Add types that will be moved back to easyscore.ts and parser.ts.

src/parser.ts

@@ -4,9 +4,10 @@
 
 import { Vex } from './vex';
 import { Grammar } from './easyscore';
+import { Rule, Match, RuleFunction, TriggerFunction, TriggerState } from './types/common';
 
 // To enable logging for this class. Set `Vex.Flow.Parser.DEBUG` to `true`.
-function L(...args) {
+function L(...args: any[]) {
   if (Parser.DEBUG) Vex.L('Vex.Flow.Parser', args);
 }
 
@@ -26,6 +27,8 @@ function flattenMatches(results) {
 // can parse any line and execute code when specific rules are met (e.g.,
 // when a string is terminated.)
 export class Parser {
+  static DEBUG: boolean = false;
+
   // For an example of a simple grammar, take a look at tests/parser_tests.js or
   // the EasyScore grammar in easyscore.js.
   constructor(grammar) {

src/types/common.d.ts

@@ -103,3 +103,25 @@ export interface ModifierContextState {
   text_line: number;
   top_text_line: number;
 }
+
+
+/* TODO: Move to EasyScore / Grammar / Parser */
+export type Match = string | Match[];
+export interface Rule {
+  // Lexer Rules
+  token?: string; // The token property is a string that is compiled into a RegExp.
+  noSpace?: boolean; // TODO: None of the EasyScore rules specify noSpace, so it is not used anywhere.
+
+  // Parser Rules
+  expect?: RuleFunction[];
+  zeroOrMore?: boolean;
+  oneOrMore?: boolean;
+  maybe?: boolean;
+  or?: boolean;
+  run?: TriggerFunction;
+}
+export interface TriggerState {
+    matches: Match[];
+}
+export type RuleFunction = () => Rule;
+export type TriggerFunction = (state?: TriggerState) => void;