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Daniel Bertalan 22195d965f DevTools: Add StateMachineGenerator utility
This program turns a description of a state machine that takes its input
byte-by-byte into C++ code. The state machine is described in a custom
format as specified below:

```
// Comments are started by two slashes, and cause the rest of the line
// to be ignored

@name ExampleStateMachine // sets the name of the generated class
@namespace Test           // sets the namespace (optional)
@begin Begin              // sets the state the parser will start in

// The rest of the file contains one or more states and an optional
// @anywhere directive. Each of these is a curly bracket delimited set
// of state transitions. State transitions contain a selector, the
// literal "=>" and a (new_state, action) tuple. Examples:
//     0x0a => (Begin, PrintLine)
//     [0x00..0x1f] => (_, Warn)      // '_' means no change
//     [0x41..0x5a] => (BeginWord, _) // '_' means no action

// Rules common to all states. These take precedence over rules in the
// specific states.
@anywhere {
    0x0a         => (Begin, PrintLine)
    [0x00..0x1f] => (_, Warn)
}

Begin {
    [0x41..0x5a] => (Word, _)
    [0x61..0x7a] => (Word, _)
    // For missing values, the transition (_, _) is implied
}

Word {
    // The entry action is run when we transition to this state from a
    // *different* state. @anywhere can't have this
    @entry IncreaseWordCount
    0x09 => (Begin, _)
    0x20 => (Begin, _)

    // The exit action is run before we transition to any *other* state
    // from here. @anywhere can't have this
    @exit EndOfWord
}
```

The generated code consists of a single class which takes a
`Function<Action, u8>` as a parameter in its constructor. This gets
called whenever an action is to be done. This is because some input
might not produce an action, but others might produce up to 3 (exit,
state transition, entry). The actions allow us to build a more
advanced parser over the simple state machine.

The sole public method, `void advance(u8)`, handles the input
byte-by-byte, managing the state changes and requesting the appropriate
Action from the handler.

Internally, the state transitions are resolved via a lookup table. This
is a bit wasteful for more complex state machines, therefore the
generator is designed to be easily extendable with a switch-based
resolver; only the private `lookup_state_transition` method needs to be
re-implemented.

My goal for this tool is to use it for implementing a standard-compliant
ANSI escape sequence parser for LibVT, as described on
<https://vt100.net/emu/dec_ansi_parser>
2021-05-16 11:50:56 +02:00
.github Meta: Add a check for periods on the end of titles to commit linter 2021-05-16 01:25:24 +01:00
AK AK+Kernel+LibELF: Remove the need for IteratorDecision::Continue 2021-05-16 10:36:52 +01:00
Base PixelPaint: Style the application name as "Pixel Paint" :^) 2021-05-16 01:11:56 +02:00
Documentation Documentation: Add my machine to hardware compatibility list (#7152) 2021-05-15 22:55:23 +02:00
Kernel AK+Kernel+LibELF: Remove the need for IteratorDecision::Continue 2021-05-16 10:36:52 +01:00
Meta Meta: Add a check for periods on the end of titles to commit linter 2021-05-16 01:25:24 +01:00
Ports Ports: Add port for Brogue (BrogueCE) 2021-05-15 10:13:43 +01:00
Tests Tests: Add LibELF tests 2021-05-15 11:02:04 +01:00
Toolchain Toolchain+Ports: Skip link tests for libstdc++v3 2021-05-09 15:35:01 +02:00
Userland DevTools: Add StateMachineGenerator utility 2021-05-16 11:50:56 +02:00
.clang-format Meta: Update .clang-format to not indent nested namespaces 2020-03-14 10:10:21 +01:00
.gitattributes Meta: Add .gitattributes file 2020-07-30 17:07:40 +02:00
.gitignore Meta: Add basic Zsh completions for serenity.sh 2021-04-22 09:55:48 +02:00
.pre-commit-config.yaml Meta: Add a post-commit commit message linter hook 2021-05-02 16:28:01 +02:00
.prettierignore Meta: Add lint-prettier.sh 2020-12-27 21:25:27 +01:00
.prettierrc Meta: Move prettier config files to the root of the repository 2020-08-24 18:21:33 +02:00
CMakeLists.txt DevTools: Add StateMachineGenerator utility 2021-05-16 11:50:56 +02:00
CONTRIBUTING.md Meta: Discourage commit subject lines ending with a period 2021-05-16 00:33:47 +01:00
LICENSE Everywhere: Use "the SerenityOS developers." in copyright headers 2021-04-29 00:59:26 +02:00
README.md Meta: Fix broken FAQ link in README 2021-05-09 09:15:56 +02:00

