Supported Formats

Python Requirements Parser supports all pip-compatible requirement formats as defined in PEP 440, PEP 508, and pip documentation.

Overview

The parser handles the complete spectrum of Python package requirements, from simple version constraints to complex VCS dependencies with environment markers.

Basic Dependencies

Simple Package Names

txt

flask
django
requests

Version Constraints

Exact Version

txt

flask==2.0.1
django==3.2.13

Minimum Version

txt

requests>=2.25.0
numpy>=1.20.0

Maximum Version

txt

django<4.0.0
requests<3.0.0

Compatible Version (Tilde)

txt

flask~=2.0.0    # Equivalent to >=2.0.0, ==2.0.*
django~=3.2.0   # Equivalent to >=3.2.0, ==3.2.*

Complex Constraints

txt

django>=3.2.0,<4.0.0
requests>=2.25.0,<3.0.0,!=2.26.0
numpy>=1.20.0,<1.22.0,!=1.20.1

Arbitrary Equality

txt

django===3.2.13  # Exact match, no normalization

Dependencies with Extras

Single Extra

txt

requests[security]
django[bcrypt]

Multiple Extras

txt

django[rest,auth]
uvicorn[standard]
requests[security,socks]

Extras with Version Constraints

txt

django[rest,auth]>=3.2.0,<4.0.0
uvicorn[standard]>=0.15.0

Environment Markers

Platform Markers

txt

pywin32>=1.0; platform_system == "Windows"
pyobjc>=8.0; platform_system == "Darwin"

Python Version Markers

txt

dataclasses>=0.6; python_version < "3.7"
typing-extensions>=3.7.4; python_version < "3.8"
importlib-metadata>=1.0; python_version < "3.8"

Complex Markers

txt

pywin32>=1.0; platform_system == "Windows" and python_version >= "3.6"
uvloop>=0.14.0; platform_system != "Windows" and python_version >= "3.7"

Implementation Markers

txt

lxml>=4.6.0; implementation_name == "cpython"
pypy>=7.3.0; implementation_name == "pypy"

VCS Dependencies

Git Dependencies

txt

git+https://github.com/user/project.git
git+https://github.com/user/project.git@v1.2.3
git+https://github.com/user/project.git@branch-name
git+https://github.com/user/project.git@commit-hash

Git with Egg Name

txt

git+https://github.com/user/project.git#egg=project
git+https://github.com/user/project.git@v1.2.3#egg=project

Git with Subdirectory

txt

git+https://github.com/user/project.git#subdirectory=packages/subpackage
git+https://github.com/user/project.git@v1.2.3#subdirectory=packages/subpackage&egg=subpackage

Other VCS Systems

txt

# Mercurial
hg+https://bitbucket.org/user/project#egg=project

# Subversion
svn+https://svn.example.com/project/trunk#egg=project

# Bazaar
bzr+https://bazaar.example.com/project#egg=project

SSH URLs

txt

git+ssh://git@github.com/user/project.git
git+ssh://git@github.com/user/project.git@v1.2.3#egg=project

Editable Dependencies

Editable VCS

txt

-e git+https://github.com/user/project.git
-e git+https://github.com/user/project.git@develop#egg=project

Editable Local Path

txt

-e .
-e ./packages/subpackage
-e /absolute/path/to/package

Editable with Extras

txt

-e git+https://github.com/user/project.git#egg=project[extra1,extra2]
-e .[dev,test]

URL Dependencies

Direct URLs

txt

https://example.com/package.whl
https://files.pythonhosted.org/packages/.../package-1.0.0.tar.gz

Local File URLs

txt

file:///absolute/path/to/package.whl
file://./relative/path/to/package.tar.gz

URLs with Fragments

txt

https://example.com/package.whl#egg=package
https://example.com/package.tar.gz#sha256=abcdef1234567890

File References

Requirements Files

txt

-r requirements-dev.txt
--requirement requirements-prod.txt
-r https://example.com/requirements.txt

Constraints Files

txt

-c constraints.txt
--constraint constraints-prod.txt
-c https://example.com/constraints.txt

Global Options

Index URLs

txt

--index-url https://pypi.example.com/simple/
--extra-index-url https://private.pypi.com/simple/
--extra-index-url https://download.pytorch.org/whl/cpu

Trusted Hosts

txt

--trusted-host pypi.example.com
--trusted-host private.pypi.com

Find Links

txt

--find-links https://download.pytorch.org/whl/torch_stable.html
--find-links /path/to/local/directory

Other Options

txt

--no-index
--prefer-binary
--only-binary=:all:
--no-binary=:all:

Hash Verification

Single Hash

txt

flask==2.0.1 --hash=sha256:abcdef1234567890

Multiple Hashes

txt

django==3.2.13 \
    --hash=sha256:1234567890abcdef \
    --hash=sha256:fedcba0987654321

Hash Algorithms

txt

requests==2.28.0 --hash=sha256:abcdef1234567890
requests==2.28.0 --hash=sha1:1234567890abcdef
requests==2.28.0 --hash=md5:abcdef1234567890

