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author | Andy Wingo <wingo@pobox.com> | 2017-02-07 09:28:39 +0100 |
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committer | Andy Wingo <wingo@pobox.com> | 2017-02-07 09:57:55 +0100 |
commit | 498f3f95684361f3591106a8f9cb9065fd649288 (patch) | |
tree | 70a8e33d1ea25c54c273a3cbe347010403dfb07c /libguile/dynstack.c | |
parent | 81e9a128c146ccd495846ecbf664b3fd2855baf1 (diff) | |
download | guile-498f3f95684361f3591106a8f9cb9065fd649288.tar.gz |
Avoid stacks in dynamically-bound values
* libguile/dynstack.h:
* libguile/dynstack.c (scm_dynstack_find_old_fluid_value): New
function.
* libguile/fluids.c (saved_dynamic_state_ref): New helper.
(scm_fluid_ref): Fix docstring.
(scm_fluid_ref_star): New function allowing access to previous values
for a fluid.
(scm_dynamic_state_ref): New internal function.
* libguile/fluids.h: Add scm_fluid_ref_star and scm_dynamic_state_ref.
* libguile/stacks.c (scm_stack_id): Adapt to %stacks not being a chain.
* libguile/throw.c (catch, throw_without_pre_unwind): Adapt to
%exception-handlers not being a chain.
* module/ice-9/boot-9.scm (catch, dispatch-exception): Instead of having
%exception-handlers be a chain, use fluid-ref* to access the chain
that is in place at the time the exception is thrown. Prevents
unintended undelimited capture of the current exception handler stack
by a delimited "catch".
(%start-stack): Similarly, don't be a chain.
* module/system/repl/debug.scm (frame->stack-vector):
* module/system/repl/error-handling.scm (call-with-error-handling):
* module/ice-9/save-stack.scm (save-stack): Adapt to %stacks not being a
chain.
* test-suite/tests/exceptions.test ("delimited exception handlers"): Add
tests.
* doc/ref/api-control.texi (Fluids and Dynamic States): Add docs.
Diffstat (limited to 'libguile/dynstack.c')
-rw-r--r-- | libguile/dynstack.c | 49 |
1 files changed, 49 insertions, 0 deletions
diff --git a/libguile/dynstack.c b/libguile/dynstack.c index ff57c430d..652d2b35a 100644 --- a/libguile/dynstack.c +++ b/libguile/dynstack.c @@ -504,6 +504,55 @@ scm_dynstack_find_prompt (scm_t_dynstack *dynstack, SCM key, return NULL; } +SCM +scm_dynstack_find_old_fluid_value (scm_t_dynstack *dynstack, SCM fluid, + size_t depth, SCM dflt) +{ + scm_t_bits *walk; + + for (walk = SCM_DYNSTACK_PREV (dynstack->top); walk; + walk = SCM_DYNSTACK_PREV (walk)) + { + scm_t_bits tag = SCM_DYNSTACK_TAG (walk); + + switch (SCM_DYNSTACK_TAG_TYPE (tag)) + { + case SCM_DYNSTACK_TYPE_WITH_FLUID: + { + if (scm_is_eq (WITH_FLUID_FLUID (walk), fluid)) + { + if (depth == 0) + return SCM_VARIABLE_REF (WITH_FLUID_VALUE_BOX (walk)); + else + depth--; + } + break; + } + case SCM_DYNSTACK_TYPE_DYNAMIC_STATE: + { + SCM state, val; + + /* The previous dynamic state may or may not have + established a binding for this fluid. */ + state = scm_variable_ref (DYNAMIC_STATE_STATE_BOX (walk)); + val = scm_dynamic_state_ref (state, fluid, SCM_UNDEFINED); + if (!SCM_UNBNDP (val)) + { + if (depth == 0) + return val; + else + depth--; + } + break; + } + default: + break; + } + } + + return dflt; +} + void scm_dynstack_wind_prompt (scm_t_dynstack *dynstack, scm_t_bits *item, scm_t_ptrdiff reloc, scm_i_jmp_buf *registers) |