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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>
|
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|---|---|---|
| .github | ||
| AK | ||
| Base | ||
| Documentation | ||
| Kernel | ||
| Meta | ||
| Ports | ||
| Tests | ||
| Toolchain | ||
| Userland | ||
| .clang-format | ||
| .gitattributes | ||
| .gitignore | ||
| .pre-commit-config.yaml | ||
| .prettierignore | ||
| .prettierrc | ||
| CMakeLists.txt | ||
| CONTRIBUTING.md | ||
| LICENSE | ||
| README.md | ||
SerenityOS
Graphical Unix-like operating system for x86 computers.
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
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
- Andreas Kling - awesomekling
Contributors
- Robin Burchell - rburchell
- Conrad Pankoff - deoxxa
- Sergey Bugaev - bugaevc
- Liav A - supercomputer7
- Linus Groh - linusg
- Ali Mohammad Pur - alimpfard
- Shannon Booth - shannonbooth
- Hüseyin ASLITÜRK - asliturk
- Matthew Olsson - mattco98
- Nico Weber - nico
- Brian Gianforcaro - bgianfo
- Ben Wiederhake - BenWiederhake
- Tom - tomuta
- Paul Scharnofske - asynts
- Itamar Shenhar - itamar8910
- Luke Wilde - Lubrsi
- Brendan Coles - bcoles
- Andrew Kaster - ADKaster
- thankyouverycool - thankyouverycool
- Idan Horowitz - IdanHo
- Gunnar Beutner - gunnarbeutner
- Tim Flynn - trflynn89
(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.