Initial commit

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

@@ -0,0 +1,101 @@
+import some from "lodash/some"
+import every from "lodash/every"
+import has from "lodash/has"
+import includes from "lodash/includes"
+import {
+  AbstractProduction,
+  Alternation,
+  Alternative,
+  NonTerminal,
+  Option,
+  Repetition,
+  RepetitionMandatory,
+  RepetitionMandatoryWithSeparator,
+  RepetitionWithSeparator,
+  Rule,
+  Terminal
+} from "./model"
+import { GAstVisitor } from "./visitor"
+import { 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 some((<Alternation>prod).definition, (subProd: IProduction) => {
+      return isOptionalProd(subProd, alreadyVisited)
+    })
+  } else if (prod instanceof NonTerminal && includes(alreadyVisited, prod)) {
+    // avoiding stack overflow due to infinite recursion
+    return false
+  } else if (prod instanceof AbstractProduction) {
+    if (prod instanceof NonTerminal) {
+      alreadyVisited.push(prod)
+    }
+    return every(
+      (<AbstractProduction>prod).definition,
+      (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"
+  } else {
+    throw Error("non exhaustive match")
+  }
+}