From 187e5a1ecae4e926e63b089809c4cfc69d03b8bb Mon Sep 17 00:00:00 2001
From: Cuttlerat <avkioller@gmail.com>
Date: Sun, 9 Jun 2019 13:28:29 +0300
Subject: [PATCH] Add reverse case function

---
 README.md               | 28 ++++++++++++++++++++++++++++
 manuscript/chapter1.txt | 26 ++++++++++++++++++++++++++
 manuscript/chapter8.txt |  2 ++
 test.sh                 |  5 +++++
 4 files changed, 61 insertions(+)

diff --git a/README.md b/README.md
index 05d23a8..68aa428 100644
--- a/README.md
+++ b/README.md
@@ -386,6 +386,32 @@ $ upper "HELLO"
 HELLO
 ```
 
+## Reverse a string case
+
+**CAVEAT:** Requires `bash` 4+
+
+**Example Function:**
+
+```sh
+reverse_case() {
+    # Usage: reverse_case "string"
+    printf '%s\n' "${1~~}"
+}
+```
+
+**Example Usage:**
+
+```shell
+$ reverse_case "hello"
+HELLO
+
+$ reverse_case "HeLlO"
+hElLo
+
+$ reverse_case "HELLO"
+hello
+```
+
 ## Trim quotes from a string
 
 **Example Function:**
@@ -1221,6 +1247,8 @@ Contrary to popular belief, there is no issue in utilizing raw escape sequences.
 | `${VAR^^}` | Uppercase all characters. | `bash 4+` |
 | `${VAR,}` | Lowercase first character. | `bash 4+` |
 | `${VAR,,}` | Lowercase all characters. | `bash 4+` |
+| `${VAR~}` | Reverse case of first character. | `bash 4+` |
+| `${VAR~~}` | Reverse case of all characters. | `bash 4+` |
 
 
 ## Default Value
diff --git a/manuscript/chapter1.txt b/manuscript/chapter1.txt
index 386ca2f..13133ac 100644
--- a/manuscript/chapter1.txt
+++ b/manuscript/chapter1.txt
@@ -209,6 +209,32 @@ $ upper "HELLO"
 HELLO
 ```
 
+## Reverse a string case
+
+**CAVEAT:** Requires `bash` 4+
+
+**Example Function:**
+
+```sh
+reverse_case() {
+    # Usage: reverse_case "string"
+    printf '%s\n' "${1~~}"
+}
+```
+
+**Example Usage:**
+
+```shell
+$ reverse_case "hello"
+HELLO
+
+$ reverse_case "HeLlO"
+hElLo
+
+$ reverse_case "HELLO"
+hello
+```
+
 ## Trim quotes from a string
 
 **Example Function:**
diff --git a/manuscript/chapter8.txt b/manuscript/chapter8.txt
index a4f4efb..8145fe4 100644
--- a/manuscript/chapter8.txt
+++ b/manuscript/chapter8.txt
@@ -48,6 +48,8 @@
 | `${VAR^^}` | Uppercase all characters. | `bash 4+` |
 | `${VAR,}` | Lowercase first character. | `bash 4+` |
 | `${VAR,,}` | Lowercase all characters. | `bash 4+` |
+| `${VAR~}` | Reverse case of first character. | `bash 4+` |
+| `${VAR~~}` | Reverse case of all characters. | `bash 4+` |
 
 
 ## Default Value
diff --git a/test.sh b/test.sh
index 90e865e..94da32e 100755
--- a/test.sh
+++ b/test.sh
@@ -28,6 +28,11 @@ test_upper() {
     assert_equals "$result" "HELLO"
 }
 
+test_reverse_case() {
+    result="$(reverse_case "HeLlO")"
+    assert_equals "$result" "hElLo"
+}
+
 test_trim_quotes() {
     result="$(trim_quotes "\"te'st' 'str'ing\"")"
     assert_equals "$result" "test string"