From bcb0d6232d5e0a9af2807e77681d059bbd0e18df Mon Sep 17 00:00:00 2001
From: Andrew Kesterson <andrew@aklabs.net>
Date: Sat, 16 Jul 2011 23:03:33 -0700
Subject: [PATCH] Bringing over original mercurial/bitbucket code

---
 exceptions.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 exceptions.c

diff --git a/exceptions.c b/exceptions.c
new file mode 100644
index 0000000..8660223
--- /dev/null
+++ b/exceptions.c
@@ -0,0 +1,79 @@
+#include <stdio.h>
+#include <setjmp.h>
+
+struct exc_status {
+	struct exc_status *next;
+	struct exc_status *prev;
+	jmp_buf buf;
+	int last_exception;
+	int last_caught;
+	int tried;
+};
+
+struct exc_status __exc_status_head;
+struct exc_status *EXC_STATUS_LIST = &__exc_status_head;
+
+int new_exc_frame(struct exc_status *es) 
+{
+	if ( !es )
+		return 1;
+	EXC_STATUS_LIST->next = es;
+	es->next = NULL;
+	es->prev = EXC_STATUS_LIST;
+	es->last_exception = 0;
+	es->last_caught = 0;
+	es->tried = 0;
+	EXC_STATUS_LIST = es;
+	return 0;
+}
+
+int clear_exc_frame()
+{
+	struct exc_status *es = EXC_STATUS_LIST;
+	if ( es->prev )
+		es->prev->next = NULL;
+	EXC_STATUS_LIST = es->prev;
+	es->last_exception = 0;
+	es->last_caught = 0;
+	es->tried = 0;
+}
+
+jmp_buf exc_buf;
+int EXC_LAST_EXCEPTION = 0;
+int EXC_LAST_CAUGHT = 0;
+int EXC_TRIED = 0;
+
+#define TRY struct exc_status es; new_exc_frame(&es); es.last_exception = sigsetjmp(es.buf, 1); switch( es.last_exception ) { case 0:
+#define CATCH(x) break; case x: es.last_caught = x;
+#define DEFAULT break; default: es.last_caught = 1;
+#define ETRY }; clear_exc_frame();
+#define FINALLY }; if ( es.last_caught || es.tried ) {
+#define THROW(x) EXC_STATUS_LIST->last_exception = x; siglongjmp(EXC_STATUS_LIST->buf, x);
+
+void testfunc(void)
+{
+	printf("Throwing 34 from testfunc\n");
+	THROW(34);
+}
+
+int main(void)
+{
+	TRY {
+		printf("Throwing 2\n");
+		THROW(2);
+	} CATCH(1) {
+		printf("Caught 1\n");
+	} CATCH(2) {
+		printf("Caught 2\n");
+		TRY {
+			testfunc();
+		} CATCH(34) {
+			printf("Caught 34!\n");
+		} ETRY
+	} DEFAULT {
+		printf("In default clause\n");
+	} FINALLY {
+		printf("In finally clause\n");
+	} ETRY
+	return 0;
+}