Consider packages in topological order

R/find.R

@@ -17,6 +17,7 @@
 #' conflict_scout()
 conflict_scout <- function(pkgs = NULL) {
   pkgs <- pkgs %||% pkgs_attached()
+  pkgs <- topo_sort(pkgs)
   objs <- lapply(pkgs, pkg_ls)
   names(objs) <- pkgs
 

R/topo.R

@@ -0,0 +1,54 @@
+pkg_dep <- function(pkg) {
+  if (pkg == "base") {
+    return()
+  }
+  ns <- asNamespace(pkg)
+  path <- ns$.__NAMESPACE__.$path
+
+  # Safety net
+  if (is.null(path)) {
+    lib <- NULL
+  } else {
+    lib <- dirname(path)
+  }
+
+  imports <- utils::packageDescription(pkg, lib.loc = lib)$Imports
+  if (is.null(imports)) {
+    return(character())
+  }
+  imports <- gsub(" *", "", imports)
+  imports <- gsub("[(][^)]+[)]", "", imports)
+  imports <- gsub("\n", "", imports)
+  strsplit(imports, ",")[[1]]
+}
+
+pkg_deps <- function(pkgs) {
+  lapply(set_names(pkgs), pkg_dep)
+}
+
+# AI generated
+topo_sort <- function(pkgs) {
+  adj_list <- pkg_deps(pkgs)
+  visited <- list()
+  stack <- character()
+
+  dfs <- function(vertex) {
+    visited[[vertex]] <<- TRUE
+
+    for (neighbor in adj_list[[vertex]]) {
+      if (!isTRUE(visited[[neighbor]])) {
+        dfs(neighbor)
+      }
+    }
+
+    stack <<- c(stack, vertex)
+  }
+
+  for (vertex in names(adj_list)) {
+    if (!isTRUE(visited[[vertex]])) {
+      dfs(vertex)
+    }
+  }
+
+  intersect(stack, pkgs)
+}

tests/testthat/_snaps/topo.md

@@ -0,0 +1,12 @@
+# topo_sort() works
+
+    Code
+      intersect(topo_sort(c("testthat", "rlang")), c("testthat", "rlang"))
+    Output
+      [1] "rlang"    "testthat"
+    Code
+      intersect(topo_sort(c("testthat", "rlang", "withr")), c("testthat", "rlang",
+        "withr"))
+    Output
+      [1] "rlang"    "withr"    "testthat"
+

tests/testthat/test-topo.R

@@ -0,0 +1,13 @@
+test_that("topo_sort() works", {
+  # Can only use packages that we import or suggest
+  expect_snapshot({
+    intersect(
+      topo_sort(c("testthat", "rlang")),
+      c("testthat", "rlang")
+    )
+    intersect(
+      topo_sort(c("testthat", "rlang", "withr")),
+      c("testthat", "rlang", "withr")
+    )
+  })
+})