tisp

commit 8ec376b55c45815204e4a4ca057ce3408c180499
parent 49f7ff371efb1645cb75aad8d1927c4ae04bfd13
Author: Ed van Bruggen <edvb@uw.edu>
Date:   Thu, 22 Mar 2018 22:24:08 -0700

Add warnf and warn to notify user of errors

warnf is formatted version of warn, prevents ISO C99 issues. Instead of
exiting the whole REPL because of an error, return NULL and display error
message.

Diffstat:
tisp.c
 | 
35
++++++++++++++++++++++++++---------

1 file changed, 26 insertions(+), 9 deletions(-)
diff --git a/tisp.c b/tisp.c
@@ -20,6 +20,16 @@
 #define cdr(P)  ((P)->v.p.cdr)
 #define nilp(P) ((P)->t == NIL)
 
+#define warnf(M, ...) do {                                                        \
+	fprintf(stderr, "%s:%d: error: " M "\n", argv0, __LINE__, ##__VA_ARGS__); \
+	return NULL;                                                              \
+} while(0)
+
+#define warn(M) do {                                                              \
+	fprintf(stderr, "%s:%d: error: " M "\n", argv0, __LINE__);                \
+	return NULL;                                                              \
+} while(0)
+
 /* typedefs */
 struct Val;
 typedef struct Val *Val;
@@ -88,8 +98,8 @@ struct Val {
 };
 
 /* functions */
-static void hash_add(Hash ht, char *key, Val val);
-static void hash_extend(Hash ht, Val args, Val vals);
+static Val  hash_add(Hash ht, char *key, Val val);
+static Hash hash_extend(Hash ht, Val args, Val vals);
 static void hash_merge(Hash ht, Hash ht2);
 
 Val read_val(Str str);
@@ -193,7 +203,7 @@ hash_grow(Hash ht)
 }
 
 /* create new key and value pair to the hash table */
-static void
+static Val
 hash_add(Hash ht, char *key, Val val)
 {
 	Entry e = entry_get(ht, key);
@@ -203,11 +213,12 @@ hash_add(Hash ht, char *key, Val val)
 		ht->size++;
 		hash_grow(ht);
 	}
+	return val;
 }
 
 /* add each binding args[i] -> vals[i] */
 /* args and vals are both scheme lists */
-static void
+static Hash
 hash_extend(Hash ht, Val args, Val vals)
 {
 	Val arg, val;
@@ -216,9 +227,10 @@ hash_extend(Hash ht, Val args, Val vals)
 		arg = car(args);
 		val = car(vals);
 		if (arg->t != SYMBOL)
-			die(1, "%s: hash_extend: Argument not a symbol", argv0);
+			warn("hash_extend: argument not a symbol");
 		hash_add(ht, arg->v.s, val);
 	}
+	return ht;
 }
 
 /* add everything from ht2 into ht */
@@ -426,11 +438,12 @@ tisp_eval(Hash env, Val v)
 			return (*f->v.pr)(env, args);
 		case FUNCTION:
 			/* tail call into the function body with the extended env */
-			hash_extend(env, f->v.f.args, eval_pair(env, args));
+			if (!(hash_extend(env, f->v.f.args, eval_pair(env, args))))
+				return NULL;
 			hash_merge(env, f->v.f.env);
 			return tisp_eval(env, f->v.f.body);
 		default:
-			die(1, "%s: Attempt to eval non primitive", argv0);
+			warn("attempt to evaluate non primitive");
 		}
 	default: break;
 	}
@@ -491,7 +504,10 @@ prim_add(Hash env, Val args)
 	Val v;
 	int i = 0;
 	for (v = eval_pair(env, args); !nilp(v); v = cdr(v))
-		i += car(v)->v.i;
+		if (car(v)->t == INTEGER)
+			i += car(v)->v.i;
+		else
+			warnf("+: expecting integer, got type [%d]", car(v)->t);
 	return mk_int(i);
 }
 
@@ -550,7 +566,8 @@ main(int argc, char *argv[])
 	}
 
 	while ((v = tisp_read(str))) {
-		v = tisp_eval(env, v);
+		if (!(v = tisp_eval(env, v)))
+			continue;
 
 		tisp_print(v);
 		putchar('\n');