From a6955cf42df675518514e4da54f36174de9eb736 Mon Sep 17 00:00:00 2001
From: Matthias Andreas Benkard <matthias@benkard.de>
Date: Thu, 12 Jun 2008 19:44:53 +0200
Subject: Simplify MLKEnvironment.
---
MLKEnvironment.h | 9 +++++--
MLKEnvironment.m | 76 +++++++++++++++++++++++++-------------------------------
2 files changed, 41 insertions(+), 44 deletions(-)
diff --git a/MLKEnvironment.h b/MLKEnvironment.h
index fe2be16..b40ea5a 100644
--- a/MLKEnvironment.h
+++ b/MLKEnvironment.h
@@ -3,12 +3,13 @@
#import "MLKLispValue.h"
-@class NSMutableDictionary, MLKLinkedList, MLKSymbol;
+@class NSMutableDictionary, MLKSymbol;
@interface MLKEnvironment : MLKLispValue
{
- MLKLinkedList *_bindings;
+ MLKEnvironment *_parent;
+ NSMutableDictionary *_bindings;
}
-(MLKEnvironment *) init;
@@ -20,4 +21,8 @@
-(void) addBinding:(MLKSymbol *)symbol to:(id)value;
-(void) setBinding:(MLKSymbol *)symbol to:(id)value;
-(id) valueForBinding:(MLKSymbol *)symbol;
+
+// Private methods.
+-(void) setBinding:(MLKSymbol *)symbol to:(id)value inEnvironment:(MLKEnvironment *)env;
+-(id) valueForBinding:(MLKSymbol *)symbol inEnvironment:(MLKEnvironment *)env;
@end
diff --git a/MLKEnvironment.m b/MLKEnvironment.m
index e37c888..6df4e11 100644
--- a/MLKEnvironment.m
+++ b/MLKEnvironment.m
@@ -5,22 +5,19 @@
#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;
+ return [self initWithParent:nil bindings:nil];
}
-(MLKEnvironment *) initWithParent:(MLKEnvironment *)parent bindings:(NSDictionary *)bindings
{
- _bindings = [[MLKLinkedList alloc] initWithCons:[parent->_bindings firstCons]];
- [_bindings push: [NSMutableDictionary dictionaryWithCapacity:10]];
+ _bindings = [[NSMutableDictionary alloc] initWithCapacity:10];
+ ASSIGN (_parent, parent);
[self addBindings: bindings];
return self;
}
@@ -37,54 +34,49 @@
-(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];
+ [self setBinding:symbol to:value inEnvironment:self];
+}
+
+-(void) setBinding:(MLKSymbol *)symbol to:(id)value inEnvironment:(MLKEnvironment *)env
+{
+ if ([[_bindings allKeys] containsObject:symbol])
+ [_bindings setObject:value forKey:symbol];
+ else
+ if (_parent)
+ [_parent setBinding:symbol to:value inEnvironment:env];
+ else
+ [[[MLKUndefinedVariableException alloc] initWithEnvironment:env
+ 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];
- }
- }
+ return [self valueForBinding:symbol];
+}
- [[[MLKUndefinedVariableException alloc] initWithEnvironment: self
- variableName: symbol]
- raise];
- return nil;
+-(id) valueForBinding:(MLKSymbol *)symbol inEnvironment:(MLKEnvironment *)env
+{
+ if ([[_bindings allKeys] containsObject:symbol])
+ return [_bindings objectForKey:symbol];
+ else
+ if (_parent)
+ return [_parent valueForBinding:symbol];
+ else
+ [[[MLKUndefinedVariableException alloc] initWithEnvironment:env
+ variableName:symbol]
+ raise];;
+
+ return nil; // avoid a stupid compiler warning
}
-(void) addBindings:(NSDictionary *)bindings
{
- int i;
- NSArray *keys = [bindings allKeys];
- int count = [keys count];
- for (i = 0; i < count; i++)
- {
- [self addBinding:[keys objectAtIndex:i] to:[bindings objectForKey:[keys objectAtIndex:i]]];
- }
+ [_bindings addEntriesFromDictionary:bindings];
}
-(void) addBinding:(MLKSymbol *)symbol to:(id)value
{
- NSMutableDictionary *dict = [[_bindings firstCons] car];
- [dict setObject:value forKey:symbol];
+ [_bindings setObject:value forKey:symbol];
}
@end
--
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