From ad05662ae05336aa5db20f9d34d5c1d5bba9d6c2 Mon Sep 17 00:00:00 2001
From: Matthias Andreas Benkard <matthias@benkard.de>
Date: Sat, 23 Aug 2008 16:34:08 +0200
Subject: Make compilers pluggable at runtime.

---
 MLKInterpreter.m   | 58 +++++++++++++++++++++++++++++-------------------------
 MLKLLVMCompiler.h  |  2 ++
 MLKLLVMCompiler.mm |  9 +++++++++
 MLKRoot.m          | 11 +++++++----
 globals.h          |  6 ++++++
 globals.m          |  3 +++
 6 files changed, 58 insertions(+), 31 deletions(-)

diff --git a/MLKInterpreter.m b/MLKInterpreter.m
index 0cdf904..7fd59ad 100644
--- a/MLKInterpreter.m
+++ b/MLKInterpreter.m
@@ -35,6 +35,7 @@
 #import "MLKRoot.h"
 #import "MLKSymbol.h"
 #import "NSObject-MLKPrinting.h"
+#import "globals.h"
 #import "runtime-compatibility.h"
 #import "special-symbols.h"
 #import "util.h"
@@ -1230,34 +1231,37 @@
         fprintf (stderr, "| ");
       fprintf (stderr, "LOAD: %s\n", [formdesc UTF8String]);
 
-#ifdef USE_LLVM
-      expansion = code;
-      result = [MLKLLVMCompiler eval:code];
-#else // !USE_LLVM
-      expansion = denullify([[MLKInterpreter
-                               eval:code
-                               inLexicalContext:[MLKLexicalContext
-                                                  globalContext]
-                               withEnvironment:[MLKLexicalEnvironment
-                                                 globalEnvironment]
-                               mode:not_compile_time_mode]
-                              objectAtIndex:0]);
-
-      if ([code isKindOfClass:[MLKCons class]] && [code cdr])
-        formdesc = [NSString stringWithFormat:@"(%@ %@ ...)",
-                               MLKPrintToString([expansion car]),
-                               MLKPrintToString([[expansion cdr] car])];
+      if (MLKLoadCompilesP)
+        {
+          expansion = code;
+          result = [MLKDefaultCompiler eval:code];
+        }
       else
-        formdesc = MLKPrintToString(expansion);
-
-      //fprintf (stderr, "; LOAD: %s\n", [formdesc UTF8String]);
-      result = [MLKInterpreter
-                 eval:expansion
-                 inLexicalContext:[MLKLexicalContext globalContext]
-                 withEnvironment:[MLKLexicalEnvironment globalEnvironment]
-                 expandOnly:NO];
-      //NSLog (@"; LOAD: Top-level form evaluated.");
-#endif  //!USE_LLVM
+        {
+          expansion = denullify([[MLKInterpreter
+                                   eval:code
+                                   inLexicalContext:[MLKLexicalContext
+                                                      globalContext]
+                                   withEnvironment:[MLKLexicalEnvironment
+                                                     globalEnvironment]
+                                   mode:not_compile_time_mode]
+                                  objectAtIndex:0]);
+
+          if ([code isKindOfClass:[MLKCons class]] && [code cdr])
+            formdesc = [NSString stringWithFormat:@"(%@ %@ ...)",
+                                 MLKPrintToString([expansion car]),
+                                 MLKPrintToString([[expansion cdr] car])];
+          else
+            formdesc = MLKPrintToString(expansion);
+
+          //fprintf (stderr, "; LOAD: %s\n", [formdesc UTF8String]);
+          result = [MLKInterpreter
+                     eval:expansion
+                     inLexicalContext:[MLKLexicalContext globalContext]
+                     withEnvironment:[MLKLexicalEnvironment globalEnvironment]
+                     expandOnly:NO];
+          //NSLog (@"; LOAD: Top-level form evaluated.");
+        }
 
       LRELEASE (pool);
 
diff --git a/MLKLLVMCompiler.h b/MLKLLVMCompiler.h
index cf2823b..8a10c86 100644
--- a/MLKLLVMCompiler.h
+++ b/MLKLLVMCompiler.h
@@ -32,6 +32,8 @@ using namespace llvm;
 #endif
 
 @interface MLKLLVMCompiler : NSObject
++(void) load;
+
 +(void) initialize;
 
 +(id) compile:(id)object
diff --git a/MLKLLVMCompiler.mm b/MLKLLVMCompiler.mm
index aa0ab79..4b63a89 100644
--- a/MLKLLVMCompiler.mm
+++ b/MLKLLVMCompiler.mm
@@ -76,6 +76,15 @@ static Constant
 
 
 @implementation MLKLLVMCompiler
++(void) load
+{
+  if (!MLKDefaultCompiler)
+    {
+      MLKDefaultCompiler = self;
+      MLKLoadCompilesP = YES;
+    }
+}
+
 +(void) initialize
 {
   module = new llvm::Module ("MLKLLVMModule");
diff --git a/MLKRoot.m b/MLKRoot.m
index 0db7483..361ce16 100644
--- a/MLKRoot.m
+++ b/MLKRoot.m
@@ -32,6 +32,7 @@
 #import "MLKSingleFloat.h"
 #import "MLKDoubleFloat.h"
 #import "NSObject-MLKPrinting.h"
+#import "globals.h"
 #import "runtime-compatibility.h"
 #import "util.h"
 
@@ -708,17 +709,19 @@ as provided by method %@ of object %@",
                          with:nil]]);
 }
 
-#ifdef USE_LLVM
 +(NSArray *) compile:(NSArray *)args
 {
+  if (!MLKDefaultCompiler)
+    [NSException raise:@"MLKNotImplementedException"
+                 format:@"It seems as though there is no compiler here."];
+
   //NSLog (@"Compiling lambda form.");
-  id thing = [MLKLLVMCompiler compile:denullify([args objectAtIndex:0])
-                              inContext:[MLKLexicalContext globalContext]];
+  id thing = [MLKDefaultCompiler compile:denullify([args objectAtIndex:0])
+                                 inContext:[MLKLexicalContext globalContext]];
   //NSLog (@"Compilation done.");
   //NSLog (@"Compiled: %@", thing);
   RETURN_VALUE (thing);
 }
-#endif
 
 +(NSArray *) fset:(NSArray *)args
 {
diff --git a/globals.h b/globals.h
index 076a1ee..3dbda38 100644
--- a/globals.h
+++ b/globals.h
@@ -16,4 +16,10 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#import <Foundation/NSObject.h>
+
+
 extern id MLKEndOfArgumentsMarker;
+
+extern id MLKDefaultCompiler;
+extern BOOL MLKLoadCompilesP;
diff --git a/globals.m b/globals.m
index 2e8ed17..8781620 100644
--- a/globals.m
+++ b/globals.m
@@ -23,6 +23,9 @@
 
 id MLKEndOfArgumentsMarker;
 
+id MLKDefaultCompiler = nil;
+BOOL MLKLoadCompilesP = NO;
+
 
 @interface MLKGlobalManager : NSObject
 +(void) load;
-- 
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