# Read sets from file and generate all strings obeying template (list or string)
def generatePatternFromFile(template='ONC', setFile='sampleset.txt'):

    return generatePattern(template, readSetsFromFile(setFile))

# Read sets from file
# Sets are defined as blocks of lines
# The first line in a block defines the key for templates
# Blocks are delimited by line breaks
def readSetsFromFile(fn):

    fh = open(fn)
    setOpen = False
    result = {}
    s = []
    key = ''

    for line in fh:
        line = line.strip()
        
        if line == '':
            result[key] = s
            setOpen = False
        elif setOpen:
            s = s + [line]
        else:
            key = line
            s = []
            setOpen = True

    if setOpen:
        result[key] = s
    
    return result

# Generate all strings obeying template (a list or string) with the sets defined
def generatePattern(template, sets):

    result = sets[template[0]]
    
    for t in template[1:]:

        result = expandPattern(result, sets[t])

    return result

# Extend a list of partial patterns with the next possible set of items in the string
def expandPattern(previous, expansions):

    result = []

    for item in previous:
        for x in expansions:
            newItem = item + x
            result = result + [newItem]

    return result