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abnf.go
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abnf.go
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package abnf // import "github.com/nathanaelle/abnf"
import (
"fmt"
"strconv"
"strings"
)
var Verbose bool
type ABNFEngine struct {
*Grammar
}
func ABNF() ABNFEngine {
g := NewGrammar("rulelist")
g.set("alpha" ,choice(extents('A','Z'),extents('a','z'))) // A-Z / a-z
g.set("bit" ,choice(single_ci('0'),single_ci('1')))
g.set("char" ,extents(0x01,0x7F)) // any 7-bit US-ASCII character excluding NUL
g.set("cr" ,single_byte(0x0D)) // carriage return
g.set("lf" ,single_byte(0x0A)) // linefeed
g.set("crlf" ,concat(g.get("cr"), g.get("lf"))) // Internet standard newline
g.set("CTL" ,choice(extents(0x00,0x1F), single_byte(0x7F))) // controls
g.set("digit" ,extents('0','9')) // 0-9
g.set("hexdig" ,choice(g.get("digit"),single_ci('A'),single_ci('B'),single_ci('C'),single_ci('D'),single_ci('E'),single_ci('F')))
g.set("dquote" ,single_byte(0x22)) // " (Double Quote)
g.set("octet" ,extents(0x00,0xFF)) // 8 bits of data
g.set("vchar" ,extents(0x21,0x7E)) // visible (printing) characters
g.set("htab" ,single_byte(0x09)) // horizontal tab
g.set("sp" ,single_byte(0x20))
g.set("wsp" ,choice(g.get("sp"),g.get("htab"))) // white space
// Use of this linear-white-space rule
// permits lines containing only white
// space that are no longer legal in
// mail headers and have caused
// interoperability problems in other
// contexts.
// Do not use when defining mail headers and use with caution in other contexts.
g.set("lwsp" ,star(0,0,group(choice(g.get("wsp"), concat(g.get("crlf"),g.get("wsp"))))))
// bracketed string of SP and VCHAR without angles
// prose description, to be used as last resort
g.set("prose-val", concat(single_ci('<'), star(0,0,group(choice(extents(0x20,0x3D), extents(0x3F,0x7E)))), single_ci('>')))
// series of concatenated bit values or single ONEOF range
g.set("bin-val", concat(single_ci('b'), star(1,0, g.get("bit") ), option( star(1,0,choice(group(single_ci('.'), star(1,0, g.get("bit") )), group(single_ci('-'),star(1,0, g.get("bit") )))))))
g.set("dec-val", concat(single_ci('d'), star(1,0, g.get("digit") ), option( star(1,0,choice(group(single_ci('.'), star(1,0, g.get("digit") )), group(single_ci('-'),star(1,0, g.get("digit") )))))))
g.set("hex-val", concat(single_ci('x'), star(1,0, g.get("hexdig") ), option( star(1,0,choice(group(single_ci('.'), star(1,0, g.get("hexdig") )), group(single_ci('-'),star(1,0, g.get("hexdig") )))))))
g.set("num-val", concat(single_ci('%'), group(choice( g.get("bin-val") , g.get("dec-val") , g.get("hex-val") ))))
// quoted string of SP and VCHAR without DQUOTE
g.set("quoted-string", concat( g.get("dquote") , star(0,0,group(choice(extents(0x20,0x21), extents(0x23,0x7E)))), g.get("dquote") ))
g.set("case-insensitive-string", concat(option(single_ci('%','i')), g.get("quoted-string")))
g.set("case-sensitive-string", concat(single_ci('%','s'), g.get("quoted-string")))
g.set("char-val", choice(g.get("Case-insensitive-string"),g.get("Case-sensitive-string")))
g.set("comment", concat(single_ci(';'), star(0,0,group(choice( g.get("wsp") , g.get("vchar") ))), g.get("crlf") ))
g.set("c-nl", choice( g.get("comment") , g.get("crlf") )) // comment or newline
g.set("c-wsp", choice( g.get("wsp") , group( g.get("c-nl") , g.get("wsp") ) ))
g.set("group", concat( single_ci('('), star(0,0, g.get("c-wsp") ), g.get("Alternation") ,star(0,0, g.get("c-wsp") ), single_ci(')')))
g.set("option", concat( single_ci('['), star(0,0, g.get("c-wsp") ), g.get("Alternation") ,star(0,0, g.get("c-wsp") ), single_ci(']')))
g.set("element", choice( g.get("Rulename") , g.get("Group") , g.get("Option") , g.get("Char-val") , g.get("Num-val") , g.get("Prose-val") ))
g.set("repeat", choice( star(1,0, g.get("digit")), group( star(0,0, g.get("digit")), single_ci('*'), star(0,0, g.get("digit")) )))
g.set("repetition", concat(option( g.get("Repeat") ), g.get("Element") ))
g.set("concatenation", concat( g.get("Repetition") , star(0,0,group(star(1,0, g.get("c-wsp") ), g.get("Repetition") ))))
