From 00374effc558c11f9b1755eae10846a5c8abe4c0 Mon Sep 17 00:00:00 2001
From: Jaco Greeff <jacogr@gmail.com>
Date: Thu, 12 Sep 2019 13:48:06 +0200
Subject: [PATCH] string <-> hex conversion utilities (#470)

* string <-> hex conversion utilities

* Add tests
---
 CHANGELOG.md                           |  4 ++++
 packages/util/src/hex/index.ts         |  1 +
 packages/util/src/hex/toString.spec.ts | 19 +++++++++++++++++++
 packages/util/src/hex/toString.ts      | 26 ++++++++++++++++++++++++++
 packages/util/src/hex/toU8a.ts         |  2 +-
 packages/util/src/string/index.ts      |  1 +
 packages/util/src/string/toHex.spec.ts | 19 +++++++++++++++++++
 packages/util/src/string/toHex.ts      | 26 ++++++++++++++++++++++++++
 8 files changed, 97 insertions(+), 1 deletion(-)
 create mode 100644 packages/util/src/hex/toString.spec.ts
 create mode 100644 packages/util/src/hex/toString.ts
 create mode 100644 packages/util/src/string/toHex.spec.ts
 create mode 100644 packages/util/src/string/toHex.ts

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 87aafddcfa..64c84d4fdc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# 1.4.0-beta.x
+
+- Added `stringToHex` and `hexToString` conversion utilities
+
 # 1.3.1
 
 - Remove the `ExtError` class, always prefer the standard JS `Error` object for errors. This would bre a breaking change for any appliactions using `ExtError`
diff --git a/packages/util/src/hex/index.ts b/packages/util/src/hex/index.ts
index acf2fe50fa..a11248194e 100644
--- a/packages/util/src/hex/index.ts
+++ b/packages/util/src/hex/index.ts
@@ -12,4 +12,5 @@ export { default as hexHasPrefix } from './hasPrefix';
 export { default as hexStripPrefix } from './stripPrefix';
 export { default as hexToBn } from './toBn';
 export { default as hexToNumber } from './toNumber';
+export { default as hexToString } from './toString';
 export { default as hexToU8a } from './toU8a';
diff --git a/packages/util/src/hex/toString.spec.ts b/packages/util/src/hex/toString.spec.ts
new file mode 100644
index 0000000000..bfecee68f3
--- /dev/null
+++ b/packages/util/src/hex/toString.spec.ts
@@ -0,0 +1,19 @@
+// Copyright 2017-2019 @polkadot/util authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import { hexToString } from '.';
+
+describe('hexToString', (): void => {
+  it('converts an empty to ""', (): void => {
+    expect(
+      hexToString()
+    ).toEqual('');
+  });
+
+  it('converts to a string from hex', (): void => {
+    expect(
+      hexToString('0x68656c6c6f')
+    ).toEqual('hello');
+  });
+});
diff --git a/packages/util/src/hex/toString.ts b/packages/util/src/hex/toString.ts
new file mode 100644
index 0000000000..db8ad539be
--- /dev/null
+++ b/packages/util/src/hex/toString.ts
@@ -0,0 +1,26 @@
+// Copyright 2017-2019 @polkadot/util authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import u8aToString from '../u8a/toString';
+import hexToU8a from './toU8a';
+
+/**
+ * @name hexToU8a
+ * @summary Creates a Uint8Array object from a hex string.
+ * @description
+ * Hex input values return the actual bytes value converted to a string. Anything that is not a hex string (including the `0x` prefix) throws an error.
+ * @example
+ * <BR>
+ *
+ * ```javascript
+ * import { hexToString } from '@polkadot/util';
+ *
+ * hexToU8a('0x68656c6c6f'); // hello
+ * ```
+ */
+export default function hexToString (_value?: string | null): string {
+  return u8aToString(
+    hexToU8a(_value)
+  );
+}
diff --git a/packages/util/src/hex/toU8a.ts b/packages/util/src/hex/toU8a.ts
index 2195ae45f2..c4e33e5edf 100644
--- a/packages/util/src/hex/toU8a.ts
+++ b/packages/util/src/hex/toU8a.ts
@@ -8,7 +8,7 @@ import hexStripPrefix from './stripPrefix';
 
 /**
  * @name hexToU8a
- * @summary Creates a Buffer object from a hex string.
+ * @summary Creates a Uint8Array object from a hex string.
  * @description
  * `null` inputs returns an empty `Uint8Array` result. Hex input values return the actual bytes value converted to a Uint8Array. Anything that is not a hex string (including the `0x` prefix) throws an error.
  * @example
diff --git a/packages/util/src/string/index.ts b/packages/util/src/string/index.ts
index a7857759d6..30d4523562 100644
--- a/packages/util/src/string/index.ts
+++ b/packages/util/src/string/index.ts
@@ -9,5 +9,6 @@
 export { default as stringCamelCase } from './camelCase';
 export { default as stringLowerFirst } from './lowerFirst';
 export { default as stringShorten } from './shorten';
+export { default as stringToHex } from './toHex';
 export { default as stringToU8a } from './toU8a';
 export { default as stringUpperFirst } from './upperFirst';
diff --git a/packages/util/src/string/toHex.spec.ts b/packages/util/src/string/toHex.spec.ts
new file mode 100644
index 0000000000..b5f18187fd
--- /dev/null
+++ b/packages/util/src/string/toHex.spec.ts
@@ -0,0 +1,19 @@
+// Copyright 2017-2019 @polkadot/util authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import { stringToHex } from '.';
+
+describe('hexToString', (): void => {
+  it('converts an empty to ""', (): void => {
+    expect(
+      stringToHex()
+    ).toEqual('0x');
+  });
+
+  it('converts to a hex from string', (): void => {
+    expect(
+      stringToHex('hello')
+    ).toEqual('0x68656c6c6f');
+  });
+});
diff --git a/packages/util/src/string/toHex.ts b/packages/util/src/string/toHex.ts
new file mode 100644
index 0000000000..06bf6c03cb
--- /dev/null
+++ b/packages/util/src/string/toHex.ts
@@ -0,0 +1,26 @@
+// Copyright 2017-2019 @polkadot/util authors & contributors
+// This software may be modified and distributed under the terms
+// of the Apache-2.0 license. See the LICENSE file for details.
+
+import u8aToHex from '../u8a/toHex';
+import stringToU8a from './toU8a';
+
+/**
+ * @name stringToHex
+ * @summary Creates a hex string from a utf-8 string
+ * @description
+ * String input values return the actual encoded hex value.
+ * @example
+ * <BR>
+ *
+ * ```javascript
+ * import { stringToHex } from '@polkadot/util';
+ *
+ * stringToU8a('hello'); // 0x68656c6c6f
+ * ```
+ */
+export default function stringToHex (value?: string): string {
+  return u8aToHex(
+    stringToU8a(value)
+  );
+}