Merge pull request #411 from LouisJackman/make-ctrl-c-interrupt-current-form

Make Ctrl-C Cancel the Current Form; Only Exit if Column 0 Outside of Form

src/boot/boot.janet

@@ -2017,19 +2017,26 @@
   (while going
     (if (env :exit) (break))
     (buffer/clear buf)
-    (chunks buf p)
-    (var pindex 0)
-    (var pstatus nil)
-    (def len (length buf))
-    (when (= len 0)
-      (parser/eof p)
-      (set going false))
-    (while (> len pindex)
-      (+= pindex (parser/consume p buf pindex))
-      (while (parser/has-more p)
-        (eval1 (parser/produce p)))
-      (when (= (parser/status p) :error)
-        (parse-err p where))))
+    (if (= (chunks buf p)
+           :cancel)
+      (do
+        # A :cancel chunk represents a cancelled form in the REPL, so reset.
+        (parser/flush p)
+        (buffer/clear buf))
+      (do
+        (var pindex 0)
+        (var pstatus nil)
+        (def len (length buf))
+        (when (= len 0)
+          (parser/eof p)
+          (set going false))
+        (while (> len pindex)
+          (+= pindex (parser/consume p buf pindex))
+          (while (parser/has-more p)
+            (eval1 (parser/produce p)))
+          (when (= (parser/status p) :error)
+            (parse-err p where))))))
+
   # Check final parser state
   (while (parser/has-more p)
     (eval1 (parser/produce p)))

src/mainclient/shell.c

@@ -25,6 +25,7 @@
 #endif
 
 #include <janet.h>
+#include <stdbool.h>
 
 #ifdef _WIN32
 #include <windows.h>
@@ -40,6 +41,8 @@ void janet_line_deinit();
 void janet_line_get(const char *p, JanetBuffer *buffer);
 Janet janet_line_getter(int32_t argc, Janet *argv);
 
+static JANET_THREAD_LOCAL bool gbl_cancel_current_repl_form = false;
+
 /*
  * Line Editing
  */
@@ -54,7 +57,17 @@ Janet janet_line_getter(int32_t argc, Janet *argv) {
     gbl_complete_env = (argc >= 3) ? janet_gettable(argv, 2) : NULL;
     janet_line_get(str, buf);
     gbl_complete_env = NULL;
-    return janet_wrap_buffer(buf);
+
+    Janet result;
+    if (gbl_cancel_current_repl_form) {
+        gbl_cancel_current_repl_form = false;
+
+        // Signal that the user bailed out of the current form
+        result = janet_ckeywordv("cancel");
+    } else {
+        result = janet_wrap_buffer(buf);
+    }
+    return result;
 }
 
 static void simpleline(JanetBuffer *buffer) {
@@ -746,8 +759,7 @@ static int line() {
                 kleft();
                 break;
             case 3:     /* ctrl-c */
-                errno = EAGAIN;
-                gbl_sigint_flag = 1;
+                gbl_cancel_current_repl_form = true;
                 clearlines();
                 return -1;
             case 4:     /* ctrl-d, eof */