Scholar (sch)

Scholar (sch) is a programmable bookmark and pseudo-search engine heavily inspired by YubNub. It is a lightweight HTTP service for executing scripts which generate URLs. These URLs are then issued to the user via an HTTP redirect.

The main use case of sch is as a search engine in a browser toolbar, with a predefined set of commands which "routes" you to the desired page or search engine.

For a hands-on explanation and demonstration of Scholar as a tool, a public hosted instance is available: https://sch.luphy.net/sch?s=sch_tree

As well as a general use doc: https://sch.luphy.net/sch?s=sch_help

A major difference is that Scholar is intended to be run locally or via a self-hosted public instance. To get an instance of Scholar up and running on a local machine, check the "Getting Started" guide below.

To learn about writing commands, check the "Usage" section.

Guidance for how to run a self-hosted public instance can also be found in the "Advanced Usage" section.

Getting Started

TL; DR

# Install scholar with pandoc
pip install scholar-search[pandoc]

# Clone and run sch against the example codex
git clone https://github.com/adammillerio/sch.git
sch run

And go to http://localhost:5000/sch?s=sch_help for usage info.

The public collection of codexes is available at adammillerio/sch_public

Detailed

Scholar can be installed via pip:

# With pandoc
pip install scholar-search[pandoc]
# Without pandoc (install via other means)
pip install scholar-search

Rendering text pages depends on pandoc. Scholar can be installed with the pandoc extra to include the pypandoc-binary package, which will also download pandoc itself.

Refer to the Pandoc Manual for more info.

Commands are loaded into Scholar via a "Codex", which is just a Python file that has a Flask app factory defined. This file can import other files or define commands directly.

A basic hello world example (hello_world.py):

#!/usr/bin/env python3
from sch import codex


@codex.command(name="hello")
def hello() -> str:
    return "https://github.com/adammillerio/sch"


# Flask Application Factory
# Run with sch --app hello_world run
def create_app():
    return codex.create_app()

An extension of the flask CLI, sch is provided, which can be used both to run an HTTP server and to perform completions via the CLI:

sch --app hello_world search hello                    
https://github.com/adammillerio/sch

An example codex with some basic commands is provided at app.py. Flask will load ./app.py by default if --app is not provided.

To start the sch webserver, run the example codex from the root of this repository:

sch run
 * Debug mode: off
INFO:werkzeug:WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
 * Running on http://127.0.0.1:5000
INFO:werkzeug:Press CTRL+C to quit

And go to http://localhost:5000/sch?s=sch_help for usage info.

This leverages Flask Application Factories, which are used to generate the final Flask implementation at the end of the root codex. Above this, the Codex can be composed via importing commands or defining them directly as neecessary.

Usage

sch is best explained via hands on examples. This will demonstrate adding a single command to sch.

The Goal

Write a scholar command, gh, which performs the following actions:

• gh - Go to GitHub homepage
  • https://github.com
• gh {repo} - View a GitHub repo
  • https://github.com/{repo}
• gh search {repo} {query} - Search a GitHub repo
  • https://github.com/search?type=code&q=repo:{repo}+{query}
• gh search all {query} - Search all of GitHub
  • https://github.com/search?type=code&q={query}

Running Commands

Scholar commands can also be run interactively via the command line, which use a Flask test request context to execute the same HTTP request flow and display the generated redirect URL:

sch search gh
https://github.com
sch search gh search adammillerio/sch test search
https://github.com/search?type=code&q=repo:adammillerio%2Fsch+test+search

Defining Commands

Commands are organized in Python source files which register commands to the root codex.

An example root codex definition file looks like this:

#!/usr/bin/env python3
from sch import codex


@codex.command("gh")
def github(*args: str) -> str:
    """go to github"""

    return "https://github.com"

All commands have the same signature, any amount of strings as arguments, which generates another string. All actual HTTP redirection is handled by Flask. In this case, this is just a bookmark that makes gh go to the home page of GitHub:

sch search gh
https://github.com

This pattern is common enough that there is an add_bookmark command for quick registration:

from sch import codex

codex.add_bookmark("gh", "https://github.com", "github git host")

Accessing Arguments

All arguments to commands are strings, but they can be arbitrarily named as well as dynamic:

from sch import codex

@codex.command("gh")
def github(repo: str, *args: str) -> str:
    """go to github or view a repo"""

    if repo:
        return f"https://github.com/{repo}"
    else:
        return "https://github.com"

Now supplying a repo goes to the repo page as expected:

sch search gh adammillerio/sch
https://github.com/adammillerio/sch

Sub-Commands

Commands can have other Commands registered under them in order to handle specific named parameters:

from sch import query_args

@github.command("search")
def github_search(repo: str, *args: str) -> str:
    """search a github repo

    return https://github.com/search?type=code&q=repo:{repo}+{*args}
    """

    return f"https://github.com/search?type=code&q=repo:{query_args(repo, *args)}"


@github_search.command("all")
def github_search_all(*args: str) -> str:
    """search all of github

    return https://github.com/search?type=code&q={*args}
    """

    return f"https://github.com/search?type=code&q={query_args(*args)}"

This registers specific handlers for gh search and gh search all, which are reflected in the tree:

sch search gh sch_tree
gh - go to github or a view a repo
+-- search - search a github repo
   +-- all - search all of github

And also implements the last two search commands:

sch search gh search adammillerio/sch search query
https://github.com/search?type=code&q=repo:adammillerio%2Fsch+search+query
./sch.sh gh search all search query
sch search gh search all search query
https://github.com/search?type=code&q=search+query

These are search "proxies", which are basically just commands which take up all the unused arguments as *args and sends them off as a search to a specific place, such as GitHub. This is done via the query_args utility function.

