Given a list of prefixes create a tree structure. (sort of how objects are stored in AWS S3. Another example could be Consul)

attach_branch.py

import json


def attach_branch(tree, branch):
    l = len(branch)
    node = branch[0]
    # If node doesn't exist get an empty subtree
    subtree = tree.get(node, {})

    if l == 1:
        # Create leaf node
        tree.update({node: subtree})
        return tree

    subtree.update(attach_branch(subtree, branch[1:]))

    tree.update({node: subtree})
    return tree


if __name__ == '__main__':
    root_list = []
    tree = {}

    prefixes = [
        'F',
        'A|B|C',
        'A|B|D',
        'B|C|D',
        'B|C|E',
        'A',
    ]

    for branch in map(lambda x: x.split('|'), prefixes):
        if len(branch) == 1:
            root_list.append(branch[0])
            continue

        tree = attach_branch(tree, branch)

    root_list.append(tree)
    print(json.dumps(root_list, indent=2))

https://ideone.com/ky5pDh