Axiom Library

A powerful PHP library for data transformation, type validation, and expression evaluation. This library provides a flexible framework for defining data schemas, transforming values, and evaluating complex expressions with type safety.

Features

• Type System: Robust type validation and transformation for numbers, strings, booleans, lists, and dictionaries
• Expression Evaluation: Support for infix expressions with custom operators
• Resolver Pattern: Pluggable resolver system for different data sources
• Symbol Registry: Named value resolution and reuse
• Operator Overloading: Extensible operator system for custom evaluation logic
• Monadic Error Handling: Built on functional programming principles using Result and Option types

Requirements

• PHP 8.4 or higher
• ext-intl extension

Installation

composer require gosuperscript/axiom

Quick Start

Basic Type Transformation

<?php

use Superscript\Axiom\Types\NumberType;
use Superscript\Axiom\Sources\StaticSource;
use Superscript\Axiom\Sources\TypeDefinition;
use Superscript\Axiom\Resolvers\DelegatingResolver;
use Superscript\Axiom\Resolvers\StaticResolver;
use Superscript\Axiom\Resolvers\ValueResolver;

// Create a resolver with basic capabilities
$resolver = new DelegatingResolver([
    StaticResolver::class,
    ValueResolver::class,
]);

// Transform a string to a number
$source = new TypeDefinition(
    type: new NumberType(),
    source: new StaticSource('42')
);

$result = $resolver->resolve($source);
$value = $result->unwrap()->unwrap(); // 42 (as integer)

Expression Evaluation

<?php

use Superscript\Axiom\Sources\InfixExpression;
use Superscript\Axiom\Sources\StaticSource;
use Superscript\Axiom\Sources\SymbolSource;
use Superscript\Axiom\SymbolRegistry;
use Superscript\Axiom\Resolvers\DelegatingResolver;
use Superscript\Axiom\Resolvers\InfixResolver;
use Superscript\Axiom\Resolvers\SymbolResolver;

// Set up resolver with symbol support
$resolver = new DelegatingResolver([
    StaticResolver::class,
    InfixResolver::class,
    SymbolResolver::class,
]);

// Register symbols
$resolver->instance(SymbolRegistry::class, new SymbolRegistry([
    'PI' => new StaticSource(3.14159),
    'radius' => new StaticSource(5),
]));

// Calculate: PI * radius * radius (area of circle)
$expression = new InfixExpression(
    left: new SymbolSource('PI'),
    operator: '*',
    right: new InfixExpression(
        left: new SymbolSource('radius'),
        operator: '*',
        right: new SymbolSource('radius')
    )
);

$result = $resolver->resolve($expression);
$area = $result->unwrap()->unwrap(); // ~78.54

Using Namespaced Symbols

The SymbolRegistry supports namespaces to organize related symbols:

<?php

use Superscript\Axiom\Sources\StaticSource;
use Superscript\Axiom\Sources\SymbolSource;
use Superscript\Axiom\SymbolRegistry;

// Create registry with namespaced symbols
$registry = new SymbolRegistry([
    // Global symbols (no namespace)
    'version' => new StaticSource('1.0.0'),
    'debug' => new StaticSource(true),
    
    // Math namespace
    'math' => [
        'pi' => new StaticSource(3.14159),
        'e' => new StaticSource(2.71828),
        'phi' => new StaticSource(1.61803),
    ],
    
    // Constants namespace
    'physics' => [
        'c' => new StaticSource(299792458),      // Speed of light
        'g' => new StaticSource(9.80665),        // Gravitational acceleration
    ],
]);

// Access global symbols
$version = $registry->get('version');           // Some('1.0.0')

// Access namespaced symbols
$pi = $registry->get('pi', 'math');            // Some(3.14159)
$c = $registry->get('c', 'physics');           // Some(299792458)

// Using with SymbolSource
$symbolSource = new SymbolSource('pi', 'math');
$result = $resolver->resolve($symbolSource);   // ~3.14159

// Namespaces provide isolation
$registry->get('pi');                           // None (no global 'pi')
$registry->get('c', 'math');                   // None (no 'c' in math namespace)

Core Concepts

Types

The library provides several built-in types for data validation and coercion:

NumberType

Validates and coerces values to numeric types (int/float):

• Numeric strings: "42" → 42
• Percentage strings: "50%" → 0.5
• Numbers: 42.5 → 42.5

StringType

Validates and coerces values to strings:

• Numbers: 42 → "42"
• Stringable objects: converted to string representation
• Special handling for null and empty values

BooleanType

Validates and coerces values to boolean:

• Truthy/falsy evaluation
• String representations: "true", "false"

ListType and DictType

For collections and associative arrays with nested type validation.

Type API: Assert vs Coerce

The Type interface provides two methods for value processing, following the @azjezz/psl pattern:

• assert(T $value): Result<Option<T>> - Validates that a value is already of the correct type
• coerce(mixed $value): Result<Option<T>> - Attempts to convert a value from any type to the target type

When to use:

• Use assert() when you expect a value to already be the correct type and want strict validation
• Use coerce() when you want to transform values from various input types (permissive conversion)

Example:

$numberType = new NumberType();

// Assert - only accepts int/float
$result = $numberType->assert(42);      // Ok(Some(42))
$result = $numberType->assert('42');    // Err(TransformValueException)

// Coerce - converts compatible types
$result = $numberType->coerce(42);      // Ok(Some(42))
$result = $numberType->coerce('42');    // Ok(Some(42))
$result = $numberType->coerce('45%');   // Ok(Some(0.45))

Both methods return Result<Option<T>, Throwable> where:

• Ok(Some(value)) - successful validation/coercion with a value
• Ok(None()) - successful but no value (e.g., empty strings)
• Err(exception) - failed validation/coercion

Note: The coerce() method provides the same functionality as the previous transform() method.

