Implementing Signature Help in an Angular Component

Signature help, also known as function signature assistance, is a crucial feature in modern IDEs that provides developers with information about function parameters, return types, and documentation while they are typing. This challenge asks you to implement a simplified version of signature help within an Angular component, enhancing the developer experience by displaying parameter information when a specific function is called. This is useful for improving code readability and reducing errors, especially when working with complex functions.

Problem Description

You need to create an Angular component that displays signature help for a predefined function when the user types the function name followed by an opening parenthesis (. The component should:

1. Detect Function Call: Recognize when the user types the function name calculateTotal followed by an opening parenthesis (.
2. Display Signature: When detected, display the function signature, including parameter names and types, in a designated area (e.g., a tooltip or a separate div).
3. Hide Signature: Hide the signature help when the user types a closing parenthesis ) or any other character that breaks the function call sequence.
4. Handle Parameter Typing: While the user is typing parameters within the parentheses, the signature help should remain visible and potentially highlight the expected parameter based on the current position. (This is a stretch goal and not strictly required for a basic implementation).
5. Clear Display: Ensure the signature help is cleared when the component is destroyed or the input changes significantly.

Key Requirements:

• The component should be reactive to changes in the input text.
• The signature help should be displayed in a visually distinct manner.
• The component should be reusable and adaptable to different function signatures.

Expected Behavior:

• When the user types calculateTotal(, the signature help for calculateTotal should appear.
• When the user types calculateTotal(price,, the signature help should remain visible.
• When the user types calculateTotal(), the signature help should disappear.
• When the user types someOtherFunction(, the signature help should not appear.

Edge Cases to Consider:

• What happens if the function name is misspelled? (The signature help should not appear).
• What happens if the user types multiple opening parentheses ((? (The signature help should still appear after the first opening parenthesis).
• What happens if the user types a closing parenthesis before an opening parenthesis? (The signature help should not appear).
• What happens if the input text is empty? (The signature help should not appear).

Examples

Example 1:

Input: "calculateTotal("
Output: Display signature help for calculateTotal(price: number, quantity: number): number
Explanation: The component detects the function call and displays the signature.

Example 2:

Input: "someOtherFunction("
Output: No signature help displayed.
Explanation: The component does not recognize the function name.

Example 3:

Input: "calculateTotal(10,"
Output: Display signature help for calculateTotal(price: number, quantity: number): number
Explanation: The signature help remains visible while the user is typing parameters.

Example 4:

Input: "calculateTotal()"
Output: No signature help displayed.
Explanation: The closing parenthesis triggers the signature help to disappear.

Constraints

• The component should be implemented using Angular's reactive forms or change detection mechanisms.
• The function signature information (parameter names and types) should be hardcoded within the component for simplicity. (e.g., const functionSignature = { name: 'calculateTotal', parameters: [{ name: 'price', type: 'number' }, { name: 'quantity', type: 'number' }], returnType: 'number' };)
• The signature help display should be contained within the component's template.
• Performance should be considered; avoid unnecessary re-renders.

Notes

• Consider using Subject or BehaviorSubject to manage the input text and trigger signature help updates.
• Regular expressions can be helpful for detecting the function call pattern.
• Focus on the core functionality of detecting the function call and displaying the signature. Advanced features like parameter highlighting are optional.
• Think about how to make the component reusable for different functions. Consider passing the function signature as an input.
• Error handling is not required for this challenge.