From: Tim Vaughan <tgvaughan@gmail.com>
Date: Mon, 4 Jul 2016 22:15:56 +0000 (+0200)
Subject: Draft character atom implementation.
X-Git-Url: https://thelambdalab.xyz/gitweb/index.cgi?p=scheme.forth.jl.git;a=commitdiff_plain;h=26a971100b29dee243a42096d52d69ca518905ea

Draft character atom implementation.
---

diff --git a/scheme.4th b/scheme.4th
index 0bbfbf5..ea02cd5 100644
--- a/scheme.4th
+++ b/scheme.4th
@@ -18,7 +18,6 @@ variable stored-parse-idx
 create parse-str 161 allot
 variable parse-str-span
 
-
 create parse-idx-stack 10 allot 
 variable parse-idx-sp
 parse-idx-stack parse-idx-sp !
@@ -204,6 +203,19 @@ parse-idx-stack parse-idx-sp !
     boolean-type
 ;
 
+: readchar ( -- char-atom )
+    inc-parse-idx
+    inc-parse-idx
+
+    S" newline" str-equiv? if '\n' character-type exit then
+    S" space" str-equiv? if bl character-type exit then
+    S" tab" str-equiv? if 9 character-type exit then
+
+    nextchar character-type
+
+    inc-parse-idx
+;
+
 \ Parse a scheme expression
 : read ( -- obj )
 
@@ -219,6 +231,11 @@ parse-idx-stack parse-idx-sp !
         exit
     then
 
+    character? if
+        readchar
+        exit
+    then
+
     eof? if
         bold fg blue ." Moriturus te saluto." reset-term ."  ok" cr
         quit
@@ -258,10 +275,20 @@ parse-idx-stack parse-idx-sp !
     then
 ;
 
+: printchar ( charobj -- )
+    drop
+    case
+        9 of ." #\tab" endof
+        bl of ." #\space" endof
+        '\n' of ." #\newline" endof
+    endcase
+;
+
 : print ( obj -- )
     ." ; "
     number-type istype? if printnum exit then
     boolean-type istype? if printbool exit then
+    character-type istype? if printchar exit then
 ;
 
 \ ---- REPL ----