Fix memleak during WFL parsing (fixes #1680, fixes #1685)

src/formula/formula.cpp

@@ -68,13 +68,9 @@ const char* const formula::id_chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNO
 formula::formula(const std::string& text, function_symbol_table* symbols)
 	: expr_()
 	, str_(text)
-	, symbols_(symbols)
-	, managing_symbols(symbols == nullptr)
+	, managed_symbols_(symbols ? nullptr : new function_symbol_table)
+	, symbols_(symbols ? symbols : managed_symbols_.get())
 {
-	if(symbols == nullptr) {
-		symbols_ = new function_symbol_table;
-	}
-
 	std::vector<tk::token> tokens;
 	std::string::const_iterator i1 = text.begin(), i2 = text.end();
 
@@ -213,27 +209,16 @@ formula::formula(const std::string& text, function_symbol_table* symbols)
 formula::formula(const tk::token* i1, const tk::token* i2, function_symbol_table* symbols)
 	: expr_()
 	, str_()
-	, symbols_(symbols)
-	, managing_symbols(symbols == nullptr)
+	, managed_symbols_(symbols ? nullptr : new function_symbol_table)
+	, symbols_(symbols ? symbols : managed_symbols_.get())
 {
-	if(symbols == nullptr) {
-		symbols_ = new function_symbol_table;
-	}
-
 	if(i1 != i2) {
 		expr_ = parse_expression(i1, i2, symbols);
 	} else {
 		expr_ = expression_ptr(new null_expression());
 	}
 }
 
-formula::~formula()
-{
-	if(managing_symbols) {
-		delete symbols_;
-	}
-}
-
 formula_ptr formula::create_optional_formula(const std::string& str, function_symbol_table* symbols)
 {
 	if(str.empty()) {

src/formula/formula.hpp

@@ -18,6 +18,7 @@
 #include "formula/formula_fwd.hpp"
 #include "formula/tokenizer.hpp"
 #include "formula/variant.hpp"
+#include <memory>
 
 namespace wfl
 {
@@ -35,8 +36,6 @@ class formula
 	formula(const std::string& str, function_symbol_table* symbols = nullptr);
 	formula(const tk::token* i1, const tk::token* i2, function_symbol_table* symbols = nullptr);
 
-	~formula();
-
 	static variant evaluate(
 			const const_formula_ptr& f,
 			const formula_callable& variables,
@@ -80,8 +79,10 @@ class formula
 
 	expression_ptr expr_;
 	std::string str_;
+	// Can't be a unique_ptr because function_symbol_table is an incomplete type,
+	// and the header it's declared in depends on this one.
+	const std::shared_ptr<function_symbol_table> managed_symbols_;
 	function_symbol_table* symbols_;
-	bool managing_symbols;
 
 	friend class formula_debugger;
 };