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chore(library/tactic/cases_tactic): improve error message for unsupported equalities

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@leodemoura Should we add a flag to introduce the equalities as
hypotheses in this case?
This commit is contained in:
Gabriel Ebner 2017-07-18 08:51:43 +01:00
parent 9c2d42b269
commit 317319ded3
1 changed files with 19 additions and 9 deletions
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28
src/library/tactic/cases_tactic.cpp
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@ -24,9 +24,8 @@ Author: Leonardo de Moura
#include "library/tactic/subst_tactic.h"
namespace lean {
struct cases_tactic_exception : public exception {
tactic_state m_state;
cases_tactic_exception(tactic_state const & s, char const * msg):exception(msg), m_state(s) {}
struct cases_tactic_exception {
vm_obj m_tactic_exception;
};
struct cases_tactic_fn {
@ -60,9 +59,13 @@ struct cases_tactic_fn {
throw exception("tactic cases failed, unexpected inductive datatype type");
}
tactic_state mk_tactic_state(expr const & mvar) {
return mk_tactic_state_for_metavar(m_env, m_opts, "cases", m_mctx, mvar);
}
/* throw exception that stores the intermediate state */
[[ noreturn ]] void throw_exception(expr const & mvar, char const * msg) {
throw cases_tactic_exception(mk_tactic_state_for_metavar(m_env, m_opts, "cases", m_mctx, mvar), msg);
throw cases_tactic_exception { tactic::mk_exception(msg, mk_tactic_state(mvar)) };
}
#define lean_cases_trace(MVAR, CODE) lean_trace(name({"tactic", "cases"}), type_context TMP_CTX = mk_type_context_for(MVAR); scope_trace_env _scope1(m_env, TMP_CTX); CODE)
@ -238,8 +241,7 @@ struct cases_tactic_fn {
}
format pp_goal(expr const & mvar) {
tactic_state tmp = mk_tactic_state_for_metavar(m_env, m_opts, "cases", m_mctx, mvar);
return tmp.pp_goal(mvar);
return mk_tactic_state(mvar).pp_goal(mvar);
}
list<expr> elim_aux_indices(list<expr> const & goals, buffer<name> const & aux_indices_H, hsubstitution_list & slist) {
@ -435,7 +437,15 @@ struct cases_tactic_fn {
return none_expr();
}
}
throw_exception(mvar, "cases tactic failed, unsupported equality");
auto s = mk_tactic_state(mvar);
throw cases_tactic_exception {
tactic::mk_exception([=] () {
return format("cases tactic failed, unsupported equality") + line()
+ format("(only equalities between constructors and/or variables are") + line()
+ format("supported, try cases on the indices):") + line()
+ s.pp_expr(H_type) + line();
}, s)
};
}
} else {
throw_exception(mvar, "cases tactic failed, equality expected");
@ -500,7 +510,7 @@ struct cases_tactic_fn {
lean_assert(is_metavar(mvar));
lean_assert(m_mctx.find_metavar_decl(mvar));
if (!is_local(H))
throw exception("cases tactic failed, argumen must be a hypothesis");
throw exception("cases tactic failed, argument must be a hypothesis");
if (!is_cases_applicable(mvar, H))
throw exception("cases tactic failed, it is not applicable to the given hypothesis");
list<name> cname_list = get_ginductive_intro_rules(m_env, m_I_decl.get_name());
@ -573,7 +583,7 @@ vm_obj tactic_cases_core(vm_obj const & H, vm_obj const & ns, vm_obj const & m,
}
return tactic::mk_success(to_obj(info_objs), set_mctx_goals(s, mctx, append(info.first, tail(s.goals()))));
} catch (cases_tactic_exception & ex) {
return tactic::mk_exception(ex.what(), ex.m_state);
return ex.m_tactic_exception;
} catch (exception & ex) {
return tactic::mk_exception(ex, s);
}