Express constraints for the first few channels and then specify ellipses?

Unless I'm missing something there seems to be no way to encode the idea that an array has at least 2 dimensions with some size constraint, but then it may also contain any other trailing dimensions. For instance, I would have thought that I would say that I could have an array with at least 2 dimensions like this:

Shape['*,*,...'] but that seems to return an InvalidShapeError.

Looking at the grammar, this seems to make sense, the line shape_expression : dimensions | dimension "," ellipsis indicates that an ellipsis is only valid when there is one dimension.

If we modify the grammar such that we are using shape_expression : dimensions | dimensions "," ellipsis, it should be possible to express what I'm looking for, however in my prototyping I couldn't parse the expression with an LALR parser, I had to use Earley instead.

Here is my prototype I made with Lark:

import lark
SHAPE_GRAMMAR = (
    '''
    // https://github.com/ramonhagenaars/nptyping/blob/master/USERDOCS.md#Shape-expressions
    ?start: shape_expression

    shape_expression     :  dimensions | dimensions "," ellipsis
    dimensions           :  dimension | dimension "," dimensions
    dimension            :  unlabeled_dimension | labeled_dimension
    labeled_dimension    :  unlabeled_dimension " " label
    unlabeled_dimension  :  number | variable | wildcard | dimension_breakdown
    wildcard             :  "*"
    dimension_breakdown  :  "[" labels "]"
    labels               :  label | label "," labels
    label                :  lletter | lletter word
    variable             :  uletter | uletter word
    word                 :  letter | word underscore | word number
    letter               :  lletter | uletter
    uletter              :  "A"|"B"|"C"|"D"|"E"|"F"|"G"|"H"|"I"|"J"|"K"|"L"|"M"|"N"|"O"|"P"|"Q"|"R"|"S"|"T"|"U"|"V"|"W"|"X"|"Y"|"Z"
    lletter              :  "a"|"b"|"c"|"d"|"e"|"f"|"g"|"h"|"i"|"j"|"k"|"l"|"m"|"n"|"o"|"p"|"q"|"r"|"s"|"t"|"u"|"v"|"w"|"x"|"y"|"z"
    number               :  digit | number digit
    digit                :  "0"|"1"|"2"|"3"|"4"|"5"|"6"|"7"|"8"|"9"
    underscore           :  "_"
    ellipsis             :  "..."
    ''')
# shape_parser = lark.Lark(SHAPE_GRAMMAR,  start='start', parser='lalr')
shape_parser = lark.Lark(SHAPE_GRAMMAR,  start='start', parser='earley')
print(shape_parser.parse('3').pretty())
print(shape_parser.parse('N,M').pretty())
print(shape_parser.parse('N,3').pretty())
print(shape_parser.parse('*,*').pretty())
print(shape_parser.parse('2,...').pretty())
print(shape_parser.parse('*,...').pretty())
print(shape_parser.parse('1,3,4,5,...').pretty())
print(shape_parser.parse('*,*,...').pretty())

ramonhagenaars / nptyping

Express constraints for the first few channels and then specify ellipses? #83