From 8e7ce9d430b439995ceddca2c4fb9e24ed323d3a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Sat, 30 Jul 2022 00:23:51 +0200
Subject: Add non-throwing variants of Query methods.
Pl has also been refactored, so that the unnecessary throw and
catch have been removed.
---
c/datalistview.cpp | 2 +-
c/pl.cpp | 12 ++++++++++++
c/pl.h | 28 +++++++++++++++++-----------
3 files changed, 30 insertions(+), 12 deletions(-)
diff --git a/c/datalistview.cpp b/c/datalistview.cpp
index fd37791..ea68f2d 100644
--- a/c/datalistview.cpp
+++ b/c/datalistview.cpp
@@ -53,7 +53,7 @@ void DataListView::ShowEpisode(const int iEpisode)
LVITEM lviKey = {LVIF_TEXT};
LVITEM lviValue = {LVIF_TEXT};
- for (int i = 0; q.NextSolution(); i++) {
+ for (int i = 0; q.NextSolution(std::nothrow); i++) {
std::wstring wsKey;
std::wstring wsValue;
diff --git a/c/pl.cpp b/c/pl.cpp
index 6e71383..665fe3a 100644
--- a/c/pl.cpp
+++ b/c/pl.cpp
@@ -55,6 +55,10 @@ Query::~Query()
PL_cut_query(m_q);
}
+int Query::Cut(std::nothrow_t)
+{
+ return PL_cut_query(m_q);
+}
int Query::Cut()
{
if (PL_cut_query(m_q)) return 1;
@@ -63,6 +67,10 @@ int Query::Cut()
}
/* Cut query and invalidate associated data. */
+int Query::Close(std::nothrow_t)
+{
+ return PL_close_query(m_q);
+}
int Query::Close()
{
if (PL_close_query(m_q)) return 1;
@@ -70,6 +78,10 @@ int Query::Close()
return 0;
}
+int Query::NextSolution(std::nothrow_t)
+{
+ return PL_next_solution(m_q);
+}
int Query::NextSolution()
{
if (PL_next_solution(m_q)) return 1;
diff --git a/c/pl.h b/c/pl.h
index 4a5ea41..c0af4bc 100644
--- a/c/pl.h
+++ b/c/pl.h
@@ -33,8 +33,11 @@ struct Query
Query(module_t ctx, predicate_t p, term_t t0);
~Query();
int Cut();
+ int Cut(std::nothrow_t);
int Close();
+ int Close(std::nothrow_t);
int NextSolution();
+ int NextSolution(std::nothrow_t);
private:
qid_t m_q;
};
@@ -92,28 +95,31 @@ inline bool PlGetN(term_t) { return true; }
template <typename T, typename... U>
inline bool PlGetN(term_t t, T x, U... xs) { return PlGet(t, x) && PlGetN(t+1, xs...); }
-/* Call Prolog predicate, propagating Prolog exceptions. */
-template <typename... T>
-int Plx(const char* const szMod, const char* const szPred, T... xs)
+/* Call Prolog predicate. */
+template <bool Except = false, typename... T>
+int Pl(const char* const szMod, const char* const szPred, T... xs)
{
Frame f;
const term_t t = PL_new_term_refs(sizeof...(T));
+
if (!PlPutN(t, xs...)) return 0;
Query q(NULL, PL_predicate(szPred, sizeof...(T), szMod), t);
- if (!q.NextSolution()) return 0;
+
+ if constexpr (Except) {
+ if (!q.NextSolution()) return 0;
+ } else {
+ if (!q.NextSolution(std::nothrow)) return 0;
+ }
+
if (!PlGetN(t, xs...)) return 0;
return 1;
}
-/* Call Prolog predicate, ignoring Prolog exceptions. */
+/* Call Prolog predicate, propagating Prolog exceptions. */
template <typename... T>
-int Pl(const char* const szMod, const char* const szPred, T... xs)
+int Plx(const char* const szMod, const char* const szPred, T... xs)
{
- try {
- return Plx(szMod, szPred, xs...);
- } catch (const term_t& t) {
- return 0;
- }
+ return Pl<true>(szMod, szPred, xs...);
}
#endif
--
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