Advanced Usage

Composing Commands

Commands can be composed without being registered to Scholar via the "generic" command decorator. For example, to make a factory for code bookmarks that generates GitHub and hosted doc links:

from sch import codex, command, Command, format_doc

def repo_command(repo: str, docs: str) -> Command:
    @command(tags=["code"])
    @format_doc(repo=repo)
    def code_repo() -> str:
        """go to {repo} on github"""

        return f"https://github.com/{repo}"

    @code_repo.command("docs")
    @format_doc(repo=repo)
    def code_repo_docs() -> str:
        """go to hosted docs for {repo}"""

        return docs
    
    return code_repo


codex.add_command(
    repo_command("pallets/click", "https://click.palletsprojects.com/en/8.1.x"),
    "click",
)
codex.add_command(
    repo_command("pallets/flask", "https://flask.palletsprojects.com/en/3.0.x/"),
    "flask",
)

Which registers code bookmark sets for click and flask:

sch search click
https://github.com/pallets/click
sch search click docs
https://click.palletsprojects.com/en/8.1.x
sch search flask
https://github.com/pallets/flask
sch search flask docs
https://flask.palletsprojects.com/en/3.0.x/

Additionally, the format_doc utility decorator can be used to format the Command's docstring after definition to provide context specific sch_help and sch_tree information.

Longform Command Help

To provide longform command help, a docstring can be provided:

from sch import codex

@codex.command("gh")
def github(repo: str, *args: str) -> str:
    """go to github or a view a repo
    
    If a repo is provided, go to the repo on GitHub.

    If no repo is provided, go to the GitHub homepage.
    """

    if repo:
        return f"https://github.com/{repo}"
    else:
        return "https://github.com"

The first line of the docstring will become the command short help, which will display in the sch_tree:

sch search gh sch_tree
gh - go to github or a view a repo
+-- search - search a github repo
   +--all - search all of github

The entire docstring will be printed if sch_help is the first argument to any command:

sch search gh sch_help
def sch gh(repo: Optional[str] = None) -> str:

        go to github or a view a repo
        
        if repo:
            return https://github.com/{repo}
        else:
            return https://github.com

Command Aliases

Commands can have aliases, which are alternative names that can be used during command resolution:

from sch import codex

@codex.command("help", aliases=["man"])
def help() -> str:
    return "/sch?s=sch_help"

sch search help sch_help      
def sch help{man}() -> str:
        return /sch?s=sch_help

sch search help         
/sch?s=sch_help

sch search man 
/sch?s=sch_help

Any command aliases will be displayed in curly braces next to the command name.

Command Tags

As an alternative method of organization, commands can be tagged on creation or during registration:

from sch import codex

@codex.command("google", tags=["google"])
def google() -> str:
    """google search""""

    return "https://google.com"


@google.command("drive", tags=["drive"])
def google_drive() -> str:
    """google drive"""

    return "https://drive.google.com"


@codex.command("youtube", tags=["google", "youtube"])
def youtube() -> str:
    """youtube"""

    return "https://youtube.com"

Tags can be used to filter the tree of commands:

sch search --tag google sch_tree
sch - scholar search engine
|-- google - google search
|   +-- drive - google drive
+-- youtube - youtube

sch search --tag drive sch_tree
sch - scholar search engine
+-- google - google search
   +-- drive - google drive

sch search --tag youtube sch_tree
sch - scholar search engine
+-- youtube - youtube

Subcommands inherit the tags of their parent command. For example, the google drive command has both the drive tag, and the google tag from the parent command.

In the web UI, all tags defined under the current view of commands will be shown at the top. Clicking any tag will manually filter to only that tag.

Default Command

If a command cannot be resolved during a query, a 404 is returned to the user. Scholar can be configured to instead run a default command with all of the provided arguments:

from sch import codex, query_args


# Default all not found commands to Google search
@codex.default_command()
def default_cmd(*args: str) -> str:
    return f"https://google.com/search?q={query_args(*args)}"

The default command is like any other command except that it is always called with ALL arguments to the query:

sch search this is not a real command
https://google.com/search?q=this+is+not+a+real+command

Auto-Reloading

To enable auto-reloading of the codex during development, run sch with the debug option, which enable's Flask's Debug Mode:

sch --debug run
 * Debug mode: on
WARNING: This is a development server. Do not use it in a production deployment. Use a production WSGI server instead.
 * Running on http://127.0.0.1:5000
Press CTRL+C to quit
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 275-051-761
127.0.0.1 - - [13/May/2024 23:02:25] "GET / HTTP/1.1" 302 -
127.0.0.1 - - [13/May/2024 23:02:25] "GET /sch?s=sch_tree HTTP/1.1" 200 -
 * Detected change in '/Users/aemiller/sch/example/base.py', reloading
 * Restarting with stat
 * Debugger is active!
 * Debugger PIN: 275-051-761

Exposing to the Internet

Sometimes it is useful to expose sch to the internet, ie to be used with mobile devices. To do this, first install a production WSGI server like Waitress:

pip install waitress

Then use the waitress-serve CLI to load and serve the Flask server:

waitress-serve --port 5000 --call app:create_app

More info on using Flask with Waitress is available in the Flask Docs

The WSGI server itself can then be exposed to the internet via reverse proxy via https. Be sure to change the URL scheme when doing this or generated URLs will be incorrect:

waitress-serve --port 5000 --url-scheme https --call app:create_app

Development

Install in development mode:

pip3 install -e '.[dev]'

Type Checking

Ensure no type errors are present with pyre:

pyre check              
ƛ No type errors found

Note: Pyre daemonizes itself on first run for faster subsequent executions. Be sure to shut it down with pyre kill when finished.

Formatting

Format code with the black formatter:

black click_tree
All done! ✨ 🍰 ✨