SerenityOS

Graphical Unix-like operating system for x86 computers.

Build status Fuzzing Status Discord

About

SerenityOS is a love letter to '90s user interfaces with a custom Unix-like core. It flatters with sincerity by stealing beautiful ideas from various other systems.

Roughly speaking, the goal is a marriage between the aesthetic of late-1990s productivity software and the power-user accessibility of late-2000s *nix. This is a system by us, for us, based on the things we like.

I (Andreas) regularly post raw hacking sessions and demos on my YouTube channel.

Sometimes I write about the system on my github.io blog.

I'm also on Patreon and GitHub Sponsors if you would like to show some support that way.

Screenshot

Screenshot as of 0f85753.png

Kernel features

  • x86 (32-bit) kernel with pre-emptive multi-threading
  • Hardware protections (SMEP, SMAP, UMIP, NX, WP, TSD, ...)
  • IPv4 stack with ARP, TCP, UDP and ICMP protocols
  • ext2 filesystem
  • POSIX signals
  • Purgeable memory
  • /proc filesystem
  • Pseudoterminals (with /dev/pts filesystem)
  • Filesystem notifications
  • CPU and memory profiling
  • SoundBlaster 16 driver
  • VMWare/QEMU mouse integration

System services

  • Launch/session daemon (SystemServer)
  • Compositing window server (WindowServer)
  • Text console manager (TTYServer)
  • DNS client (LookupServer)
  • Network protocols server (RequestServer and WebSocket)
  • Software-mixing sound daemon (AudioServer)
  • Desktop notifications (NotificationServer)
  • HTTP server (WebServer)
  • Telnet server (TelnetServer)
  • DHCP client (DHCPClient)

Libraries

  • C++ templates and containers (AK)
  • Event loop and utilities (LibCore)
  • 2D graphics library (LibGfx)
  • GUI toolkit (LibGUI)
  • Cross-process communication library (LibIPC)
  • HTML/CSS engine (LibWeb)
  • JavaScript engine (LibJS)
  • Markdown (LibMarkdown)
  • Audio (LibAudio)
  • PCI database (LibPCIDB)
  • Terminal emulation (LibVT)
  • Out-of-process network protocol I/O (LibProtocol)
  • Mathematical functions (LibM)
  • ELF file handling (LibELF)
  • POSIX threading (LibPthread)
  • Higher-level threading (LibThread)
  • Transport Layer Security (LibTLS)
  • HTTP and HTTPS (LibHTTP)

Userland features

  • Unix-like libc and userland
  • Shell with pipes and I/O redirection
  • On-line help system (both terminal and GUI variants)
  • Web browser (Browser)
  • C++ IDE (HackStudio)
  • IRC client
  • Desktop synthesizer (Piano)
  • Various desktop apps & games
  • Color themes

How do I read the documentation?

Man pages are available online at man.serenityos.org. These pages are generated from the Markdown source files in Base/usr/share/man and updated automatically.

When running SerenityOS you can use man for the terminal interface, or help for the GUI.

How do I build and run this?

See the SerenityOS build instructions

Before opening an issue

Please see the issue policy.

FAQ: Frequently Asked Questions

Get in touch

IRC: #serenityos on the Freenode IRC network.

Discord: SerenityOS Discord

Author

Contributors

(And many more!) The people listed above have landed more than 100 commits in the project. :^)

License

SerenityOS is licensed under a 2-clause BSD license.