Implement "limit-last" mode for multipleOptions

We're flipping the order of the arguments array before and after running
through it in order to retroactively inject stuff into result.argv. This
is a SERIOUSLY suboptimal approach, but because I don't predict that the
"limit-last" option will be used that often, a sloppy approach is better
than blowing days of effort over a "clean" approach.

index.js

@@ -219,19 +219,14 @@ function getOpts(input, optdef, config){
 				break;
 			}
 
-			/** Use the first option; treat any following duplicates as items of argv */
-			case "limit-first":{
+			/** Use the first/last options; treat any following/preceding duplicates as argv items respectively */
+			case "limit-first":
+			case "limit-last":{
 				let values = Array.isArray(value) ? value : [value];
 				result.argv.push(option.prevMatchedName, ...values);
 				break;
 			}
 
-			/** Use only the last option; treat any preceding duplicates as items of argv */
-			case "limit-last":{
-
-				break;
-			}
-
 
 			/** Chuck a hissy-fit if that's what the author wants */
 			case "error":{
@@ -322,6 +317,26 @@ function getOpts(input, optdef, config){
 	};
 
 
+	/** Reverses the argument order of the given array, keeping options and their parameter lists intact */
+	let flip = function(input){
+		input = input.reverse();
+
+		/** Flip any options back into the right order */
+		for(let i = 0, l = input.length; i < l; ++i){
+			let arg = input[i];
+			let opt = shortNames[arg] || longNames[arg];
+
+			if(opt){
+				let from    = Math.max(0, i - opt.arity);
+				let to      = i + 1;
+				let extract = input.slice(from, to).reverse();
+				input.splice(from, extract.length, ...extract);
+			}
+		}
+
+		return input;
+	};
+
 
 	/** Tackle bundling: make sure there's at least one option with a short name to work with */
 	let nameKeys = Object.keys(shortNames);
@@ -379,6 +394,11 @@ function getOpts(input, optdef, config){
 	}
 
 
+	/** If we're handling duplicate options with "limit-last", flip the input order */
+	if("limit-last" === multipleOptions)
+		input = flip(input);
+
+
 	/** Start processing the arguments we were given to handle */
 	for(let i = 0, l = input.length; i < l; ++i){
 		let arg = input[i];
@@ -428,6 +448,11 @@ function getOpts(input, optdef, config){
 	/** Ended abruptly? */
 	if(currentOption) wrapItUp();
 
+
+	/** Check if we need to flip the returned .argv array back into the right order again */
+	if("limit-last" === multipleOptions)
+		result.argv = flip(result.argv);
+
 	return result;
 }
 

test/tests.json

@@ -74,6 +74,17 @@
 		}
 	},
 
+	{
+		"name": "Duplicate-option handling: limit-last",
+		"input": "alpha --set-size 640 480 beta --set-size 800 600 gamma --set-size 1024 768",
+		"config": {"noAliasPropagation": "first-only", "multipleOptions": "limit-last"},
+		"optdef": {"-s, --set-size": "<width=\\d+> <height=\\d+>"},
+		"expected": {
+			"options": {"setSize": ["1024", "768"]},
+			"argv": ["alpha", "--set-size", "640", "480", "beta", "--set-size", "800", "600", "gamma"]
+		}
+	},
+
 	{
 		"name": "Duplicate-option handling: error",
 		"input": "--arg 1 alpha --arg 2",