[1].name).to eq(:zebra)
-        expect(subject[1]).not_to be_binary
+        action_sequence =
+          described_class.build(rep) do |b|
+            b.add_snapshot(:giraffe, nil)
+            b.add_filter(:RuleMemSpec_filter_t2t, arguments: 'irrelevant')
+            b.add_snapshot(:zebra, nil)
+          end
+
+        expect(action_sequence.snapshots_defs.size).to eq(2)
+        expect(action_sequence.snapshots_defs[0].name).to eq(:giraffe)
+        expect(action_sequence.snapshots_defs[0]).not_to be_binary
+        expect(action_sequence.snapshots_defs[1].name).to eq(:zebra)
+        expect(action_sequence.snapshots_defs[1]).not_to be_binary
       end
 
       it 'generated follow-up binary snapshot def if previous filter is text-to-bianry' do
-        action_sequence.add_snapshot(:giraffe, nil)
-        action_sequence.add_filter(:RuleMemSpec_filter_t2b, arguments: 'irrelevant')
-        action_sequence.add_snapshot(:zebra, nil)
-
-        expect(subject.size).to eq(2)
-        expect(subject[0].name).to eq(:giraffe)
-        expect(subject[0]).not_to be_binary
-        expect(subject[1].name).to eq(:zebra)
-        expect(subject[1]).to be_binary
+        action_sequence =
+          described_class.build(rep) do |b|
+            b.add_snapshot(:giraffe, nil)
+            b.add_filter(:RuleMemSpec_filter_t2b, arguments: 'irrelevant')
+            b.add_snapshot(:zebra, nil)
+          end
+
+        expect(action_sequence.snapshots_defs.size).to eq(2)
+        expect(action_sequence.snapshots_defs[0].name).to eq(:giraffe)
+        expect(action_sequence.snapshots_defs[0]).not_to be_binary
+        expect(action_sequence.snapshots_defs[1].name).to eq(:zebra)
+        expect(action_sequence.snapshots_defs[1]).to be_binary
       end
     end
 
@@ -207,35 +251,44 @@ def run(content, params = {}); end
       let(:item) { Nanoc::Int::Item.new(Nanoc::Int::BinaryContent.new('/asdf.dat'), {}, '/foo.md') }
 
       it 'generates initial binary snapshot def' do
-        action_sequence.add_snapshot(:giraffe, nil)
-
-        expect(subject.size).to eq(1)
-        expect(subject[0].name).to eq(:giraffe)
-        expect(subject[0]).to be_binary
+        action_sequence =
+          described_class.build(rep) do |b|
+            b.add_snapshot(:giraffe, nil)
+          end
+
+        expect(action_sequence.snapshots_defs.size).to eq(1)
+        expect(action_sequence.snapshots_defs[0].name).to eq(:giraffe)
+        expect(action_sequence.snapshots_defs[0]).to be_binary
       end
 
       it 'generated follow-up binary snapshot def if previous filter is binary' do
-        action_sequence.add_snapshot(:giraffe, nil)
-        action_sequence.add_filter(:RuleMemSpec_filter_b2b, arguments: 'irrelevant')
-        action_sequence.add_snapshot(:zebra, nil)
-
-        expect(subject.size).to eq(2)
-        expect(subject[0].name).to eq(:giraffe)
-        expect(subject[0]).to be_binary
-        expect(subject[1].name).to eq(:zebra)
-        expect(subject[1]).to be_binary
+        action_sequence =
+          described_class.build(rep) do |b|
+            b.add_snapshot(:giraffe, nil)
+            b.add_filter(:RuleMemSpec_filter_b2b, arguments: 'irrelevant')
+            b.add_snapshot(:zebra, nil)
+          end
+
+        expect(action_sequence.snapshots_defs.size).to eq(2)
+        expect(action_sequence.snapshots_defs[0].name).to eq(:giraffe)
+        expect(action_sequence.snapshots_defs[0]).to be_binary
+        expect(action_sequence.snapshots_defs[1].name).to eq(:zebra)
+        expect(action_sequence.snapshots_defs[1]).to be_binary
       end
 
