# Qubit Common

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> [!WARNING]
> This crate is deprecated and is no longer recommended for new code.
> The original functionality has been split into four focused crates:
> [`qubit-datatype`](https://crates.io/crates/qubit-datatype) for `DataType`, `DataTypeOf`, and conversion utilities;
> [`qubit-argument`](https://crates.io/crates/qubit-argument) for argument validation;
> [`qubit-error`](https://crates.io/crates/qubit-error) for boxed error helpers;
> and [`qubit-serde`](https://crates.io/crates/qubit-serde) for reusable serde adapters.
> Please depend on those crates directly instead of `qubit-common`.

A comprehensive Rust utility library providing language-level fundamental tools and data type support for Qubit projects.

## Overview

Qubit Common is designed to provide essential language-level utilities that are commonly needed across Rust applications. It offers robust argument validation, comprehensive data type definitions, and core utility functions that follow Rust idioms and best practices.

## Features

### 🔧 **Data Type System**
- **Universal Data Type Enum**: Comprehensive `DataType` enum supporting all basic Rust types and common third-party types
- **Compile-time Type Mapping**: `DataTypeOf` trait for compile-time type-to-data-type queries
- **Serialization Support**: Built-in JSON/YAML serialization for all data types
- **Data Conversion**: Reusable `DataConverter` and `DataConverters` for converting single runtime values or batches between supported `DataType`-backed Rust types

### 🛡️ **Argument Validation**
- **Numeric Validation**: Range checks, equality comparisons, and bounds validation
- **String Validation**: Pattern matching, length constraints, and format validation
- **Collection Validation**: Size limits, element constraints, and null checks
- **Option Validation**: Null safety and optional value handling
- **Method Chaining**: Fluent API design for readable validation chains

### 🎯 **Core Utilities**
- **Error Handling**: Comprehensive error types with detailed context
- **Boxed Error Helpers**: `BoxError`, `BoxResult`, `DynError`, and `IntoBoxError` for type-erased integration errors
- **State Validation**: Application state checking and validation
- **Condition Checking**: Flexible condition and assertion utilities

## Installation

Add this to your `Cargo.toml`:

```toml
[dependencies]
qubit-common = "0.7.0"
```

## Quick Start

### Data Type Usage

```rust
use qubit_common::lang::{DataType, DataTypeOf};

// Get data type information
let data_type = DataType::Int32;
assert_eq!(data_type.as_str(), "int32");

// Compile-time type mapping
assert_eq!(i32::DATA_TYPE, DataType::Int32);
assert_eq!(String::DATA_TYPE, DataType::String);

// Serialization
let json = serde_json::to_string(&DataType::Float64).unwrap();
assert_eq!(json, "\"float64\"");
```

### Data Conversion

```rust
use std::time::Duration;

use qubit_common::lang::converter::{
    DataConversionResult,
    DataConverter,
    DataConverters,
    DataListConversionResult,
};

fn read_settings() -> DataConversionResult<(u16, bool, Duration)> {
    let port = DataConverter::from("8080").to::<u16>()?;
    let enabled = DataConverter::from("true").to::<bool>()?;
    let timeout = DataConverter::from("1500000000ns").to::<Duration>()?;

    Ok((port, enabled, timeout))
}

fn read_ports(values: &[String]) -> DataListConversionResult<Vec<u16>> {
    DataConverters::from(values).to_vec()
}
```

`DataConverter` is a lightweight source-value wrapper. It accepts borrowed or
owned inputs through `From` implementations and returns `DataConversionError`
when a conversion is unsupported, empty, invalid, or out of range.

`DataConverters` applies the same single-value conversion rules to borrowed
slices, borrowed vectors, owned vectors, or arbitrary iterators. It returns
converted values in source order and reports the zero-based failing index when
an element cannot be converted.

