feat: Add option to load config in sync mode (#67)

* feat: Add option to load config in sync mode * docs: Clarify usage for transform func in async, sync * refactor: Use funcRunner for chaining funcs and avoid code repetition * chore: Correct comment in creteExplorer for cache * docs: Add returns annotation for funcRunner * refactor: Set func name to funcRunner * test: Add tests for funcRunner * test: rm mysterious test failing on node <= 4
cosmiconfig · Jul 18, 2017 · bed5dc0 · bed5dc0
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diff --git a/README.md b/README.md
@@ -14,7 +14,7 @@ For example, if your module's name is "soursocks," cosmiconfig will search out c
 - a `soursocks.config.js` file exporting a JS object (anywhere down the file tree)
 - a CLI `--config` argument
 
-cosmiconfig continues to search in these places all the way down the file tree until it finds acceptable configuration (or hits the home directory). And it does all this asynchronously, so it shouldn't get in your way.
+cosmiconfig continues to search in these places all the way down the file tree until it finds acceptable configuration (or hits the home directory). And it does all this asynchronously by default, so it shouldn't get in your way.
 
 Additionally, all of these search locations are configurable: you can customize filenames or turn off any location.
 
@@ -49,6 +49,8 @@ explorer.load(yourSearchPath)
 The function `cosmiconfig()` searches for a configuration object and returns a Promise,
 which resolves with an object containing the information you're looking for.
 
+You can also pass option `sync: true` to load the config synchronously.
+
 So let's say `var yourModuleName = 'goldengrahams'` — here's how cosmiconfig will work:
 
 - Starting from `process.cwd()` (or some other directory defined by the `searchPath` argument to `load()`), it looks for configuration objects in three places, in this order:
@@ -168,11 +170,21 @@ Default: `true`
 
 If `false`, no caches will be used.
 
+##### sync
+
+Type: `boolean`
+Default: `false`
+
+If `true`, config will be loaded synchronously.
+
 ##### transform
 
-Type: `Function` returning a Promise
+Type: `Function`
+
+A function that transforms the parsed configuration. Receives the result object with `config` and `filepath` properties.
 
-A function that transforms the parsed configuration. Receives the result object with `config` and `filepath` properties, and must return a Promise that resolves with the transformed result.
+If the option `sync` is `false`(default), the function must return a Promise that resolves with the transformed result.
+Otherwise, `transform` should be a synchronous function which returns the transformed result.
 
 The reason you might use this option instead of simply applying your transform function some other way is that *the transformed result will be cached*. If your transformation involves additional filesystem I/O or other potentially slow processing, you can use this option to avoid repeating those steps every time a given configuration is loaded.
 
@@ -217,7 +229,7 @@ Performs both `clearFileCache()` and `clearDirectoryCache()`.
 - Built-in support for JSON, YAML, and CommonJS formats.
 - Stops at the first configuration found, instead of finding all that can be found down the filetree and merging them automatically.
 - Options.
-- Asynchronicity.
+- Asynchronous by default, can be forced to use synchronous mode.
 
 ## Contributing & Development
 

diff --git a/index.js b/index.js
@@ -17,6 +17,7 @@ module.exports = function (moduleName, options) {
     rcStrictJson: false,
     stopDir: oshomedir(),
     cache: true,
+    sync: false,
   }, options);
 
   if (options.argv && parsedCliArgs[options.argv]) {

diff --git a/lib/createExplorer.js b/lib/createExplorer.js
@@ -6,12 +6,14 @@ var loadPackageProp = require('./loadPackageProp');
 var loadRc = require('./loadRc');
 var loadJs = require('./loadJs');
 var loadDefinedFile = require('./loadDefinedFile');
+var funcRunner = require('./funcRunner');
 
 module.exports = function (options) {
+  // When `options.sync` is `false`(default),
   // These cache Promises that resolve with results, not the results themselves
   var fileCache = (options.cache) ? new Map() : null;
   var directoryCache = (options.cache) ? new Map() : null;
-  var transform = options.transform || identityPromise;
+  var transform = options.transform || (options.sync) ? identitySync : identityPromise;
 
   function clearFileCache() {
     if (fileCache) fileCache.clear();
@@ -32,56 +34,68 @@ module.exports = function (options) {
       if (fileCache && fileCache.has(absoluteConfigPath)) {
         return fileCache.get(absoluteConfigPath);
       }
-      var result = loadDefinedFile(absoluteConfigPath, options)
-        .then(transform);
+      var result = (!options.sync)
+        ? loadDefinedFile(absoluteConfigPath, options)
+            .then(transform)
+        :  transform(loadDefinedFile(absoluteConfigPath, options));
       if (fileCache) fileCache.set(absoluteConfigPath, result);
       return result;
     }
 
