feat(common): Checks and CodedError classes

Utilities for easier one-liners that can verify arguments or
execution state in a much more concise way compared to
if conditions throwing manually. Makes the code less verbose
and requires less typing as well.

Also: added a bools utlity class for checking strict boolean
typing of a value and a new string utility method as well.

Fixes #266

Signed-off-by: Peter Somogyvari <peter.somogyvari@accenture.com>

packages/cactus-common/src/main/typescript/bools.ts

@@ -0,0 +1,15 @@
+export class Bools {
+  /**
+   * Determines if a value is strictly a boolean `true` or `false`. Anything else
+   * will result in the method returning `false`.
+   *
+   * Useful in cases where you have an optional boolean parameter that you need
+   * to assign a default value to by determining if it had been set or not.
+   *
+   * @param val The value to be decided on whether it's strictly boolean `true`
+   * or `false`.
+   */
+  public static isBooleanStrict(val: unknown): boolean {
+    return val === true || val === false;
+  }
+}

packages/cactus-common/src/main/typescript/checks.ts

@@ -0,0 +1,21 @@
+import { CodedError } from "./coded-error";
+
+export class Checks {
+  /**
+   * Verifies that a boolean condition is met or throws an Error if it is not.
+   *
+   * @param checkResult Determines the outcome of the check via it's truthyness.
+   * @param subjectOfCheck The error message if `checkResult` is falsy.
+   * @param code The code of the error if `checkResult is falsy.
+   */
+  public static truthy(
+    checkResult: any,
+    subjectOfCheck: string = "variable",
+    code: string = "-1"
+  ): void {
+    if (!checkResult) {
+      const message = `"${subjectOfCheck}" is falsy, need a truthy value.`;
+      throw new CodedError(message, code);
+    }
+  }
+}

packages/cactus-common/src/main/typescript/coded-error.ts

@@ -0,0 +1,14 @@
+/**
+ * Utility class for better exception handling by way of having a code property
+ * which is designated to uniquely identify the type of exception that was
+ * thrown, essentially acting as a discriminator property.
+ */
+export class CodedError extends Error {
+  constructor(public readonly message: string, public readonly code: string) {
+    super(message);
+  }
+
+  sameCode(codedError: CodedError): boolean {
+    return this.code === codedError?.code;
+  }
+}

packages/cactus-common/src/main/typescript/public-api.ts

@@ -3,12 +3,17 @@ export { Logger, ILoggerOptions } from "./logging/logger";
 export { LogLevelDesc } from "loglevel";
 export { Objects } from "./objects";
 export { Strings } from "./strings";
+export { Bools } from "./bools";
+export { Checks } from "./checks";
+export { CodedError } from "./coded-error";
+
 export {
   JsObjectSigner,
   IJsObjectSignerOptions,
   SignatureFunction,
   VerifySignatureFunction,
   HashFunction,
 } from "./js-object-signer";
+
 export { ISignerKeyPair } from "./signer-key-pair";
 export { Secp256k1Keys } from "./secp256k1-keys";

packages/cactus-common/src/main/typescript/strings.ts

@@ -1,3 +1,5 @@
+import { Checks } from "./checks";
+
 export class Strings {
   public static replaceAll(
     source: string,
@@ -6,4 +8,14 @@ export class Strings {
   ): string {
     return source.replace(new RegExp(searchValue, "gm"), replaceValue);
   }
+
+  public static isString(val: any): boolean {
+    return typeof val === "string" || val instanceof String;
+  }
+
+  public static dropNonPrintable(val: string): string {
+    const fnTag = "Strings#dropNonPrintable()";
+    Checks.truthy(Strings.isString(val), `${fnTag} Strings.isString(val)`);
+    return val.replace(/[^ -~]+/g, "");
+  }
 }