boolean (PsiBuilder builder) { final PsiBuilder.Marker seq = builder.mark(); final boolean b = parseExprSingle(builder); if (b && builder.getTokenType() == XPathTokenTypes.COMMA) { do { builder.advanceLexer(); if (!parseExprSingle(builder)) { builder.error(XPathBundle.message("parsing.error.expression.expected")); } } while (builder.getTokenType() == XPathTokenTypes.COMMA); seq.done(XPath2ElementTypes.SEQUENCE); } else { seq.drop(); } return b; }