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