From b6fa8261e69f1d44614e40f628e7102c47844ec9 Mon Sep 17 00:00:00 2001
From: Torsten Ruger <torsten@villataika.fi>
Date: Wed, 30 Aug 2017 17:21:13 +0300
Subject: [PATCH] first stab at moms if

---
 lib/mom/instruction.rb              | 11 +++++++++++
 lib/mom/jump.rb                     | 14 ++++++++++++++
 lib/mom/truth_check.rb              | 21 +++++++++++++++++++++
 lib/vool/statement.rb               |  3 ++-
 lib/vool/statements/if_statement.rb | 21 ++++++++++++++++++++-
 lib/vool/vool_compiler.rb           |  2 +-
 test/vool/to_mom/test_if.rb         | 27 +++++++++++++++++++++++++++
 7 files changed, 96 insertions(+), 3 deletions(-)
 create mode 100644 lib/mom/jump.rb
 create mode 100644 lib/mom/truth_check.rb
 create mode 100644 test/vool/to_mom/test_if.rb

diff --git a/lib/mom/instruction.rb b/lib/mom/instruction.rb
index df1cce24..29af863d 100644
--- a/lib/mom/instruction.rb
+++ b/lib/mom/instruction.rb
@@ -4,8 +4,19 @@ module Mom
   class Instruction
   end
 
+  # basically a label
+  class Noop
+    attr_reader :name
+    def initialize(name)
+      @name = name
+    end
+  end
+
+
 end
 
 require_relative "simple_call"
+require_relative "truth_check"
+require_relative "jump"
 require_relative "slot_load"
 require_relative "return_sequence"
diff --git a/lib/mom/jump.rb b/lib/mom/jump.rb
new file mode 100644
index 00000000..05094710
--- /dev/null
+++ b/lib/mom/jump.rb
@@ -0,0 +1,14 @@
+module Mom
+
+  # unconditional jump to the instruction given as target
+  # 
+  class Jump < Instruction
+    attr_reader :target
+
+    def initialize(target)
+      @target = target
+    end
+  end
+
+
+end
diff --git a/lib/mom/truth_check.rb b/lib/mom/truth_check.rb
new file mode 100644
index 00000000..dd9202b7
--- /dev/null
+++ b/lib/mom/truth_check.rb
@@ -0,0 +1,21 @@
+module Mom
+
+  # The funny thing about the ruby truth is that is is anything but false or nil
+  #
+  # 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
+
+    def initialize(condition , true_block , false_block , merge_block)
+      @condition , @true_block , @false_block , @merge_block = condition , true_block , false_block , merge_block
+    end
+  end
+
+
+end
diff --git a/lib/vool/statement.rb b/lib/vool/statement.rb
index e8b9a8b7..57d1069b 100644
--- a/lib/vool/statement.rb
+++ b/lib/vool/statement.rb
@@ -1,6 +1,6 @@
 # Virtual
 # Object Oriented
-# Langiage
+# Language
 #
 # VOOL is the abstraction of ruby, ruby minus some of the fluff
 #      fluff is generally what makes ruby nice to use, like 3 ways to achieve the same thing
@@ -12,6 +12,7 @@
 #
 # This allows us to write compilers or passes of the compiler(s) as functions on the
 # classes.
+#
 module Vool
 
   # Base class for all statements in the tree. Derived classes correspond to known language
diff --git a/lib/vool/statements/if_statement.rb b/lib/vool/statements/if_statement.rb
index 2185c5c6..62620057 100644
--- a/lib/vool/statements/if_statement.rb
+++ b/lib/vool/statements/if_statement.rb
@@ -2,13 +2,32 @@ module Vool
   class IfStatement < Statement
     attr_reader :condition , :if_true , :if_false
 
-    def initialize( cond , if_true , if_false = [])
+    def initialize( cond , if_true , if_false = nil)
       @condition = cond
       @if_true = if_true
       @if_false = if_false
       simplify_condition
     end
 
+    def to_mom( method )
+      if_true = @if_true.to_mom( method )
+      if_false = @if_false.to_mom( method )
+      make_condition( if_true , if_false )
+    end
+
+    # conditions in ruby are almost always method sends (as even comparisons are)
+    # currently we just deal with straight up values which get tested
+    # for the funny ruby logic (everything but false and nil is true)
+    def make_condition( if_true , if_false )
+      merge = Mom::Noop.new(:merge)
+      if_true = [if_true] unless if_true.is_a?(Array)
+      if_true << Mom::Jump.new(merge)
+      if_false = [if_false] unless if_false.is_a?(Array)
+      if_false << Mom::Jump.new(merge)
+      check = Mom::TruthCheck.new( @condition , if_true , if_false , merge)
+      [ check , if_true , if_false , merge ]
+    end
+
     def collect(arr)
       @if_true.collect(arr)
       @if_false.collect(arr)
diff --git a/lib/vool/vool_compiler.rb b/lib/vool/vool_compiler.rb
index 721fcd3b..23c9870c 100644
--- a/lib/vool/vool_compiler.rb
+++ b/lib/vool/vool_compiler.rb
@@ -2,7 +2,7 @@ require_relative "ruby_compiler"
 
 module Vool
   class VoolCompiler
-    
+
     def self.compile( ruby_source )
       statements = RubyCompiler.compile( ruby_source )
       statements.create_objects
diff --git a/test/vool/to_mom/test_if.rb b/test/vool/to_mom/test_if.rb
new file mode 100644
index 00000000..033c61d8
--- /dev/null
+++ b/test/vool/to_mom/test_if.rb
@@ -0,0 +1,27 @@
+
+require_relative "helper"
+
+module Vool
+  class TestIfMom < MiniTest::Test
+    include MomCompile
+
+    def setup
+      Risc.machine.boot
+      @stats = compile_first_method( "if(@a) ; 5.mod4 ; else; 4.mod4 ; end")
+      @first = @stats.first
+    end
+
+    def test_if_compiles_as_array
+      assert_equal Array , @first.class , @stats
+    end
+    def test_condition_compiles_to_check
+      assert_equal Mom::TruthCheck , @first.first.class , @stats
+    end
+    def test_condition_is_instance
+      assert_equal Vool::InstanceVariable , @first.first.condition.class , @stats
+    end
+    def test_true_block_is_second
+      assert_equal  @first[1] , @first.first.true_block , @stats
+    end
+  end
+end