From 508b4902f6e6df7387b617a67c6fe5e248ee2c38 Mon Sep 17 00:00:00 2001
From: Matthias Andreas Benkard <matthias@benkard.de>
Date: Thu, 12 Jun 2008 20:27:29 +0200
Subject: Add class MLKDynamicContext.

---
 GNUmakefile         |  4 ++--
 MLKDynamicContext.h | 26 ++++++++++++++++++++++
 MLKDynamicContext.m | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 91 insertions(+), 2 deletions(-)
 create mode 100644 MLKDynamicContext.h
 create mode 100644 MLKDynamicContext.m

diff --git a/GNUmakefile b/GNUmakefile
index 53176e7..4655041 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -18,8 +18,8 @@
 include $(GNUSTEP_MAKEFILES)/common.make
 
 TOOL_NAME = etoilisp
-etoilisp_OBJC_FILES = MLKCons.m MLKEnvironment.m MLKLinkedList.m	\
-                      MLKLispValue.m MLKSymbol.m			\
+etoilisp_OBJC_FILES = MLKCons.m MLKDynamicContext.m MLKEnvironment.m	\
+                      MLKLinkedList.m MLKLispValue.m MLKSymbol.m	\
                       MLKUndefinedVariableException.m
 
 BUNDLE_NAME = Test
diff --git a/MLKDynamicContext.h b/MLKDynamicContext.h
new file mode 100644
index 0000000..f515901
--- /dev/null
+++ b/MLKDynamicContext.h
@@ -0,0 +1,26 @@
+/* -*- mode: objc; coding: utf-8 -*- */
+/* Copyright 2008, Matthias Benkard. */
+
+@class MLKClosure, MLKEnvironment, NSLinkedList, NSMutableDictionary, NSString;
+
+
+@interface MLKDynamicContext
+{
+  MLKEnvironment *_conditionHandlers;
+  MLKEnvironment *_restarts;
+  MLKClosure *_currentConditionHandler;
+  MLKEnvironment *_environment;
+  MLKDynamicContext *_parent;
+}
+
+-(MLKDynamicContext *) initWithParent:(MLKDynamicContext *)aContext
+                            variables:(NSDictionary *)vars
+                             handlers:(NSDictionary *)handlers
+                             restarts:(NSDictionary *)restarts
+                       currentHandler:(MLKClosure *)handler;
+
+-(MLKDynamicContext *) pushContext;
+
++(MLKDynamicContext *) currentContext;
++(MLKDynamicContext *) popContext;
+@end
diff --git a/MLKDynamicContext.m b/MLKDynamicContext.m
new file mode 100644
index 0000000..2d8312f
--- /dev/null
+++ b/MLKDynamicContext.m
@@ -0,0 +1,63 @@
+/* -*- mode: objc; coding: utf-8 -*- */
+/* Copyright 2008, Matthias Benkard. */
+
+#import <Foundation/NSDictionary.h>
+#import <Foundation/NSArray.h>
+#import <Foundation/NSThread.h>
+
+#import "MLKDynamicContext.h"
+#import "MLKEnvironment.h"
+#import "MLKLinkedList.h"
+
+
+#define MAKE_ENVIRONMENT(variable, parent, parent_member)               \
+  (variable                                                             \
+   ? (id) [[MLKEnvironment alloc]                                       \
+            initWithParent:(parent                                      \
+                            ? (id) parent_member                        \
+                            : nil)                                      \
+                  bindings:vars]                                        \
+   : (id) (parent ? (id) parent_member : nil));
+
+
+@implementation MLKDynamicContext
+-(MLKDynamicContext *) initWithParent:(MLKDynamicContext *)aContext
+                            variables:(NSDictionary *)vars
+                             handlers:(NSDictionary *)handlers
+                             restarts:(NSDictionary *)restarts
+                       currentHandler:(MLKClosure *)handler
+{
+  _parent = (aContext ? aContext : [MLKDynamicContext currentContext]);
+  _environment = MAKE_ENVIRONMENT(vars, _parent, _parent->_environment);
+  _conditionHandlers = MAKE_ENVIRONMENT(handlers,
+                                        _parent,
+                                        _parent->_conditionHandlers);
+  _restarts = MAKE_ENVIRONMENT(restarts, _parent, _parent->_restarts);
+  _currentConditionHandler = (handler
+                              ? (id) handler
+                              : (_parent
+                                 ? (id) _parent->_currentConditionHandler
+                                 : nil));
+  return self;
+}
+
+-(MLKDynamicContext *) pushContext
+{
+  return [[[NSThread currentThread] threadDictionary]
+           objectForKey:@"MLKDynamicContext"];
+}
+
++(MLKDynamicContext *) currentContext
+{
+  return [[[NSThread currentThread] threadDictionary]
+           objectForKey:@"MLKDynamicContext"];
+}
+
++(MLKDynamicContext *) popContext
+{
+  MLKDynamicContext *context = [self currentContext];
+  [[[NSThread currentThread] threadDictionary] setObject:context->_parent
+                                               forKey:@"MLKDynamicContext"];
+  return context;
+}
+@end
-- 
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