README.md

YaccGo

Through Google has tool about yacc named goyacc, But it generate go code can not debug! see the issue

golang/vscode-go#1674 (comment)

I tried to modify the codes, It is not good readable, and I have no patient to do it, So I write a YaccGo

YaccGo is an understandable and debugable Yacc in Go. . It is written in Go and generates parsers written in Go ,typescript, rust ...

Quick Start

clone the code

make all
# generate the typescript parser code
bin/yaccgo generate typescript examples/exprts.y expts.ts

at your y file You should do as follower more in manual

Trace

After generate the parse code, modify the var IsTrace bool = false to var IsTrace bool = true , then you can see the trace of the parser. feature completed for go, other are WIP. for example:

bin/yaccgo generate go examples/ladd.y out/ladd.go

then you modify the ladd.go file, change code var IsTrace bool = false to var IsTrace bool = true, then

go run out/ladd.go

You can see trace information

look ahead NUM, use Reduce:PROG -> , go to state 1
Shift PROG, push state 1
Shift NUM, push state 3
look ahead PLUS, use Reduce:E -> NUM , go to state 2
Shift E, push state 2
Shift PLUS, push state 5
Shift NUM, push state 3
look ahead NL, use Reduce:E -> NUM , go to state 6
Shift E, push state 6
look ahead NL, use Reduce:E -> E PLUS E , go to state 2
Shift E, push state 2
Shift NL, push state 4
3
look ahead $, use Reduce:PROG -> PROG E NL , go to state 1
Shift PROG, push state 1
0

parser with context

if you want build several parser in one app, you should use generate parser with context. Now it is just supported in Go add -o option in generate command, for example:

 bin/yaccgo generate go  -o examples/e.y  out/e.go 

then, you should make context before using the parser, for example like this:

func main() {
	c := MakeParserContext()
	v := c.Parser("nnn")
	fmt.Println(v)
}

Web Debuger

If you want to debug the parser visually, you can use yaccgo debuger in browser.

1. generate http debuger parser

./bin/yaccgo generate go --httpdebug=true examples/exprhttp.y out/expr.go

2. run http debuger

go run out/expr.go

3. open the debugTool.html in browser

Design

LALR1 Algorithm Base on

https://hassan-ait-kaci.net/pdf/others/p615-deremer.pdf

Lexer inspired from

https://www.youtube.com/watch?v=HxaD_trXwRE

RoadMap

1. support language:

• go

• typescript

• rust

2. DotGraph

   surpose your machine has got dot , or you can install it from https://graphviz.org/download/

   if you want to see the LALR DFA(deterministic finite automata) diagram. use the -g or --dotg=

   for example:

   bin/yaccgo generate go -g./expr.png -o ./examples/exprobj.y ./out/exprobj.go

you can see the diagram as follow:

Project use yaccgo

see wiki and add your own project to it

Contributing

Welcome to contributing, We appreciate your help! please make sure

• staticcheck no error
• codes should has test

ChangeLogs

2022.5.30

1. Optimize the packtable use action default values and goto default values
2. use the template to generate the Code
3. reserve the old codes but it will deprecate them in future 2022.9.22
4. add the oop code generator 2022.11.4
5. support dot graphviz

License

MIT