-    if (!searchPath) return Promise.resolve(null);
+    if (!searchPath) return (!options.sync) ? Promise.resolve(null) : null;
 
     var absoluteSearchPath = path.resolve(process.cwd(), searchPath);
 
-    return isDirectory(absoluteSearchPath)
-      .then(function (searchPathIsDirectory) {
-        var directory = (searchPathIsDirectory)
+    return (!options.sync)
+      ? isDirectory(absoluteSearchPath)
+        .then(function (searchPathIsDirectory) {
+          var directory = (searchPathIsDirectory)
+            ? absoluteSearchPath
+            : path.dirname(absoluteSearchPath);
+          return searchDirectory(directory);
+        })
+      : searchDirectory(
+          isDir.sync(absoluteSearchPath)
           ? absoluteSearchPath
-          : path.dirname(absoluteSearchPath);
-        return searchDirectory(directory);
-      });
+          : path.dirname(absoluteSearchPath)
+        );
   }
 
   function searchDirectory(directory) {
     if (directoryCache && directoryCache.has(directory)) {
       return directoryCache.get(directory);
     }
 
-    var result = Promise.resolve()
-      .then(function () {
-        if (!options.packageProp) return;
-        return loadPackageProp(directory, options);
-      })
-      .then(function (result) {
-        if (result || !options.rc) return result;
-        return loadRc(path.join(directory, options.rc), options);
-      })
-      .then(function (result) {
-        if (result || !options.js) return result;
-        return loadJs(path.join(directory, options.js));
-      })
-      .then(function (result) {
-        if (result) return result;
-
-        var splitPath = directory.split(path.sep);
-        var nextDirectory = (splitPath.length > 1)
-          ? splitPath.slice(0, -1).join(path.sep)
-          : null;
-
-        if (!nextDirectory || directory === options.stopDir) return null;
-
-        return searchDirectory(nextDirectory);
-      })
-      .then(transform);
+    var result = funcRunner(
+      !options.sync ? Promise.resolve() : undefined,
+      [
+        function () {
+          if (!options.packageProp) return;
+          return loadPackageProp(directory, options);
+        },
+        function (result) {
+          if (result || !options.rc) return result;
+          return loadRc(path.join(directory, options.rc), options);
+        },
+        function (result) {
+          if (result || !options.js) return result;
+          return loadJs(path.join(directory, options.js), options);
+        },
+        function (result) {
+          if (result) return result;
+
+          var splitPath = directory.split(path.sep);
+          var nextDirectory = (splitPath.length > 1)
+            ? splitPath.slice(0, -1).join(path.sep)
+            : null;
+
+          if (!nextDirectory || directory === options.stopDir) return null;
+
+          return searchDirectory(nextDirectory);
+        },
+        transform,
+      ]
+    );
 
     if (directoryCache) directoryCache.set(directory, result);
     return result;
@@ -107,3 +121,7 @@ function isDirectory(filepath) {
 function identityPromise(x) {
   return Promise.resolve(x);
 }
+
+function identitySync(x) {
+  return x;
+}
diff --git a/lib/funcRunner.js b/lib/funcRunner.js
@@ -0,0 +1,25 @@
+'use strict';
+
+var isPromise = require('is-promise');
+
+/**
+ * Runs given functions. If the `init` param is a promise, functions are
+ * chained using `p.then()`. Otherwise, functions are chained by passing
+ * the result of each function to the next.
+ *
+ * @param {*} init
+ * @param {Array<Function>} funcs
+ * @returns {*} A promise if `init` was one, otherwise result of function
+ * chain execution.
+ */
+module.exports = function funcRunner(init, funcs) {
+  var async = isPromise(init);
+
+  var res = init;
+  funcs.forEach(function (func) {
+    if (async === true) res = res.then(func);
+    else res = func(res);
+  });
+
+  return res;
+};
diff --git a/lib/loadDefinedFile.js b/lib/loadDefinedFile.js
@@ -6,7 +6,7 @@ var readFile = require('./readFile');
 var parseJson = require('./parseJson');
 
 module.exports = function (filepath, options) {
-  return readFile(filepath, { throwNotFound: true }).then(function (content) {
+  function parseContent(content) {
     var parsedConfig = (function () {
       switch (options.format) {
         case 'json':
@@ -32,7 +32,12 @@ module.exports = function (filepath, options) {
       config: parsedConfig,
       filepath: filepath,
     };
-  });
+  }
+
+  return (!options.sync)
+    ? readFile(filepath, { throwNotFound: true })
+      .then(parseContent)
+    : parseContent(readFile.sync(filepath, { throwNotFound: true }));
 };
 
 function tryAllParsing(content, filepath) {

diff --git a/lib/loadJs.js b/lib/loadJs.js
@@ -3,13 +3,17 @@
 var requireFromString = require('require-from-string');
 var readFile = require('./readFile');
 
