Add PyCall.iterable

lib/pycall.rb

@@ -5,6 +5,7 @@ module PyCall
   require 'pycall/pyobject_wrapper'
   require 'pycall/pytypeobject_wrapper'
   require 'pycall/pymodule_wrapper'
+  require 'pycall/iterable_wrapper'
   require 'pycall/init'
 
   module_function
@@ -73,6 +74,10 @@ def import_module(name)
     LibPython::Helpers.import_module(name)
   end
 
+  def iterable(obj)
+    IterableWrapper.new(obj)
+  end
+
   def len(obj)
     case obj
     when PyObjectWrapper

lib/pycall/iterable_wrapper.rb

@@ -0,0 +1,32 @@
+module PyCall
+  class IterableWrapper
+    include Enumerable
+
+    def initialize(obj)
+      @obj = check_iterable(obj)
+    end
+
+    private def check_iterable(obj)
+      unless PyCall.hasattr?(obj, :__iter__)
+        raise ArgumentError, "%p object is not iterable" % obj
+      end
+      obj
+    end
+
+    def each
+      return enum_for(__method__) unless block_given?
+      iter = @obj.__iter__()
+      while true
+        begin
+          yield iter.__next__()
+        rescue PyCall::PyError => err
+          if err.type == PyCall.builtins.StopIteration
+            break
+          else
+            raise err
+          end
+        end
+      end
+    end
+  end
+end

test/helper.rb

@@ -1,2 +1,8 @@
 require "pycall"
+require "pathname"
 require "test-unit"
+
+test_dir = Pathname.new(__dir__)
+python_dir = test_dir + "python"
+
+PyCall.sys.path.append(python_dir.to_s)

test/python/pycall/simple_iterable.py

@@ -0,0 +1,19 @@
+class IntGenerator(object):
+    def __init__(self, start, stop):
+        self.start = start
+        self.stop = stop
+        self.current = None
+
+    def __iter__(self):
+        self.current = self.start
+        return self
+
+    def __next__(self):
+        if self.current == self.stop:
+            raise StopIteration()
+        value = self.current
+        self.current += 1
+        return value
+
+if __name__ == "__main__":
+    print(list(IntGenerator(105, 115)))

test/test-pycall.rb

@@ -2,4 +2,18 @@ class PyCallTest < Test::Unit::TestCase
   def test_VERSION
     assert_not_nil(PyCall::VERSION)
   end
+
+  def test_iterable
+    simple_iterable = PyCall.import_module("pycall.simple_iterable")
+    int_gen = simple_iterable.IntGenerator.new(10, 25)
+    iterable = PyCall.iterable(int_gen)
+    assert_equal({
+                   enumerable_p: true,
+                   each_to_a: (10 .. 24).to_a,
+                 },
+                 {
+                   enumerable_p: iterable.is_a?(Enumerable),
+                   each_to_a: iterable.each.to_a
+                 })
+  end
 end