CypherCstToAstVisitor.java 文件源码

private <T extends ParseTree> CypherBinaryExpression toBinaryExpressions(List<ParseTree> children, Function<T, CypherAstBase> itemTransform) {
    CypherAstBase left = null;
    CypherBinaryExpression.Op op = null;
    for (int i = 0; i < children.size(); i++) {
        ParseTree child = children.get(i);
        if (child instanceof TerminalNode) {
            CypherBinaryExpression.Op newOp = CypherBinaryExpression.Op.parseOrNull(child.getText());
            if (newOp != null) {
                if (op == null) {
                    op = newOp;
                } else {
                    throw new MemgraphException("unexpected op, found too many ops in a row");
                }
            }
        } else {
            //noinspection unchecked
            CypherAstBase childObj = itemTransform.apply((T) child);
            if (left == null) {
                left = childObj;
            } else {
                if (op == null) {
                    throw new MemgraphException("unexpected binary expression. expected an op between expressions");
                }
                left = new CypherBinaryExpression(left, op, childObj);
            }
            op = null;
        }
    }
    return (CypherBinaryExpression) left;
}