How do I parenthesize an expression?

Question

I have an idea for a simple program to make that will help me with operator precedence in languages like C. The most difficult part of this is parenthesizing the expression. For example, I want this:

*a.x++ = *b.x++

Converted to this:

((*(((a).(x))++)) = (*(((b).(x))++)))

Which I did manually in these steps:

           *a.x++ = *b.x++
       *(a).(x)++ = *(b).(x)++
     *((a).(x))++ = *((b).(x))++
   *(((a).(x))++) = *(((b).(x))++)
 (*(((a).(x))++)) = (*(((b).(x))++))
((*(((a).(x))++)) = (*(((b).(x))++)))

What is the best way to accomplish this? Is there already a solution out there that I could use? I'd prefer to do this in either PHP, C, C++, Python, or Ruby.

(This isn't the whole idea of my program, it is only the first step.)

Answer 1

Just pick up a parser for your selected language, for instance C parser, parse the expression/source code and print the AST back in the way you want.

test.c:

void main(void){
    int c = 2;
}

terminal:

$ python
>>> import pycparser
>>> test = pycparser.parse_file('test.c')
>>> test.show()
FileAST: 
  FuncDef: 
    Decl: main, [], []
      FuncDecl: 
        ParamList: 
          Typename: []
            TypeDecl: None, []
              IdentifierType: ['void']
        TypeDecl: main, []
          IdentifierType: ['void']
    Compound: 
      Decl: c, [], []
        TypeDecl: c, []
          IdentifierType: ['int']
        Constant: int, 2
>>> for node in test.ext:
...     print node
...
<pycparser.c_ast.FuncDef object at 0x7fe1436db750>
>>>