core: convert filter_constraint_data_to_string to C++

Return an std::string to avoid memory management headaches.

While doing that, convert time.c to C++ so that
format_datetime directly returns an std::string.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

Subsurface-mobile.pro

@@ -95,7 +95,7 @@ SOURCES += subsurface-mobile-main.cpp \
 	core/strtod.c \
 	core/tag.c \
 	core/taxonomy.c \
-	core/time.c \
+	core/time.cpp \
 	core/trip.c \
 	core/units.c \
 	core/uemis.c \

core/CMakeLists.txt

@@ -181,7 +181,7 @@ set(SUBSURFACE_CORE_LIB_SRCS
 	tag.h
 	taxonomy.c
 	taxonomy.h
-	time.c
+	time.cpp
 	timer.c
 	timer.h
 	trip.c

core/filterconstraint.cpp

@@ -622,27 +622,23 @@ filter_constraint::~filter_constraint()
 		delete data.string_list;
 }
 
-extern "C" char *filter_constraint_data_to_string(const filter_constraint *c)
+std::string filter_constraint_data_to_string(const filter_constraint *c)
 {
-	QString s;
 	if (filter_constraint_is_timestamp(c->type)) {
-		char *from_s = format_datetime(c->data.timestamp_range.from);
+		std::string from_s = format_datetime(c->data.timestamp_range.from);
-		char *to_s = format_datetime(c->data.timestamp_range.to);
+		std::string to_s = format_datetime(c->data.timestamp_range.to);
-		s = QString(from_s) + ',' + QString(to_s);
+		return from_s + ',' + to_s;
-		free(from_s);
-		free(to_s);
 	} else if (filter_constraint_is_string(c->type)) {
 		// TODO: this obviously breaks if the strings contain ",".
 		// That is currently not supported by the UI, but one day we might
 		// have to escape the strings.
-		s = c->data.string_list->join(",");
+		return c->data.string_list->join(",").toStdString();
 	} else if (filter_constraint_is_multiple_choice(c->type)) {
-		s = QString::number(c->data.multiple_choice);
+		return std::to_string(c->data.multiple_choice);
 	} else {
-		s = QString::number(c->data.numerical_range.from) + ',' +
+		return std::to_string(c->data.numerical_range.from) + ',' +
-		    QString::number(c->data.numerical_range.to);
+		       std::to_string(c->data.numerical_range.to);
 	}
-	return copy_qstring(s);
 }
 
 void filter_constraint_set_stringlist(filter_constraint &c, const QString &s)

core/filterconstraint.h

@@ -116,7 +116,6 @@ extern bool filter_constraint_has_date_widget(enum filter_constraint_type);
 extern bool filter_constraint_has_time_widget(enum filter_constraint_type);
 extern int filter_constraint_num_decimals(enum filter_constraint_type);
 extern bool filter_constraint_is_valid(const struct filter_constraint *constraint);
-extern char *filter_constraint_data_to_string(const struct filter_constraint *constraint); // caller takes ownership of returned string
 
 #ifdef __cplusplus
 }
@@ -152,6 +151,8 @@ void filter_constraint_set_timestamp_from(filter_constraint &c, timestamp_t from
 void filter_constraint_set_timestamp_to(filter_constraint &c, timestamp_t to); // convert according to current units (metric or imperial)
 void filter_constraint_set_multiple_choice(filter_constraint &c, uint64_t);
 bool filter_constraint_match_dive(const filter_constraint &c, const struct dive *d);
+std::string filter_constraint_data_to_string(const struct filter_constraint *constraint); // caller takes ownership of returned string
+
 #endif
 
 #endif

core/save-git.cpp

@@ -957,7 +957,6 @@ static void format_one_filter_constraint(int preset_id, int constraint_id, struc
 {
 	const struct filter_constraint *constraint = filter_preset_constraint(preset_id, constraint_id);
 	const char *type = filter_constraint_type_to_string(constraint->type);
-	char *data;
 
 	show_utf8(b, "constraint type=", type, "");
 	if (filter_constraint_has_string_mode(constraint->type)) {
@@ -970,9 +969,8 @@ static void format_one_filter_constraint(int preset_id, int constraint_id, struc
 	}
 	if (constraint->negate)
 		put_format(b, " negate");
-	data = filter_constraint_data_to_string(constraint);
+	std::string data = filter_constraint_data_to_string(constraint);
-	show_utf8(b, " data=", data, "\n");
+	show_utf8(b, " data=", data.c_str(), "\n");
-	free(data);
 }
 
