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Parse and canonicalize an lme4-style formula

Source: R/parse-formula.R
mm_parse_formula.Rd

mm_parse_formula() parses a formula string through the Rust formula parser and returns its canonical Display rendering. This is the Phase 0 round-trip primitive: equivalent formula spellings produce identical canonical strings, so equivalence-class testing in R is just string comparison on the canonical form.

Usage

mm_parse_formula(formula)

Arguments

formula

A single character string (length 1, non-NA, non-empty), or a one-sided / two-sided R formula object. R formula objects are coerced to character via format() before parsing.

Value

A single character string: the canonical rendering of the parsed formula.

Errors

Parse failures are signalled as a typed mm_formula_error condition (also inheriting from mm_condition and error). The condition object carries the original input string in its formula field. Catch with tryCatch(..., mm_formula_error = handler).

Examples

mm_parse_formula("y ~ x + (1 | g)")
#> [1] "y ~ 1 + x + (1 | g)"
mm_parse_formula(y ~ x + (1 | g))
#> [1] "y ~ 1 + x + (1 | g)"