feat: add argument handler

src/lib/usage/Args.ts

@@ -0,0 +1,160 @@
+import { regExpEsc } from '@klasa/utils';
+
+const enum Quote {
+	Single = "''",
+	Double = '""',
+	SmartSingle = '‘’',
+	SmartDouble = '“”'
+}
+
+const enum Dash {
+	Single = '-',
+	Double = '--',
+	Long = '—'
+}
+
+const kQuote = [Quote.Single[0], Quote.Double[0], Quote.SmartSingle[0], Quote.SmartDouble[0]];
+const kDashThin = [Dash.Single, Dash.Long].join('|');
+const kDashWide = [Dash.Double, Dash.Long].join('|');
+
+export class Flag {
+	public readonly kDash: Dash;
+	public readonly kName: string;
+	public readonly kValue: string | null;
+	public readonly kIndex: number;
+
+	public constructor(dash: Dash, name: string, value: string | null, index: number) {
+		this.kDash = dash;
+		this.kName = name.toLowerCase();
+		this.kValue = value;
+		this.kIndex = index;
+	}
+
+	public get length() {
+		return this.kValue === null ? this.kName.length : this.kName.length + this.kValue.length;
+	}
+
+	public get fullLength() {
+		return this.kDash.length + this.length;
+	}
+
+	public get offset() {
+		return this.kIndex + this.fullLength;
+	}
+
+	public static make(options: readonly string[]): RegExp | null {
+		if (options.length === 0) return null;
+
+		// Escape and separate both parts
+		const wide: string[] = [];
+		const thin: string[] = [];
+		for (const option of options) {
+			if (option.length === 0) continue;
+
+			const escaped = regExpEsc(option);
+			if (option.length === 1) thin.push(escaped);
+			else wide.push(escaped);
+		}
+
+		// Generate the RegExp for both parts:
+		const widePath = wide.length === 0 ? null : `(${kDashWide})(${wide.join('|')})(=|\\s|$)`;
+		const thinPath = thin.length === 0 ? null : `(${kDashThin})(${thin.join('|')})(?=\\s|$)`;
+
+		// Concatenate both parts:
+		// (?, ?):
+		//   (string, ?):
+		//     - (string, string): -> wide + thin
+		//     - (string, null): -> wide
+		//   (null, ?):
+		//     - (null, string): -> thin
+		//     - (null, null): -> null
+		const mixed = widePath ? (thinPath ? `(?:${widePath}|${thinPath})` : widePath) : thinPath ? thinPath : null;
+
+		if (mixed === null) return mixed;
+
+		return new RegExp(`\B${mixed}`, 'ig');
+	}
+
+	/**
+	 *
+	 * @param content The content to parse
+	 * @param allowedFlags The regexp with the allowed flags
+	 * @example
+	 * const content = '--hello=world --wow —Hi';
+	 * const allowedFlags = Args.makeFlags(['hello', 'hi', 'i']);
+	 * // -> /\B(?:(--|—)(hello|hi)(=|\s|$)|(-|—)(i)(?=\s|$))/ig
+	 *
+	 * for (const flag of Flag.getPotentialFlags(content, allowedFlags)) {
+	 *   console.log(flag);
+	 *   // Flag {
+	 *   //   kDash: '--',
+	 *   //   kName: 'hello',
+	 *   //   kValue: 'world',
+	 *   //   kIndex: 0 }
+	 *   //
+	 *   // Flag {
+	 *   //   kDash: '—',
+	 *   //   kName: 'hi',
+	 *   //   kValue: null,
+	 *   //   kIndex: 20 }
+	 * }
+	 */
+	public static *parse(content: string, allowedFlags: RegExp) {
+		let match: RegExpExecArray | null = null;
+		while ((match = allowedFlags.exec(content))) {
+			// Single-dash
+			if (match[4] === undefined) {
+				yield new Flag(match[4] as Dash, match[5], null, match.index);
+				continue;
+			}
+
+			const dash = match[1] as Dash;
+			const name = match[2];
+			if (match[3] === '=') {
+				yield new Flag(dash, name, null, match.index);
+				continue;
+			}
+
+			yield new Flag(dash, name, null, match.index);
+		}
+	}
+}
+
+export class Args {
+	// eslint-disable-next-line @typescript-eslint/explicit-member-accessibility
+	#content: string;
+	// TODO(kyranet): make this a Cache
+	// eslint-disable-next-line @typescript-eslint/explicit-member-accessibility
+	#flags = new Map<string, Flag>();
+
+	public constructor(content: string) {
+		this.#content = content;
+	}
+
+	private static get(content: string, allowQuotes: boolean) {
+		const quoted = kQuote.includes(content[0]);
+		return quoted ? (allowQuotes ? Args.getQuoted(content.substring(1)) : null) : Args.getSimple(content);
+	}
+
+	private static getSimple(content: string): string | null {
+		return content;
+	}
+
+	private static getQuoted(content: string): string | null {
+		return content;
+	}
+
+	private static findQuoteEnd(parameter: string, quote: Quote): number {
+		const closing = quote[1];
+
+		let i = 0;
+		let escaped = false;
+		for (const character of parameter) {
+			if (character === '\\') escaped = !escaped;
+			else if (character === closing) return i;
+			i += character.length;
+		}
+
+		return -1;
+	}
+}