From 3b6f3669a584830ca9be9e1f70fe941c91d2009c Mon Sep 17 00:00:00 2001
From: Fabio Niephaus <code@fniephaus.com>
Date: Mon, 13 Nov 2017 14:12:39 +0100
Subject: [PATCH] Implement Binding interface

https://ruby-doc.org/core-2.4.0/Binding.html
---
 tests/objects/test_bindingobject.py | 38 +++++++++++++++++++++++++++++
 topaz/objects/bindingobject.py      | 38 +++++++++++++++++++++++++++--
 2 files changed, 74 insertions(+), 2 deletions(-)

diff --git a/tests/objects/test_bindingobject.py b/tests/objects/test_bindingobject.py
index ea3701e24..ee1f8bda1 100644
--- a/tests/objects/test_bindingobject.py
+++ b/tests/objects/test_bindingobject.py
@@ -33,3 +33,41 @@ def test_unused_closure(self, space):
         return binding.eval('12')
         """)
         assert space.int_w(w_res) == 12
+
+    def test_local_variable_definedp(self, space):
+        w_res = space.execute("""
+        a = 5
+        return binding.local_variable_defined?('a')
+        """)
+        assert w_res == space.w_true
+
+    def test_local_variable_get(self, space):
+        w_res = space.execute("""
+        a = 5
+        return binding.local_variable_get('a')
+        """)
+        assert space.int_w(w_res) == 5
+
+    def test_local_variable_set(self, space):
+        w_res = space.execute("""
+        a = 5
+        binding.local_variable_set('a', 42)
+        return a
+        """)
+        assert space.int_w(w_res) == 42
+
+    def test_local_variables(self, space):
+        w_res = space.execute("""
+        a = 5
+        x = 'foo'
+        return binding.local_variables
+        """)
+        res_w = space.listview(w_res)
+        assert space.str_w(res_w[0]) == 'a'
+        assert space.str_w(res_w[1]) == 'x'
+
+    def test_receiver(self, space):
+        w_res = space.execute("""
+        return binding.receiver == self
+        """)
+        assert w_res == space.w_true
diff --git a/topaz/objects/bindingobject.py b/topaz/objects/bindingobject.py
index f7408384e..6b429306f 100644
--- a/topaz/objects/bindingobject.py
+++ b/topaz/objects/bindingobject.py
@@ -1,11 +1,14 @@
+from rpython.rlib import jit
+
 from topaz.astcompiler import SymbolTable
+from topaz.closure import ClosureCell
 from topaz.module import ClassDef
 from topaz.objects.objectobject import W_Object
 
 
 class W_BindingObject(W_Object):
     classdef = ClassDef("Binding", W_Object.classdef)
-    _immutable_fields_ = ["names[*]", "cells[*]", "w_self", "lexical_scope"]
+    _immutable_fields_ = ["names[*]?", "cells[*]?", "w_self", "lexical_scope"]
 
     def __init__(self, space, names, cells, w_self, lexical_scope):
         W_Object.__init__(self, space)
@@ -22,8 +25,39 @@ def method_eval(self, space, source):
         for name in self.names:
             symtable.cells[name] = symtable.FREEVAR
         bc = space.compile(source, "(eval)", symtable=symtable)
-        frame = space.create_frame(bc, w_self=self.w_self, lexical_scope=self.lexical_scope)
+        frame = space.create_frame(
+            bc, w_self=self.w_self, lexical_scope=self.lexical_scope)
         for idx, cell in enumerate(self.cells):
             frame.cells[idx + len(bc.cellvars)] = cell
         with space.getexecutioncontext().visit_frame(frame):
             return space.execute_frame(frame, bc)
+
+    @classdef.method("local_variable_defined?", key="symbol")
+    def method_local_variable_definedp(self, space, key):
+        return space.newbool(key in self.names)
+
+    @jit.unroll_safe
+    @classdef.method("local_variable_get", key="symbol")
+    def method_local_variable_get(self, space, key):
+        for idx, name in enumerate(self.names):
+            if name == key:
+                return self.cells[idx].get(space, None, 0)
+        return space.w_nil
+
+    @jit.unroll_safe
+    @classdef.method("local_variable_set", key="symbol")
+    def method_local_variable_set(self, space, key, w_value):
+        for idx, name in enumerate(self.names):
+            if name == key:
+                self.cells[idx].set(space, None, 0, w_value)
+                return
+        self.names.append(key)
+        self.cells.append(ClosureCell(w_value))
+
+    @classdef.method("local_variables")
+    def method_local_variables(self, space):
+        return space.newarray([space.newstr_fromstr(n) for n in self.names])
+
+    @classdef.method("receiver")
+    def method_receiver(self, space):
+        return self.w_self