### Argument Validation

```rust
use qubit_common::lang::argument::{
    NumericArgument, StringArgument, CollectionArgument, ArgumentResult
};
use regex::Regex;

fn process_user_input(
    age: i32,
    username: &str,
    tags: &[String],
) -> ArgumentResult<()> {
    // Numeric validation
    let age = age.require_in_closed_range("age", 0, 150)?;

    // String validation with chaining
    let username_pattern = Regex::new(r"^[a-zA-Z][a-zA-Z0-9_]{2,19}$").unwrap();
    let username = username
        .require_non_blank("username")?
        .require_match("username", &username_pattern)?;

    // Collection validation
    let tags = tags
        .require_non_empty("tags")?
        .require_length_at_most("tags", 10)?;

    println!("Age: {}, Username: {}, Tag count: {}", age, username, tags.len());
    Ok(())
}
```

### State and Condition Checking

```rust
use qubit_common::lang::argument::{
    check_argument_with_message, check_bounds, check_state_with_message, ArgumentResult
};

fn process_data(
    offset: usize,
    length: usize,
    total_length: usize,
    items: &[String],
) -> ArgumentResult<()> {
    // Basic argument checking
    check_argument_with_message(total_length > 0, "total_length must be positive")?;

    // State validation
    check_state_with_message(!items.is_empty(), "items cannot be empty")?;

    // Bounds checking
    check_bounds(offset, length, total_length)?;

    Ok(())
}
```

### Boxed Error Helpers

`BoxError` and `BoxResult<T>` are convenience aliases for places where the
concrete error type is intentionally erased, such as callbacks, small executable
entry points, integration glue, and stored source errors. `DynError` names the
shared `dyn Error + Send + Sync + 'static` object bounds, while `IntoBoxError`
provides an explicit conversion method for `map_err` and manual `Err`
construction.

Prefer concrete error types for public APIs where callers need structured
recovery. Use boxed helpers when the caller only needs to propagate, log, or
store the original source error.

```rust
use qubit_common::lang::error::{BoxResult, IntoBoxError};

fn parse_port(text: &str) -> BoxResult<u16> {
    text.parse::<u16>()
        .map_err(|error| error.into_box_error())
}

let port = parse_port("8080").expect("valid port should parse");
assert_eq!(port, 8080);
assert!(parse_port("not-a-port").is_err());
```

## Supported Data Types

The [`DataType`](https://docs.rs/qubit-common/latest/qubit_common/lang/enum.DataType.html) enum lists every variant; string forms use `as_str()` (for example `int32`, `instant`, `stringmap`). Types below also note [`DataTypeOf`](https://docs.rs/qubit-common/latest/qubit_common/lang/trait.DataTypeOf.html) where implemented.

### Basic Types
- **Integers**: `i8`, `i16`, `i32`, `i64`, `i128`, `u8`, `u16`, `u32`, `u64`, `u128`
- **Platform integers**: `isize`, `usize` (`DataType::IntSize`, `DataType::UIntSize`)
- **Floats**: `f32`, `f64`
- **Other**: `bool`, `char`, `String`

### Date/Time Types
- **Chrono**: `NaiveDate` → `DataType::Date`, `NaiveTime` → `Time`, `NaiveDateTime` → `DateTime`, `DateTime<Utc>` → `Instant` (UTC instant, analogous to Java `Instant`)

### Big Number Types
- **Arbitrary Precision**: `BigInt`, `BigDecimal`

### Duration, Maps, JSON, and URL
- **Duration**: `std::time::Duration` → `DataType::Duration`
- **String map**: `HashMap<String, String>` → `DataType::StringMap`
- **JSON value**: `serde_json::Value` → `DataType::Json`
- **URL**: `url::Url` → `DataType::Url` with [`DataTypeOf`](https://docs.rs/qubit-common/latest/qubit_common/lang/trait.DataTypeOf.html) implemented; the crate depends on [`url`](https://crates.io/crates/url) so the convention is fixed at the type level.

