fix issue #1520

R/brmsterms.R

@@ -921,6 +921,7 @@ all_terms <- function(x) {
 
 # generate a regular expression to extract special terms
 # @param type one or more special term types to be extracted
+# TODO: rule out expressions such as mi(y) + mi(x)
 regex_sp <- function(type = "all") {
   choices <- c("all", "sp", "sm", "gp", "cs", "mmc", "ac", all_sp_types())
   type <- unique(match.arg(type, choices, several.ok = TRUE))
@@ -969,13 +970,14 @@ find_terms <- function(x, type, complete = TRUE, ranef = FALSE) {
   if (complete) {
     matches <- lapply(out, get_matches_expr, pattern = regex)
     # each term may contain only one special function call
-    inv <- out[lengths(matches) > 1L]
-    if (!length(inv)) {
+    invalid <- out[lengths(matches) > 1L]
+    if (!length(invalid)) {
       # each term must be exactly equal to the special function call
-      inv <- out[unlist(matches) != out]
+      invalid <- out[unlist(matches) != out]
     }
-    if (length(inv)) {
-      stop2("The term '", inv[1], "' is invalid in brms syntax.")
+    # TODO: some terms can be part of I() calls (#1520); reflect this here?
+    if (length(invalid)) {
+      stop2("The term '", invalid[1], "' is invalid in brms syntax.")
     }
   }
   out

R/conditional_effects.R

@@ -564,14 +564,14 @@ get_all_effects_type <- function(x, type) {
     term_parts <- unlist(strsplit(terms[i], split = ":"))
     vars <- vector("list", length(term_parts))
     for (j in seq_along(term_parts)) {
-      if (grepl_expr(regex_type, term_parts[j])) {
-        # evaluate a special term to extract variables
-        tmp <- eval2(term_parts[j])
-        vars[[j]] <- setdiff(unique(c(tmp$term, tmp$by)), "NA")
-      } else {
-        # extract all variables from an ordinary term
-        vars[[j]] <- all_vars(term_parts[j])
+      matches <- get_matches_expr(regex_type, term_parts[j])
+      for (k in seq_along(matches)) {
+        # evaluate special terms to extract variables
+        tmp <- eval2(matches[[k]])
+        c(vars[[j]]) <- setdiff(unique(c(tmp$term, tmp$by)), "NA")
       }
+      # extract all variables not part of any special term
+      c(vars[[j]]) <- setdiff(all_vars(term_parts[j]), all_vars(matches))
     }
     vars <- unique(unlist(vars))
     out[[i]] <- str2formula(vars, collapse = "*")