abnf-parser

Go library for Parsing the syntax defined in ABNF.

1. Concept

1.1. Finder

This library provides Finders.
Finder is the struct that has the methods named Find and Copy.

type Finder interface {
	Find(data []byte) (found bool, end int)
	Copy() Finder
}

1.1.1. Finder.Find

Finder.Find(data []byte) (found bool, end int) method finds the specific ABNF syntax such as ALPHA, DIGIT, Concatenation, Alternatives, etc. from the beginning of the data.
If it finds the syntax, it returns true as found and the end of the syntax as end.

Example

For example, this library provides AlphaFinder.
This Finder finds ALPHA from data.
When you call its Find method with data []byte{ 'a', 'b', 'c', }, it search ALPHA from the beginning of data. Then it returns true, 1 because data has 'a' at the beginning.

package main

import (
	"fmt"

	abnfp "github.com/um7a/abnf-parser"
)

func main() {
	var data []byte = []byte{'a', 'b', 'c'}
	alpha := abnfp.NewAlphaFinder()
	found, end := alpha.Find(data)
	fmt.Printf("%v, %v\n", found, end) // -> true, 1
}

1.1.2. Finder.Copy

Finder.Copy() Finder method returns the copy of the Finder.
Some Finders have other finders as its child. This method also copies them. Note that this is the deep copy.

Example

package main

import (
	"fmt"

	abnfp "github.com/um7a/abnf-parser"
)

func main() {
	alpha1 := abnfp.NewAlphaFinder()
	alpha2 := alpha1.Copy()

	var data []byte = []byte{'a', 'b', 'c'}
	found, end := alpha2.Find(data)
	fmt.Printf("%v, %v\n", found, end) // -> true, 1
}

1.2. Parse

The only utility provided by this library other than Finder is Parse function.

func Parse(data []byte, finder Finder) (parsed []byte, remaining []byte)

Parse function returns the parsed data as parsed and the remaining data as remaining.

Example

For example, when data is []byte{'a', 'b', 'c'} and finder is AlphaFinder,
Parse function parses ALPHA from data and returns []byte{'a'}, []byte{'b', 'c'}

package main

import (
	"fmt"

	abnfp "github.com/um7a/abnf-parser"
)

func main() {
	var data []byte = []byte{'a', 'b', 'c'}
	parsed, remaining := abnfp.Parse(data, abnfp.NewAlphaFinder())
	fmt.Printf("parsed: %s, remaining: %s\n", parsed, remaining)
	// -> parsed: a, remaining: bc
}