Implement most of the Common Lisp reader.

1 files changed, 148 insertions, 0 deletions

diff --git a/MLKReader.m b/MLKReader.m
new file mode 100644
index 0000000..fba2ef2
--- /dev/null
+++ b/MLKReader.m
@@ -0,0 +1,148 @@
+/* -*- mode: objc; coding: utf-8 -*- */
+/* Étoilisp/Mulklisp, a Common Lisp subset for the Étoilé runtime.
+ * Copyright (C) 2008  Matthias Andreas Benkard.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#import "MLKReader.h"
+#import "MLKCharacter.h"
+#import "MLKReadtable.h"
+#import "MLKEndOfFileError.h"
+#import "MLKReaderError.h"
+#import "MLKDynamicContext.h"
+#import "MLKEnvironment.h"
+#import "MLKPackage.h"
+
+#import <Foundation/NSArray.h>
+#import <Foundation/NSString.h>
+
+
+@implementation MLKReader
++(id) readFromStream:(MLKStream *)stream
+            eofError:(BOOL)eofError
+            eofValue:(id)eofValue
+           recursive:(BOOL)recursive
+  preserveWhitespace:(BOOL)preserveWhitespace
+{
+  unichar ch;
+  NSMutableString *token;
+  MLKReadtable *readtable;
+  BOOL escaped;
+
+  readtable = [[[MLKDynamicContext currentContext] environment]
+                valueForBinding:[[MLKPackage commonLisp]
+                                  intern:@"*READTABLE*"]];
+  
+ start:
+  if ([stream isEOF])
+    {
+      if (eofError)
+        [[[MLKEndOfFileError alloc] initWithStream:stream] raise];
+      else
+        return eofValue;
+    }
+
+  ch = [stream readChar];
+  if ([readtable isWhitespaceCharacter:ch])
+    goto start;
+  
+  if ([readtable isMacroCharacter:ch])
+    {
+      NSArray *returnValues;
+      MLKClosure *macrofun = [readtable macroFunctionForCharacter:ch];
+      NSArray *args = [NSArray arrayWithObjects:
+                                 stream,
+                                 [MLKCharacter characterWithUnichar:ch],
+                               nil];
+      if ([args count] != 2)
+        {
+          args = [NSMutableArray arrayWithCapacity:2];
+          [((NSMutableArray*)args) addObject:stream];
+          [((NSMutableArray*)args) addObject:[MLKCharacter
+                                               characterWithUnichar:ch]];
+        }
+      returnValues = [macrofun applyToArray:args];
+      if ([returnValues count])
+        return [returnValues objectAtIndex:0];
+      else
+        goto start;
+    }
+  
+  escaped = NO;
+  
+  if ([readtable isSingleEscapeCharacter:ch])
+    {
+      if ([stream isEOF])
+        [[[MLKEndOfFileError alloc] initWithStream:stream] raise];
+
+      token = [NSMutableString stringWithCapacity:8];
+      [token appendFormat:@"%C", [stream readChar]];
+    }
+
+  if ([readtable isMultipleEscapeCharacter:ch])
+    {
+      token = [NSMutableString stringWithCapacity:8];      
+      escaped = YES;
+    }
+
+  if ([readtable isConstituentCharacter:ch])
+    {
+      token = [NSMutableString stringWithCapacity:8];
+      [token appendFormat:@"%C", [stream readChar]];
+    }
+
+  while (![stream isEOF])
+    {
+      ch = [stream readChar];
+      if ([readtable isConstituentCharacter:ch] ||
+          [readtable isNonTerminatingMacroCharacter:ch] ||
+          (escaped && [readtable isWhitespaceCharacter:ch]))
+        {
+          if (escaped)
+            [token appendFormat:@"%C", ch];
+          else
+            [token appendFormat:@"%C", [readtable charWithReadtableCase:ch]];
+        }
+      else if ([readtable isSingleEscapeCharacter:ch])
+        {
+          if ([stream isEOF])
+            [[[MLKEndOfFileError alloc] initWithStream:stream] raise];
+          
+          token = [NSMutableString stringWithCapacity:8];
+          [token appendFormat:@"%C", [stream readChar]];
+        }
+      else if ([readtable isMultipleEscapeCharacter:ch])
+        escaped = !escaped;
+      else if ([readtable isTerminatingMacroCharacter:ch])
+        {
+          [stream unreadChar];
+          break;
+        }
+      else if ([readtable isWhitespaceCharacter:ch])
+        {
+          if (preserveWhitespace)
+            [stream unreadChar];
+          break;
+        }
+      else if ([readtable isInvalidCharacter:ch])
+        {
+          [[[MLKReaderError alloc] initWithStream:stream] raise];
+        }
+    }
+
+  // FIXME: Check the token for invalid syntax.
+  return token;
+}
+@end