# XPath "function" elements that transform their subpaths

import util

import xpath

##### Functions

funcs = {}

def process(path):

    if path == []: return path

    # Process subpaths

    path[1:] = process(path[1:])

    branches = path[0].other_branches

    for i, branch in enumerate(branches): branches[i] = process(branch)

    name = path[0].name

    if name.startswith('_') and name in funcs:

        return funcs[name](path.pop(0).attrs, path)

    else: return path

#### XPath functions

# Function names must start with _ to avoid collisions with real tags

# Functions take arguments (args, path)

def _forEach(args, path):

    '''Replaces '_val' in `do` with each item in the `in` list'''

    in_, do = [a[0] for a in args]

    assert in_.name == 'in'

    assert do.name == 'do'

    in_ = in_.attrs

    do = do.value

    for_path = []

    for with_, in in_: for_path += xpath.parse(do.replace('_val', with_.name))

    return for_path + path

funcs['_forEach'] = _forEach