EasyScript

A simple scripting language interpreter that blends Python and JavaScript syntax, designed for easy expression evaluation, business rule processing, and LDAP/user object manipulation.

Features

• Hybrid Syntax: Combines the best of Python and JavaScript syntax
• JavaScript-style String Concatenation: Automatic string conversion (e.g., "hello" + 5 → "hello5")
• Python-style Boolean Operators: Supports and, or, and not operators
• Object Property Access: Dot notation for accessing object properties (user.cn, user.mail)
• Built-in Variables: Pre-defined variables (day, month, year) with support for object injection
• Built-in Functions: Essential functions like len(), log(), abs(), min(), max(), round()
• Regex Matching: Pattern matching with ~ operator (string ~ pattern)
• Conditional Logic: Support for if-then-else statements (the then keyword is required)
• Mixed Boolean Values: Supports both True/False and true/false
• Comments: Both Python-style (#) and JavaScript-style (//) comments supported
• REPL Mode: Interactive command-line interface for testing expressions
• Null Support: Built-in null keyword for null values

Quick Start

Command Line / REPL Usage

# Run EasyScript directly
python -m easyscript

# Or use the REPL interactively
python -m easyscript --repl

In REPL mode, you can interactively test expressions:

EasyScript REPL (type 'exit' to quit, 'help' for commands)
> 5 + 3 * 2
13
> "Hello " + "World"
Hello World
> abs(-15)
15
> min(10, 5, 20)
5

Python Integration

from easyscript import EasyScriptEvaluator

# Create an evaluator instance
evaluator = EasyScriptEvaluator()

# Basic arithmetic
result = evaluator.evaluate("3 + 5")  # Returns: 8

# New built-in functions
result = evaluator.evaluate("abs(-10)")  # Returns: 10
result = evaluator.evaluate("min(5, 3, 8)")  # Returns: 3
result = evaluator.evaluate("max(5, 3, 8)")  # Returns: 8
result = evaluator.evaluate("round(3.7)")  # Returns: 4

# String concatenation
result = evaluator.evaluate('"Hello " + "World"')  # Returns: "Hello World"

# JavaScript-style string + number
result = evaluator.evaluate('"Count: " + 42')  # Returns: "Count: 42"

# Null values
result = evaluator.evaluate("null")  # Returns: None

# Built-in variables
result = evaluator.evaluate("year")  # Returns: current year

# Object injection
class User:
    def __init__(self):
        self.cn = "John Doe"
        self.mail = "john@example.com"

user = User()
result = evaluator.evaluate("user.cn", {"user": user})  # Returns: "John Doe"

# Log function (prints and returns value)
result = evaluator.evaluate('log("Debug info")')  # Prints: Debug info, Returns: "Debug info"

# Regex matching
result = evaluator.evaluate('user.mail ~ ".*@.*"', {"user": user})  # Returns: True

# Conditional logic
result = evaluator.evaluate('if len(user.cn) > 3 then true else false', {"user": user})  # Returns: True

# Comments in expressions (both styles supported)
result = evaluator.evaluate('5 + 3 # Python-style comment')  # Returns: 8
result = evaluator.evaluate('5 + 3 // JavaScript-style comment')  # Returns: 8

Syntax Examples

Basic Operations

// Arithmetic
3 + 5 * 2        // 13
10 / 2 - 1       // 4.0

// Built-in functions
abs(-15)         // 15
min(10, 5, 20)   // 5
max(10, 5, 20)   // 20
round(3.7)       // 4
round(3.14159, 2) // 3.14

// String operations
"Hello " + "World"           // "Hello World"
"Value: " + 42               // "Value: 42"
len("Hello")                 // 5
log("Debug: " + 42)          // Prints: Debug: 42, Returns: "Debug: 42"

// Null values
null                         // null
null == null                 // True

// Comparisons
5 > 3                        // True
"abc" == "abc"               // True
len("test") >= 4             // True

// Regex matching
"hello" ~ "h.*o"             // True
"test123" ~ "[0-9]+"         // True
"email@domain.com" ~ ".*@.*" // True

Boolean Logic

// Python-style boolean operators
true and false               // False
true or false                // True
not true                     // False
not false                    // True

// Operator precedence (not has higher precedence)
not true and false           // False (equivalent to: (not true) and false)
not (true and false)         // True

// Mixed case support
True and False               // False
true and False               // False
not True                     // False

Conditional Expressions

// if-then-else syntax (then keyword is mandatory)
if 5 > 3 then "greater" else "not greater"      // "greater"
if false then "yes" else "no"                    // "no"

// Conditions can be complex expressions
if len("hello") >= 5 then "long" else "short"   // "long"
if year > 2020 and month == 12 then "recent december" else "other time"

// Nested conditionals
if user.active then (if user.role == "admin" then "admin user" else "regular user") else "inactive"

