Merge pull request #131 from faultyserver/bug/self_closures

Closes #81. Capture `self` as part of a closure.

.gitignore

@@ -7,4 +7,5 @@
 
 # The myst executable
 /myst
-/bytecode_generator
+# DWARF file from compiling on macOS
+/myst.dwarf

spec/interpreter/invocation_spec.cr

@@ -115,4 +115,28 @@ describe "Interpreter - Invocation" do
 
   it_invokes TYPE_DEFS, "Foo.foo",    val(:static_foo)
   it_invokes TYPE_DEFS, "%Foo{}.foo", val(:instance_foo)
+
+
+  it "restores the value of `self` after executing with a receiver" do
+    itr = Interpreter.new
+    original_self = itr.current_self
+
+    parse_and_interpret %q(
+      "hello, world".size
+    ), interpreter: itr
+
+    itr.current_self.should eq(original_self)
+  end
+
+  it "restores the value of `self` after executing a closure" do
+    itr = Interpreter.new
+    original_self = itr.current_self
+
+    parse_and_interpret %q(
+      @sum = 0
+      [1, 2, 3].each{ |e| @sum += e }
+    ), interpreter: itr
+
+    itr.current_self.should eq(original_self)
+  end
 end

spec/interpreter/nodes/anonymous_function_spec.cr

@@ -16,13 +16,32 @@ describe "Interpreter - AnonymousFunction" do
 
   it "acts like a closure" do
     itr = parse_and_interpret %q(
-      fn
-        ->(a) { a + 1 }
+      def foo
+        :called_foo
+      end
+
+      func = fn
+        ->() { foo }
       end
+
+      func()
     )
 
-    functor = itr.stack.pop.as(TFunctor)
-    functor.closure?.should eq(true)
+    itr.stack.last.should eq(val(:called_foo))
+  end
+
+  it "captures the value of `self` as part of the closure" do
+    itr = parse_and_interpret %q(
+      @sum = 0
+      func = fn
+        ->(a) { @sum += a }
+      end
+
+      func(6)
+      @sum
+    )
+
+    itr.stack.last.should eq(val(6))
   end
 
   it "allows clauses of various arities" do

spec/interpreter/nodes/block_spec.cr

@@ -63,4 +63,14 @@ describe "Interpreter - Block" do
 
     itr.stack.last.should eq(val(6))
   end
+
+  it "captures the value of `self` as part of the closure" do
+    itr = parse_and_interpret %q(
+      @sum = 0
+      [1, 2, 3].each{ |e| @sum += e }
+      @sum
+    )
+
+    itr.stack.last.should eq(val(6))
+  end
 end

src/myst/interpreter/invocation.cr

@@ -21,9 +21,15 @@ module Myst
 
     def invoke
       @selfstack_size_at_entry = @itr.self_stack.size
-      # If the invocation has a receiver, use it as the current value of `self`
-      # for the duration of the Invocation.
-      @itr.push_self(@receiver.not_nil!) if @receiver
+      case
+      when @receiver
+        # If the invocation has a receiver, use it as the current value of `self`
+        # for the duration of the Invocation.
+        @itr.push_self(@receiver.not_nil!)
+      when @func.closure?
+        # If the invoked functor is a closure, use the closed value of `self`.
+        @itr.push_self(@func.closed_self)
+      end
 
       result = @func.clauses.each do |clause|
         @itr.push_scope_override(@func.new_scope)
@@ -36,7 +42,7 @@ module Myst
 
       # After the invocation, restore the current value of `self` to whatever
       # it had been previously.
-      @itr.pop_self if @receiver
+      @itr.pop_self(to_size: @selfstack_size_at_entry)
       result || @itr.__raise_runtime_error("No clause matches with given arguments: #{@args.inspect}")
     rescue ex : BreakException
       if ex.caught?

src/myst/interpreter/nodes/anonymous_function.cr

@@ -14,7 +14,7 @@ module Myst
           current_scope
         end
 
-      functor = TFunctor.new([] of Callable, scope, closure: true)
+      functor = TFunctor.new([] of Callable, scope, closure: true, closed_self: current_self)
 
       node.clauses.each do |clause|
         functor.add_clause(TFunctorDef.new(clause))

src/myst/interpreter/nodes/def.cr

@@ -27,7 +27,7 @@ module Myst
           scope.assign(node.name, functor)
         end
       else
-        functor = TFunctor.new([] of Callable, scope, closure: true)
+        functor = TFunctor.new([] of Callable, scope, closure: true, closed_self: current_self)
       end
 
       functor.add_clause(TFunctorDef.new(node))

src/myst/interpreter/value.cr

@@ -286,8 +286,9 @@ module Myst
     property  clauses         : Array(Callable)
     property  lexical_scope   : Scope
     property? closure         : Bool
+    property!  closed_self     : Value?
 
-    def initialize(@clauses=[] of Callable, @lexical_scope : Scope=Scope.new, @closure : Bool=false)
+    def initialize(@clauses=[] of Callable, @lexical_scope : Scope=Scope.new, @closure : Bool=false, @closed_self : Value?=nil)
     end
 
     def add_clause(definition : Callable)