[FLINK-3736] Move toRexNode and toAggCall logic into Expressions

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Implemented
• Fix Version/s: 1.1.0
• Component/s: Table SQL / API
• Assignee: Yijie Shen
• Reporter: Yijie Shen
• Created: 11/Apr/16 18:00
• Updated: 12/Apr/16 16:52
• Resolved: 12/Apr/16 16:52

Description

Since we have a one-to-one mapping from Flink Expression to Calcite RexNode, and we will implement more and more expressions to make flink-table a full-fledged module, I think it's worthwhile to let each Expression take care of its own behaviour on conversion to RexNode.