Beginnings of a Lisp compiler.

1 files changed, 61 insertions, 0 deletions

diff --git a/MLKEnvironment.m b/MLKEnvironment.m
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index 0000000..56bafb7
--- /dev/null
+++ b/MLKEnvironment.m
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+/* -*- mode: objc; coding: utf-8 -*- */
+/* Copyright 2008, Matthias Benkard. */
+
+#import <Foundation/NSDictionary.h>
+#import <Foundation/NSArray.h>
+
+#import "MLKEnvironment.h"
+#import "MLKLinkedList.h"
+#import "MLKCons.h"
+#import "MLKUndefinedVariableException.h"
+
+
+@implementation MLKEnvironment
+-(MLKEnvironment *) init
+{
+  _bindings = [[MLKLinkedList alloc] init];
+  return self;
+}
+
+-(MLKEnvironment *) initWithParent:(MLKEnvironment *)parent
+{
+  ASSIGN (_bindings, parent->_bindings);
+  return self;
+}
+
+-(void) setBinding:(MLKSymbol *)symbol to:(id)value
+{
+  MLKCons *cons;
+  for (cons = [_bindings firstCons]; cons; cons = [cons cdr])
+    {
+      NSMutableDictionary *dict = [cons car];
+      if ([[dict allKeys] containsObject:symbol])
+        {
+          [dict setObject:value forKey:symbol];
+          break;
+        }
+    }
+  
+  [[[MLKUndefinedVariableException alloc] initWithEnvironment: self
+                                          variableName: symbol]
+    raise];
+}
+
+-(id) valueForBinding:(MLKSymbol *)symbol
+{
+  MLKCons *cons;
+  for (cons = [_bindings firstCons]; cons; cons = [cons cdr])
+    {
+      NSMutableDictionary *dict = [cons car];
+      if ([[dict allKeys] containsObject:symbol])
+        {
+          return [dict objectForKey:symbol];
+        }
+    }
+
+  [[[MLKUndefinedVariableException alloc] initWithEnvironment: self
+                                          variableName: symbol]
+    raise];
+  return nil;
+}
+@end