Function getBaseClass

tools/tslint/noImplicitOverrideAbstractRule.ts:107–125

Gets the base class for the given class declaration.

(
  node: ts.ClassDeclaration,
  typeChecker: ts.TypeChecker,
)

/** Gets the base class for the given class declaration. */
function getBaseClass(
  node: ts.ClassDeclaration,
  typeChecker: ts.TypeChecker,
): ts.ClassDeclaration | null {
  const baseTypes = getExtendsHeritageExpressions(node);

  if (baseTypes.length > 1) {
    throw Error('Class unexpectedly extends from multiple types.');
  }

  const baseClass = typeChecker.getTypeAtLocation(baseTypes[0]).getSymbol();
  const baseClassDecl = baseClass?.valueDeclaration ?? baseClass?.declarations?.[0];

  if (baseClassDecl !== undefined && ts.isClassDeclaration(baseClassDecl)) {
    return baseClassDecl;
  }

  return null;
}

/** Gets the `extends` base type expressions of the specified class. */
function getExtendsHeritageExpressions(