mirror of
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515 lines
12 KiB
Go
515 lines
12 KiB
Go
package functions
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import (
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"fmt"
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)
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// RowNumberFunction 行号函数
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type RowNumberFunction struct {
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*BaseFunction
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CurrentRowNumber int64
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}
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func NewRowNumberFunction() *RowNumberFunction {
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return &RowNumberFunction{
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BaseFunction: NewBaseFunction("row_number", TypeWindow, "窗口函数", "返回当前行号", 0, 0),
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CurrentRowNumber: 0,
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}
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}
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func (f *RowNumberFunction) Validate(args []interface{}) error {
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return f.ValidateArgCount(args)
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}
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func (f *RowNumberFunction) Execute(ctx *FunctionContext, args []interface{}) (interface{}, error) {
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f.CurrentRowNumber++
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return f.CurrentRowNumber, nil
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}
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func (f *RowNumberFunction) Reset() {
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f.CurrentRowNumber = 0
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}
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// WindowStartFunction 窗口开始时间函数
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type WindowStartFunction struct {
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*BaseFunction
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windowStart interface{}
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}
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func NewWindowStartFunction() *WindowStartFunction {
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return &WindowStartFunction{
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BaseFunction: NewBaseFunction("window_start", TypeWindow, "窗口函数", "返回窗口开始时间", 0, 0),
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}
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}
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func (f *WindowStartFunction) Validate(args []interface{}) error {
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return f.ValidateArgCount(args)
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}
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func (f *WindowStartFunction) Execute(ctx *FunctionContext, args []interface{}) (interface{}, error) {
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if ctx.WindowInfo != nil {
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return ctx.WindowInfo.WindowStart, nil
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}
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return f.windowStart, nil
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}
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// 实现AggregatorFunction接口
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func (f *WindowStartFunction) New() AggregatorFunction {
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return &WindowStartFunction{
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BaseFunction: f.BaseFunction,
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}
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}
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func (f *WindowStartFunction) Add(value interface{}) {
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// 窗口开始时间通常不需要累积计算
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f.windowStart = value
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}
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func (f *WindowStartFunction) Result() interface{} {
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return f.windowStart
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}
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func (f *WindowStartFunction) Reset() {
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f.windowStart = nil
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}
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func (f *WindowStartFunction) Clone() AggregatorFunction {
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return &WindowStartFunction{
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BaseFunction: f.BaseFunction,
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windowStart: f.windowStart,
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}
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}
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// WindowEndFunction 窗口结束时间函数
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type WindowEndFunction struct {
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*BaseFunction
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windowEnd interface{}
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}
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func NewWindowEndFunction() *WindowEndFunction {
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return &WindowEndFunction{
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BaseFunction: NewBaseFunction("window_end", TypeWindow, "窗口函数", "返回窗口结束时间", 0, 0),
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}
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}
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func (f *WindowEndFunction) Validate(args []interface{}) error {
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return f.ValidateArgCount(args)
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}
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func (f *WindowEndFunction) Execute(ctx *FunctionContext, args []interface{}) (interface{}, error) {
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if ctx.WindowInfo != nil {
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return ctx.WindowInfo.WindowEnd, nil
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}
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return f.windowEnd, nil
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}
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// 实现AggregatorFunction接口
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func (f *WindowEndFunction) New() AggregatorFunction {
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return &WindowEndFunction{
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BaseFunction: f.BaseFunction,
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}
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}
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func (f *WindowEndFunction) Add(value interface{}) {
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// 窗口结束时间通常不需要累积计算
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f.windowEnd = value
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}
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func (f *WindowEndFunction) Result() interface{} {
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return f.windowEnd
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}
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func (f *WindowEndFunction) Reset() {
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f.windowEnd = nil
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}
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func (f *WindowEndFunction) Clone() AggregatorFunction {
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return &WindowEndFunction{
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BaseFunction: f.BaseFunction,
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windowEnd: f.windowEnd,
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}
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}
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// ExpressionFunction 表达式函数，用于处理自定义表达式
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type ExpressionFunction struct {
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*BaseFunction
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values []interface{}
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}
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func NewExpressionFunction() *ExpressionFunction {
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return &ExpressionFunction{
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BaseFunction: NewBaseFunction("expression", TypeCustom, "表达式函数", "处理自定义表达式", 0, -1),
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values: make([]interface{}, 0),
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}
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}
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func (f *ExpressionFunction) Validate(args []interface{}) error {
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return f.ValidateArgCount(args)
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}
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func (f *ExpressionFunction) Execute(ctx *FunctionContext, args []interface{}) (interface{}, error) {
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// 表达式函数的具体实现由表达式引擎处理
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if len(args) == 0 {
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return nil, nil
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}
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return args[len(args)-1], nil
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}
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// 实现AggregatorFunction接口
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func (f *ExpressionFunction) New() AggregatorFunction {
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return &ExpressionFunction{
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BaseFunction: f.BaseFunction,
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values: make([]interface{}, 0),
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}
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}
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func (f *ExpressionFunction) Add(value interface{}) {
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f.values = append(f.values, value)
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}
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func (f *ExpressionFunction) Result() interface{} {
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// 表达式聚合器的结果处理由表达式引擎处理