       it 'generated follow-up textual snapshot def if previous filter is binary-to-text' do
-        action_sequence.add_snapshot(:giraffe, nil)
-        action_sequence.add_filter(:RuleMemSpec_filter_b2t, arguments: 'irrelevant')
-        action_sequence.add_snapshot(:zebra, nil)
-
-        expect(subject.size).to eq(2)
-        expect(subject[0].name).to eq(:giraffe)
-        expect(subject[0]).to be_binary
-        expect(subject[1].name).to eq(:zebra)
-        expect(subject[1]).not_to be_binary
+        action_sequence =
+          described_class.build(rep) do |b|
+            b.add_snapshot(:giraffe, nil)
+            b.add_filter(:RuleMemSpec_filter_b2t, arguments: 'irrelevant')
+            b.add_snapshot(:zebra, nil)
+          end
+
+        expect(action_sequence.snapshots_defs.size).to eq(2)
+        expect(action_sequence.snapshots_defs[0].name).to eq(:giraffe)
+        expect(action_sequence.snapshots_defs[0]).to be_binary
+        expect(action_sequence.snapshots_defs[1].name).to eq(:zebra)
+        expect(action_sequence.snapshots_defs[1]).not_to be_binary
       end
     end
   end
diff --git a/spec/nanoc/base/services/executor_spec.rb b/spec/nanoc/base/services/executor_spec.rb
index 18b9eceb40..3a975f5508 100644
--- a/spec/nanoc/base/services/executor_spec.rb
+++ b/spec/nanoc/base/services/executor_spec.rb
@@ -408,8 +408,8 @@ def run(_content, params = {})
     end
 
     let(:action_sequence) do
-      Nanoc::Int::ActionSequence.new(rep).tap do |seq|
-        seq.add_filter(:erb, {})
+      Nanoc::Int::ActionSequence.build(rep) do |b|
+        b.add_filter(:erb, {})
       end
     end
 
diff --git a/spec/nanoc/base/services/outdatedness_checker_spec.rb b/spec/nanoc/base/services/outdatedness_checker_spec.rb
index e7c7f6eddf..f806cf2342 100644
--- a/spec/nanoc/base/services/outdatedness_checker_spec.rb
+++ b/spec/nanoc/base/services/outdatedness_checker_spec.rb
@@ -32,8 +32,8 @@
   end
 
   let(:old_action_sequence_for_item_rep) do
-    Nanoc::Int::ActionSequence.new(item_rep).tap do |seq|
-      seq.add_filter(:erb, {})
+    Nanoc::Int::ActionSequence.build(item_rep) do |b|
+      b.add_filter(:erb, {})
     end
   end
 
@@ -74,8 +74,8 @@
 
       context 'action sequence differs' do
         let(:new_action_sequence_for_item_rep) do
-          Nanoc::Int::ActionSequence.new(item_rep).tap do |seq|
-            seq.add_filter(:super_erb, {})
+          Nanoc::Int::ActionSequence.build(item_rep) do |b|
+            b.add_filter(:super_erb, {})
           end
         end
 
@@ -92,8 +92,8 @@
 
       context 'action sequence differs' do
         let(:new_action_sequence_for_item_rep) do
-          Nanoc::Int::ActionSequence.new(item_rep).tap do |seq|
-            seq.add_filter(:super_erb, {})
+          Nanoc::Int::ActionSequence.build(item_rep) do |b|
+            b.add_filter(:super_erb, {})
           end
         end
 
@@ -123,8 +123,8 @@
     let(:items) { Nanoc::Int::IdentifiableCollection.new(config, [item, other_item]) }
 
     let(:old_action_sequence_for_other_item_rep) do
-      Nanoc::Int::ActionSequence.new(other_item_rep).tap do |seq|
-        seq.add_filter(:erb, {})
+      Nanoc::Int::ActionSequence.build(other_item_rep) do |b|
+        b.add_filter(:erb, {})
       end
     end
 
@@ -252,9 +252,9 @@
 
       context 'path changed' do
         let(:new_action_sequence_for_other_item_rep) do
-          Nanoc::Int::ActionSequence.new(other_item_rep).tap do |seq|
-            seq.add_filter(:erb, {})
-            seq.add_snapshot(:donkey, '/giraffe.txt')
+          Nanoc::Int::ActionSequence.build(other_item_rep) do |b|
+            b.add_filter(:erb, {})
+            b.add_snapshot(:donkey, '/giraffe.txt')
           end
         end
 
