feat: add basic functionality

Author: mlavrinenko

.editorconfig

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+root = true
+
+[*]
+indent_style = space
+indent_size = 4
+charset = utf-8
+end_of_line = LF
+insert_final_newline = true
+trim_trailing_whitespace = true
+max_line_length = 120
+
+[COMMIT_EDITMSG]
+max_line_length = 0

.github/workflows/ci.yml

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+name: Healthchecks
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php: ['8.1', '8.2', '8.3']
+
+    steps:
+    - uses: actions/checkout@v3
+
+    - name: Setup PHP
+      uses: shivammathur/setup-php@v2
+      with:
+        php-version: ${{ matrix.php }}
+        coverage: none
+
+    - name: Validate composer.json
+      run: composer validate --strict
+
+    - name: Cache Composer packages
+      id: composer-cache
+      uses: actions/cache@v3
+      with:
+        path: vendor
+        key: ${{ runner.os }}-php-${{ hashFiles('**/composer.lock') }}
+        restore-keys: |
+          ${{ runner.os }}-php-
+
+    - name: Install dependencies
+      run: composer install --prefer-dist --no-progress
+
+    - name: Lint code
+      run: composer lint
+
+    - name: Test code
+      run: composer test

.gitignore

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+/.devbox
+/vendor

README.md

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+# Evalue
+
+Store and execute PHP code snippets using Evalue class.
+
+## Features
+
+- store PHP code for multiple executions;
+- provide context variables during construction and execution;
+- support for complex PHP code snippets;
+- automatic stripping of `<?php` tags;
+- variable scope isolation between runs;
+
+## Installation
+
+```bash
+composer require maximaster/evalue
+```
+
+![CI](https://github.com/maximaster/evalue/workflows/CI/badge.svg)
+
+## Usage
+
+### Basic Usage
+
+```php
+use Maximaster\Evalue\Evalue;
+
+// Create an Evalue instance with PHP code
+$evalue = new Evalue('return $number * 2;');
+
+// Run the code with context
+$result = $evalue->run(['number' => 21]); // Returns 42
+```
+
+### With Constructor Context
+
+```php
+$evalue = new Evalue(
+    'return $greeting . " " . $name;',
+    ['greeting' => 'Hello']
+);
+
+// Run with additional context
+$result = $evalue->run(['name' => 'John']); // Returns "Hello John"
+```
+
+### Complex Code Examples
+
+```php
+// Multi-line code
+$code = <<<'PHP'
+    $sum = 0;
+    for($i = 1; $i <= $max; $i++) {
+        $sum += $i;
+    }
+    return $sum;
+PHP;
+
+$evalue = new Evalue($code);
+$result = $evalue->run(['max' => 5]); // Returns 15
+```
+
+### Context Overriding
+
+```php
+$evalue = new Evalue(
+    'return $name;',
+    ['name' => 'John']
+);
+
+// Constructor context can be overridden in run()
+$result = $evalue->run(['name' => 'Jane']); // Returns "Jane"
+```
+
+## Security
+
+⚠️ **Warning**: This library uses PHP's `eval()` function. Only use it with trusted code. Never execute user-provided
+code without proper validation and sanitization.
+
+## Context Rules
+
+Variable names in the context must follow PHP's variable naming conventions:
+
+- Must start with a letter or underscore
+- Can contain letters, numbers, underscores
+- Supports extended ASCII characters (e.g., `π`, `área`, `über`)
+
+Invalid examples:
+```php
+$evalue->run([
+    '123name' => 'invalid',    // Invalid: starts with number
+    'my-var' => 'invalid',     // Invalid: contains hyphen
+    'my var' => 'invalid'      // Invalid: contains space
+]);
+```
+
+## Development / Contribution
+
+```bash
+composer test   # runs kahlan tests.
+composer lint   # runs static analysis to check the code.
+composer ci     # both test & lint.
+composer fix    # automatically fixes some lint errors.
+```

composer.json

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+{
+    "name": "maximaster/evalue",
+    "description": "Eval as class.",
+    "type": "library",
+    "license": "MIT",
+    "require": {
+        "php": ">=8.1"
+    },
+    "require-dev": {
+        "kahlan/kahlan": "^6.0",
+        "symplify/easy-coding-standard": "^12.5",
+        "phpstan/phpstan": "^2.1"
+    },
+    "scripts": {
+        "test": "kahlan",
+        "lint": [
+            "ecs",
+            "phpstan"
+        ],
+        "fix": "ecs --fix",
+        "qa": [
+            "composer test",
+            "composer lint"
+        ]
+    },
+    "autoload": {
+        "psr-4": {
+            "Maximaster\\Evalue\\": "src/"
+        }
+    },
+    "authors": [
+        {
+            "name": "Лавриненко Максим",
+            "email": "maxim.lavrinenko@maximaster.ru"
+        }
+    ]
+}