[Yul] ExpressionJoiner: code cleanup

* ensure public API is only containing `run(Block&)`, all the rest is private API / implementation details
* adding some comments to class data members to quicker understand their meaning
* eliminate unnecessary `operator()(If&)` as it's not changing default behaviour of `ASTModifier`
* simplify readability of `visit(Expression&)`'s impl, also moving assert's into "isLatestStatementVarDeclOf", as this one is already ensuring exactly that.
* ctor impl's use of ReferenceCounter use shortened.
* renamed and improved `isLatestStatementVarDeclOf` to better match its meaning (especially since it's only used once)

1 files changed, 13 insertions, 13 deletions

diff --git a/libyul/optimiser/ExpressionJoiner.h b/libyul/optimiser/ExpressionJoiner.h
index df18e58f..4f06cc0f 100644
--- a/libyul/optimiser/ExpressionJoiner.h
+++ b/libyul/optimiser/ExpressionJoiner.h
@@ -73,29 +73,29 @@ class NameCollector;
 class ExpressionJoiner: public ASTModifier
 {
 public:
-	virtual void operator()(FunctionalInstruction&) override;
-	virtual void operator()(FunctionCall&) override;
-	virtual void operator()(If&) override;
-	virtual void operator()(Switch&) override;
-	virtual void operator()(Block& _block) override;
-
-	using ASTModifier::visit;
-	virtual void visit(Expression& _e) override;
-
 	static void run(Block& _ast);
+
 private:
 	explicit ExpressionJoiner(Block& _ast);
 
+	void operator()(Block& _block) override;
+	void operator()(FunctionalInstruction&) override;
+	void operator()(FunctionCall&) override;
+
+	using ASTModifier::visit;
+	void visit(Expression& _e) override;
+
 	void handleArguments(std::vector<Expression>& _arguments);
 
 	void decrementLatestStatementPointer();
 	void resetLatestStatementPointer();
 	Statement* latestStatement();
-	bool isLatestStatementVarDeclOf(Identifier const& _identifier);
+	bool isLatestStatementVarDeclJoinable(Identifier const& _identifier);
 
-	Block* m_currentBlock = nullptr;
-	size_t m_latestStatementInBlock = 0;
-	std::map<std::string, size_t> m_references;
+private:
+	Block* m_currentBlock = nullptr;            ///< Pointer to currently block holding the visiting statement.
+	size_t m_latestStatementInBlock = 0;        ///< Offset to m_currentBlock's statements of the last visited statement.
+	std::map<std::string, size_t> m_references; ///< Holds reference counts to all variable declarations in current block.
 };
 
 }