altos/lisp: Make read() return eof atom on end of file

Also make it an exception to hit eof in the middle of an sexpr.

Signed-off-by: Keith Packard <keithp@keithp.com>

diff --git a/src/lisp/ao_lisp.h b/src/lisp/ao_lisp.h
index d265ea7bb9db23daab33404eb4691b63d1e533bc..6122a2edf5f6406ad991afe10a29bc459ecad3f2 100644 (file)
--- a/src/lisp/ao_lisp.h
+++ b/src/lisp/ao_lisp.h
@@ -42,6 +42,7 @@ extern uint8_t ao_lisp_const[AO_LISP_POOL_CONST];
 #define _ao_lisp_atom_delay    _atom("delay")
 #define _ao_lisp_atom_eval     _atom("eval")
 #define _ao_lisp_atom_read     _atom("read")
+#define _ao_lisp_atom_eof      _atom("eof")
 #else
 #include "ao_lisp_const.h"
 #ifndef AO_LISP_POOL
@@ -76,6 +77,7 @@ extern uint16_t               ao_lisp_top;
 #define AO_LISP_DIVIDE_BY_ZERO 0x02
 #define AO_LISP_INVALID                0x04
 #define AO_LISP_UNDEFINED      0x08
+#define AO_LISP_EOF            0x10
 
 extern uint8_t         ao_lisp_exception;
 

diff --git a/src/lisp/ao_lisp_read.c b/src/lisp/ao_lisp_read.c
index 3a2ef7f1f15cef109e81589a1adcd6e33132f61a..7a5751cef0315a7ec4662b3a49ab6ab0490a6592 100644 (file)
--- a/src/lisp/ao_lisp_read.c
+++ b/src/lisp/ao_lisp_read.c
@@ -12,6 +12,7 @@
  * General Public License for more details.
  */
 
+#define DBG_EVAL 0
 #include "ao_lisp.h"
 #include "ao_lisp_read.h"
 
@@ -270,7 +271,7 @@ lex(void)
        for (;;) {
                c = lexc();
                if (lex_class & ENDOFFILE)
-                       return AO_LISP_NIL;
+                       return END;
 
                if (lex_class & WHITE)
                        continue;
@@ -278,7 +279,7 @@ lex(void)
                if (lex_class & COMMENT) {
                        while ((c = lexc()) != '\n') {
                                if (lex_class & ENDOFFILE)
-                                       return AO_LISP_NIL;
+                                       return END;
                        }
                        continue;
                }
@@ -364,6 +365,8 @@ static struct ao_lisp_cons  *read_stack;
 static int
 push_read_stack(int cons, int in_quote)
 {
+       DBGI("push read stack %p %d\n", read_cons, in_quote);
+       DBG_IN();
        if (cons) {
                read_stack = ao_lisp_cons_cons(ao_lisp_cons_poly(read_cons),
                                               ao_lisp_cons_cons(ao_lisp_int_poly(in_quote),
@@ -394,6 +397,8 @@ pop_read_stack(int cons)
                read_cons_tail = 0;
                read_stack = 0;
        }
+       DBG_OUT();
+       DBGI("pop read stack %p %d\n", read_cons, in_quote);
        return in_quote;
 }
 
@@ -413,6 +418,7 @@ ao_lisp_read(void)
                been_here = 1;
        }
        parse_token = lex();
+       DBGI("token %d (%s)\n", parse_token, token_string);
 
        cons = 0;
        in_quote = 0;
@@ -424,12 +430,15 @@ ao_lisp_read(void)
                        cons++;
                        in_quote = 0;
                        parse_token = lex();
+                       DBGI("token %d (%s)\n", parse_token, token_string);
                }
 
                switch (parse_token) {
-               case ENDOFFILE:
+               case END:
                default:
-                       v = AO_LISP_NIL;
+                       if (cons)
+                               ao_lisp_error(AO_LISP_EOF, "unexpected end of file");
+                       return _ao_lisp_atom_eof;
                        break;
                case NAME:
                        atom = ao_lisp_atom_intern(token_string);
@@ -490,6 +499,7 @@ ao_lisp_read(void)
                }
 
                parse_token = lex();
+               DBGI("token %d (%s)\n", parse_token, token_string);
        }
        return v;
 }

diff --git a/src/lisp/ao_lisp_rep.c b/src/lisp/ao_lisp_rep.c
index d780186a2768e3fc633f22ca8174e352cee5d4ff..ef7dbaf283db697f0c0e0f0c34e6c5831a0e90ed 100644 (file)
--- a/src/lisp/ao_lisp_rep.c
+++ b/src/lisp/ao_lisp_rep.c
@@ -20,9 +20,8 @@ ao_lisp_read_eval_print(void)
        ao_poly in, out = AO_LISP_NIL;
        for(;;) {
                in = ao_lisp_read();
-               if (!in)
+               if (in == _ao_lisp_atom_eof)
                        break;
-//             printf ("in: "); ao_lisp_poly_print(in); printf("\n");
                out = ao_lisp_eval(in);
                if (ao_lisp_exception) {
                        ao_lisp_exception = 0;