-module.exports = function (filepath) {
-  return readFile(filepath).then(function (content) {
+module.exports = function (filepath, options) {
+  function parseJsFile(content) {
     if (!content) return null;
 
     return {
       config: requireFromString(content, filepath),
       filepath: filepath,
     };
-  });
+  }
+
+  return (!options.sync)
+    ? readFile(filepath).then(parseJsFile)
+    : parseJsFile(readFile.sync(filepath));
 };
diff --git a/lib/loadPackageProp.js b/lib/loadPackageProp.js
@@ -7,7 +7,7 @@ var parseJson = require('./parseJson');
 module.exports = function (packageDir, options) {
   var packagePath = path.join(packageDir, 'package.json');
 
-  return readFile(packagePath).then(function (content) {
+  function parseContent(content) {
     if (!content) return null;
     var parsedContent = parseJson(content, packagePath);
     var packagePropValue = parsedContent[options.packageProp];
@@ -17,5 +17,9 @@ module.exports = function (packageDir, options) {
       config: packagePropValue,
       filepath: packagePath,
     };
-  });
+  }
+
+  return (!options.sync)
+    ? readFile(packagePath).then(parseContent)
+    : parseContent(readFile.sync(packagePath));
 };
diff --git a/lib/loadRc.js b/lib/loadRc.js
@@ -4,16 +4,21 @@ var yaml = require('js-yaml');
 var requireFromString = require('require-from-string');
 var readFile = require('./readFile');
 var parseJson = require('./parseJson');
+var funcRunner = require('./funcRunner');
 
 module.exports = function (filepath, options) {
-  return loadExtensionlessRc().then(function (result) {
+  function afterLoadExtensionlessRc(result) {
     if (result) return result;
     if (options.rcExtensions) return loadRcWithExtensions();
     return null;
-  });
+  }
+
+  return (!options.sync)
+    ? loadExtensionlessRc().then(afterLoadExtensionlessRc)
+    : afterLoadExtensionlessRc(loadExtensionlessRc());
 
   function loadExtensionlessRc() {
-    return readRcFile().then(function (content) {
+    function parseExtensionlessRcFile(content) {
       if (!content) return null;
 
       var pasedConfig = (options.rcStrictJson)
@@ -25,11 +30,15 @@ module.exports = function (filepath, options) {
         config: pasedConfig,
         filepath: filepath,
       };
-    });
+    }
+
+    return (!options.sync)
+      ? readRcFile().then(parseExtensionlessRcFile)
+      : parseExtensionlessRcFile(readRcFile());
   }
 
   function loadRcWithExtensions() {
-    return readRcFile('json').then(function (content) {
+    function parseJsonRcFile(content) {
       if (content) {
         var successFilepath = filepath + '.json';
         return {
@@ -40,7 +49,9 @@ module.exports = function (filepath, options) {
       // If not content was found in the file with extension,
       // try the next possible extension
       return readRcFile('yaml');
-    }).then(function (content) {
+    }
+
+    function parseYmlRcFile(content) {
       if (content) {
         // If the previous check returned an object with a config
         // property, then it succeeded and this step can be skipped
@@ -53,7 +64,9 @@ module.exports = function (filepath, options) {
         };
       }
       return readRcFile('yml');
-    }).then(function (content) {
+    }
+
+    function parseYamlRcFile(content) {
       if (content) {
         if (content.config) return content;
         var successFilepath = filepath + '.yml';
@@ -63,7 +76,9 @@ module.exports = function (filepath, options) {
         };
       }
       return readRcFile('js');
-    }).then(function (content) {
+    }
+
+    function parseJsRcFile(content) {
       if (content) {
         if (content.config) return content;
         var successFilepath = filepath + '.js';
@@ -73,13 +88,20 @@ module.exports = function (filepath, options) {
         };
       }
       return null;
-    });
+    }
+
+    return funcRunner(
+      readRcFile('json'),
+      [parseJsonRcFile, parseYmlRcFile, parseYamlRcFile, parseJsRcFile]
+    );
   }
 
   function readRcFile(extension) {
     var filepathWithExtension = (extension)
       ? filepath + '.' + extension
       : filepath;
-    return readFile(filepathWithExtension);
+    return (!options.sync)
+      ? readFile(filepathWithExtension)
+      : readFile.sync(filepathWithExtension);
   }
 };