First commit.

Signed-off-by: Chen Xiao <abigwc@gmail.com>

client/node_modules/@chevrotain/gast/src/helpers.ts

@@ -0,0 +1,96 @@
+import {
+  AbstractProduction,
+  Alternation,
+  Alternative,
+  NonTerminal,
+  Option,
+  Repetition,
+  RepetitionMandatory,
+  RepetitionMandatoryWithSeparator,
+  RepetitionWithSeparator,
+  Rule,
+  Terminal,
+} from "./model.js";
+import type { IProduction, IProductionWithOccurrence } from "@chevrotain/types";
+
+export function isSequenceProd(
+  prod: IProduction,
+): prod is { definition: IProduction[] } & IProduction {
+  return (
+    prod instanceof Alternative ||
+    prod instanceof Option ||
+    prod instanceof Repetition ||
+    prod instanceof RepetitionMandatory ||
+    prod instanceof RepetitionMandatoryWithSeparator ||
+    prod instanceof RepetitionWithSeparator ||
+    prod instanceof Terminal ||
+    prod instanceof Rule
+  );
+}
+
+export function isOptionalProd(
+  prod: IProduction,
+  alreadyVisited: NonTerminal[] = [],
+): boolean {
+  const isDirectlyOptional =
+    prod instanceof Option ||
+    prod instanceof Repetition ||
+    prod instanceof RepetitionWithSeparator;
+  if (isDirectlyOptional) {
+    return true;
+  }
+
+  // note that this can cause infinite loop if one optional empty TOP production has a cyclic dependency with another
+  // empty optional top rule
+  // may be indirectly optional ((A?B?C?) | (D?E?F?))
+  if (prod instanceof Alternation) {
+    // for OR its enough for just one of the alternatives to be optional
+    return (<Alternation>prod).definition.some((subProd: IProduction) => {
+      return isOptionalProd(subProd, alreadyVisited);
+    });
+  } else if (prod instanceof NonTerminal && alreadyVisited.includes(prod)) {
+    // avoiding stack overflow due to infinite recursion
+    return false;
+  } else if (prod instanceof AbstractProduction) {
+    if (prod instanceof NonTerminal) {
+      alreadyVisited.push(prod);
+    }
+    return (<AbstractProduction>prod).definition.every(
+      (subProd: IProduction) => {
+        return isOptionalProd(subProd, alreadyVisited);
+      },
+    );
+  } else {
+    return false;
+  }
+}
+
+export function isBranchingProd(
+  prod: IProduction,
+): prod is { definition: IProduction[] } & IProduction {
+  return prod instanceof Alternation;
+}
+
+export function getProductionDslName(prod: IProductionWithOccurrence): string {
+  /* istanbul ignore else */
+  if (prod instanceof NonTerminal) {
+    return "SUBRULE";
+  } else if (prod instanceof Option) {
+    return "OPTION";
+  } else if (prod instanceof Alternation) {
+    return "OR";
+  } else if (prod instanceof RepetitionMandatory) {
+    return "AT_LEAST_ONE";
+  } else if (prod instanceof RepetitionMandatoryWithSeparator) {
+    return "AT_LEAST_ONE_SEP";
+  } else if (prod instanceof RepetitionWithSeparator) {
+    return "MANY_SEP";
+  } else if (prod instanceof Repetition) {
+    return "MANY";
+  } else if (prod instanceof Terminal) {
+    return "CONSUME";
+    /* c8 ignore next 3 */
+  } else {
+    throw Error("non exhaustive match");
+  }
+}