refactor: Switch parsing and composing

Refactor the switch parsing and composing. The main function uses ES6,
is now called `toChildProcessArgs()` (which is more accurate). It also
relies on hardcoded values for specific switches (see top of the file).

util/switches.js

@@ -1,68 +1,87 @@
-'use strict';
+/**
+ * Switches that can be toggled on or off (boolean switches). Default values
+ * are based on the 7-zip documentation.
+ */
+const swDefaultBool = {
+  sdel: false, // Delete files after compression
+  spl: false, // Set Large Pages mode
+  sni: false, // Store NT security information
+  so: false, // Write data to stdout
+  spd: false, // Disable wildcard matching for file names
+  spe: false, // Eliminate duplication of root folder for extract command
+  spf: false, // Use fully qualified file paths
+  ssw: false, // Compress files open for writing
+  stl: false, // Set archive timestamp from the most recently modified file
+  y: true // Assume Yes on all queries
+}
+
+/**
+ * Switches that ca be toggles on or of. Their default values changes according
+ * to the context (command, platform, ...).
+ */
+const swContextBool = {
+  sns: undefined, // Store NTFS alternate Streams
+  ssc: undefined // Set Sensitive Case mode
+}
+
+/**
+ * Switches that can be applied multiple times
+ */
+const swRepeating = {
+  ai: undefined,
+  ax: undefined,
+  i: undefined,
+  x: undefined
+}
 
 /**
  * Transform an object of options into an array that can be passed to the
  * spawned child process.
  * @param  {Object} switches An object of options
  * @return {array} Array to pass to the `run` function.
  */
-module.exports = function (switches) {
-
-  // Default value for switches
-  switches = switches || {};
-
-  var a = [];
-  // Set default values of boolean switches
-  switches.so  = (switches.so  === true)  ? true  : false;
-  switches.spl = (switches.spl === true)  ? true  : false;
-  switches.ssc = (switches.ssc === false) ? false : true ;
-  switches.ssw = (switches.ssw === true)  ? true  : false;
-  switches.y   = (switches.y   === false) ? false : true ;
+export default function toChildProcessArgs (switches = swDefaultBool) {
+  const swDefaultBoolKeys = Object.keys(swDefaultBool)
+  const swContextBoolKeys = Object.keys(swContextBool)
+  const swRepeatingKeys = Object.keys(swRepeating)
+  let cmdArgs = []
 
-  var s;
-  /*jshint forin:false*/
-  for (s in switches) {
-
-    // Switches that are set or not. Just add them to the array if they are
-    // present. Differ the `ssc` switch treatment to later in the function.
-    if (switches[s] === true && s !== 'ssc') {
-      a.push('-' + s);
+  Object.entries(switches).forEach(([swName, swVal]) => {
+    // Handle wildcards
+    if (swName === 'wildcards') {
+      cmdArgs.unshift(swVal)
+      return
     }
 
-    // Switches with a value. Detect if the value contains a space. If it does
-    // wrap the value with double quotes. Else just add the switch and its value
-    // to the string. Doubles quotes are used for parsing with a RegExp later.
-    if (typeof switches[s] !== 'boolean') {
-
-      // Special treatment for wilcards
-      if (s === 'wildcards') {
-        a.unshift(switches.wildcards);
-      }
-
-      // Allow raw switches to be added to the command, repeating switches like
-      // -i is not possible otherwise.
-      else if (s === 'raw') {
-        switches.raw.forEach(function (rawValue) {
-          a.push(rawValue);
-        });
-      }
-
-      else if (switches[s].indexOf(' ') === -1) {
-        a.push('-' + s + switches[s]);
-      }
-
-      else {
-        a.push('-' + s + '"' + switches[s] + '"');
+    // Handle boolean switches
+    if (swDefaultBoolKeys.includes(swName)) {
+      if (swVal === true) {
+        cmdArgs.push(`-${swName}`)
       }
+      return
     }
 
-    // Special treatment for `-ssc`
-    if (s === 'ssc') {
-      a.push((switches.ssc === true) ? '-ssc' : '-ssc-');
+    // Handle context boolean switches
+    if (swContextBoolKeys.includes(swName)) {
+      let swSuffix = (swVal === true) ? '' : '-'
+      cmdArgs.push(`-${swName}${swSuffix}`)
+      return
     }
 
-  }
+    // Handle repeating switches. They can be string or array
+    if (swRepeatingKeys.includes(swName)) {
+      if (typeof swVal === 'string') {
+        swVal = [swVal]
+      }
+      swVal.forEach(([swRepeatingString]) => {
+        cmdArgs.push(`-${swName}${swRepeatingString}`)
+      })
+      return
+    }
 
-  return a;
+    // Handle switches with arguments
+    cmdArgs.push(`-${swName}${swVal}`)
+  })
 
-};
+  return cmdArgs
+}