# Map spreadsheet manipulation

import re

import Parser

import strings

import util

def col_info(col_name, require_root=False):

    '''@return tuple (label, root, prefixes)'''

    def syntax_err(): raise Parser.SyntaxError('Column name must have '

        'syntax "datasrc[format,...]:root" (formats optional): '+col_name)

    match = re.match(r'^([^\[:]*)(?:\[([^\]]*?)\])?(?::(.*))?$', col_name)

    if not match: syntax_err()

    label, prefixes, root = match.groups()

    if require_root and root == None: syntax_err()

    return label, root, strings.split(',', util.coalesce(prefixes, ''))

def col_formats(col_name):

    label, root, prefixes = col_info(col_name)

    return [label]+prefixes

def combinable(*headers):

    return strings.overlaps(*[','.join(col_formats(h[0])) for h in headers])

def is_nonexplicit_empty_mapping(row):

    return reduce(util.and_, (v == '' for v in row[1:]))

def merge_values(*vals):

    new = []

    for val in vals:

        if val != '' and val not in new: new.append(val)

    return '; '.join(new)

def merge_rows(*rows):

    '''e.g. ['a','b'] + ['','y','z'] = ['a','b; y','z']'''

    def get(row, i):

        try: return row[i]

        except IndexError: return ''

    return [merge_values(*[get(row, i) for row in rows])

        for i in xrange(max(map(len, rows)))]

def merge_mappings(in_, out):

    '''e.g. ['in','join','in_comments'] + ['join','out','out_comments'] =

    ['in','out','in_comments; out_comments']'''

    new = [in_[0], out[1]] # mapping

    new[2:] = merge_rows(in_[2:], out[2:]) # comments

    return new