g.set("alternation", concat( g.get("Concatenation") , star(0,0,group(star(0,0, g.get("c-wsp") ), single_ci('/'), star(0,0, g.get("c-wsp") ), g.get("Concatenation") ))))
g.set("elements", concat( g.get("Alternation") , star(0,0, g.get("wsp") )))
// basic rules definition and incremental alternatives
g.set("defined-as", concat(star(0,0, g.get("c-wsp") ), group(choice(single_ci('='),single_ci('=','/'))), star(0,0, g.get("c-wsp") )))
g.set("rulename", concat( g.get("alpha") , star(0,0,group( choice( g.get("alpha") , g.get("digit") , single_ci('-'))))))
// continues if next line starts with white space
g.set("rule", concat( g.get("Rulename") , g.get("Defined-as") , g.get("Elements") , g.get("c-nl") ))
g.set("rulelist", star(1,0,group(choice( g.get("Rule") , group(star(0,0, g.get("wsp") ), g.get("c-nl") )))))
return ABNFEngine { g }
}
func (ABNFEngine) Compile(T Target, start string) *Grammar {
g := NewGrammar(start)
cleaned_target := T.Drop("c-wsp","c-nl").Merge("Defined-as","Rulename","dquote","digit","hexdig","quoted-string","alpha","")
for _,rule := range cleaned_target.Childs {
switch string(rule.Childs[1].Value) {
case "=": g.set(string(rule.Childs[0].Value), compile(g,rule.Childs[2]))
default: panic("don't know hwo to : "+ rule.String())
}
}
return g
}
func to_int(b[]byte,base int) int {
v,_ := strconv.ParseInt(string(b), base, 64)
return int(v)
}
func to_byte(b[]byte,base int) byte {
v,_ := strconv.ParseInt(string(b), base, 64)
return byte(v)
}
func compile(g *Grammar, target Target) Expression {
switch strings.ToUpper(target.Rule) {
case "RULENAME":
return g.get(string(target.Value))
case "GROUP":
return group(compile(g,target.Childs[1]))
case "OPTION":
return option(compile(g,target.Childs[1]))
case "ALTERNATION":
exprs := []Expression {}
for i,c := range target.Childs {
if i%2 == 0 {
exprs = append(exprs, compile(g,c))
}
}
return choice(exprs...)
case "CONCATENATION":
exprs := []Expression {}
for _,c := range target.Childs {
exprs = append(exprs, compile(g,c))
}
return concat(exprs...)
case "REPETITION":
if len(target.Childs) == 1 {
return star(1,1,compile(g,target.Childs[0]))
}
repeat := target.Childs[0]
min := 0
max := 0
switch len(repeat.Childs){
case 3:
min = to_int(repeat.Childs[0].Value,10)
max = to_int(repeat.Childs[2].Value,10)
case 2:
if(string(repeat.Childs[1].Value) == "*"){
min = to_int(repeat.Childs[0].Value,10)
} else {
max = to_int(repeat.Childs[1].Value,10)
}
case 1:
if(string(repeat.Childs[0].Value) != "*"){
min = to_int(repeat.Childs[0].Value,10)
max = to_int(repeat.Childs[0].Value,10)
}
}
return star(min,max,compile(g,target.Childs[1]))
case "QUOTED-STRING":
return single_ci(target.Value[1:len(target.Value)-1]...)
case "CASE-INSENSITIVE-STRING":
return mutator_ci(compile(g,target.Childs[len(target.Childs)-1]))
case "CASE-SENSITIVE-STRING":
return mutator_cs(compile(g,target.Childs[1]))
case "NUM-VAL":
return compile(g,target.Childs[1])
case "HEX-VAL":
if len(target.Childs) == 2 {
min := to_byte(target.Childs[1].Value,16)
return single_byte(min)
}
if len(target.Childs) == 4 && string(target.Childs[2].Value) == "-" {
min := to_byte(target.Childs[1].Value,16)
max := to_byte(target.Childs[3].Value,16)
return extents(min,max)
}
panic("Don't know how to cope with "+target.String() )
case "DEC-VAL":
if len(target.Childs) == 2 {
min := to_byte(target.Childs[1].Value,10)
return single_byte(min)
}
if len(target.Childs) == 4 && string(target.Childs[2].Value) == "-" {
min := to_byte(target.Childs[1].Value,10)
max := to_byte(target.Childs[3].Value,10)
return extents(min,max)
}
panic("Don't know how to cope with "+target.String() )
default:
if len(target.Childs) > 0 && len(target.Value) > 0 {
panic("Don't know how to cope with "+target.String() )
}
if len(target.Childs) == 0 && len(target.Value) == 0 {
panic("Don't know how to cope with "+target.String() )
}
if len(target.Childs) == 0 && len(target.Value) > 0 {
return single_cs(target.Value...)
}
if len(target.Childs) == 1 {
return compile(g,target.Childs[0])
}
fmt.Println("Don't know how to cope with "+target.Rule )
for _,c := range target.Childs {
fmt.Println("[", c.String() ,"]")
}
panic("Don't know how to cope with "+target.String() )
}
}