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parse_string.js

@@ -0,0 +1,55 @@
+/**
+* Parses a string and returns a list consisting of one of
+* length-1-`string` (`char`) or `symbol`, representing the
+* tokens the scanner finds.
+* Every time a token is successfully found, a symbol representing
+* the token is inserted, otherwise the current character is
+* used instead.
+* @param {string} str The string to scan.
+* @param {string[]} toks A list of possible tokens to find.
+* @return {(string|symbol)[]} A list representing the scanner's findings.
+*/
+const parse_string = function parse_string(str="", toks=null) {
+	if(
+		str.length <= 0 ||
+		(toks ?? null) === null ||
+		toks.length <= 0
+	) return new Array();
+
+	let parsed_array = new Array();
+	let tok_entpts = new Map();
+	for(let i = 0; i < toks.length; i++) {
+		const c = toks[i][0];
+		if(tok_entpts.has(c)) {
+			const v = tok_entpts.get(c);
+			if(v instanceof Array) v.push( toks[i] );
+			else tok_entpts.set(c, [v, toks[i]]);
+		} else tok_entpts.set(c, toks[i]);
+	}
+
+	for(let i = 0; i < str.length; i++) {
+		const c = str[i];
+		if(tok_entpts.has(c)) {
+			const v = tok_entpts.get(c);
+			if(typeof v === "string") {
+				const slc = str.slice(i, i+v.length);
+				const tvs = slc === v;
+				if(tvs) {
+					parsed_array.push( Symbol.for(slc) );
+					i += v.length-1;
+				} else parsed_array.push(c);
+			}
+			if(v instanceof Array) for(const tok of v) {
+				const slc = str.slice(i, i+tok.length);
+				const tvs = slc === tok;
+				if(tvs) {
+					parsed_array.push( Symbol.for(tok) );
+					i += tok.length-1;
+					break;
+				} else parsed_array.push(c);
+			};
+		} else parsed_array.push(c);
+	}
+
+	return parsed_array;
+}