 /*

core/save-xml.cpp

@@ -657,7 +657,6 @@ static void save_filter_presets(struct membuffer *b)
 		free(fulltext);
 
 		for (int j = 0; j < filter_preset_constraint_count(i); j++) {
-			char *data;
 			const struct filter_constraint *constraint = filter_preset_constraint(i, j);
 			const char *type = filter_constraint_type_to_string(constraint->type);
 			put_format(b, "  <constraint");
@@ -673,9 +672,8 @@ static void save_filter_presets(struct membuffer *b)
 			if (constraint->negate)
 				put_format(b, " negate='1'");
 			put_format(b, ">");
-			data = filter_constraint_data_to_string(constraint);
+			std::string data = filter_constraint_data_to_string(constraint);
-			show_utf8(b, data, "", "", 0);
+			show_utf8(b, data.c_str(), "", "", 0);
-			free(data);
 			put_format(b, "</constraint>\n");
 		}
 		put_format(b, " </filterpreset>\n");

core/subsurface-time.h

@@ -16,12 +16,15 @@ extern int utc_weekday(timestamp_t timestamp);
 
 /* parse and format date times of the form YYYY-MM-DD hh:mm:ss */
 extern timestamp_t parse_datetime(const char *s); /* returns 0 on error */
-extern char *format_datetime(timestamp_t timestamp); /* ownership of string passed to caller */
 
 extern const char *monthname(int mon);
 
 #ifdef __cplusplus
 }
+
+#include <string>
+std::string format_datetime(timestamp_t timestamp); /* ownership of string passed to caller */
+
 #endif
 
 #endif

core/time.cpp

@@ -2,6 +2,7 @@
 #include "subsurface-time.h"
 #include "subsurface-string.h"
 #include "gettext.h"
+#include <QtCore> // for QT_TRANSLATE_NOOP
 #include <string.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -32,7 +33,7 @@
  * are unnecessary once you're counting minutes (32-bit minutes:
  * 8000+ years).
  */
-void utc_mkdate(timestamp_t timestamp, struct tm *tm)
+extern "C" void utc_mkdate(timestamp_t timestamp, struct tm *tm)
 {
 	static const unsigned int mdays[] = {
 		31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31,
@@ -99,7 +100,7 @@ void utc_mkdate(timestamp_t timestamp, struct tm *tm)
 	tm->tm_mon = m;
 }
 
-timestamp_t utc_mktime(const struct tm *tm)
+extern "C" timestamp_t utc_mktime(const struct tm *tm)
 {
 	static const int mdays[] = {
 		0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334
@@ -146,7 +147,7 @@ timestamp_t utc_mktime(const struct tm *tm)
  * out unused calculations. If it turns out to be a bottle neck
  * we will have to cache a struct tm per dive.
  */
-int utc_year(timestamp_t timestamp)
+extern "C" int utc_year(timestamp_t timestamp)
 {
 	struct tm tm;
 	utc_mkdate(timestamp, &tm);
@@ -161,7 +162,7 @@ int utc_year(timestamp_t timestamp)
  * at throwing out unused calculations, so this is more efficient
  * than it looks.
  */
-int utc_weekday(timestamp_t timestamp)
+extern "C" int utc_weekday(timestamp_t timestamp)
 {
 	struct tm tm;
 	utc_mkdate(timestamp, &tm);
@@ -173,7 +174,7 @@ int utc_weekday(timestamp_t timestamp)
  * an 64-bit decimal and return 64-bit timestamp. On failure or
  * if passed an empty string, return 0.
  */
-extern timestamp_t parse_datetime(const char *s)
+extern "C" timestamp_t parse_datetime(const char *s)
 {
 	int y, m, d;
 	int hr, min, sec;
@@ -200,19 +201,19 @@ extern timestamp_t parse_datetime(const char *s)
  * Format 64-bit timestamp in the form "YYYY-MM-DD hh:mm:ss".
  * Returns the empty string for timestamp = 0
  */
-extern char *format_datetime(timestamp_t timestamp)
+std::string format_datetime(timestamp_t timestamp)
 {
 	char buf[32];
 	struct tm tm;
 
 	if (!timestamp)
-		return strdup("");
+		return std::string();
 
 	utc_mkdate(timestamp, &tm);
 	snprintf(buf, sizeof(buf), "%04u-%02u-%02u %02u:%02u:%02u",
 		 tm.tm_year, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
 
-	return strdup(buf);
+	return std::string(buf);
 }
 
 /* Turn month (0-12) into three-character short name */