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liquid/expression/scanner.rl
2017-07-12 14:25:41 -04:00

115 lines
2.4 KiB
Ragel

package expression
import "strconv"
%%{
machine expression;
write data;
access lex.;
variable p lex.p;
variable pe lex.pe;
}%%
type lexer struct {
data []byte
p, pe, cs int
ts, te, act int
val func(Context) interface{}
}
func (l* lexer) token() string {
return string(l.data[l.ts:l.te])
}
func newLexer(data []byte) *lexer {
lex := &lexer{
data: data,
pe: len(data),
}
%% write init;
return lex
}
func (lex *lexer) Lex(out *yySymType) int {
eof := lex.pe
tok := 0
%%{
action Bool {
tok = LITERAL
out.val = lex.token() == "true"
fbreak;
}
action Identifier {
tok = IDENTIFIER
out.name = lex.token()
fbreak;
}
action Int {
tok = LITERAL
n, err := strconv.ParseInt(lex.token(), 10, 64)
if err != nil {
panic(err)
}
out.val = int(n)
fbreak;
}
action Float {
tok = LITERAL
n, err := strconv.ParseFloat(lex.token(), 64)
if err != nil {
panic(err)
}
out.val = n
fbreak;
}
action String {
tok = LITERAL
// TODO unescape \x
out.val = string(lex.data[lex.ts+1:lex.te-1])
fbreak;
}
action Relation { tok = RELATION; out.name = lex.token(); fbreak; }
identifier = (alpha | '_') . (alnum | '_' | '-')* '?'? ;
# TODO what can a property name contain?
property = '.' (alnum | '_' | '-')+ '?' ? ;
int = '-'? digit+ ;
float = '-'? (digit+ '.' digit* | '.' digit+) ;
string = '"' (any - '"')* '"' | "'" (any - "'")* "'" ; # TODO escapes
main := |*
"%assign " => { tok = ASSIGN; fbreak; };
"{%cycle " => { tok = ARGLIST; fbreak; };
"%loop " => { tok = LOOP; fbreak; };
int => Int;
float => Float;
string => String;
("true" | "false") => Bool;
"nil" => { tok = LITERAL; out.val = nil; fbreak; };
"==" => { tok = EQ; fbreak; };
"!=" => { tok = NEQ; fbreak; };
">=" => { tok = GE; fbreak; };
"<=" => { tok = LE; fbreak; };
"and" => { tok = AND; fbreak; };
"or" => { tok = OR; fbreak; };
"contains" => { tok = CONTAINS; fbreak; };
"for" => { tok = FOR; fbreak; };
"in" => { tok = IN; fbreak; };
identifier ':' => { tok = KEYWORD; out.name = string(lex.data[lex.ts:lex.te-1]); fbreak; };
identifier => Identifier;
property => { tok = PROPERTY; out.name = string(lex.data[lex.ts+1:lex.te]); fbreak; };
space+;
any => { tok = int(lex.data[lex.ts]); fbreak; };
*|;
write exec;
}%%
return tok
}
func (lex *lexer) Error(e string) {
// fmt.Println("scan error:", e)
}