Sources

Sources represent different ways to provide data:

• StaticSource: Direct values
• SymbolSource: Named references to other sources (with optional namespace support)
• TypeDefinition: Combines a type with a source for validation and coercion
• InfixExpression: Mathematical/logical expressions
• UnaryExpression: Single-operand expressions

Symbol Registry

The SymbolRegistry provides a centralized way to manage named values and organize them using namespaces:

Key Features:

• Global Symbols: Direct symbol registration without namespace isolation
• Namespaced Symbols: Group related symbols under namespaces for better organization
• Isolation: Symbols in different namespaces are isolated from each other
• Type Safety: Only Source instances can be registered

Registration Format:

new SymbolRegistry([
    'globalSymbol' => new StaticSource(value),    // Global scope
    'namespace' => [                               // Namespaced scope
        'symbol1' => new StaticSource(value1),
        'symbol2' => new StaticSource(value2),
    ],
])

Use Cases:

• Organize constants by category (math, physics, config)
• Prevent naming conflicts between different domains
• Create clear separation between different symbol contexts
• Improve code maintainability with logical grouping

Resolvers

Resolvers handle the evaluation of sources:

• StaticResolver: Resolves static values
• ValueResolver: Applies type coercion using the coerce() method
• InfixResolver: Evaluates binary expressions
• SymbolResolver: Looks up named symbols
• DelegatingResolver: Chains multiple resolvers together

Operators

The library supports various operators through the overloader system:

• Binary: +, -, *, /, %, **
• Comparison: ==, !=, <, <=, >, >=
• Logical: &&, ||
• Special: has, in, intersects

Advanced Usage

Custom Types

Implement the Type interface to create custom data validations and coercions:

<?php

use Superscript\Axiom\Types\Type;
use Superscript\Monads\Result\Result;
use Superscript\Monads\Result\Err;
use Superscript\Axiom\Exceptions\TransformValueException;
use function Superscript\Monads\Result\Ok;
use function Superscript\Monads\Option\Some;

class EmailType implements Type
{
    public function assert(mixed $value): Result
    {
        // Strict validation - only accepts valid email strings
        if (is_string($value) && filter_var($value, FILTER_VALIDATE_EMAIL)) {
            return Ok(Some($value));
        }
        
        return new Err(new TransformValueException(type: 'email', value: $value));
    }
    
    public function coerce(mixed $value): Result
    {
        // Permissive conversion - attempts to convert to email format
        $stringValue = is_string($value) ? $value : strval($value);
        $trimmed = trim($stringValue);
        
        if (filter_var($trimmed, FILTER_VALIDATE_EMAIL)) {
            return Ok(Some($trimmed));
        }
        
        return new Err(new TransformValueException(type: 'email', value: $value));
    }
    
    public function compare(mixed $a, mixed $b): bool
    {
        return $a === $b;
    }
    
    public function format(mixed $value): string
    {
        return (string) $value;
    }
}

Custom Resolvers

Create specialized resolvers for specific data sources:

<?php

use Superscript\Axiom\Resolvers\Resolver;
use Superscript\Axiom\Source;
use Superscript\Monads\Result\Result;

class DatabaseResolver implements Resolver
{
    public function resolve(Source $source): Result
    {
        // Custom resolution logic
        // Connect to database, fetch data, etc.
    }
    
    public static function supports(Source $source): bool
    {
        return $source instanceof DatabaseSource;
    }
}

Development

Setup

1. Clone the repository
2. Install dependencies: composer install
3. Run tests: composer test

Testing

The library uses PHPUnit for testing with 100% code coverage requirements:

# Run all tests
composer test

# Individual test suites
composer test:unit      # Unit tests
composer test:types     # Static analysis (PHPStan)
composer test:infection # Mutation testing

Code Quality

• PHPStan: Level max static analysis
• Infection: Mutation testing for test quality
• Laravel Pint: Code formatting
• 100% Code Coverage: Required for all new code

Architecture

The library follows several design patterns:

• Strategy Pattern: Different resolvers for different source types
• Chain of Responsibility: DelegatingResolver chains multiple resolvers
• Factory Pattern: Type system for creating appropriate transformations
• Functional Programming: Extensive use of Result and Option monads

Error Handling

All type validation and coercion operations return Result<Option<T>, Throwable> types:

• Result::Ok(Some(value)): Successful validation/coercion with value
• Result::Ok(None()): Successful validation/coercion with no value (null/empty)
• Result::Err(exception): Validation/coercion failed with error

This approach ensures:

• No exceptions for normal control flow
• Explicit handling of success/failure cases
• Type-safe null handling

License

This library is open-sourced software licensed under the MIT license.

Contributing

Contributions are welcome! Please see CONTRIBUTING.md for details on how to contribute to this project.

Security

If you discover any security-related issues, please review our Security Policy for information on how to responsibly report vulnerabilities.