control flow for code

Author: dorianmariecom

lib/code.rb

@@ -49,6 +49,7 @@ def evaluate
       Node::Code.new(Code.parse(source)).evaluate(
         context: context,
         error: error,
+        global_control_flow_root: true,
         input: input,
         object: object,
         output: output,

lib/code/error.rb

@@ -2,20 +2,22 @@
 
 class Code
   class Error < StandardError
-    class Break < Error
+    class ControlFlow < Error
       attr_reader :code_value
 
       def initialize(value = nil)
         @code_value = value.to_code
       end
     end
 
-    class Next < Error
-      attr_reader :code_value
+    class Break < ControlFlow; end
 
-      def initialize(value = nil)
-        @code_value = value.to_code
-      end
-    end
+    class Next < ControlFlow; end
+
+    class Continue < Next; end
+
+    class Return < ControlFlow; end
+
+    class Retry < ControlFlow; end
   end
 end

lib/code/format.rb

@@ -318,7 +318,7 @@ def format_dictionary_statement_code(statement_code)
 
     def format_call(call, indent:)
       name = call[:name]
-      raw_arguments = Array(call[:arguments])
+      raw_arguments = call[:arguments].presence || []
       arguments = raw_arguments.map { |arg| format_call_argument(arg) }
       statement =
         if arguments.empty?
@@ -336,6 +336,8 @@ def format_call(call, indent:)
     end
 
     def format_call_argument(argument)
+      return format_code_inline(Array(argument), indent: 0) unless argument.is_a?(Hash)
+
       value = format_code_inline(argument[:value], indent: 0)
       return value unless argument.key?(:name)
 

lib/code/node/code.rb

@@ -11,13 +11,37 @@ def initialize(parsed)
       end
 
       def evaluate(**args)
+        global_control_flow_root = args.fetch(:global_control_flow_root, false)
+        control_flow_scope = args.fetch(:control_flow_scope, nil)
+        statement_args =
+          if global_control_flow_root
+            args.merge(global_control_flow_root: false)
+          else
+            args
+          end
         last = Object::Nothing.new
 
-        (@statements || []).each do |statement|
-          last = statement.evaluate(**args, object: Object::Global.new)
+        begin
+          (@statements || []).each do |statement|
+            last = statement.evaluate(**statement_args, object: Object::Global.new)
+          end
+        rescue Error::Retry
+          retry if control_flow_scope == :group
+
+          raise
+        rescue Error::Break => e
+          return e.code_value if control_flow_scope == :group
+
+          raise
         end
 
         last
+      rescue Error::ControlFlow => e
+        raise unless global_control_flow_root
+
+        retry if e.is_a?(Error::Retry)
+
+        e.code_value
       end
 
       def resolve(**args)

lib/code/node/right_operation.rb

@@ -28,21 +28,9 @@ def evaluate(**args)
             @left.evaluate(**args)
           end
         when "while"
-          left = Object::Nothing.new
-
-          left = @left&.evaluate(**args) || Object::Nothing.new while (
-            @right&.evaluate(**args) || Object::Nothing.new
-          ).truthy?
-
-          left
+          evaluate_conditional_loop(condition_truthy: true, **args)
         when "until"
-          left = Object::Nothing.new
-
-          left = @left&.evaluate(**args) || Object::Nothing.new while (
-            @right&.evaluate(**args) || Object::Nothing.new
-          ).falsy?
-
-          left
+          evaluate_conditional_loop(condition_truthy: false, **args)
         when "rescue"
           begin
             @left&.evaluate(**args) || Object::Nothing.new
@@ -69,6 +57,32 @@ def evaluate(**args)
           )
         end
       end
+
+      private
+
+      def evaluate_conditional_loop(condition_truthy:, **args)
+        left = Object::Nothing.new
+
+        while loop_condition_truthy?(condition_truthy, **args)
+          begin
+            left = @left&.evaluate(**args) || Object::Nothing.new
+          rescue Error::Next, Error::Continue => e
+            left = e.code_value
+            next
+          rescue Error::Retry
+            retry
+          rescue Error::Break => e
+            return e.code_value
+          end
+        end
+
+        left
+      end
+
+      def loop_condition_truthy?(condition_truthy, **args)
+        condition = (@right&.evaluate(**args) || Object::Nothing.new).truthy?
+        condition_truthy ? condition : !condition
+      end
     end
   end
 end

lib/code/node/statement.rb

@@ -11,6 +11,7 @@ def initialize(parsed)
         elsif parsed.key?(:boolean)
           @statement = Boolean.new(parsed.delete(:boolean))
         elsif parsed.key?(:group)
+          @control_flow_scope = :group
           @statement = Code.new(parsed.delete(:group))
         elsif parsed.key?(:call)
           @statement = Call.new(parsed.delete(:call))
@@ -56,7 +57,12 @@ def initialize(parsed)
       end
 
       def evaluate(**args)
-        @statement&.evaluate(**args) || Object::Nothing.new
+        if @control_flow_scope == :group
+          @statement&.evaluate(**args, control_flow_scope: @control_flow_scope) ||
+            Object::Nothing.new
+        else
+          @statement&.evaluate(**args) || Object::Nothing.new
+        end
       end
 
       def resolve(**args)