@@ -296,9 +296,9 @@
 
       context 'path changed' do
         let(:new_action_sequence_for_other_item_rep) do
-          Nanoc::Int::ActionSequence.new(other_item_rep).tap do |seq|
-            seq.add_filter(:erb, {})
-            seq.add_snapshot(:donkey, '/giraffe.txt')
+          Nanoc::Int::ActionSequence.build(other_item_rep) do |b|
+            b.add_filter(:erb, {})
+            b.add_snapshot(:donkey, '/giraffe.txt')
           end
         end
 
@@ -329,9 +329,9 @@
 
       context 'path changed' do
         let(:new_action_sequence_for_other_item_rep) do
-          Nanoc::Int::ActionSequence.new(other_item_rep).tap do |seq|
-            seq.add_filter(:erb, {})
-            seq.add_snapshot(:donkey, '/giraffe.txt')
+          Nanoc::Int::ActionSequence.build(other_item_rep) do |b|
+            b.add_filter(:erb, {})
+            b.add_snapshot(:donkey, '/giraffe.txt')
           end
         end
 
@@ -356,9 +356,9 @@
 
       context 'path changed' do
         let(:new_action_sequence_for_other_item_rep) do
-          Nanoc::Int::ActionSequence.new(other_item_rep).tap do |seq|
-            seq.add_filter(:erb, {})
-            seq.add_snapshot(:donkey, '/giraffe.txt')
+          Nanoc::Int::ActionSequence.build(other_item_rep) do |b|
+            b.add_filter(:erb, {})
+            b.add_snapshot(:donkey, '/giraffe.txt')
           end
         end
 
@@ -389,9 +389,9 @@
 
       context 'rules changed' do
         let(:new_action_sequence_for_other_item_rep) do
-          Nanoc::Int::ActionSequence.new(other_item_rep).tap do |seq|
-            seq.add_filter(:erb, {})
-            seq.add_filter(:donkey, {})
+          Nanoc::Int::ActionSequence.build(other_item_rep) do |b|
+            b.add_filter(:erb, {})
+            b.add_filter(:donkey, {})
           end
         end
 
diff --git a/spec/nanoc/base/services/outdatedness_rules_spec.rb b/spec/nanoc/base/services/outdatedness_rules_spec.rb
index 49739dc489..68b8aa41ef 100644
--- a/spec/nanoc/base/services/outdatedness_rules_spec.rb
+++ b/spec/nanoc/base/services/outdatedness_rules_spec.rb
@@ -305,8 +305,8 @@
       let(:rule_class) { Nanoc::Int::OutdatednessRules::RulesModified }
 
       let(:old_mem) do
-        Nanoc::Int::ActionSequence.new(item_rep).tap do |mem|
-          mem.add_filter(:erb, {})
+        Nanoc::Int::ActionSequence.build(item_rep) do |b|
+          b.add_filter(:erb, {})
         end
       end
 
@@ -323,9 +323,9 @@
 
       context 'memory is different' do
         let(:new_mem) do
-          Nanoc::Int::ActionSequence.new(item_rep).tap do |mem|
-            mem.add_filter(:erb, {})
-            mem.add_filter(:donkey, {})
+          Nanoc::Int::ActionSequence.build(item_rep) do |b|
+            b.add_filter(:erb, {})
+            b.add_filter(:donkey, {})
           end
         end
 
@@ -463,9 +463,9 @@
 
       context 'unknown filter' do
         let(:mem) do
-          Nanoc::Int::ActionSequence.new(item_rep).tap do |mem|
-            mem.add_snapshot(:donkey, '/foo.md')
-            mem.add_filter(:asdf, {})
+          Nanoc::Int::ActionSequence.build(item_rep) do |b|
+            b.add_snapshot(:donkey, '/foo.md')
+            b.add_filter(:asdf, {})
           end
         end
 
@@ -474,9 +474,9 @@
 
       context 'known filter, not always outdated' do
         let(:mem) do
-          Nanoc::Int::ActionSequence.new(item_rep).tap do |mem|
-            mem.add_snapshot(:donkey, '/foo.md')
-            mem.add_filter(:erb, {})
+          Nanoc::Int::ActionSequence.build(item_rep) do |b|
+            b.add_snapshot(:donkey, '/foo.md')
+            b.add_filter(:erb, {})
           end
         end
 
