feat: Add --only flag to a --by command

cli.js

@@ -9,6 +9,7 @@ const byCommand = require("./commands/by");
 const helpCommand = require("./commands/help");
 const knownFlags = [
   "by",
+  "only",
   "modulesOnly",
   "filesOnly",
   "directOnly",

commands/by.js

@@ -2,15 +2,43 @@
 
 /*::
 import type { UpdateProgressBar } from '../lib/console/progress-bar';
+import type { Reason, Module } from '../lib/analyze';
 */
 
 const { analyze, print, getStats } = require("../lib");
 const validate = require("../lib/validate");
 const { log, invalidStatsJson } = require("../lib/console/messages");
 
+const isDepsChainBy = (depsChain /*: Array<string> */, by /*: string */) => {
+  return depsChain.indexOf(by) !== -1;
+};
+
+const modulesFollowingDepsChain = (
+  modules /*: Array<Module> */,
+  by /*:string*/
+) =>
+  modules.filter(
+    mod =>
+      mod.reasons.some(
+        reason => reason.moduleName === by || reason.clearName === by
+      ) || (mod.depsChains || []).some(deps => isDepsChainBy(deps, by))
+  );
+
+const isSingleReasonBy = (reasons /*: Array<Reason> */, by /*: string */) =>
+  reasons.length === 1 &&
+  (reasons[0].moduleName === by || reasons[0].clearName === by);
+
+const modulesOnlyBy = (modules /*: Array<Module> */, by /*: string */) =>
+  modulesFollowingDepsChain(modules, by).filter(
+    mod =>
+      isSingleReasonBy(mod.reasons, by) ||
+      ((mod.depsChains || []).length &&
+        (mod.depsChains || []).every(depsChain => isDepsChainBy(depsChain, by)))
+  );
+
 module.exports = function byCommand(
   statsFilePath /*: string */,
-  flags /*: { limit: number, by: string, ignore?: string } */,
+  flags /*: { limit: number, by: string, only?: boolean, ignore?: string } */,
   pattern /*: string */,
   updateProgressBar /*: UpdateProgressBar */ = () => {}
 ) {
@@ -24,13 +52,9 @@ module.exports = function byCommand(
   const ignore = flags.ignore ? flags.ignore.split(",") : [];
   const report = analyze(stats, ignore, updateProgressBar);
 
-  const modules = report.modules.filter(
-    mod =>
-      mod.reasons.some(
-        reason =>
-          reason.moduleName === flags.by || reason.clearName === flags.by
-      ) || (mod.depsChains || []).some(deps => deps.indexOf(flags.by) !== -1)
-  );
+  const modules = flags.only
+    ? modulesOnlyBy(report.modules, flags.by)
+    : modulesFollowingDepsChain(report.modules, flags.by);
 
   const limit /*: number */ = pattern ? 0 : flags.limit >= 0 ? flags.limit : 20;
   print(modules, report.chunks, { by: flags.by }, limit);

commands/help.js

@@ -22,6 +22,7 @@ module.exports = function help() {
     chalk.green("By options [--by]:"),
     `  ${chalk.yellow("--ignore")}           Comma separated list of glob pattern to exclude modules from final output`,
     `  ${chalk.yellow("--limit")}            Limits output of reasons and files [default: 20]`,
+    `  ${chalk.yellow("--only")}             Limits output to only include modules that were included by specified module exclusively`,
     ``,
     chalk.green("Other options:"),
     `  ${chalk.yellow("-v, --version")}      Shows version.`,