More type deductions for matrix multiplication

[dirkschumacher]

mat %*% colvec = colvec
rowvec %*% mat = rowvec
mat %*% mat = mat
T %*% <scalar> = T
<scalar> %*% T = T

[dirkschumacher]

The relevant code is here:

armacmp/R/ast-classes.R

Lines 830 to 858 in 5777a3f

	get_cpp_type = function() {
	arma_type <- find_arma_cpp_types(self$get_tail_elements())
	arma_cpp_types <- vapply(arma_type, function(x) x$get_cpp_type(), character(1L))
	if (length(arma_type) == 2L) {
	is_integer_arma_type <- function(type) {
	grepl("^arma::i", type)
	}
	is_unsigned_integer_arma_type <- function(type) {
	grepl("^arma::u", type)
	}
	is_double_arma_type <- function(type) {
	type %in% paste0("arma::", c("vec", "colvec", "rowvec", "mat"))
	}
	# TODO: revisit these rules and contemplate
	if (any(sapply(arma_cpp_types, is_double_arma_type))) {
	return("arma::mat")
	}
	if (any(sapply(arma_cpp_types, is_integer_arma_type))) {
	return("arma::imat")
	}
	if (all(sapply(arma_cpp_types, is_unsigned_integer_arma_type))) {
	return("arma::umat")
	}
	}
	if (length(arma_type) == 1L) {
	return(arma_type[[1L]]$get_cpp_type())
	}
	"arma::mat"
	}

[dirkschumacher]

There is also a lot of room for refactoring and making this stuff smarter :)