Python Package Management with requirements.txt

The requirements.txt file is a cornerstone of reproducible Python environments. It allows developers to list all the external packages and their specific versions that a project depends on. This challenge asks you to simulate the core functionality of installing packages based on a requirements.txt file. This is crucial for ensuring that any developer or deployment environment can reliably recreate the exact setup needed to run a project.

Problem Description

Your task is to write a Python function that simulates the installation of Python packages listed in a requirements.txt file. You will be given a string representing the content of a requirements.txt file and a function that simulates the actual package installation. Your function should parse the requirements.txt content and call the provided installer for each valid package specification.

Key Requirements:

1. Parse requirements.txt content: The function must correctly interpret each line of the requirements.txt input string.
2. Handle package names: Extract the name of each package.
3. Handle version specifiers: Recognize and parse common version specifiers like ==, >=, <=, >, <, ~=.
4. Ignore comments and empty lines: Lines starting with # and entirely empty lines should be ignored.
5. Call the installer: For each valid package specification, call the provided install_package function with the package name and its version specifier(s).
6. Error Handling (Optional but Recommended): Consider how to handle malformed lines or unsupported specifiers gracefully (though for this challenge, you can assume valid, common formats if you prefer).

Provided Installer Function (Do NOT modify):

def install_package(package_name: str, version_specifier: str = None):
    """
    Simulates installing a Python package.
    In a real scenario, this would use pip or a similar tool.
    """
    if version_specifier:
        print(f"Simulating installation of {package_name} with specifier: {version_specifier}")
    else:
        print(f"Simulating installation of {package_name}")

Expected Behavior:

Your function will take a string as input, representing the requirements.txt content. It will then iterate through this content, parse each line, and for every line that specifies a package, it will call the install_package function with the correct arguments.

Examples

Example 1:

Input requirements_content:

requests numpy==1.23.5 pandas>=1.5.0,<2.0.0 Flask~=2.2.0

Output:

Simulating installation of requests Simulating installation of numpy with specifier: ==1.23.5 Simulating installation of pandas with specifier: >=1.5.0,<2.0.0 Simulating installation of Flask with specifier: ~=2.2.0

**Explanation:** The function parses each line. "requests" has no version specifier. "numpy" has a specific version. "pandas" has a range. "Flask" has a compatible release specifier. Each is passed to `install_package`.

**Example 2:**

Input requirements_content:

# This is a comment
Django # Inline comment

beautifulsoup4==4.11.1 # A popular parsing library

Output:

Simulating installation of Django
Simulating installation of beautifulsoup4 with specifier: ==4.11.1

Explanation: The function ignores the first line because it's a comment. It correctly extracts "Django" from the second line, ignoring the inline comment. It then parses "beautifulsoup4" and its specific version.

Example 3:

Input requirements_content:

flask

Another comment

sqlalchemy>=1.4

Output:

Simulating installation of flask Simulating installation of sqlalchemy with specifier: >=1.4

**Explanation:** Leading/trailing whitespace on lines is ignored. Empty lines are skipped.

## Constraints

-   The `requirements_content` string will contain standard `requirements.txt` formats.
-   Package names will consist of alphanumeric characters and hyphens.
-   Supported version specifiers include `==`, `>=`, `<=`, `>`, `<`, `~=`.
-   Inline comments start with `#` after the package specification.
-   Lines can be empty or contain only whitespace.
-   You will not be tested on extremely complex or malformed specifiers (e.g., multiple constraints not separated by commas, invalid characters in package names).

## Notes

-   You'll need to split the input string into individual lines.
-   For each line, you'll need to strip whitespace and check if it's a comment or empty.
-   Regular expressions can be very helpful for parsing the package name and version specifiers, but string manipulation alone can also work.
-   The `install_package` function is provided and should not be modified. Your goal is to call it correctly.
-   Think about how to extract the version specifier string as a whole, including multiple parts if they exist (like `pandas>=1.5.0,<2.0.0`).