add constant

app/models/logic.rb

@@ -0,0 +1,17 @@
+module Logic
+  def self.from_h(h)
+    class_from_name(h['op']).from_h(h)
+  end
+
+  def self.from_json(s)
+    from_h(JSON.parse(s))
+  end
+
+  def self.class_from_name(name)
+    [Constant]
+      .find { |c| c.name == name }
+  end
+
+  def constant(value) = Logic::Constant.new(value)
+
+end

app/models/logic/constant.rb

@@ -0,0 +1,39 @@
+class Logic::Constant < Logic::Term
+  attr_reader :value
+
+  def initialize(value)
+    @value = value
+  end
+
+  def compute(_champs = nil) = @value
+
+  def to_s = @value.to_s
+
+  def type
+    case @value
+    when TrueClass, FalseClass
+      :boolean
+    when Integer, Float
+      :number
+    else
+      @value.class.name.downcase.to_sym
+    end
+  end
+
+  def errors(_stable_ids = nil) = []
+
+  def to_h
+    {
+      "op" => self.class.name,
+      "value" => @value
+    }
+  end
+
+  def self.from_h(h)
+    self.new(h['value'])
+  end
+
+  def ==(other)
+    self.class == other.class && @value == other.value
+  end
+end

app/models/logic/term.rb

@@ -0,0 +1,5 @@
+class Logic::Term
+  def to_json
+    to_h.to_json
+  end
+end

spec/models/logic/constant_spec.rb

@@ -0,0 +1,24 @@
+describe Logic::Constant do
+  include Logic
+
+  describe '#compute' do
+    it { expect(constant(1).compute).to eq(1) }
+  end
+
+  describe '#type' do
+    it { expect(constant(1).type).to eq(:number) }
+    it { expect(constant(1.0).type).to eq(:number) }
+    it { expect(constant('a').type).to eq(:string) }
+    it { expect(constant(true).type).to eq(:boolean) }
+    it { expect(constant(false).type).to eq(:boolean) }
+  end
+
+  describe '#errors' do
+    it { expect(constant(1).errors).to eq([]) }
+  end
+
+  describe '#==' do
+    it { expect(constant(1)).to eq(constant(1)) }
+    it { expect(constant(1)).not_to eq(constant('a')) }
+  end
+end

spec/models/logic_spec.rb

@@ -0,0 +1,8 @@
+describe Logic do
+  include Logic
+
+  it 'serializes deserializes' do
+    expect(Logic.from_h(constant(1).to_h)).to eq(constant(1))
+    expect(Logic.from_json(constant(1).to_json)).to eq(constant(1))
+  end
+end