diff options
| -rw-r--r-- | lib.h | 5 | ||||
| -rw-r--r-- | txr.1 | 59 | ||||
| -rw-r--r-- | unwind.c | 47 | ||||
| -rw-r--r-- | unwind.h | 1 |
4 files changed, 110 insertions, 2 deletions
@@ -968,6 +968,11 @@ INLINE val default_bool_arg(val arg) return if3(missingp(arg), nil, arg); } +INLINE val default_arg_strict(val arg, val dfl) +{ + return if3(missingp(arg), dfl, arg); +} + #define list_collect_decl(OUT, PTAIL) \ val OUT = nil; \ loc PTAIL = mkcloc(OUT) @@ -27000,7 +27000,9 @@ and .code handle-frame are used by the .code get-frames -function to represent information about the currently established +and +.code find-frame +functions to represent information about the currently established exception catches (see the .code catch macro) and handlers @@ -27093,6 +27095,57 @@ structure may be passed as an argument to the .code invoke-catch function. +.coNP Function @ find-frame +.synb +.mets (find-frame >> [ exception-symbol <> [ frame-type ]]) +.syne +.desc +The +.code find-frame +function locates the first (innermost) instance of a specific kind of +exception frame (a catch frame or a handler frame) which is eligible +for processing an exception of a specific type. If such a frame +is found, it is returned. The returned frame object is of the same kind as the +objects which comprise the list returned by the function +.codn get-frames . +If such a frame is not found, +.code nil +is returned. + +The +.meta exception-symbol +argument specifies a match by exception type: the candidate frame +must specify in its list of matches at least one type which is an exception +supertype of +.metn exception-symbol . +If this argument is omitted, it defaults to +.code nil +which finds any handler that matches at least one type. There is no way to +search for handlers which match an empty set of types; the +.code find-frame +function skips such frames. + +The +.meta frame-type +argument specifies which frame type to find. Useful values for this +argument are the structure type names +.code catch-frame +and +.code handle-frame +or the actual structure type objects which these type names denote. +If any other value is specified, the function returns +.code nil . +If the argument is omitted, it defaults to the type of the +.code catch-frame +structure. That is to say, by default, the function looks for catch +frames. + +Thus, if +.code find-frame +is called with no arguments at all it finds the innermost catch frame, +if any exists, or else returns +.codn nil . + .coNP Function @ invoke-catch .synb .mets (invoke-catch < catch-frame < symbol << argument *) @@ -27107,7 +27160,9 @@ described by the argument, which must be a structure of type .code catch-frame returned by a call to -.codn get-frames . +.code get-frame +or +.codn find-frame . The control transfer is possible only if the catch frame represented by @@ -252,6 +252,52 @@ val uw_get_frames(void) return out; } +val uw_find_frame(val extype, val frtype) +{ + uw_frame_t *ex; + uw_frtype_t et; + + extype = default_bool_arg(extype); + frtype = default_arg_strict(frtype, catch_frame_type); + + if (symbolp(frtype)) { + frtype = find_struct_type(frtype); + if (!frtype) + return nil; + } + + if (frtype == catch_frame_type) + et = UW_CATCH; + else if (frtype == handle_frame_type) + et = UW_HANDLE; + else + return nil; + + if (frtype != catch_frame_type && frtype != handle_frame_type) + return nil; + + for (ex = uw_stack; ex != 0; ex = ex->uw.up) { + if (ex->uw.type == et && ex->ca.visible) { + val match; + for (match = ex->ca.matches; match; match = cdr(match)) + if (uw_exception_subtype_p(extype, car(match))) + break; + if (match) { + args_decl(args, ARGS_MIN); + val fr = make_struct(frtype, nil, args); + slotset(fr, types_s, ex->ca.matches); + if (et == UW_CATCH) + slotset(fr, jump_s, cptr(coerce(mem_t *, ex))); + else + slotset(fr, fun_s, ex->ha.fun); + return fr; + } + } + } + + return nil; +} + val uw_invoke_catch(val catch_frame, val sym, struct args *args) { uw_frame_t *ex, *ex_point; @@ -609,6 +655,7 @@ void uw_late_init(void) reg_var(unhandled_hook_s = intern(lit("*unhandled-hook*"), user_package), nil); reg_fun(intern(lit("get-frames"), user_package), func_n0(uw_get_frames)); + reg_fun(intern(lit("find-frame"), user_package), func_n2o(uw_find_frame, 0)); reg_fun(intern(lit("invoke-catch"), user_package), func_n2v(uw_invoke_catch)); } @@ -127,6 +127,7 @@ void uw_pop_until(uw_frame_t *); uw_frame_t *uw_current_frame(void); uw_frame_t *uw_current_exit_point(void); val uw_get_frames(void); +val uw_find_frame(val extype, val frtype); val uw_invoke_catch(val catch_frame, val sym, struct args *); void uw_init(void); void uw_late_init(void); |