Keep a Scalar Config Option's Value When Deserializing Fails

A failed stream extraction writes 0 into its target, so Float, Int, Percent and FloatOrPercent options were overwritten before deserialize reported the error, and Point/Point3 kept a partially scanned value. Parse into a temporary and assign only on success; FloatOrPercent sets its percent flag only then too.

src/libslic3r/Config.hpp

@@ -841,8 +841,12 @@ public:
     {
         UNUSED(append);
         std::istringstream iss(str);
-        iss >> this->value;
-        return !iss.fail();
+        double value;
+        iss >> value;
+        if (iss.fail())
+            return false;
+        this->value = value;
+        return true;
     }
 
     bool operator==(const ConfigOption &rhs) const override
@@ -1033,8 +1037,12 @@ public:
     {
         UNUSED(append);
         std::istringstream iss(str);
-        iss >> this->value;
-        return !iss.fail();
+        int value;
+        iss >> value;
+        if (iss.fail())
+            return false;
+        this->value = value;
+        return true;
     }
 
     ConfigOptionInt& operator=(const ConfigOption *opt)
@@ -1252,8 +1260,12 @@ public:
         UNUSED(append);
         // don't try to parse the trailing % since it's optional
         std::istringstream iss(str);
-        iss >> this->value;
-        return !iss.fail();
+        double value;
+        iss >> value;
+        if (iss.fail())
+            return false;
+        this->value = value;
+        return true;
     }
 
 private:
@@ -1365,10 +1377,14 @@ public:
     bool deserialize(const std::string &str, bool append = false) override
     {
         UNUSED(append);
-        this->percent = str.find_first_of("%") != std::string::npos;
         std::istringstream iss(str);
-        iss >> this->value;
-        return !iss.fail();
+        double value;
+        iss >> value;
+        if (iss.fail())
+            return false;
+        this->value   = value;
+        this->percent = str.find_first_of("%") != std::string::npos;
+        return true;
     }
 
 private:
@@ -1538,8 +1554,12 @@ public:
     {
         UNUSED(append);
         char dummy;
-        return sscanf(str.data(), " %lf , %lf %c", &this->value(0), &this->value(1), &dummy) == 2 ||
-               sscanf(str.data(), " %lf x %lf %c", &this->value(0), &this->value(1), &dummy) == 2;
+        Vec2d value;
+        if (sscanf(str.data(), " %lf , %lf %c", &value(0), &value(1), &dummy) != 2 &&
+            sscanf(str.data(), " %lf x %lf %c", &value(0), &value(1), &dummy) != 2)
+            return false;
+        this->value = value;
+        return true;
     }
 
 private:
@@ -1658,8 +1678,12 @@ public:
     {
         UNUSED(append);
         char dummy;
-        return sscanf(str.data(), " %lf , %lf , %lf %c", &this->value(0), &this->value(1), &this->value(2), &dummy) == 3 ||
-               sscanf(str.data(), " %lf x %lf x %lf %c", &this->value(0), &this->value(1), &this->value(2), &dummy) == 3;
+        Vec3d value;
+        if (sscanf(str.data(), " %lf , %lf , %lf %c", &value(0), &value(1), &value(2), &dummy) != 3 &&
+            sscanf(str.data(), " %lf x %lf x %lf %c", &value(0), &value(1), &value(2), &dummy) != 3)
+            return false;
+        this->value = value;
+        return true;
     }
 
 private:

tests/libslic3r/test_config.cpp

@@ -1263,6 +1263,55 @@ TEST_CASE("read_cli rejects an invalid scalar numeric value", "[Config]") {
     REQUIRE_FALSE(config.read_cli(3, argv, &extra, &keys));
 }
 
+TEST_CASE("A scalar option keeps its value when deserializing fails", "[Config]") {
+    using Catch::Matchers::WithinAbs;
+
+    SECTION("float") {
+        ConfigOptionFloat opt(7.5);
+        REQUIRE_FALSE(opt.deserialize("abc"));
+        CHECK_THAT(opt.value, WithinAbs(7.5, 1e-9));
+    }
+    SECTION("int") {
+        ConfigOptionInt opt(3);
+        REQUIRE_FALSE(opt.deserialize("abc"));
+        CHECK(opt.value == 3);
+    }
+    SECTION("percent") {
+        ConfigOptionPercent opt(40.);
+        REQUIRE_FALSE(opt.deserialize("abc%"));
+        CHECK_THAT(opt.value, WithinAbs(40., 1e-9));
+    }
+    SECTION("float or percent") {
+        ConfigOptionFloatOrPercent opt(0.4, false);
+        REQUIRE_FALSE(opt.deserialize("abc%"));
+        CHECK_THAT(opt.value, WithinAbs(0.4, 1e-9));
+        CHECK_FALSE(opt.percent);
+    }
+    SECTION("point") {
+        ConfigOptionPoint opt(Vec2d(1., 2.));
+        REQUIRE_FALSE(opt.deserialize("5,abc"));
+        CHECK(opt.value == Vec2d(1., 2.));
+    }
+    SECTION("point3") {
+        ConfigOptionPoint3 opt(Vec3d(1., 2., 3.));
+        REQUIRE_FALSE(opt.deserialize("5,6,abc"));
+        CHECK(opt.value == Vec3d(1., 2., 3.));
+    }
+}
+
+TEST_CASE("A scalar option still takes a valid value", "[Config]") {
+    using Catch::Matchers::WithinAbs;
+
+    ConfigOptionFloatOrPercent opt(0.4, false);
+    REQUIRE(opt.deserialize("50%"));
+    CHECK_THAT(opt.value, WithinAbs(50., 1e-9));
+    CHECK(opt.percent);
+
+    ConfigOptionPoint point;
+    REQUIRE(point.deserialize("3x4"));
+    CHECK(point.value == Vec2d(3., 4.));
+}
+
 TEST_CASE("read_cli appends values when a vector option is repeated", "[Config]") {
     Slic3r::DynamicPrintConfig config;
     t_config_option_keys extra, keys;