## API Reference

### Data Types
- [`DataType`](https://docs.rs/qubit-common/latest/qubit_common/lang/enum.DataType.html) - Universal data type enumeration
- [`DataTypeOf`](https://docs.rs/qubit-common/latest/qubit_common/lang/trait.DataTypeOf.html) - Compile-time type mapping trait

### Data Conversion
- [`DataConverter`](https://docs.rs/qubit-common/latest/qubit_common/lang/converter/enum.DataConverter.html) - Runtime value conversion wrapper
- [`DataConverters`](https://docs.rs/qubit-common/latest/qubit_common/lang/converter/struct.DataConverters.html) - Batch runtime value conversion adapter
- [`DataConversionError`](https://docs.rs/qubit-common/latest/qubit_common/lang/converter/enum.DataConversionError.html) - Error type for unsupported or invalid conversions
- [`DataConversionResult`](https://docs.rs/qubit-common/latest/qubit_common/lang/converter/type.DataConversionResult.html) - Result alias returned by conversion APIs
- [`DataListConversionError`](https://docs.rs/qubit-common/latest/qubit_common/lang/converter/struct.DataListConversionError.html) - Error type that includes the failing batch element index
- [`DataListConversionResult`](https://docs.rs/qubit-common/latest/qubit_common/lang/converter/type.DataListConversionResult.html) - Result alias returned by batch conversion APIs

### Argument Validation
- [`NumericArgument`](https://docs.rs/qubit-common/latest/qubit_common/lang/argument/trait.NumericArgument.html) - Numeric validation methods
- [`StringArgument`](https://docs.rs/qubit-common/latest/qubit_common/lang/argument/trait.StringArgument.html) - String validation methods
- [`CollectionArgument`](https://docs.rs/qubit-common/latest/qubit_common/lang/argument/trait.CollectionArgument.html) - Collection validation methods
- [`OptionArgument`](https://docs.rs/qubit-common/latest/qubit_common/lang/argument/trait.OptionArgument.html) - Option validation methods

### Core Functions
- [`check_argument`](https://docs.rs/qubit-common/latest/qubit_common/lang/argument/fn.check_argument.html) - Basic argument validation
- [`check_state`](https://docs.rs/qubit-common/latest/qubit_common/lang/argument/fn.check_state.html) - State validation
- [`check_bounds`](https://docs.rs/qubit-common/latest/qubit_common/lang/argument/fn.check_bounds.html) - Bounds checking

### Error Helpers
- [`DynError`](https://docs.rs/qubit-common/latest/qubit_common/lang/error/type.DynError.html) - Shared dynamic error object bounds
- [`BoxError`](https://docs.rs/qubit-common/latest/qubit_common/lang/error/type.BoxError.html) - Owned boxed dynamic error
- [`BoxResult`](https://docs.rs/qubit-common/latest/qubit_common/lang/error/type.BoxResult.html) - Result alias using `BoxError`
- [`IntoBoxError`](https://docs.rs/qubit-common/latest/qubit_common/lang/error/trait.IntoBoxError.html) - Explicit conversion trait for boxing concrete errors

## Error Handling

Argument validation functions return `ArgumentResult<T>`, which is an alias for
`Result<T, ArgumentError>`. `ArgumentError` stores a human-readable validation
message and implements the standard error traits.

```rust
use qubit_common::lang::argument::{ArgumentError, ArgumentResult};

fn validate_input(value: i32) -> ArgumentResult<i32> {
    if value > 0 {
        Ok(value)
    } else {
        Err(ArgumentError::new("value must be positive"))
    }
}

match validate_input(0) {
    Ok(result) => println!("Validation passed: {result}"),
    Err(error) => eprintln!("Validation failed: {error}"),
}
```

## Dependencies

- **serde**: Serialization support
- **serde_json**: JSON serialization
- **bigdecimal**: Arbitrary precision decimal arithmetic
- **chrono**: Date and time handling
- **num-bigint**: Big integer support
- **num-traits**: Numeric conversion support
- **regex**: Pattern matching
- **url**: Parsed URL type (`url::Url`) bound to `DataType::Url`

## Testing & Code Coverage

This project maintains comprehensive test coverage with detailed validation of all functionality.

