README
¶
abnf
ABNF LL-parser by golang
How to use
Make Parser function
Make parser function that implement Rule interface. Functions that returns Basic Operator Rule are provided by this package.
For example,
abnf.C(Rule...)function returns Rule that concatenate all argument Rules.abnf.V(rune)function returns Rule that match argument rune.abnf.ALPHA()function returns Rule that match any alphanumeric text.abnf.ETX()function returns Rule that match no more text is left.
Combile multiple Basic Operator by set each function to arguement.
abnf.C(abnf.V('-'), abnf.ALPHANUM()) will make Rule that match aplhanumeric text taht start with -.
Parse Text by created Parser
Call abnf.ParseString(string, Rule) function with created Rule. The string will parsed and parsed item Tree is returned.
If text is not match with Rule, nil is returned.
Get parsed value from Tree
Tree contains parsed value with tag. tree.Child(tag).V returns value that correlated with specified tag.
Tag is defined while making parser function. There is special function abnf.K(Rule, tag) that make Special Rule that define tag.
Example
This sample parse FQDN.
Identity ::= label *("." label)
label ::= ALPHANUM *ldhstr
ldhstr ::= ALPHANUM / ("-" ALPHANUM)
const (
idFQDN int = iota
)
type Identity string
func ParseIdentity(str string) (id Identity, e error) {
t := abnf.ParseString(str, _identity())
if t == nil {
e = fmt.Errorf("Invalid id text")
} else {
id = Identity(t.Child(idFQDN).V)
}
return
}
func _identity() abnf.Rule {
return abnf.C(_fqdn(), abnf.ETX())
}
func _fqdn() abnf.Rule {
return abnf.K(abnf.C(_label(), abnf.R0(abnf.C(abnf.V('.'), _label()))), idFQDN)
}
func _label() abnf.Rule {
return abnf.C(abnf.ALPHANUM(), abnf.R0(_ldhstr()))
}
func _ldhstr() abnf.Rule {
return abnf.A(abnf.ALPHANUM(), abnf.C(abnf.V('-'), abnf.ALPHANUM()))
}
Notice
This parser is LL parser. You should modify somae of ABNF definition to apply them this package.
License
MIT
Documentation
¶
Index ¶
- type Rule
- func A(r ...Rule) Rule
- func ALPHA() Rule
- func ALPHANUM() Rule
- func BIT() Rule
- func C(r ...Rule) Rule
- func CHAR() Rule
- func CR() Rule
- func CRLF() Rule
- func CTL() Rule
- func DIGIT() Rule
- func DQUOTE() Rule
- func ETX() Rule
- func HEXDIG() Rule
- func HTAB() Rule
- func K(r Rule, k int) Rule
- func LF() Rule
- func LHEX() Rule
- func LWSP() Rule
- func N(r Rule) Rule
- func O(r Rule) Rule
- func OCTET() Rule
- func R0(r Rule) Rule
- func R1(r Rule) Rule
- func RN(n int, r Rule) Rule
- func RV(min int, max int, r Rule) Rule
- func SP() Rule
- func V(c rune) Rule
- func VCHAR() Rule
- func VI(s string) Rule
- func VIL(sl ...string) Rule
- func VL(cl ...rune) Rule
- func VR(h rune, t rune) Rule
- func VS(s string) Rule
- func VSL(sl ...string) Rule
- func WSP() Rule
- type Tree
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Rule ¶
type Rule func(s *scanner) []rune
Rule is rule function of ABNF
func A ¶
A is Alternatives(Rule1 / Rule2) Incremental Alternatives: Rule1 =/ Rule2 different or ETX -> nil
func O ¶
O is Optional Sequence([RULE]) match -> []rune of match value different or ETX -> empty []rune
func RV ¶
RV is Variable Repetition(*Rule) match -> []rune of match value different or ETX -> nil If max=-1 then max=infinity.
type Tree ¶
Tree is tree structure that contains pair of key and value
func ParseReader ¶
func ParseReader(r io.RuneReader, blen, slen int, f Rule) *Tree
ParseReader parse reader value by Rule
func (*Tree) AllChildren ¶
AllChildren return all children
Source Files