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