@@ -485,9 +485,9 @@
 
       context 'known filter, always outdated' do
         let(:mem) do
-          Nanoc::Int::ActionSequence.new(item_rep).tap do |mem|
-            mem.add_snapshot(:donkey, '/foo.md')
-            mem.add_filter(:xsl, {})
+          Nanoc::Int::ActionSequence.build(item_rep) do |b|
+            b.add_snapshot(:donkey, '/foo.md')
+            b.add_filter(:xsl, {})
           end
         end
 
diff --git a/spec/nanoc/rule_dsl/action_sequence_calculator_spec.rb b/spec/nanoc/rule_dsl/action_sequence_calculator_spec.rb
index 740dd04ffe..8797a3da64 100644
--- a/spec/nanoc/rule_dsl/action_sequence_calculator_spec.rb
+++ b/spec/nanoc/rule_dsl/action_sequence_calculator_spec.rb
@@ -175,21 +175,23 @@
   describe '#compact_snapshots' do
     subject { action_sequence_calculator.compact_snapshots(action_sequence) }
 
-    let(:action_sequence) { Nanoc::Int::ActionSequence.new(rep) }
-    let(:rep) { double(:rep) }
-
-    before do
-      action_sequence.add_snapshot(:a1, nil)
-      action_sequence.add_snapshot(:a2, '/a2.md')
-      action_sequence.add_snapshot(:a3, nil)
-      action_sequence.add_filter(:erb, awesomeness: 'high')
-      action_sequence.add_snapshot(:b1, '/b1.md')
-      action_sequence.add_snapshot(:b2, nil)
-      action_sequence.add_snapshot(:b3, '/b3.md')
-      action_sequence.add_filter(:erb, awesomeness: 'high')
-      action_sequence.add_snapshot(:c, nil)
+    let(:action_sequence) do
+      Nanoc::Int::ActionSequence.build(rep) do |b|
+        b.add_snapshot(:a1, nil)
+        b.add_snapshot(:a2, '/a2.md')
+        b.add_snapshot(:a3, nil)
+        b.add_filter(:erb, awesomeness: 'high')
+        b.add_snapshot(:b1, '/b1.md')
+        b.add_snapshot(:b2, nil)
+        b.add_snapshot(:b3, '/b3.md')
+        b.add_filter(:erb, awesomeness: 'high')
+        b.add_snapshot(:c, nil)
+      end
     end
 
+    let(:item) { Nanoc::Int::Item.new('asdf', {}, '/foo.md') }
+    let(:rep) { Nanoc::Int::ItemRep.new(item, :default) }
+
     example do
       expect(subject[0]).to be_a(Nanoc::Int::ProcessingActions::Snapshot)
       expect(subject[0].snapshot_names).to eql(%i[a1 a2 a3])

From 408172d945b6d6c58479a959a2f6a66c840b5980 Mon Sep 17 00:00:00 2001
From: Denis Defreyne <denis.defreyne@stoneship.org>
Date: Sun, 16 Apr 2017 14:05:04 +0200
Subject: [PATCH 6/7] Make ActionSequence immutable

---
 lib/nanoc/base/entities/action_sequence.rb    | 30 -------------------
 .../base/services/action_sequence_builder.rb  | 26 +++++++++++-----
 lib/nanoc/rule_dsl/recording_executor.rb      |  1 -
 3 files changed, 19 insertions(+), 38 deletions(-)

diff --git a/lib/nanoc/base/entities/action_sequence.rb b/lib/nanoc/base/entities/action_sequence.rb
index 39b319d97d..e52c7e9d7f 100644
--- a/lib/nanoc/base/entities/action_sequence.rb
+++ b/lib/nanoc/base/entities/action_sequence.rb
@@ -27,25 +27,6 @@ def [](idx)
       @actions[idx]
     end
 
-    contract Symbol, Hash => self
-    def add_filter(filter_name, params)
-      @actions << Nanoc::Int::ProcessingActions::Filter.new(filter_name, params)
-      self
-    end
-
-    contract String, C::Maybe[Hash] => self
-    def add_layout(layout_identifier, params)
-      @actions << Nanoc::Int::ProcessingActions::Layout.new(layout_identifier, params)
-      self
-    end
-
-    contract Symbol, C::Maybe[String] => self
-    def add_snapshot(snapshot_name, path)
-      will_add_snapshot(snapshot_name)
-      @actions << Nanoc::Int::ProcessingActions::Snapshot.new([snapshot_name], path ? [path] : [])
-      self
-    end
-
     contract C::None => C::ArrayOf[Nanoc::Int::ProcessingAction]
     def snapshot_actions
       @actions.select { |a| a.is_a?(Nanoc::Int::ProcessingActions::Snapshot) }
@@ -92,16 +73,5 @@ def snapshots_defs
 
