update readme

allow default values on required opts

README.md

@@ -1,3 +1,40 @@
-A command parser for Discord bots. Should work with any JS library.
+A command parser initially made for quickly making discord bots, but works as a standalone parser too.
 
-You're expected to implement a string -> abstraction resolver yourself and pass it to the parser.
+Your commands are expected to inherit from the Command class
+
+**Example usage**  
+```js
+
+const commands: Command[] = [
+    new Command({
+        name: 'ping',
+        options: [
+            {
+                name: 'respond',            //
+                type: OptionType.BOOLEAN,   // Boolean type expects the parser to have some kind of string -> boolean resolver, see the resolver interface for which methods are expected
+                required: true,             // Will throw error if not provided
+                defaultValue: true,         // The value that will be given back if no value is given, or if option is required but not provided
+                flag: true                  // The parser will look for the option in the "--respond value" form
+            }
+        ]
+    })
+]; // Command definitions
+
+const parser = new Parser({commands, prefix: ''}); // Empty prefix
+const parsed = await parser.parseMessage('ping --respond');
+
+/**
+ * Parsed will be an object cotaining properties args, command, subcommand, and subcommandgroup
+ * the args property is an object of the given options mapped by their names, e.g.
+ * {
+ *   respond: {
+ *     ... properties,
+ *     value: true
+ *   }
+ * }
+ * 
+*/
+
+```
+
+Some of the option types have built-in parsers (e.g. numbers, strings), but others will require the resolver implementation, and in some cases CommandOption extensions.

src/Parser.ts

@@ -23,7 +23,8 @@ type ParserOptions = {
     commands: Iterable<Command>,
     prefix?: string,
     debug?: boolean,
-    resolver?: IResolver<unknown, unknown, unknown, unknown, unknown>
+    resolver?: IResolver<unknown, unknown, unknown, unknown, unknown>,
+    allowDefaultOnRequired?: boolean
 }
 
 type ParseOptions = {
@@ -39,14 +40,12 @@ const flagReg = /(?:^| )(?<flag>(?:--[a-z0-9]{3,})|(?:-[a-z]{1,2}))(?:$| )/iu;
 class Parser extends EventEmitter {
 
     private commands: ExtendedMap<string, Command>;
-
     private _debug = false;
-
     prefix: string;
-
     resolver?: IResolver<unknown, unknown, unknown, unknown, unknown>;
+    allowDefaultOnRequired: boolean;
 
-    constructor ({ commands, prefix, debug = false, resolver }: ParserOptions) {
+    constructor ({ commands, prefix, debug = false, resolver, allowDefaultOnRequired }: ParserOptions) {
 
         super();
 
@@ -57,6 +56,7 @@ class Parser extends EventEmitter {
         this.resolver = resolver;
         
         this.prefix = prefix || '';
+        this.allowDefaultOnRequired = allowDefaultOnRequired ?? true;
 
     }
 
@@ -311,10 +311,17 @@ class Parser extends EventEmitter {
         // }
 
         this.debug(`Making sure required options were given.`);
-        for (const req of options.filter((opt) => opt.required))
-            if (!args[req.name]) 
+        for (const req of options.filter((opt) => opt.required)) {
+            if (!args[req.name]) {
+                if (req.defaultValue === null || !this.allowDefaultOnRequired)
                     throw new ParseError(`${req.name} is a required option`);
                 
+                const opt = req.clone();
+                opt.value = req.defaultValue;
+                args[req.name] = opt;
+            }
+        }
+        
         if (strings.length) 
             throw new ParseError(`Unrecognised option(s): "${strings.join('", "')}"`);