Security News
Internet Archive Hacked, 31 Million Record Compromised
The Internet Archive's "Wayback Machine" has been hacked and defaced, with 31 millions records compromised.
github.com/mna/pigeon
The pigeon command generates parsers based on a parsing expression grammar (PEG). Its grammar and syntax is inspired by the PEG.js project, while the implementation is loosely based on the parsing expression grammar for C# 3.0 article. It parses Unicode text encoded in UTF-8.
See the godoc page for detailed usage. Also have a look at the Pigeon Wiki for additional information about Pigeon and PEG in general.
Github user @mna created the package in April 2015, and @breml is the package's maintainer as of May 2017.
Starting of June 2023, the backwards compatibility support for pigeon
is changed to follow the official Go Security Policy.
Over time, the Go ecosystem is evolving.
On one hand side, packages like golang.org/x/tools, which are critical dependencies of pigeon
, do follow the official Security Policy and with pigeon
not following the same guidelines, it was no longer possible to include recent versions of these dependencies and with this it was no longer possible to include critical bugfixes.
On the other hand there are changes to what is considered good practice by the greater community (e.g. change from interface{}
to any
). For users following (or even enforcing) these good practices, the code generated by pigeon
does no longer meet the bar of expectations.
Last but not least, following the Go Security Policy over the last years has been a smooth experience and therefore updating Go on a regular bases feels like duty that is reasonable to be put on users of pigeon
.
This observations lead to the decision to follow the same Security Policy as Go.
Provided you have Go correctly installed with the $GOPATH and $GOBIN environment variables set, run:
$ go get -u github.com/mna/pigeon
This will install or update the package, and the pigeon
command will be installed in your $GOBIN directory. Neither this package nor the parsers generated by this command require any third-party dependency, unless such a dependency is used in the code blocks of the grammar.
$ pigeon [options] [PEG_GRAMMAR_FILE]
By default, the input grammar is read from stdin
and the generated code is printed to stdout
. You may save it in a file using the -o
flag.
Given the following grammar:
{
// part of the initializer code block omitted for brevity
var ops = map[string]func(int, int) int {
"+": func(l, r int) int {
return l + r
},
"-": func(l, r int) int {
return l - r
},
"*": func(l, r int) int {
return l * r
},
"/": func(l, r int) int {
return l / r
},
}
func toAnySlice(v any) []any {
if v == nil {
return nil
}
return v.([]any)
}
func eval(first, rest any) int {
l := first.(int)
restSl := toAnySlice(rest)
for _, v := range restSl {
restExpr := toAnySlice(v)
r := restExpr[3].(int)
op := restExpr[1].(string)
l = ops[op](l, r)
}
return l
}
}
Input <- expr:Expr EOF {
return expr, nil
}
Expr <- _ first:Term rest:( _ AddOp _ Term )* _ {
return eval(first, rest), nil
}
Term <- first:Factor rest:( _ MulOp _ Factor )* {
return eval(first, rest), nil
}
Factor <- '(' expr:Expr ')' {
return expr, nil
} / integer:Integer {
return integer, nil
}
AddOp <- ( '+' / '-' ) {
return string(c.text), nil
}
MulOp <- ( '*' / '/' ) {
return string(c.text), nil
}
Integer <- '-'? [0-9]+ {
return strconv.Atoi(string(c.text))
}
_ "whitespace" <- [ \n\t\r]*
EOF <- !.
The generated parser can parse simple arithmetic operations, e.g.:
18 + 3 - 27 * (-18 / -3)
=> -141
More examples can be found in the examples/
subdirectory.
See the package documentation for detailed usage.
See the CONTRIBUTING.md file.
The BSD 3-Clause license. See the LICENSE file.
FAQs
Unknown package
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Security News
The Internet Archive's "Wayback Machine" has been hacked and defaced, with 31 millions records compromised.
Security News
TC39 is meeting in Tokyo this week and they have approved nearly a dozen proposals to advance to the next stages.
Security News
Our threat research team breaks down two malicious npm packages designed to exploit developer trust, steal your data, and destroy data on your machine.