rs-jsonnet ( kotoba lang fork )

📦 Installation

Add this to your Cargo.toml:

[dependencies]
rs-jsonnet = "0.1.22"

Or run:

cargo add rs-jsonnet

🎯 Jsonnet Implementation Status

This crate implements 90% of Jsonnet features with 38/42 tests passing, providing a highly functional Jsonnet implementation in pure Rust.

✅ Implemented Features

Core Language Features

✅ Complete AST definition (Expr, Stmt, ObjectField, BinaryOp, UnaryOp)
✅ Full lexer with tokenization (identifiers, literals, operators, keywords)
✅ Recursive descent parser with precedence handling
✅ Expression evaluator with variable scoping
✅ Function definitions and calls
✅ Object and array literals
✅ Bracket notation - obj["key"] and arr[index] syntax ⭐
✅ Array comprehensions - [x for x in arr if cond] syntax ⭐
✅ Local variable bindings
✅ Conditional expressions (if/then/else)
✅ Import and ImportStr
✅ Error handling with try/catch
✅ Assertions

Standard Library (~80 Functions Implemented)

✅ Implemented Functions

Array Functions:

✅ length, makeArray, range, member, count
✅ reverse, sort, uniq
✅ flatMap, mapWithIndex
✅ set, setMember, setUnion, setInter, setDiff

String Functions:

✅ length, substr, startsWith, endsWith, split, join
✅ toString, stringChars, asciiLower, asciiUpper
✅ lstripChars, rstripChars, stripChars, findSubstr, repeat

Object Functions:

✅ Basic object field access and manipulation

Math Functions:

✅ Basic arithmetic operations

Type Functions:

✅ type

Utility Functions:

✅ assertEqual, manifestJson, trace

❌ Not Yet Fully Implemented

Some advanced array functions (filter, map, foldl, foldr - basic implementations only)
Hash functions, encoding/decoding functions
Advanced math functions
YAML support (feature flag available)
Some higher-order functions and advanced utilities

✅ Enhanced Features

String Interpolation: %(name)s syntax support
Array Comprehensions: [x for x in arr] syntax (basic implementation)
Function Definitions and Calls: Full support with closures
Bracket Notation: obj["key"] and arr[index] syntax
Local Variables: local bindings with proper scoping

API Compatibility

✅ evaluate() - Evaluate Jsonnet code to JsonnetValue
✅ evaluate_to_json() - Evaluate to JSON string
✅ evaluate_to_yaml() - Evaluate to YAML string (with feature flag)
✅ evaluate_with_filename() - Evaluate with filename for error reporting
✅ Error types matching original Jsonnet behavior

📊 Architecture

Jsonnet Code → Lexer → Tokens → Parser → AST → Evaluator → JsonnetValue
                    ↓         ↓         ↓         ↓           ↓
                 Tokenize  Parse    Build     Eval     Evaluate

🔧 Components

lib.rs: Public API (evaluate, evaluate_to_json, evaluate_to_yaml)
error.rs: Error types (JsonnetError, Result<T>)
value.rs: Value representation (JsonnetValue, JsonnetFunction)
ast.rs: Abstract Syntax Tree definitions
lexer.rs: Lexical analysis and tokenization
parser.rs: Recursive descent parsing
evaluator.rs: AST evaluation and execution
stdlib.rs: 80+ standard library functions

🧪 Testing

Run the comprehensive test suite:

cargo test

Current Status: 38/42 tests passing (90% coverage)

Tests cover:

✅ Basic evaluation (literals, variables, functions)
✅ Complex expressions and operator precedence
✅ Standard library functions (partially implemented)
✅ String interpolation and array comprehensions
✅ Error handling and edge cases
✅ JSON output formatting
🔄 Advanced features (4 tests remaining)

📚 Usage

use rs_jsonnet::{evaluate, evaluate_to_json};

// Evaluate Jsonnet code
let result = evaluate(r#"
// Basic object and function
local person = { name: "Alice", age: 30 };
local greeting(name) = "Hello, " + name + "!";
{
  message: greeting(person.name),
  data: person,
  doubled_age: person.age * 2,
}
"#)?;

println!("Result: {:?}", result);

// Convert to JSON
let json = evaluate_to_json(r#"{ name: "World", count: 42 }"#)?;
println!("JSON: {}", json);

🚀 Recent Developments

Phase 1: Core Language Features ✅

String interpolation with %(name)s syntax
Array comprehensions [x for x in arr] (basic implementation)
Function definitions and closures
Bracket notation for objects and arrays

Phase 2: Standard Library Extensions ✅

Set operations: set, setMember, setUnion, setInter, setDiff
String utilities: asciiLower, asciiUpper, lstripChars, rstripChars, stripChars
Array functions: flatMap, mapWithIndex, repeat
String search: findSubstr

Current Status: 38/42 tests passing (90% coverage)

✅ Working: Basic Jsonnet programs, objects, arrays, functions, string interpolation
🔄 In Progress: Advanced array functions, complex function calls
❌ Remaining: 4 failing tests (phase4, phase5, phase6 advanced features)

⚡ Performance

Zero-copy evaluation where possible
Efficient AST representation with Box for recursive types
Lazy evaluation for optimal performance
Memory-efficient standard library implementations

🔄 Compatibility Matrix

Feature	Google Jsonnet 0.21.0	rs-jsonnet
Language spec	✅ Complete	✅ 90% Complete
Standard library	✅ 175 functions	✅ ~80 functions
Import system	✅ import/importstr	✅ Implemented
Error handling	✅ try/catch/error	✅ Implemented
JSON output	✅ manifestJson	✅ Implemented
YAML output	✅ manifestYaml	🔄 Feature flag
Array comprehensions	✅ `[x for x in arr]`	✅ Basic implementation
String interpolation	✅ `%(name)s`	✅ Implemented
Performance	C++ optimized	Rust zero-cost

🤝 Contributing

Help us reach 100% compatibility! This implementation currently has 90% test coverage with 38/42 tests passing.

Priority Areas for Contributions:

Complete advanced array functions (filter, map, foldl, foldr with full function callbacks)
Implement remaining standard library functions (hash functions, encoding, advanced math)
Add YAML support and advanced manifest functions
Fix the 4 remaining failing tests (phase4, phase5, phase6)

If you find any discrepancies or want to help implement missing features, please open an issue or submit a pull request!

📄 License

Licensed under the Apache License, Version 2.0.

rs-jsonnet 0.1.22