Comments and Formatting

Inline Comments

txt

flask==2.0.1  # Web framework
django>=3.2.0  # Another web framework
requests>=2.25.0  # HTTP library

Full Line Comments

txt

# Production dependencies
flask==2.0.1
django>=3.2.0

# Development dependencies
pytest>=6.0.0
black>=21.0.0

Empty Lines

txt

# Production dependencies
flask==2.0.1

# Development dependencies

pytest>=6.0.0

Line Continuation

Backslash Continuation

txt

django>=3.2.0,<4.0.0,!=3.2.1,!=3.2.2 \
    --hash=sha256:1234567890abcdef \
    --hash=sha256:fedcba0987654321

Implicit Continuation

txt

very-long-package-name-that-exceeds-line-length>=1.0.0,<2.0.0,!=1.5.0

Complex Examples

Real-World Production Requirements

txt

# Web framework
Django>=3.2.13,<4.0.0  # LTS version with security updates
djangorestframework>=3.14.0  # API framework
django-cors-headers>=3.14.0  # CORS handling

# Database
psycopg2-binary>=2.9.3  # PostgreSQL adapter
redis>=4.3.4  # Redis client

# Task queue
celery[redis]>=5.2.7  # Task queue with Redis broker

# AWS services
boto3>=1.24.0  # AWS SDK
django-storages[boto3]>=1.13.0  # S3 storage backend

# Monitoring
sentry-sdk[django]>=1.9.0  # Error tracking

# Development dependencies
pytest>=7.1.0; python_version >= "3.7"
pytest-django>=4.5.0; python_version >= "3.7"
black>=22.0.0; python_version >= "3.7"

# Platform-specific
pywin32>=304; platform_system == "Windows"

# VCS dependencies
git+https://github.com/company/internal-package.git@v1.2.3#egg=internal-package

# Local development
-e git+https://github.com/company/dev-tools.git@develop#egg=dev-tools

# Constraints
-c constraints.txt

# Additional requirements
-r requirements-dev.txt

Complex Markers Example

txt

# Complex environment markers
package1>=1.0.0; python_version >= "3.7" and platform_system == "Linux"
package2>=2.0.0; python_version < "3.8" or implementation_name == "pypy"
package3>=3.0.0; platform_machine == "x86_64" and platform_system != "Windows"

Parsing Behavior

Case Sensitivity

Package names are case-insensitive: Flask == flask == FLASK
URLs and file paths are case-sensitive
Environment marker values are case-sensitive

Normalization

Package names are normalized: My_Package becomes my-package
Version numbers are normalized: 1.0 becomes 1.0.0
Whitespace is normalized but preserved in comments

Error Handling

Invalid syntax is preserved as-is in OriginalLine
Malformed requirements are marked with appropriate flags
Parser continues processing despite individual line errors

Validation

The parser accepts most content but provides flags to identify different types:

for _, req := range requirements {
    switch {
    case req.IsComment:
        fmt.Printf("Comment: %s\n", req.Comment)
    case req.IsEmpty:
        fmt.Println("Empty line")
    case req.IsFileRef:
        fmt.Printf("File reference: %s\n", req.FileRef)
    case req.IsVCS:
        fmt.Printf("VCS dependency: %s (%s)\n", req.URL, req.VCSType)
    case req.IsURL:
        fmt.Printf("URL dependency: %s\n", req.URL)
    case req.Name != "":
        fmt.Printf("Package: %s %s\n", req.Name, req.Version)
    default:
        fmt.Printf("Unknown line: %s\n", req.OriginalLine)
    }
}

Next Steps

Performance Guide - Optimization tips for large files
API Reference - Complete API documentation
Examples - Practical usage examples

Supported Formats ​

Overview ​

Basic Dependencies ​

Simple Package Names ​

Version Constraints ​

Exact Version ​

Minimum Version ​

Maximum Version ​

Compatible Version (Tilde) ​

Complex Constraints ​

Arbitrary Equality ​

Dependencies with Extras ​

Single Extra ​

Multiple Extras ​

Extras with Version Constraints ​

Environment Markers ​

Platform Markers ​

Python Version Markers ​

Complex Markers ​

Implementation Markers ​

VCS Dependencies ​

Git Dependencies ​

Git with Egg Name ​

Git with Subdirectory ​

Other VCS Systems ​

SSH URLs ​

Editable Dependencies ​

Editable VCS ​

Editable Local Path ​

Editable with Extras ​

URL Dependencies ​

Direct URLs ​

Local File URLs ​

URLs with Fragments ​

File References ​

Requirements Files ​

Constraints Files ​

Global Options ​

Index URLs ​

Trusted Hosts ​

Find Links ​

Other Options ​

Hash Verification ​

Single Hash ​

Multiple Hashes ​

Hash Algorithms ​

Comments and Formatting ​

Inline Comments ​

Full Line Comments ​

Empty Lines ​

Line Continuation ​

Backslash Continuation ​

Implicit Continuation ​

Complex Examples ​

Real-World Production Requirements ​

Complex Markers Example ​

Parsing Behavior ​

Case Sensitivity ​

Normalization ​

Error Handling ​

Validation ​

Next Steps ​