Compare two naxps

naxp_compare() says how b stands to a: what happens to text and encoded values held under a if b replaces it. naxp_first_divergent_value() finds the lowest encoded value the two decode differently.

Usage

naxp_compare(a, b, budget = NULL)

naxp_first_divergent_value(a, b)

Arguments

a

The naxp the data was encoded with: a naxp from naxp_parse(), a pattern string or a naxp_encoded vector, whose naxp is used.

b

The naxp proposed to replace it, likewise.

budget

NULL for the library's default budget of 200 000 product states, or a positive whole number.

Value

• naxp_compare(): a named character vector with elements accepted_text, encoding and canonical_forms.

• naxp_first_divergent_value(): a single encoded value, or 0 where every value both naxps hold decodes alike. Values only one naxp holds do not count. It is an integer where both naxps' encoded values are integers, and otherwise a double.

Details

naxp_compare() gives three set relationships, each from a's point of view:

• accepted_text: how the strings a accepts stand to those b accepts.

• encoding: how the (text, encoded value) pairs a defines stand to those b defines. Replacing a with b is safe for stored values exactly when this is "equal" or "subset_of".

• canonical_forms: how the canonical forms a prints stand to those b prints.

Each is "equal", "subset_of", "superset_of" or "incomparable".

The encoding relationship is decided by walking the two naxps together, which has a budget. No naxp anybody has reason to write comes near the default, but a pair that does cannot be decided, and naxp_compare() then raises an error rather than guess.

Examples

with_space <- naxp_parse(r"(\9\9\9\9 \s!! \A\A)")
without_space <- naxp_parse(r"(\9\9\9\9 \s!? \A\A)")

naxp_compare(with_space, without_space)
#>   accepted_text        encoding canonical_forms 
#>         "equal"         "equal"  "incomparable" 
naxp_first_divergent_value(with_space, without_space)
#> [1] 1