Merge pull request #4182 from thehans/master

Stack usage optimization for tostream_visitor
openscad · Mar 19, 2022 · 398d59f · 398d59f
2 parents a6392b3 + 5a574ad
commit 398d59f
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Showing 2 changed files with 53 additions and 94 deletions.
diff --git a/src/core/Value.cc b/src/core/Value.cc
@@ -291,75 +291,12 @@ const str_utf8_wrapper& Value::toStrUtf8Wrapper() const {
   return boost::get<str_utf8_wrapper>(this->value);
 }
 
-class tostring_visitor : public boost::static_visitor<std::string>
-{
-public:
-  template <typename T> std::string operator()(const T& op1) const {
-    assert(false && "unhandled tostring_visitor type");
-    return boost::lexical_cast<std::string>(op1);
-  }
-
-  std::string operator()(const str_utf8_wrapper& op1) const {
-    return op1.toString();
-  }
-
-  std::string operator()(const double& op1) const {
-    char buffer[DC_BUFFER_SIZE];
-    double_conversion::StringBuilder builder(buffer, DC_BUFFER_SIZE);
-    double_conversion::DoubleToStringConverter dc(DC_FLAGS, DC_INF, DC_NAN, DC_EXP,
-                                                  DC_DECIMAL_LOW_EXP, DC_DECIMAL_HIGH_EXP, DC_MAX_LEADING_ZEROES, DC_MAX_TRAILING_ZEROES);
-    return DoubleConvert(op1, buffer, builder, dc);
-  }
-
-  std::string operator()(const UndefType&) const {
-    return "undef";
-  }
-
-  std::string operator()(const bool& v) const {
-    return v ? "true" : "false";
-  }
-
-  std::string operator()(const EmbeddedVectorType&) const {
-    assert(false && "Error: unexpected visit to EmbeddedVectorType!");
-    return "";
-  }
-
-  std::string operator()(const VectorType& v) const {
-    // Create a single stream and pass reference to it for list elements for optimization.
-    std::ostringstream stream;
-    stream << '[';
-    if (!v.empty()) {
-      auto it = v.begin();
-      it->toStream(stream);
-      for (++it; it != v.end(); ++it) {
-        stream << ", ";
-        it->toStream(stream);
-      }
-    }
-    stream << ']';
-    return stream.str();
-  }
-
-  std::string operator()(const ObjectType& v) const {
-    return STR(v);
-  }
-
-  std::string operator()(const RangePtr& v) const {
-    return STR(*v);
-  }
-
-  std::string operator()(const FunctionPtr& v) const {
-    return STR(*v);
-  }
-};
-
 // Optimization to avoid multiple stream instantiations and copies to str for long vectors.
 // Functions identically to "class tostring_visitor", except outputting to stream and not returning strings
 class tostream_visitor : public boost::static_visitor<>
 {
 public:
   std::ostringstream& stream;
-
   mutable char buffer[DC_BUFFER_SIZE];
   mutable double_conversion::StringBuilder builder;
   double_conversion::DoubleToStringConverter dc;
@@ -394,10 +331,10 @@ class tostream_visitor : public boost::static_visitor<>
     stream << '[';
     if (!v.empty()) {
       auto it = v.begin();
-      it->toStream(stream);
+      boost::apply_visitor(*this, it->getVariant());
       for (++it; it != v.end(); ++it) {
         stream << ", ";
-        it->toStream(stream);
+        boost::apply_visitor(*this, it->getVariant());
       }
     }
     stream << ']';
@@ -416,26 +353,62 @@ class tostream_visitor : public boost::static_visitor<>
   }
 };
 
-std::string Value::toString() const
+class tostring_visitor : public boost::static_visitor<std::string>
 {
-  return boost::apply_visitor(tostring_visitor(), this->value);
-}
+public:
+  template <typename T> std::string operator()(const T& op1) const {
+    assert(false && "unhandled tostring_visitor type");
+    return boost::lexical_cast<std::string>(op1);
+  }
 
-// helper called by tostring_visitor methods to avoid extra instantiations
-std::string Value::toString(const tostring_visitor *visitor) const
-{
-  return boost::apply_visitor(*visitor, this->value);
-}
+  std::string operator()(const str_utf8_wrapper& op1) const {
+    return op1.toString();
+  }
 
-void Value::toStream(std::ostringstream& stream) const
-{
-  boost::apply_visitor(tostream_visitor(stream), this->value);
-}
+  std::string operator()(const double& op1) const {
+    char buffer[DC_BUFFER_SIZE];
+    double_conversion::StringBuilder builder(buffer, DC_BUFFER_SIZE);
+    double_conversion::DoubleToStringConverter dc(DC_FLAGS, DC_INF, DC_NAN, DC_EXP,
+                                                  DC_DECIMAL_LOW_EXP, DC_DECIMAL_HIGH_EXP, DC_MAX_LEADING_ZEROES, DC_MAX_TRAILING_ZEROES);
+    return DoubleConvert(op1, buffer, builder, dc);
+  }
+
+  std::string operator()(const UndefType&) const {
+    return "undef";
+  }
+
+  std::string operator()(const bool& v) const {
+    return v ? "true" : "false";
+  }
+
+  std::string operator()(const EmbeddedVectorType&) const {
+    assert(false && "Error: unexpected visit to EmbeddedVectorType!");
+    return "";
+  }
+
+  std::string operator()(const VectorType& v) const {
+    // Create a single stream and pass reference to it for list elements for optimization.
+    std::ostringstream stream;
+    (tostream_visitor(stream))(v);
+    return stream.str();
+  }
+
+  std::string operator()(const ObjectType& v) const {
+    return STR(v);
+  }
 
-// helper called by tostream_visitor methods to avoid extra instantiations
-void Value::toStream(const tostream_visitor *visitor) const
+  std::string operator()(const RangePtr& v) const {
+    return STR(*v);
+  }
+
+  std::string operator()(const FunctionPtr& v) const {
+    return STR(*v);
+  }
+};
+
+std::string Value::toString() const
 {
-  boost::apply_visitor(*visitor, this->value);
+  return boost::apply_visitor(tostring_visitor(), this->value);
 }
 
 std::string Value::toEchoString() const
@@ -447,16 +420,6 @@ std::string Value::toEchoString() const
   }
 }
 
-// helper called by tostring_visitor methods to avoid extra instantiations
-std::string Value::toEchoString(const tostring_visitor *visitor) const
-{
-  if (type() == Value::Type::STRING) {
-    return std::string("\"") + toString(visitor) + '"';
-  } else {
-    return toString(visitor);
-  }
-}
-
 std::string UndefType::toString() const {
   std::ostringstream stream;
   if (!reasons->empty()) {

diff --git a/src/core/Value.h b/src/core/Value.h
@@ -578,13 +578,9 @@ class Value
   bool getDouble(double& v) const;
   bool getFiniteDouble(double& v) const;
   std::string toString() const;
-  std::string toString(const tostring_visitor *visitor) const;
   std::string toEchoString() const;
-  std::string toEchoString(const tostring_visitor *visitor) const;
   const UndefType& toUndef();
   std::string toUndefString() const;
-  void toStream(std::ostringstream& stream) const;
-  void toStream(const tostream_visitor *visitor) const;
   std::string chrString() const;
   bool getVec2(double& x, double& y, bool ignoreInfinite = false) const;
   bool getVec3(double& x, double& y, double& z) const;