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// 这里只返回最后一个计算结果
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if len(f.values) == 0 {
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return nil
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}
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return f.values[len(f.values)-1]
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}
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func (f *ExpressionFunction) Reset() {
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f.values = make([]interface{}, 0)
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}
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func (f *ExpressionFunction) Clone() AggregatorFunction {
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clone := &ExpressionFunction{
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BaseFunction: f.BaseFunction,
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values: make([]interface{}, len(f.values)),
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}
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copy(clone.values, f.values)
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return clone
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}
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// ExpressionAggregatorFunction 表达式聚合器函数 - 用于处理非聚合函数在聚合查询中的情况
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type ExpressionAggregatorFunction struct {
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*BaseFunction
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lastResult interface{}
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}
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func NewExpressionAggregatorFunction() *ExpressionAggregatorFunction {
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return &ExpressionAggregatorFunction{
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BaseFunction: NewBaseFunction("expression", TypeCustom, "表达式聚合器", "处理表达式计算", 1, -1),
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lastResult: nil,
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}
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}
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func (f *ExpressionAggregatorFunction) Validate(args []interface{}) error {
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return f.ValidateArgCount(args)
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}
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func (f *ExpressionAggregatorFunction) Execute(ctx *FunctionContext, args []interface{}) (interface{}, error) {
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// 对于表达式聚合器，直接返回最后一个值
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if len(args) > 0 {
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return args[len(args)-1], nil
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}
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return nil, nil
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}
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// 实现AggregatorFunction接口
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func (f *ExpressionAggregatorFunction) New() AggregatorFunction {
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return &ExpressionAggregatorFunction{
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BaseFunction: f.BaseFunction,
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lastResult: nil,
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}
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}
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func (f *ExpressionAggregatorFunction) Add(value interface{}) {
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// 对于表达式聚合器，保存最后一个计算结果
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// 表达式的计算结果应该是每个数据项的计算结果
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f.lastResult = value
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}
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func (f *ExpressionAggregatorFunction) Result() interface{} {
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// 对于表达式聚合器，返回最后一个计算结果
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// 注意：对于字符串函数如CONCAT，每个数据项都会产生一个结果
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// 在窗口聚合中，我们返回最后一个计算的结果
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return f.lastResult
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}
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func (f *ExpressionAggregatorFunction) Reset() {
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f.lastResult = nil
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}
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func (f *ExpressionAggregatorFunction) Clone() AggregatorFunction {
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return &ExpressionAggregatorFunction{
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BaseFunction: f.BaseFunction,
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lastResult: f.lastResult,
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}
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}
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// FirstValueFunction 返回窗口中第一个值
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type FirstValueFunction struct {
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*BaseFunction
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firstValue interface{}
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hasValue bool
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}
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func NewFirstValueFunction() *FirstValueFunction {
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return &FirstValueFunction{
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BaseFunction: NewBaseFunction("first_value", TypeWindow, "窗口函数", "返回窗口中第一个值", 1, 1),
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hasValue: false,
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}
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}
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func (f *FirstValueFunction) Validate(args []interface{}) error {
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return f.ValidateArgCount(args)
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}
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func (f *FirstValueFunction) Execute(ctx *FunctionContext, args []interface{}) (interface{}, error) {
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return f.firstValue, nil
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}
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// 实现AggregatorFunction接口
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func (f *FirstValueFunction) New() AggregatorFunction {
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return &FirstValueFunction{
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BaseFunction: f.BaseFunction,
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hasValue: false,
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}
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}
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func (f *FirstValueFunction) Add(value interface{}) {
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if !f.hasValue {
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f.firstValue = value
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f.hasValue = true
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}
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}
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func (f *FirstValueFunction) Result() interface{} {
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return f.firstValue
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}
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func (f *FirstValueFunction) Reset() {
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f.firstValue = nil
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f.hasValue = false
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}
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func (f *FirstValueFunction) Clone() AggregatorFunction {
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return &FirstValueFunction{
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BaseFunction: f.BaseFunction,
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firstValue: f.firstValue,
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hasValue: f.hasValue,
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}
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}
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// LeadFunction 返回当前行之后第N行的值
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type LeadFunction struct {
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*BaseFunction
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values []interface{}
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offset int
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defaultValue interface{}
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hasDefault bool
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}
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func NewLeadFunction() *LeadFunction {
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return &LeadFunction{
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BaseFunction: NewBaseFunction("lead", TypeWindow, "窗口函数", "返回当前行之后第N行的值", 1, 3),
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values: make([]interface{}, 0),
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offset: 1, // 默认偏移量为1
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}
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}
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func (f *LeadFunction) Validate(args []interface{}) error {
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if err := f.ValidateArgCount(args); err != nil {
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return err
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}
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// 验证第二个参数（offset）是否为整数
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if len(args) >= 2 {
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if offset, ok := args[1].(int); ok {
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f.offset = offset
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} else {
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return fmt.Errorf("offset must be an integer")
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}
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}
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// 设置默认值
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if len(args) >= 3 {
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f.defaultValue = args[2]
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f.hasDefault = true
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}
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return nil
