From dab4e74659dee835330cd6c7b9422c981c2e0937 Mon Sep 17 00:00:00 2001
From: Torsten Ruger <torsten@villataika.fi>
Date: Mon, 4 Sep 2017 21:00:08 +0300
Subject: [PATCH] Reworking if statement

Using 2 phase approach
Flattening tbd
---
 lib/mom/check.rb                    |  9 +++++++++
 lib/mom/if_statement.rb             | 14 ++++++++++++++
 lib/mom/instruction.rb              | 12 ++++++++++--
 lib/mom/truth_check.rb              | 16 ++++++----------
 lib/vool/statements/if_statement.rb | 22 ++++++++--------------
 5 files changed, 47 insertions(+), 26 deletions(-)
 create mode 100644 lib/mom/check.rb
 create mode 100644 lib/mom/if_statement.rb

diff --git a/lib/mom/check.rb b/lib/mom/check.rb
new file mode 100644
index 00000000..85248a30
--- /dev/null
+++ b/lib/mom/check.rb
@@ -0,0 +1,9 @@
+module Mom
+
+  # A base class for conditions in MOM
+  # Just a marker, no real functionality for now
+
+  class Check < Instruction
+
+  end
+end
diff --git a/lib/mom/if_statement.rb b/lib/mom/if_statement.rb
new file mode 100644
index 00000000..c42794af
--- /dev/null
+++ b/lib/mom/if_statement.rb
@@ -0,0 +1,14 @@
+module Mom
+  class IfStatement < Instruction
+    attr_reader :condition , :if_true , :if_false
+
+    attr_accessor :hoisted
+
+    def initialize( cond , if_true , if_false = nil)
+      @condition = cond
+      @if_true = if_true
+      @if_false = if_false
+    end
+  end
+
+end
diff --git a/lib/mom/instruction.rb b/lib/mom/instruction.rb
index 29af863d..9ee78d82 100644
--- a/lib/mom/instruction.rb
+++ b/lib/mom/instruction.rb
@@ -2,10 +2,17 @@ module Mom
 
   # Base class for MOM instructions
   class Instruction
+    attr :next_instruction
+
+    # flattening will change the structure from a tree to a linked list (and use
+    # next_instruction to do so)
+    def flatten
+      raise "not implemented"
+    end
   end
 
-  # basically a label
-  class Noop
+  # A label with a name
+  class Label
     attr_reader :name
     def initialize(name)
       @name = name
@@ -16,6 +23,7 @@ module Mom
 end
 
 require_relative "simple_call"
+require_relative "if_statement"
 require_relative "truth_check"
 require_relative "jump"
 require_relative "slot_load"
diff --git a/lib/mom/truth_check.rb b/lib/mom/truth_check.rb
index dd9202b7..389993af 100644
--- a/lib/mom/truth_check.rb
+++ b/lib/mom/truth_check.rb
@@ -1,3 +1,5 @@
+require_relative "check"
+
 module Mom
 
   # The funny thing about the ruby truth is that is is anything but false or nil
@@ -5,17 +7,11 @@ module Mom
   # To implement the normal ruby logic, we check for false or nil and jump
   # to the false branch. true_block follows implicitly
   #
-  # The class only carries the blocks for analysis, and does
-  #  - NOT imply any order
-  # - will not "handle" the blocks in subsequent processing.
-  #
-  class TruthCheck < Instruction
-    attr_reader :condition , :true_block , :false_block , :merge_block
+  class TruthCheck < Check
+    attr_reader :condition
 
-    def initialize(condition , true_block , false_block , merge_block)
-      @condition , @true_block , @false_block , @merge_block = condition , true_block , false_block , merge_block
+    def initialize(condition)
+      @condition  = condition 
     end
   end
-
-
 end
diff --git a/lib/vool/statements/if_statement.rb b/lib/vool/statements/if_statement.rb
index 365f734c..c675301e 100644
--- a/lib/vool/statements/if_statement.rb
+++ b/lib/vool/statements/if_statement.rb
@@ -10,19 +10,19 @@ module Vool
     end
 
     def to_mom( method )
-      merge = Mom::Noop.new(:merge)
-      if_true = add_jump(@if_true.to_mom( method ) , merge)
-      if_false = add_jump(@if_false.to_mom( method ) , merge)
-      cond = hoist_condition( method )
-      check = Mom::TruthCheck.new( cond.pop , if_true , if_false , merge)
-      [ *cond , check , if_true , if_false , merge ]
+      if_true =   @if_true.to_mom( method )
+      if_false =  @if_false.to_mom( method )
+      condition , hoisted  = hoist_condition( method )
+      check = Mom::IfStatement.new( Mom::TruthCheck.new(condition) , if_true , if_false )
+      check.hoisted = hoisted.to_mom(method) if hoisted
+      check
     end
 
     def hoist_condition( method )
       return [@condition] if @condition.is_a?(Vool::Named)
       local = method.create_tmp
-      assign = LocalAssignment.new( local , @condition).to_mom(method)
-      [assign , Vool::LocalVariable.new(local)]
+      assign = LocalAssignment.new( local , @condition)
+      [Vool::LocalVariable.new(local) , assign]
     end
 
     def collect(arr)
@@ -44,11 +44,5 @@ module Vool
       @if_true != nil
     end
 
-    private
-    def add_jump( block , merge)
-      block = [block] unless block.is_a?(Array)
-      block << Mom::Jump.new(merge)
-      block
-    end
   end
 end