add transition label parser

src/VisualEditor/label_ast.ts

@@ -0,0 +1,53 @@
+export type TransitionLabel = {
+  trigger: Trigger;
+  guard: Expression;
+  actions: Action[];
+}
+
+
+export type Trigger = EventTrigger | AfterTrigger;
+
+export type EventTrigger = {
+  kind: "event";
+  event: string;
+}
+
+export type AfterTrigger = {
+  kind: "after";
+  durationMs: number;
+}
+
+
+export type Action = Assignment | RaiseEvent;
+
+export type Assignment = {
+  kind: "assignment";
+  lhs: string;
+  rhs: Expression;
+}
+
+export type RaiseEvent = {
+  kind: "raise";
+  event: string;
+}
+
+
+export type Expression = BinaryExpression | UnaryExpression | VarRef;
+
+export type BinaryExpression = {
+  kind: "binaryExpr";
+  operator: "+" | "-" | "*" | "/" | "&&" | "||";
+  lhs: Expression;
+  rhs: Expression;
+}
+
+export type UnaryExpression = {
+  kind: "unaryExpr";
+  operator: "!" | "-";
+  expr: Expression;
+}
+
+export type VarRef = {
+  kind: "ref";
+  variable: string;
+}