Python recursive function called too many times

Question

This is a follow-up to this question: Python parse text file into nested dictionaries

I initially accepted the answer which suggested to format the input with regexes, but after looking closer at the input, there are still some problems that I cannot can process with the proposed regexes.

So I am back at recursively parsing the lines into a dictionary.

What I have so far is:

def parseToDictionary(input):
    key = ''
    value = ''
    result = {}

    if input[0].startswith('{'): # remove {
        del input[0]

    result.clear() # clear the dict for each recursion

    for idx, line in enumerate(input):
        line = line.rstrip() # remove trailing returns

        if line.startswith('['):
            key = line
            value = parseToDictionary(input[idx+1:]) # parse the next level
        elif line.startswith('}'): # reached the end of a block
            return result
        else:
            elements = line.split('\t')
            key = elements[0]
            if len(elements) > 1:
                value = elements[1]
            else:
                value = 'Not defined' # some keys may not have a value, so set a generic value here
        if key:
            result[key] = value

    return result

Here is an example (very simplified!) input:

[HEADER1]
{
key1    value
key2    long value, with a comma
[HEADER2]
{
key 1234
emptykey
}
}

The output is:

'[HEADER2]': 
{
    'emptykey': 'Not defined', 
    'key': '1234'
}, 
'key2': 'long value, with a comma', 
'key1': 'value', 
'[HEADER1]': 
{
    'emptykey': 'Not defined', 
    'key2': 'long value, with a comma', 
    'key1': 'value', 
    'key': '1234', 
    '[HEADER2]': 
    {
        'emptykey': 'Not defined', 
        'key': '1234'
    }
 }, 
 'emptykey': 'Not defined', 
 'key': '1234'
 }

But it should be:

'[HEADER1]': 
{
    'key1': 'value', 
    'key2': 'long value, with a comma', 
    '[HEADER2]': 
    {
        'emptykey': 'Not defined', 
        'key': '1234'
    }
 }

So each line that starts with an [ is the key for the next block. Inside each blocks are multiple key-value pairs, and there could also be another nested level. What goes wrong is that some blocks are parsed multiple times, and I cannot figure out where it goes wrong.

The input parameter is mydatafile.split('\n')

Who can help me out?

What is input? Is it a list of tokens?

Tom Karzes
– Tom Karzes

2017-10-28 21:02:47 +00:00
Commented Oct 28, 2017 at 21:02 — Tom Karzes
– Tom Karzes, Commented Oct 28, 2017 at 21:02
I have added that to the question

koen
– koen

2017-10-28 21:11:38 +00:00
Commented Oct 28, 2017 at 21:11 — koen
– koen, Commented Oct 28, 2017 at 21:11

Daniel · Accepted Answer · 2017-10-28 21:02:54Z

2

You have to skip the lines, that are processsed in the subsections:

def parse_to_dictionary(lines):
    def parse_block(lines):
        contents = {}
        if next(lines).strip() != '{':
            raise AssertionError("'{' expected")
        for line in lines:
            line = line.strip()
            if line == '}':
                return contents
            elif line[0] == '[':
                contents[line] = parse_block(lines)
            else:
                parts = line.split('\t', 1)
                contents[parts[0]] = None if len(parts) == 1 else parts[1]

    lines = iter(lines)
    key = next(lines)                
    if key[0] != '[':
        raise AssertionError("format error")
    return {key: parse_block(lines)}

answered Oct 28, 2017 at 21:02

Daniel

42.9k4 gold badges57 silver badges82 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

koen Over a year ago

Since the first line is not {, i will fail immediately. What I really try to do is just to skip the lines with {.

koen Over a year ago

So to fix that, I commented out the raise AssertionError("'{' expected") line and indented the for-loop. Works perfect now.

koen Over a year ago

Disregard these comments, there was an error in my input file.

Collectives™ on Stack Overflow

Python recursive function called too many times

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related