lib/code/node/while.rb

@@ -20,29 +20,61 @@ def initialize(parsed)
       def evaluate(**args)
         case @operator
         when WHILE_KEYWORD
-          last = Object::Nothing.new
-
-          last = @body&.evaluate(**args) || Object::Nothing.new while (
-            @statement&.evaluate(**args) || Object::Nothing.new
-          ).truthy?
-
-          last
+          evaluate_conditional_loop(condition_truthy: true, **args)
         when UNTIL_KEYWORD
-          last = Object::Nothing.new
-
-          last = @body&.evaluate(**args) || Object::Nothing.new while (
-            @statement&.evaluate(**args) || Object::Nothing.new
-          ).falsy?
-
-          last
+          evaluate_conditional_loop(condition_truthy: false, **args)
         when LOOP_KEYWORD
-          loop { @body&.evaluate(**args) || Object::Nothing.new }
-          Object::Nothing.new
+          evaluate_infinite_loop(**args)
         else
           Object::Nothing.new
         end
-      rescue Error::Break => e
-        e.code_value
+      end
+
+      private
+
+      def evaluate_conditional_loop(condition_truthy:, **args)
+        last = Object::Nothing.new
+
+        while loop_condition_truthy?(condition_truthy, **args)
+          begin
+            last = @body&.evaluate(**args) || Object::Nothing.new
+          rescue Error::Next, Error::Continue => e
+            last = e.code_value
+            next
+          rescue Error::Retry
+            retry
+          rescue Error::Break => e
+            return e.code_value
+          end
+        end
+
+        last
+      end
+
+      def evaluate_infinite_loop(**args)
+        last = Object::Nothing.new
+
+        loop do
+          begin
+            last = @body&.evaluate(**args) || Object::Nothing.new
+          rescue Error::Next, Error::Continue => e
+            last = e.code_value
+            next
+          rescue Error::Retry
+            retry
+          rescue Error::Break => e
+            return e.code_value
+          end
+        end
+
+        last
+      end
+
+      def loop_condition_truthy?(condition_truthy, **args)
+        condition =
+          (@statement&.evaluate(**args) || Object::Nothing.new).truthy?
+
+        condition_truthy ? condition : !condition
       end
     end
   end

lib/code/object/function.rb

@@ -72,6 +72,8 @@ def code_call(*arguments, **globals)
         end
 
         code_body.code_evaluate(**globals, context: code_context)
+      rescue Error::Return => e
+        e.code_value
       end
 
       def signature_for_call

lib/code/object/global.rb

@@ -23,9 +23,18 @@ def call(**args)
         when "break"
           sig(args) { Object.repeat }
           raise Error::Break, code_value || Nothing.new
+        when "continue"
+          sig(args) { Object.repeat }
+          raise Error::Continue, code_value || Nothing.new
         when "next"
           sig(args) { Object.repeat }
           raise Error::Next, code_value || Nothing.new
+        when "redo", "retry"
+          sig(args) { Object.repeat }
+          raise Error::Retry, code_value || Nothing.new
+        when "return"
+          sig(args) { Object.repeat }
+          raise Error::Return, code_value || Nothing.new
         when "Class"
           sig(args) { Object.repeat }
           if code_arguments.any?

spec/code_spec.rb

@@ -313,6 +313,7 @@ def evaluate_with_output(input)
     ["[1, 2, 3]", "[1, 2, 3]"],
     ["[1, 2, 3].include?(2)", "true"],
     ["[1, 2, 3].include?(4)", "false"],
+    ["[1, 2, 3].map { |i| continue(0) if i.even? i ** 2}", "[1, 0, 9]"],
     ["[1, 2, 3].map { |i| next if i == 2 i ** 2}", "[1, nothing, 9]"],
     ["[1, 2, 3].map { |i| next(0) if i.even? i ** 2}", "[1, 0, 9]"],
     ["[1, 2, 3].select { |n| n.even? }", "[2]"],
@@ -328,9 +329,17 @@ def evaluate_with_output(input)
     ["[]", "[]"],
     ["\r\n", "nothing"],
     ["a = 0 [1, 2, 3].each { |i| next if i == 2 a += i } a", "4"],
+    ["a = 0\nb = 0\nwhile a < 4\n  a += 1\n  continue if a == 2\n  b += a\nend\nb", "8"],
     ["a = 0 loop a += 1 break end a", "1"],
+    ["a = 1\nbegin\n  a += 1\n  break if a > 3\n  retry\nend\na", "4"],
+    ["x = loop break(42) end x", "42"],
+    ["a = 0 a += 1 retry if a < 3 a", "3"],
     ["a = 0\nuntil a > 10 a += 1 end a", "11"],
     ["a = 0\nwhile a < 10 a += 1 end a", "10"],
+    [
+      "a = 0\nretried = false\nwhile a < 2\n  a += 1\n  retry if a == 1 && !retried && (retried = true)\nend\na",
+      "2"
+    ],
     ["a = 1 3.times { a += 1 } a", "4"],
     ["a = 1 a *= 2 a", "2"],
     ["a = 1 a += 1 a", "2"],
@@ -360,9 +369,15 @@ def evaluate_with_output(input)
     ["if false 1 elsif false 2", "nothing"],
     ["if false 1 elsif true 2", "2"],
     ["if false 1", "nothing"],
+    ["break(5)", "5"],
+    ["continue(6)", "6"],
     ["if true 1", "1"],
+    ["next(7)", "7"],
     ["not not false", "false"],
     ["not true", "false"],
+    ["retry(8)", "8"],
+    ["return(9)", "9"],
+    ["f = () => { return(3) 4 } f()", "3"],
     ["a = 1 orirginal = 2 orirginal", "2"],
     ["a = 1 andy = 2 andy", "2"],
     ["ifonly = 1 ifonly", "1"],