Refactor parseOptions()

Eliminates redundant calls and checks.

(cherry picked from commit dd2c9c8)

lib/command.js

@@ -1439,12 +1439,9 @@ Expecting one of '${allowedValues.join("', '")}'`);
     let dest = operands;
     const args = argv.slice();
 
-    function maybeOption(arg) {
-      return arg.length > 1 && arg[0] === '-';
-    }
-
     // parse options
     let activeVariadicOption = null;
+    let onlyKnownOptionsSoFar = true;
     while (args.length) {
       const arg = args.shift();
 
@@ -1455,13 +1452,15 @@ Expecting one of '${allowedValues.join("', '")}'`);
         break;
       }
 
-      if (activeVariadicOption && !maybeOption(arg)) {
+      const isArgFlag = isFlag(arg);
+
+      if (activeVariadicOption && !isArgFlag) {
         this.emit(`option:${activeVariadicOption.name()}`, arg);
         continue;
       }
       activeVariadicOption = null;
 
-      if (maybeOption(arg)) {
+      if (isArgFlag) {
         const option = this._findOption(arg);
         // recognised option, call listener to assign value with possible custom processing
         if (option) {
@@ -1472,7 +1471,7 @@ Expecting one of '${allowedValues.join("', '")}'`);
           } else if (option.optional) {
             let value = null;
             // historical behaviour is optional value is following arg unless an option
-            if (args.length > 0 && !maybeOption(args[0])) {
+            if (args.length > 0 && !isFlag(args[0])) {
               value = args.shift();
             }
             this.emit(`option:${option.name()}`, value);
@@ -1482,63 +1481,70 @@ Expecting one of '${allowedValues.join("', '")}'`);
           activeVariadicOption = option.variadic ? option : null;
           continue;
         }
-      }
 
-      // Look for combo options following single dash, eat first one if known.
-      if (arg.length > 2 && arg[0] === '-' && arg[1] !== '-') {
-        const option = this._findOption(`-${arg[1]}`);
-        if (option) {
-          if (option.required || (option.optional && this._combineFlagAndOptionalValue)) {
-            // option with value following in same argument
-            this.emit(`option:${option.name()}`, arg.slice(2));
-          } else {
-            // boolean option, emit and put back remainder of arg for further processing
-            this.emit(`option:${option.name()}`);
-            args.unshift(`-${arg.slice(2)}`);
+        // Look for combo options following single dash, eat first one if known.
+        if (arg.length > 2 && arg[1] !== '-') {
+          const option = this._findOption(`-${arg[1]}`);
+          if (option) {
+            if (option.required || (option.optional && this._combineFlagAndOptionalValue)) {
+              // option with value following in same argument
+              this.emit(`option:${option.name()}`, arg.slice(2));
+            } else {
+              // boolean option, emit and put back remainder of arg for further processing
+              this.emit(`option:${option.name()}`);
+              args.unshift(`-${arg.slice(2)}`);
+            }
+            continue;
           }
-          continue;
         }
-      }
 
-      // Look for known long flag with value, like --foo=bar
-      if (/^--[^=]+=/.test(arg)) {
-        const index = arg.indexOf('=');
-        const option = this._findOption(arg.slice(0, index));
-        if (option && (option.required || option.optional)) {
-          this.emit(`option:${option.name()}`, arg.slice(index + 1));
-          continue;
+        // Look for known long flag with value, like --foo=bar
+        if (/^--[^=]+=/.test(arg)) {
+          const index = arg.indexOf('=');
+          const option = this._findOption(arg.slice(0, index));
+          if (option && (option.required || option.optional)) {
+            this.emit(`option:${option.name()}`, arg.slice(index + 1));
+            continue;
+          }
         }
       }
 
-      // Not a recognised option by this command.
-      // Might be a command-argument, or subcommand option, or unknown option, or help command or option.
+      // Not a recognised option by this command. Might be
+      // - a subcommand,
+      // - an option unknown to this command,
+      // - or a command-argument.
+
+      if (onlyKnownOptionsSoFar) {
+        const stopAtSubcommand = (
+          this._enablePositionalOptions || this._passThroughOptions
+        );
+        if (stopAtSubcommand) {
+          if (!isArgFlag && this._findCommand(arg)) {
+            operands.push(arg);
+            unknown.push(...args);
+            break;
+          } else if (!isArgFlag &&
+            arg === this._helpCommandName &&
+            this._hasImplicitHelpCommand()
+          ) {
+            operands.push(arg, ...args);
+            break;
+          } else if (this._defaultCommandName) {
+            unknown.push(arg, ...args);
+            break;
+          }
+        }
+      }
+      onlyKnownOptionsSoFar = false;
 
       // An unknown option means further arguments also classified as unknown so can be reprocessed by subcommands.
-      if (maybeOption(arg)) {
+      if (isArgFlag) {
         dest = unknown;
       }
 
-      // If using positionalOptions, stop processing our options at subcommand.
-      if ((this._enablePositionalOptions || this._passThroughOptions) && operands.length === 0 && unknown.length === 0) {
-        if (this._findCommand(arg)) {
-          operands.push(arg);
-          if (args.length > 0) unknown.push(...args);
-          break;
-        } else if (arg === this._helpCommandName && this._hasImplicitHelpCommand()) {
-          operands.push(arg);
-          if (args.length > 0) operands.push(...args);
-          break;
-        } else if (this._defaultCommandName) {
-          unknown.push(arg);
-          if (args.length > 0) unknown.push(...args);
-          break;
-        }
-      }
-
       // If using passThroughOptions, stop processing options at first command-argument.
       if (this._passThroughOptions) {
-        dest.push(arg);
-        if (args.length > 0) dest.push(...args);
+        dest.push(arg, ...args);
         break;
       }
 
@@ -2193,4 +2199,14 @@ function getCommandAndParents(startCommand) {
   return result;
 }
 
+/**
+ * @param {string} arg
+ * @returns {boolean}
+ * @api private
+ */
+
+function isFlag(arg) {
+  return arg.length > 1 && arg[0] === '-';
+}
+
 exports.Command = Command;