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}
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func (f *LeadFunction) Execute(ctx *FunctionContext, args []interface{}) (interface{}, error) {
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if err := f.Validate(args); err != nil {
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return nil, err
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}
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// 获取偏移量
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if len(args) >= 2 {
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if offset, ok := args[1].(int); ok {
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f.offset = offset
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} else {
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return nil, fmt.Errorf("offset must be an integer")
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}
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}
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// 获取默认值
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if len(args) >= 3 {
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f.defaultValue = args[2]
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f.hasDefault = true
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}
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// Lead函数需要在窗口处理完成后才能确定值
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// 这里返回默认值，实际实现需要在窗口引擎中处理
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if f.hasDefault {
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return f.defaultValue, nil
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}
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return nil, nil
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}
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// 实现AggregatorFunction接口
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func (f *LeadFunction) New() AggregatorFunction {
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return &LeadFunction{
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BaseFunction: f.BaseFunction,
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values: make([]interface{}, 0),
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offset: f.offset,
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defaultValue: f.defaultValue,
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hasDefault: f.hasDefault,
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}
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}
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func (f *LeadFunction) Add(value interface{}) {
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f.values = append(f.values, value)
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}
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func (f *LeadFunction) Result() interface{} {
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// Lead函数的结果需要在所有数据添加完成后计算
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// 如果没有足够的数据，返回默认值
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if len(f.values) == 0 && f.hasDefault {
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return f.defaultValue
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}
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// 这里简化实现，返回nil
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return nil
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}
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func (f *LeadFunction) Reset() {
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f.values = make([]interface{}, 0)
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f.offset = 1
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f.defaultValue = nil
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f.hasDefault = false
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}
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func (f *LeadFunction) Clone() AggregatorFunction {
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clone := &LeadFunction{
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BaseFunction: f.BaseFunction,
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values: make([]interface{}, len(f.values)),
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offset: f.offset,
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defaultValue: f.defaultValue,
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hasDefault: f.hasDefault,
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}
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copy(clone.values, f.values)
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return clone
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}
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// NthValueFunction 返回窗口中第N个值
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type NthValueFunction struct {
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*BaseFunction
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values []interface{}
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n int
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}
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func NewNthValueFunction() *NthValueFunction {
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return &NthValueFunction{
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BaseFunction: NewBaseFunction("nth_value", TypeWindow, "窗口函数", "返回窗口中第N个值", 2, 2),
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values: make([]interface{}, 0),
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n: 1, // 默认第1个值
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}
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}
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func (f *NthValueFunction) Validate(args []interface{}) error {
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if err := f.ValidateArgCount(args); err != nil {
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return err
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}
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// 验证N值
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n := 1
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if nVal, ok := args[1].(int); ok {
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n = nVal
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} else if nVal, ok := args[1].(int64); ok {
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n = int(nVal)
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} else {
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return fmt.Errorf("nth_value n must be an integer")
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}
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if n <= 0 {
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return fmt.Errorf("nth_value n must be positive, got %d", n)
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}
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// 设置n值
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f.n = n
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return nil
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}
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func (f *NthValueFunction) Execute(ctx *FunctionContext, args []interface{}) (interface{}, error) {
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if err := f.Validate(args); err != nil {
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return nil, err
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}
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// 获取N值
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n := 1
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if nVal, ok := args[1].(int); ok {
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n = nVal
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} else if nVal, ok := args[1].(int64); ok {
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n = int(nVal)
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} else {
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return nil, fmt.Errorf("nth_value n must be an integer")
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}
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if n <= 0 {
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return nil, fmt.Errorf("nth_value n must be positive, got %d", n)
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}
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// 返回第N个值（1-based索引）
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if len(f.values) >= n {
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return f.values[n-1], nil
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}
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return nil, nil
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}
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// 实现AggregatorFunction接口
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func (f *NthValueFunction) New() AggregatorFunction {
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return &NthValueFunction{
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BaseFunction: f.BaseFunction,
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values: make([]interface{}, 0),
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n: f.n,
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}
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}
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func (f *NthValueFunction) Add(value interface{}) {
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f.values = append(f.values, value)
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}
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func (f *NthValueFunction) Result() interface{} {
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if len(f.values) >= f.n && f.n > 0 {
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return f.values[f.n-1]
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}
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return nil
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}
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func (f *NthValueFunction) Reset() {
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f.values = make([]interface{}, 0)
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}
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func (f *NthValueFunction) Clone() AggregatorFunction {
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clone := &NthValueFunction{
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BaseFunction: f.BaseFunction,
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values: make([]interface{}, len(f.values)),
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n: f.n,
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}
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copy(clone.values, f.values)
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return clone
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}
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