Python递归修改字典

Question

I have a Python AST parser that converts expressions like 1==1 or 2==2 or 3==3 into this dictionary:

{ 'args': [ {'args': [{'value': 1}, {'value': 1}], 'function': '=='},
            {'args': [{'value': 2}, {'value': 2}], 'function': '=='},
            {'args': [{'value': 3}, {'value': 3}], 'function': '=='}],
  'function': 'or'}

This is then converted to JSON and POSTed to and API endpoint, however the API only understands binary or operations. So the pasted dictionary above needs to be converted (nested) into the following:

{ 'args': [ { 'args': [ { 'args': [{'value': 1}, {'value': 1}],
                          'function': '=='},
                        { 'args': [{'value': 2}, {'value': 2}],
                          'function': '=='}],
              'function': 'or'},
            {'args': [{'value': 3}, {'value': 3}], 'function': '=='}],
  'function': 'or'}

Doing this from the Python AST is not possible because the BoolOp has 3 elements so I think it's best to do it recursively. However I can't visualize a correct way to achieve this iterating the dictionary in a recursive manner.

edit:

The dictionary can be deeply nested like:

{ 'args': [ {'args': [{'value': 1}, {'value': 1}], 'function': '=='},
            {'args': [{'value': 2}, {'value': 2}], 'function': '=='},
            { 'args': [ { 'args': [{'value': 3}, {'value': 3}],
                          'function': '=='},
                        { 'args': [{'value': 4}, {'value': 4}],
                          'function': '=='},
                        { 'args': [{'value': 5}, {'value': 5}],
                          'function': '=='}],
              'function': 'or'}],
  'function': 'and'}

Answer 1

You could do something like this:

def _nest_ors(args):
    assert len(args) >= 2

    if len(args) == 2:
        return {
            'function': 'or',
            'args': args
        }

    return {
        'function': 'or',
        'args': [args[0], _nest_ors(args[1:])]
    }


def fix_ors(ast):
    assert ast['function'] == 'or'

    return _nest_ors(ast['args'])


expression = {'args': [{'args': [{'value': 1}, {'value': 1}], 'function': '=='},
                       {'args': [{'value': 2}, {'value': 2}], 'function': '=='},
                       {'args': [{'value': 3}, {'value': 3}], 'function': '=='}],
              'function': 'or'}

print(fix_ors(expression))

If you have really huge expressions, you will have to replace the recursion with an iterative solution.