       snapshot_defs
     end
-
-    private
-
-    def will_add_snapshot(name)
-      @_snapshot_names ||= Set.new
-      if @_snapshot_names.include?(name)
-        raise Nanoc::Int::Errors::CannotCreateMultipleSnapshotsWithSameName.new(@item_rep, name)
-      else
-        @_snapshot_names << name
-      end
-    end
   end
 end
diff --git a/lib/nanoc/base/services/action_sequence_builder.rb b/lib/nanoc/base/services/action_sequence_builder.rb
index 9794934dc1..25a6fe67c8 100644
--- a/lib/nanoc/base/services/action_sequence_builder.rb
+++ b/lib/nanoc/base/services/action_sequence_builder.rb
@@ -2,32 +2,44 @@ module Nanoc::Int
   class ActionSequenceBuilder
     include Nanoc::Int::ContractsSupport
 
-    def initialize(rep)
-      @rep = rep
-      @action_sequence = Nanoc::Int::ActionSequence.new(rep)
+    def initialize(item_rep)
+      @item_rep = item_rep
+      @actions = []
     end
 
     contract Symbol, Hash => self
     def add_filter(filter_name, params)
-      @action_sequence.add_filter(filter_name, params)
+      @actions << Nanoc::Int::ProcessingActions::Filter.new(filter_name, params)
       self
     end
 
     contract String, C::Maybe[Hash] => self
     def add_layout(layout_identifier, params)
-      @action_sequence.add_layout(layout_identifier, params)
+      @actions << Nanoc::Int::ProcessingActions::Layout.new(layout_identifier, params)
       self
     end
 
     contract Symbol, C::Maybe[String] => self
     def add_snapshot(snapshot_name, path)
-      @action_sequence.add_snapshot(snapshot_name, path)
+      will_add_snapshot(snapshot_name)
+      @actions << Nanoc::Int::ProcessingActions::Snapshot.new([snapshot_name], path ? [path] : [])
       self
     end
 
     contract C::None => Nanoc::Int::ActionSequence
     def action_sequence
-      @action_sequence
+      Nanoc::Int::ActionSequence.new(@item_rep, actions: @actions)
+    end
+
+    private
+
+    def will_add_snapshot(name)
+      @_snapshot_names ||= Set.new
+      if @_snapshot_names.include?(name)
+        raise Nanoc::Int::Errors::CannotCreateMultipleSnapshotsWithSameName.new(@item_rep, name)
+      else
+        @_snapshot_names << name
+      end
     end
   end
 end
diff --git a/lib/nanoc/rule_dsl/recording_executor.rb b/lib/nanoc/rule_dsl/recording_executor.rb
index 24b8503180..36c8f696a1 100644
--- a/lib/nanoc/rule_dsl/recording_executor.rb
+++ b/lib/nanoc/rule_dsl/recording_executor.rb
@@ -5,7 +5,6 @@ class RecordingExecutor
 
       contract Nanoc::Int::ItemRep => C::Any
       def initialize(rep)
-        @action_sequence = Nanoc::Int::ActionSequence.new(rep)
         @action_sequence_builder = Nanoc::Int::ActionSequenceBuilder.new(rep)
 
         @any_layouts = false

From 28dee7c7b2ca73ac6eff42622101f029f4f33539 Mon Sep 17 00:00:00 2001
From: Denis Defreyne <denis.defreyne@stoneship.org>
Date: Sun, 16 Apr 2017 14:05:59 +0200
Subject: [PATCH 7/7] Memoize ActionSequence#serialize

---
 lib/nanoc/base/entities/action_sequence.rb | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/nanoc/base/entities/action_sequence.rb b/lib/nanoc/base/entities/action_sequence.rb
index e52c7e9d7f..30d6f4022f 100644
--- a/lib/nanoc/base/entities/action_sequence.rb
+++ b/lib/nanoc/base/entities/action_sequence.rb
@@ -2,6 +2,7 @@ module Nanoc::Int
   class ActionSequence
     include Nanoc::Int::ContractsSupport
     include Enumerable
+    extend Nanoc::Int::Memoization
 
     attr_reader :item_rep
     attr_reader :actions
@@ -38,7 +39,7 @@ def paths
     end
 
     # TODO: Add contract
-    def serialize
+    memoized def serialize
       to_a.map(&:serialize)
     end