root/trunk/pyramid/dictutils.py

import syck
from pyramid import yamlRegistry as Y
import mergetrees

def merge(a, b, dir=None, partialbuild=False):

    if (isinstance(a, Y.sectionnav) and
        isinstance(b, Y.sectionnav) and dir is not None):
        # special case. If b is the same as a, it has been inhereited -
        # sectionnav's should not inherit in this fashion however
        # TODO: this fix might cause problems in the future. e.g. if
        # the second level nav were exactly the same as the first level nav?
        if a == b:
            b = []
        if partialbuild:
            a = b
        else:
            mergetrees.merge(a, b, dir)

    elif isinstance(b, dict) and isinstance(a, dict):
        for bkey in b.keys():
            if a.has_key(bkey):
                a[bkey] = merge(a[bkey], b[bkey], dir,
                                partialbuild=partialbuild)
            else:
                a[bkey] = b[bkey]
    else:
        a = b
    return a

class stackdict(dict):

    parent = None

    def __init__(self, parent=None):
        if parent is not None:
            self.parent = parent
            merge(self, parent)

    def popStack(self):
        return self.parent

# Test code:
if __name__ == "__main__":

    def keyval(text):
        ''' Factory to convert a string into key:val pair (split on last space)
        '''
        t = text.split(' ')
        return { ''.join(t[:-1]) : t[-1] }

    x = '''
a: 1
b:
  x: 12
  y: 13
  z: 14
c: 3
    '''

    y = '''
b:
  x: 15
  z:
    p: 98
    q: 99
c: 3P0
    '''


    xd = syck.load(x, Loader=Y.Loader, implicit_typing=False)
    yd = syck.load(y, Loader=Y.Loader, implicit_typing=False)

    z = merge(xd, yd)

    print z

    print '-------------------'

    d = stackdict()
    d['a'] = 1
    d['b'] = {'x':1, 'y':2 }
    print d

    d = stackdict(d)
    d['a'] = 2
    print d

    d = stackdict(d)
    d['b'] = {'x':2, 'y': {'p':4 } }
    d['c'] = 100
    print d

    while 1:
        d = d.popStack()
        if d is None:
            break
        print d