Exceptions!!!

src/stack.h

@@ -2,7 +2,6 @@
 #define INCLUDED_STACK_H
 
 #include "base.h"
-#include "list.h"
 
 #include <setjmp.h>
 #include <stdnoreturn.h>
@@ -49,8 +48,8 @@ struct _StackFrame {
         } unwind_protect;
         struct {
             jmp_buf *target;
-            LispVal **variable;
             LispVal *exceptions; // list of exception symbols to catch
+            size_t datum; // extra value to identify this case
         } condition_case;
         struct {
             LispVal *symbol;
@@ -72,6 +71,7 @@ struct UnwindInformation {
         struct {
             LispVal *name;
             LispVal *data;
+            size_t handler_datum;
         } exception;
     };
 };
@@ -110,6 +110,24 @@ static ALWAYS_INLINE StackFrame *LISP_STACK_REF(void) {
     return &the_stack.frames[the_stack.depth - 1];
 }
 
+static ALWAYS_INLINE LispVal *EXCEPTION_NAME(void) {
+    assert(the_stack.unwind_info.set
+           && the_stack.unwind_info.cause == UNWIND_EXCEPTION);
+    return the_stack.unwind_info.exception.name;
+}
+
+static ALWAYS_INLINE LispVal *EXCEPTION_DATA(void) {
+    assert(the_stack.unwind_info.set
+           && the_stack.unwind_info.cause == UNWIND_EXCEPTION);
+    return the_stack.unwind_info.exception.data;
+}
+
+static ALWAYS_INLINE size_t EXCEPTION_HANDLER_DATUM(void) {
+    assert(the_stack.unwind_info.set
+           && the_stack.unwind_info.cause == UNWIND_EXCEPTION);
+    return the_stack.unwind_info.exception.handler_datum;
+}
+
 // functions
 void push_call_frame(LispVal *name, LispVal *args);
 // replace the args in the top stack frame with ARGS and mark them as evaluated
@@ -121,8 +139,7 @@ void set_stack_evaluated_args(StackFrame *restrict ref, LispVal *fobj,
 void push_unwind_protect_frame(jmp_buf *buf);
 
 // condition case
-void push_condition_case_frame(jmp_buf *buf, LispVal **variable,
-                               LispVal *exceptions);
+void push_condition_case_frame(jmp_buf *buf, LispVal *exceptions, size_t datum);
 
 // local references
 void push_local_reference_frame(void);
@@ -153,6 +170,8 @@ static ALWAYS_INLINE LispVal *UNWIND_AND_RETURN(StackFrame *frame,
 }
 noreturn void continue_unwinding(void);
 
+noreturn void lisp_signal(LispVal *name, LispVal *data);
+
 #define UNWIND_PROTECT(body, cleanup)                        \
     {                                                        \
         jmp_buf _internal_jb;                                \
@@ -162,8 +181,23 @@ noreturn void continue_unwinding(void);
             {body};                                          \
             unwind_to(_internal_target);                     \
         } else {                                             \
-            cleanup                                          \
+            {cleanup};                                       \
+            continue_unwinding();                            \
         }                                                    \
     };
 
+#define CONDITION_CASE(exceptions, body, handler)                    \
+    {                                                                \
+        jmp_buf _internal_jb;                                        \
+        StackFrame *_internal_target = LISP_STACK_REF();             \
+        if (setjmp(_internal_jb) == 0) {                             \
+            push_condition_case_frame(&_internal_jb, exceptions, 0); \
+            {body};                                                  \
+            unwind_to(_internal_target);                             \
+        } else {                                                     \
+            {handler};                                               \
+            unwind_to(_internal_target);                             \
+        }                                                            \
+    };
+
 #endif