// Numeric results
if user.age >= 18 then user.age else 0

// Using with object properties
if user.department == "IT" then user.salary * 1.1 else user.salary

Comments

// Python-style comments using #
5 + 3 # This is a comment
"hello" + "world" # Comments can appear at end of line

# Full line comments are supported
5 + 3  # Result: 8

// JavaScript-style comments using //
5 + 3 // This is also a comment
"hello" + "world" // JavaScript-style comment

// Both comment styles can be mixed
5 # Python comment
+ 3 // JavaScript comment
* 2 # Result: 16

// Comments in multi-line expressions
5 # first number
+ 3 // second number
* 2 # multiply result

Object Injection and Access

// Create and inject custom objects
from easyscript import EasyScriptEvaluator

class User:
    def __init__(self):
        self.cn = "John Doe"
        self.mail = "john.doe@company.com"
        self.department = "Engineering"

user = User()
evaluator = EasyScriptEvaluator()

// Access injected object properties
evaluator.evaluate("user.cn", {"user": user})                      // "John Doe"
evaluator.evaluate("user.mail", {"user": user})                    // "john.doe@company.com"

// Use in expressions
evaluator.evaluate('"Hello " + user.cn', {"user": user})           // "Hello John Doe"
evaluator.evaluate('len(user.mail) > 10', {"user": user})          // True
evaluator.evaluate('user.mail ~ ".*@.*"', {"user": user})          // True (email validation)

Conditional Statements

// Basic conditional - 'then' keyword is required
if 5 > 3 then true else false        // True

// String results
if len(user.cn) > 3 then "Long name" else "Short name"    // "Long name"

// Complex conditions
if user.department == "Engineering" and len(user.cn) > 3 then "Valid engineer" else "Invalid"

// Nested expressions
if year > 2020 then year - 2020 else 0   // Returns difference from 2020

// Boolean expressions
if user.active then "Active user" else "Inactive user"

Built-in Variables

EasyScript provides several built-in variables:

• day: Current day of the month
• month: Current month (1-12)
• year: Current year

Additional objects can be injected using the variables parameter.

Use Cases

EasyScript is particularly useful for:

• Business Rule Processing: Evaluate complex business logic with simple syntax
• LDAP/Directory Services: Process user attributes and directory data
• Configuration Management: Dynamic configuration based on conditions
• Data Validation: Validate data with readable expressions
• Template Processing: Generate dynamic content based on user data

Installation

Simply install the package or download the easyscript.py file:

pip install easyscript

from easyscript import EasyScriptEvaluator

Requirements

• Python 3.6+
• No external dependencies

Running Tests

Run the included test suite to verify functionality:

# Basic functionality tests
python tests/test_easyscript.py

# Object injection examples (includes LDAPUser example class)
python tests/test_easyscript_user.py

# Or run all tests
python -m pytest tests/

Note: The LDAPUser class used in tests is just an example of object injection and is located in tests/test_helpers.py. It's not part of the main library.

Object Injection

EasyScript's power comes from injecting your own objects and data:

from easyscript import EasyScriptEvaluator

evaluator = EasyScriptEvaluator()

# Inject any Python object
class Config:
    def __init__(self):
        self.debug = True
        self.api_url = "https://api.example.com"

class User:
    def __init__(self, name, email):
        self.name = name
        self.email = email
        self.active = True

# Create instances
config = Config()
user = User("Alice", "alice@company.com")

# Inject multiple objects
variables = {
    'config': config,
    'user': user,
    'version': '1.0'
}

# Use in expressions
result = evaluator.evaluate('user.name + " - " + config.api_url', variables)
# Returns: "Alice - https://api.example.com"

result = evaluator.evaluate('if user.active and config.debug then "Debug mode" else "Production mode"', variables)
# Returns: "Debug mode"

result = evaluator.evaluate('user.email ~ ".*@company\.com"', variables)
# Returns: True

Contributing

Contributions are welcome! Feel free to:

• Report bugs
• Suggest new features
• Submit pull requests
• Improve documentation

License

This project is released under the MIT License. See the LICENSE file for details.

Examples

Real-world Usage Scenarios

User Access Control:

if user.department == "IT" and len(user.cn) > 0 then true else false

Dynamic Greetings:

if month >= 6 and month <= 8 then "Summer greetings, " + user.givenName else "Hello, " + user.givenName

Data Validation:

# Inject user object
user = User("john", "john@company.com")
variables = {"user": user}

result = evaluator.evaluate('if len(user.mail) > 5 and user.mail ~ ".*@.*" then true else false', variables)

Pattern Matching:

result = evaluator.evaluate('if user.username ~ "^[a-z]+$" then "Valid username" else "Invalid username"', variables)
result = evaluator.evaluate('if user.mail ~ ".*@company\.com$" then "Company email" else "External email"', variables)

Configuration Logic:

if user.title == "Manager" or user.department == "Executive" then "admin" else "user"