Fixing memoize edge cases with predicate and bang methods (#1727)

* Fixing memoize edge cases with predicate and bang methods. Fixes #1396

* cleaning up code and applying suggestions

spec/lucky/memoize_spec.cr

@@ -8,6 +8,8 @@ private class ObjectWithMemoizedMethods
   getter times_method_1_called = 0
   getter times_method_2_called = 0
   getter times_method_3_called = 0
+  getter times_method_4_called = 0
+  getter times_method_5_called = 0
 
   memoize def method_1 : String
     @times_method_1_called += 1
@@ -23,6 +25,16 @@ private class ObjectWithMemoizedMethods
     @times_method_3_called += 1
     arg_a + ", " + arg_b
   end
+
+  memoize def method_4? : Bool
+    @times_method_4_called += 1
+    true
+  end
+
+  memoize def method_5! : String
+    @times_method_5_called += 1
+    "Boom!"
+  end
 end
 
 describe "memoizations" do
@@ -81,4 +93,36 @@ describe "memoizations" do
     object.method_3("arg-a", "arg-b").should eq("arg-a, arg-b")
     object.times_method_3_called.should eq 3
   end
+
+  it "works with predicate methods" do
+    object = ObjectWithMemoizedMethods.new
+
+    object.method_4?.should eq(true)
+    object.method_4?.should eq(true)
+    object.method_4?.should eq(true)
+    object.times_method_4_called.should eq(1)
+  end
+
+  it "Works with bang methods" do
+    object = ObjectWithMemoizedMethods.new
+
+    object.method_5!.should eq("Boom!")
+    object.method_5!.should eq("Boom!")
+    object.method_5!.should eq("Boom!")
+    object.times_method_5_called.should eq(1)
+  end
+
+  it "calls uncached with predicate and bang methods" do
+    object = ObjectWithMemoizedMethods.new
+
+    object.method_4__uncached?.should eq(true)
+    object.method_4__uncached?.should eq(true)
+    object.method_4__uncached?.should eq(true)
+    object.times_method_4_called.should eq(3)
+
+    object.method_5__uncached!.should eq("Boom!")
+    object.method_5__uncached!.should eq("Boom!")
+    object.method_5__uncached!.should eq("Boom!")
+    object.times_method_5_called.should eq(3)
+  end
 end

src/lucky/memoizable.cr

@@ -25,15 +25,30 @@ module Lucky::Memoizable
       raise "All arguments must have an explicit type restriction for memoized methods" if method_def.args.any? &.restriction.is_a?(Nop)
     %}
 
-    @__memoized_{{method_def.name}} : Tuple(
+    {%
+      special_ending = nil
+      safe_method_name = method_def.name
+    %}
+
+    {%
+      if method_def.name.ends_with?('?')
+        special_ending = "?"
+        safe_method_name = method_def.name.tr("?", "")
+      elsif method_def.name.ends_with?('!')
+        special_ending = "!"
+        safe_method_name = method_def.name.tr("!", "")
+      end
+    %}
+
+    @__memoized_{{safe_method_name}} : Tuple(
       {{ method_def.return_type }},
       {% for arg in method_def.args %}
         {{ arg.restriction }},
       {% end %}
     )?
 
     # Returns uncached value
-    def {{ method_def.name }}__uncached(
+    def {{ safe_method_name }}__uncached{% if special_ending %}{{ special_ending.id }}{% end %}(
       {% for arg in method_def.args %}
         {{ arg.name }} : {{ arg.restriction }},
       {% end %}
@@ -44,7 +59,7 @@ module Lucky::Memoizable
     # Checks the passed arguments against the memoized args
     # and runs the method body if it is the very first call
     # or the arguments do not match
-    def {{ method_def.name }}__tuple_cached(
+    def {{ safe_method_name }}__tuple_cached{% if special_ending %}{{ special_ending.id }}{% end %}(
       {% for arg in method_def.args %}
         {{ arg.name }} : {{ arg.restriction }},
       {% end %}
@@ -55,10 +70,10 @@ module Lucky::Memoizable
       {% end %}
     )
       {% for arg, index in method_def.args %}
-        @__memoized_{{ method_def.name }} = nil if {{arg.name}} != @__memoized_{{ method_def.name }}.try &.at({{index}} + 1)
+        @__memoized_{{ safe_method_name }} = nil if {{arg.name}} != @__memoized_{{ safe_method_name }}.try &.at({{index}} + 1)
       {% end %}
-      @__memoized_{{ method_def.name }} ||= -> do
-        result = {{ method_def.name }}__uncached(
+      @__memoized_{{ safe_method_name }} ||= -> do
+        result = {{ safe_method_name }}__uncached{% if special_ending %}{{ special_ending.id }}{% end %}(
           {% for arg in method_def.args %}
             {{arg.name}},
           {% end %}
@@ -79,7 +94,7 @@ module Lucky::Memoizable
         {{ arg.name }} : {{ arg.restriction }}{% if has_default %} = {{ arg.default_value }}{% end %},
       {% end %}
     ) : {{ method_def.return_type }}
-      {{ method_def.name }}__tuple_cached(
+      {{ safe_method_name }}__tuple_cached{% if special_ending %}{{ special_ending.id }}{% end %}(
         {% for arg in method_def.args %}
           {{arg.name}},
         {% end %}