Generic Data Processor with Associated Types

This challenge focuses on understanding and implementing associated types in Rust. Associated types allow traits to define placeholder types that implementing types must specify, leading to more flexible and expressive generic code. You will create a trait that defines a data processing pipeline where different stages can operate on different, but related, data types.

Problem Description

Your task is to design and implement a trait, DataProcessor, which represents a generic data processing pipeline. This trait should have an associated type, InputType, representing the type of data the processor accepts, and another associated type, OutputType, representing the type of data the processor produces. The trait will also include a method, process, which takes an instance of InputType and returns an instance of OutputType.

You will then implement this DataProcessor trait for a few concrete types to demonstrate its usage.

Key Requirements:

1. Define DataProcessor Trait: Create a trait named DataProcessor.
2. Associated Types:
   • Define an associated type InputType.
   • Define an associated type OutputType.
3. process Method: Define a method process within the trait:
   • It should accept self by value (or mutable reference, your choice, but specify it clearly).
   • It should take one argument of type Self::InputType.
   • It should return a value of type Self::OutputType.
4. Implementations: Provide at least two concrete implementations of DataProcessor for different scenarios.
   • Example Implementation 1: A processor that takes a String and returns its length as an usize.
   • Example Implementation 2: A processor that takes a Vec<i32> and returns the sum of its elements as an i32.

Expected Behavior:

When an instance of a type implementing DataProcessor is used, you should be able to call its process method with the correct input type and receive the correctly processed output type.

Edge Cases:

• Consider how an empty input might be handled (though for this challenge, simple successful processing is sufficient).
• Ensure type safety is maintained throughout.

Examples

Example 1: String Length Processor

// Assume StringLengthProcessor is implemented
let mut processor = StringLengthProcessor;
let input_string = String::from("Hello, Rust!");
let output_length = processor.process(input_string);

println!("Input: \"Hello, Rust!\", Output: {}", output_length); // Expected: Input: "Hello, Rust!", Output: 12

Explanation: The StringLengthProcessor takes a String as InputType and returns an usize as OutputType. Calling process with "Hello, Rust!" results in the length 12.

Example 2: Vector Sum Processor

// Assume VectorSumProcessor is implemented
let mut processor = VectorSumProcessor;
let input_vector = vec![1, 2, 3, 4, 5];
let output_sum = processor.process(input_vector);

println!("Input: [1, 2, 3, 4, 5], Output: {}", output_sum); // Expected: Input: [1, 2, 3, 4, 5], Output: 15

Explanation: The VectorSumProcessor takes a Vec<i32> as InputType and returns an i32 as OutputType. Calling process with vec![1, 2, 3, 4, 5] results in the sum 15.

Constraints

• The DataProcessor trait must be defined using associated types.
• Implementations should be clear and idiomatic Rust.
• Focus on correct trait definition and usage, not complex error handling or optimization.

Notes

• Associated types are declared using the type keyword within a trait definition.
• When implementing a trait with associated types, you must specify concrete types for each associated type using the type keyword in the impl block.
• Think about what makes associated types useful compared to generic parameters on the trait itself. For instance, a trait with associated types can only have one implementation per type for that trait, whereas a trait with generic parameters could have multiple implementations with different generic arguments.