From 98f28569b631d36a6f129a17ea7589b48884c1eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Sun, 24 Jul 2022 02:05:30 +0200
Subject: Fix PL_get_tchars.

See c6cd2f1.
---
 c/main.cpp |  6 +++---
 c/pl.cpp   | 26 +++++++++++++++-----------
 c/pl.h     |  4 ++--
 3 files changed, 20 insertions(+), 16 deletions(-)

diff --git a/c/main.cpp b/c/main.cpp
index 6865e4c..d59fd1d 100644
--- a/c/main.cpp
+++ b/c/main.cpp
@@ -64,9 +64,9 @@ void OnTerminate() noexcept
 	try {
 		std::rethrow_exception(std::current_exception());
         } catch (const term_t& t) {
-		TCHAR* tsz;
-		if (PL_get_tchars(t, &tsz, CVT_WRITE))
-			TerminateMsg<TCHAR>(TEXT("a Prolog exception"), tsz);
+		std::basic_string<TCHAR> tstr;
+		if (PlString(t, &tstr))
+			TerminateMsg<TCHAR>(TEXT("a Prolog exception"), tstr.c_str());
 		else
 			TerminateMsg<char>("a Prolog exception", NULL);
 	} catch (const Win32Error& e) {
diff --git a/c/pl.cpp b/c/pl.cpp
index 46ed717..a1849db 100644
--- a/c/pl.cpp
+++ b/c/pl.cpp
@@ -78,16 +78,20 @@ int Query::NextSolution()
 }
 
 /* Convert Prolog term to normal or wide characters. */
-int PL_get_tchars(const term_t t, TCHAR** const pTsz, const int iFlags)
+template <>
+int PlString<char>(const term_t t, std::string* const pStr, const int iFlags)
 {
-#ifdef UNICODE
-	size_t len;
-	if (!PL_get_wchars(t, &len, pTsz, iFlags))
-		return 0;
-	return len;
-#else
-	if (!PL_get_chars(t, pTsz, iFlags))
-		return 0;
-	return -1;
-#endif
+	char* sz;
+	int r = PL_get_chars(t, &sz, iFlags);
+	if (r) *pStr = sz;
+	return r;
+}
+
+template <>
+int PlString<wchar_t>(const term_t t, std::wstring* const pWstr, const int iFlags)
+{
+	char* sz;
+	int r = PL_get_chars(t, &sz, iFlags);
+	if (r) *pWstr = BstrFromSz<wchar_t>(sz);
+	return r;
 }
diff --git a/c/pl.h b/c/pl.h
index d1c01c4..4a44f72 100644
--- a/c/pl.h
+++ b/c/pl.h
@@ -7,8 +7,6 @@
 
 #include "common.h"
 
-int PL_get_tchars(term_t t, TCHAR** pTsz, int iFlags);
-
 struct Frame
 {
 	Frame();
@@ -39,6 +37,8 @@ private:
 	qid_t m_q;
 };
 
+template <typename T> int PlString(term_t t, std::basic_string<T>* pBstr, int iFlags = CVT_WRITE);
+
 /* Polymorphic aliases for PL_put_*, PL_get_*. */
 inline int PlPut(term_t t, int x) { return PL_put_integer(t, x); }
 inline int PlPut(term_t t, long x) { return PL_put_integer(t, x); }
-- 
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