Improve pick()

src/config/normalize/lib/wild_wild_path/set.js

@@ -13,9 +13,6 @@ export const set = function (target, queryOrPaths, value) {
 // Ignore properties when one of their ancestors was matched too.
 // Uses `iterate()` to keep memory consumption low.
 export const reduceParents = function (target, queryOrPaths, setFunc) {
-  // eslint-disable-next-line fp/no-let
-  let newTarget = target
-
   const paths = []
 
   // eslint-disable-next-line fp/no-loops
@@ -24,12 +21,12 @@ export const reduceParents = function (target, queryOrPaths, setFunc) {
     if (!parentIsSet(paths, path)) {
       // eslint-disable-next-line fp/no-mutating-methods
       paths.push(path)
-      // eslint-disable-next-line fp/no-mutation
-      newTarget = setFunc(newTarget, path, 0)
+      // eslint-disable-next-line fp/no-mutation, no-param-reassign
+      target = setFunc(target, path, 0)
     }
   }
 
-  return newTarget
+  return target
 }
 
 // If both a parent and a child property are set, the parent prevails

src/config/normalize/lib/wild_wild_path_utils/common.js

@@ -1,4 +1,4 @@
-import { list } from '../wild_wild_path/main.js'
+import { list, iterate, parent } from '../wild_wild_path/main.js'
 
 // `list()` but without missing entries
 export const listExisting = function (target, queryOrPath) {
@@ -8,3 +8,42 @@ export const listExisting = function (target, queryOrPath) {
 const isExisting = function ({ missing }) {
   return !missing
 }
+
+// Modify a target object multiple times for each matched property.
+// Ignore properties when one of their ancestors was matched too.
+// Uses `iterate()` to keep memory consumption low.
+export const reduceParents = function ({
+  target,
+  newTarget,
+  queryOrPaths,
+  setFunc,
+  condition = returnTrue,
+}) {
+  const paths = []
+
+  // eslint-disable-next-line fp/no-loops
+  for (const entry of iterate(target, queryOrPaths)) {
+    // eslint-disable-next-line max-depth
+    if (shouldUseEntry(entry, paths, condition)) {
+      // eslint-disable-next-line fp/no-mutating-methods
+      paths.push(entry.path)
+      // eslint-disable-next-line fp/no-mutation, no-param-reassign
+      newTarget = setFunc(newTarget, entry, 0)
+    }
+  }
+
+  return newTarget
+}
+
+const returnTrue = function () {
+  return true
+}
+
+const shouldUseEntry = function (entry, paths, condition) {
+  return !entry.missing && !parentIsSet(paths, entry.path) && condition(entry)
+}
+
+// If both a parent and a child property are set, the parent prevails
+const parentIsSet = function (paths, path) {
+  return paths.some((previousPath) => parent(previousPath, path))
+}

src/config/normalize/lib/wild_wild_path_utils/pick.js

@@ -1,11 +1,15 @@
 import { set } from '../wild_wild_path/main.js'
 
-import { listExisting } from './common.js'
+import { listExisting, reduceParents } from './common.js'
 
 // Returns an object with only the properties being queried.
-export const pick = function (target, queryOrPath) {
-  const entries = listExisting(target, queryOrPath)
-  return entries.reduce(pickEntry, {})
+export const pick = function (target, queryOrPaths) {
+  return reduceParents({
+    target,
+    newTarget: {},
+    queryOrPaths,
+    setFunc: pickEntry,
+  })
 }
 
 const pickEntry = function (target, { path, value }) {