boolean (PsiBuilder builder) { if (builder.getTokenType() == XPathTokenTypes.MINUS) { final PsiBuilder.Marker expr = builder.mark(); builder.advanceLexer(); if (!parseUnionExpression(builder)) { builder.error(XPathBundle.message("parsing.error.expression.expected")); } expr.done(XPathElementTypes.PREFIX_EXPRESSION); return true; } else { return parseUnionExpression(builder); } }