What programming languages are context-free?

Question

Or, to be a little more precise: which programming languages are defined by a context-free grammar?

From what I gather C++ is not context-free due to things like mac

Answer 1

VHDL is somewhat context sensitive:

VHDL is context-sensitive in a mean way. Consider this statement inside a process:

jinx := foo(1);

Well, depending on the objects defined in the scope of the process (and its enclosing scopes), this can be either:

• A function call
• Indexing an array
• Indexing an array returned by a parameter-less function call

To parse this correctly, a parser has to carry a hierarchical symbol table (with enclosing scopes), and the current file isn't even enough. foo can be a function defined in a package. So the parser should first analyze the packages imported by the file it's parsing, and figure out the symbols defined in them.

This is just an example. The VHDL type/subtype system is a similarly context-sensitive mess that's very difficult to parse.

(Eli Bendersky, “Parsing VHDL is [very] hard”, 2009)