From 573d2da85e21b0468e69b8d6493e430e6eed1980 Mon Sep 17 00:00:00 2001
From: Ad5001 <mail@ad5001.eu>
Date: Tue, 28 Dec 2021 00:44:16 +0100
Subject: [PATCH] First commit!

---
 README.md           | 55 +++++++++++++++++++++++++++++
 example/Example.shn |  7 ++++
 example/Object.shc  | 12 +++++++
 example/script.sh   | 16 +++++++++
 oop.sh              | 85 +++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 175 insertions(+)
 create mode 100644 README.md
 create mode 100644 example/Example.shn
 create mode 100644 example/Object.shc
 create mode 100644 example/script.sh
 create mode 100644 oop.sh

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..6d9161b
--- /dev/null
+++ b/README.md
@@ -0,0 +1,55 @@
+# BashOOP
+
+This idea was inspired from https://stackoverflow.com/a/40981277 in order to be adapted into making a proper OOP with constructors, properties and namespace system for bash.
+
+## Reference:
+
+- .shn: **SH**ell **N**amespace
+- .shc: **SH**ell **C**lass
+
+## Example syntax:
+
+### Declaring objects.
+
+`script.sh`:
+This is the main script which will use our objects.
+
+```bash
+. $OOP_ROOT/oop.sh # Import library.
+
+importNamespace Example.shn
+
+Example.Object t "Test"
+```
+
+`Example.shn`:
+This file declares our namespace and all the objects within it.
+
+```bash
+# Namespace declaration.
+namespace Example
+# If namespace is set to null (no argument), then the object will be declared globally.
+# Otherwise, the object will be declared within the namespace.
+
+# Object declaration, from class name to file name.
+class Object "Object.shc"
+
+```
+
+`Object.shc`:
+This file will contain the object code.
+
+```bash
+# Property declaration
+property Object.name
+
+# Optional constructor.
+Object.constructor() {
+    Object.name = $1
+}
+
+# Example function
+Object.print() {
+    echo "Example OOP from $($this.name)!"
+}
+```
diff --git a/example/Example.shn b/example/Example.shn
new file mode 100644
index 0000000..24a833c
--- /dev/null
+++ b/example/Example.shn
@@ -0,0 +1,7 @@
+# Namespace declaration.
+namespace Example
+# If namespace is set to null (no argument), then the object will be declared globally.
+# Otherwise, the object will be declared within the namespace.
+
+# Object declaration, from class name to file name.
+class Object "Object.shc"
diff --git a/example/Object.shc b/example/Object.shc
new file mode 100644
index 0000000..f418e85
--- /dev/null
+++ b/example/Object.shc
@@ -0,0 +1,12 @@
+# Property declaration
+property Object.name
+
+# Optional constructor.
+Object.constructor() {
+    Object.name = $1
+}
+
+# Example function
+Object.print() {
+    echo "Example OOP from $(this.name)!"
+}
diff --git a/example/script.sh b/example/script.sh
new file mode 100644
index 0000000..d86c616
--- /dev/null
+++ b/example/script.sh
@@ -0,0 +1,16 @@
+#!/bin/bash
+OOP_ROOT=..
+
+. $OOP_ROOT/oop.sh # Import library.
+
+importNamespace Example.shn
+
+Example.Object t1 "Test"
+Example.Object t2 "Example"
+
+t1.print
+t2.print
+
+t1.name = "New name"
+
+t1.print
diff --git a/oop.sh b/oop.sh
new file mode 100644
index 0000000..47f14a4
--- /dev/null
+++ b/oop.sh
@@ -0,0 +1,85 @@
+#!/bin/bash
+
+# This file contains all functions required to create a namespace.
+# Internal variables are marked with a beginning underscore, like in most other languages.
+# Signatures are a list of arguments.. Those within <> are mandatory, the ones within [] are optional.
+_namespace=""
+_namespacePath=""
+
+# Namespace declaration.
+# Signature: ([string namespaceName])
+namespace() {
+    _namespace=$1;
+}
+
+# Imports a namespace into the current shell.
+# Signature: (<string namespaceFile>)
+importNamespace() {
+    namespaceFile=$1
+    # Save the path in order to get the absolute path of the file.
+    _namespacePath=$(realpath $(dirname $namespaceFile))
+    . $namespaceFile
+}
+
+# Creates an object instance.
+# Signature: (<string type>, <string associatedFile>, <string variableName>, [string[] constructorArguments])
+_createObject() {
+    type=$1
+    associatedFile=$2
+    varName=$3
+    constructorArguments=${@:4}
+    
+    # Declare dummy constructor.
+    eval "$varName.constructor() { :; }"
+    # Create property array.
+    eval "declare -Ag _${varName}_properties"
+    # Imports the file and replace all "<Type>." with the variable name.
+    . <(sed s/this\\./$varName./g <(sed s/$type\\./$varName./g $associatedFile))
+    # Call the constructor
+    eval "$varName.constructor $constructorArguments"
+}
+
+# Object creation.
+# Signature: (<string type>, <string associatedFile>)
+class() {
+    type=$1 # Type of the object as declared within the file.
+    associatedFile=$2
+    objFullName=$type # Type of the object referenced elsewhere
+    
+    if [ "$_namespace" != "" ]; then
+        objFullName="${_namespace}.$type"
+    fi
+    
+    if [ ${associatedFile::1} != "/" ]; then # Relative path, we save only the absolute path
+        associatedFile="$_namespacePath/$associatedFile"
+    fi
+    # Declares a new function for object initialisation.
+    eval "$objFullName() { _createObject $type $associatedFile \$@;  }"
+}
+
+# Associated function for properties
+# Signature: (<string variableName>, <string propertyName>, [string operator, string value])
+_accessProperty() {
+    varName=$1
+    prop=$2
+    if [ "$3" == "=" ]; then
+        eval "_${varName}_properties[$prop]='${@:4}'"
+    else
+        eval "echo \${_${varName}_properties[$prop]}"
+    fi
+}
+
+# Declares a property.
+# Signature: (<string propertyFullName>)
+property() {
+    propertyFullName=$1
+    # Split the name by ".". First element is variable name,
+    # second is property name.
+    propertyNames=($(echo $propertyFullName | tr "." "\n"))
+    varName=${propertyNames[0]}
+    prop=${propertyNames[1]}
+    # Default value
+    eval "_${varName}_properties[$prop]=''"
+    # Property alias 
+    eval "$propertyFullName() { _accessProperty $varName $prop \$@;  }"
+}