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|
package urn
import (
"fmt"
)
var (
errPrefix = "expecting the prefix to be the \"urn\" string (whatever case) [col %d]"
errIdentifier = "expecting the identifier to be string (1..31 alnum chars, also containing dashes but not at its start) [col %d]"
errSpecificString = "expecting the specific string to be a string containing alnum, hex, or others ([()+,-.:=@;$_!*']) chars [col %d]"
errNoUrnWithinID = "expecting the identifier to not contain the \"urn\" reserved string [col %d]"
errHex = "expecting the specific string hex chars to be well-formed (%%alnum{2}) [col %d]"
errParse = "parsing error [col %d]"
)
%%{
machine urn;
# unsigned alphabet
alphtype uint8;
action mark {
m.pb = m.p
}
action tolower {
m.tolower = append(m.tolower, m.p - m.pb)
}
action set_pre {
output.prefix = string(m.text())
}
action set_nid {
output.ID = string(m.text())
}
action set_nss {
raw := m.text()
output.SS = string(raw)
// Iterate upper letters lowering them
for _, i := range m.tolower {
raw[i] = raw[i] + 32
}
output.norm = string(raw)
}
action err_pre {
m.err = fmt.Errorf(errPrefix, m.p)
fhold;
fgoto fail;
}
action err_nid {
m.err = fmt.Errorf(errIdentifier, m.p)
fhold;
fgoto fail;
}
action err_nss {
m.err = fmt.Errorf(errSpecificString, m.p)
fhold;
fgoto fail;
}
action err_urn {
m.err = fmt.Errorf(errNoUrnWithinID, m.p)
fhold;
fgoto fail;
}
action err_hex {
m.err = fmt.Errorf(errHex, m.p)
fhold;
fgoto fail;
}
action err_parse {
m.err = fmt.Errorf(errParse, m.p)
fhold;
fgoto fail;
}
pre = ([uU][rR][nN] @err(err_pre)) >mark %set_pre;
nid = (alnum >mark (alnum | '-'){0,31}) %set_nid;
hex = '%' (digit | lower | upper >tolower){2} $err(err_hex);
sss = (alnum | [()+,\-.:=@;$_!*']);
nss = (sss | hex)+ $err(err_nss);
fail := (any - [\n\r])* @err{ fgoto main; };
main := (pre ':' (nid - pre %err(err_urn)) $err(err_nid) ':' nss >mark %set_nss) $err(err_parse);
}%%
%% write data noerror noprefix;
// Machine is the interface representing the FSM
type Machine interface {
Error() error
Parse(input []byte) (*URN, error)
}
type machine struct {
data []byte
cs int
p, pe, eof, pb int
err error
tolower []int
}
// NewMachine creates a new FSM able to parse RFC 2141 strings.
func NewMachine() Machine {
m := &machine{}
%% access m.;
%% variable p m.p;
%% variable pe m.pe;
%% variable eof m.eof;
%% variable data m.data;
return m
}
// Err returns the error that occurred on the last call to Parse.
//
// If the result is nil, then the line was parsed successfully.
func (m *machine) Error() error {
return m.err
}
func (m *machine) text() []byte {
return m.data[m.pb:m.p]
}
// Parse parses the input byte array as a RFC 2141 string.
func (m *machine) Parse(input []byte) (*URN, error) {
m.data = input
m.p = 0
m.pb = 0
m.pe = len(input)
m.eof = len(input)
m.err = nil
m.tolower = []int{}
output := &URN{}
%% write init;
%% write exec;
if m.cs < first_final || m.cs == en_fail {
return nil, m.err
}
return output, nil
}
|
