Add keywords to lexer

1 files changed, 11 insertions, 1 deletions

diff --git a/src/modules/lexer/lexer.scm b/src/modules/lexer/lexer.scm
index e07ab67..dae7107 100644
--- a/src/modules/lexer/lexer.scm
+++ b/src/modules/lexer/lexer.scm
@@ -30,7 +30,7 @@ current input port."
        'semi-colon)
 
       ((char-alphabetic? chr)
-       (read-identifier chr))
+       (lookup-keyword (read-identifier chr)))
 
       ((char-numeric? chr)
        (read-constant chr))
@@ -57,3 +57,13 @@ current input port."
 	     (read-identifier-helper (cons (read-char) chrs-so-far)))
 	    (#t (reverse chrs-so-far)))))
   (list->string (read-identifier-helper (list chr))))
+
+(define (lookup-keyword id)
+  "Given identifier ID, converts it to a keyword
+if one is known."
+  (let ((found (assoc
+		id
+		'(("int" . int)
+		  ("void" . void)
+		  ("return" . return)))))
+    (if found (cdr found) id)))