### Coverage Metrics

Current test coverage statistics:

| Module | Region Coverage | Line Coverage | Function Coverage |
|--------|----------------|---------------|-------------------|
| collection.rs | 100.00% | 100.00% | 100.00% |
| condition.rs | 100.00% | 100.00% | 100.00% |
| error.rs | 100.00% | 100.00% | 100.00% |
| numeric.rs | 100.00% | 100.00% | 100.00% |
| **option.rs** | **76.19%** | **84.09%** | **100.00%** |
| string.rs | 100.00% | 100.00% | 100.00% |
| data_type.rs | 100.00% | 100.00% | 100.00% |
| pair.rs | 100.00% | 100.00% | 100.00% |
| triple.rs | 100.00% | 100.00% | 100.00% |
| **Total** | **98.38%** | **98.99%** | **100.00%** |

### Understanding Coverage Metrics

#### Why isn't option.rs at 100% Region Coverage?

The `option.rs` module shows 76.19% region coverage despite having **100% executable code coverage**. This is due to a known characteristic of LLVM's coverage instrumentation:

**LLVM Region Coverage Includes Non-Executable Code**:
- Trait definitions and signatures
- Type parameter declarations
- `where` clause constraints
- Generic bounds
- Empty lines between declarations

These declarative elements are assigned region IDs by LLVM but are **not executable code**. The actual implementation code in `option.rs` has **100% coverage** (verified by examining the detailed report - no `^` markers indicating uncovered code).

**Example**:
```rust
pub trait OptionArgument<T> {              // ← Counted as region
    fn require_non_null(                   // ← Counted as region
        self,                              // ← Counted as region
        name: &str                         // ← Counted as region
    ) -> ArgumentResult<T>;                // ← Counted as region

    fn require_non_null_and<F>(            // ← Counted as region
        self, name: &str,
        predicate: F,
        error_msg: &str
    ) -> ArgumentResult<T>
    where                                  // ← Counted as region
        F: FnOnce(&T) -> bool;             // ← Counted as region
}
```

**Why This Happens**:
- `option.rs` has ~88 lines of trait definitions with complex generic constraints
- Simple modules like `error.rs` have fewer declarative regions
- This is a known limitation in LLVM coverage (GitHub Issue [rust#79417](https://github.com/rust-lang/rust/issues/79417))
- C++ projects using LLVM coverage face similar issues with templates

**What Matters**:
- ✅ **Function Coverage: 100%** - All functions are tested
- ✅ **Line Coverage: 84.09%** - High actual code coverage
- ✅ **Executable Code: 100%** - All implementation logic is tested
- ⚠️ **Region Coverage: 76.19%** - Includes non-executable declarations

### Running Tests

```bash
# Run all tests
cargo test

# Run with coverage report
./coverage.sh

# Generate text format report
./coverage.sh text

# Generate detailed report for specific module
cargo llvm-cov test --text | grep -A 50 "option.rs"
```

### Coverage Tool Limitations

The coverage statistics are generated using `cargo-llvm-cov`. When interpreting the results:

1. **Focus on Function and Line Coverage** - These are the most meaningful metrics
2. **Region Coverage may be lower** - Especially for modules with extensive trait definitions
3. **Verify with detailed reports** - Check for `^` markers in uncovered regions
4. **Known LLVM issue** - Non-executable declarations are counted as regions

For more details, see:
- [LLVM Coverage Documentation](https://doc.rust-lang.org/rustc/instrument-coverage.html)
- [Rust Issue #79417](https://github.com/rust-lang/rust/issues/79417) - Doctest coverage mapping
- Project coverage reports in `target/llvm-cov/html/`

## License

Copyright (c) 2025 - 2026. Haixing Hu, Qubit Co. Ltd. All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

See [LICENSE](LICENSE) for the full license text.

## Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

When contributing tests, note that achieving 100% region coverage is not always feasible for modules with extensive trait definitions. Focus on ensuring all executable code paths are tested.

## Author

**Haixing Hu** - *Qubit Co. Ltd.*

---

Project repository: [github.com/qubit-ltd/rs-common](https://github.com/qubit-ltd/rs-common).
