Implement AVG, COUNT, MAX, MIN, SUM functions

query_executors/memory_executor/aggregate_functions.go

@@ -0,0 +1,131 @@
+package memoryexecutor
+
+import (
+	"math"
+
+	"github.com/pikami/cosmium/parsers"
+)
+
+func (c memoryExecutorContext) aggregate_Avg(arguments []interface{}, row RowType) interface{} {
+	selectExpression := arguments[0].(parsers.SelectItem)
+	sum := 0.0
+	count := 0
+
+	if array, isArray := row.([]RowType); isArray {
+		for _, item := range array {
+			value := c.getFieldValue(selectExpression, item)
+			if numericValue, ok := value.(float64); ok {
+				sum += numericValue
+				count++
+			} else if numericValue, ok := value.(int); ok {
+				sum += float64(numericValue)
+				count++
+			}
+		}
+	}
+
+	if count > 0 {
+		return sum / float64(count)
+	} else {
+		return nil
+	}
+}
+
+func (c memoryExecutorContext) aggregate_Count(arguments []interface{}, row RowType) interface{} {
+	selectExpression := arguments[0].(parsers.SelectItem)
+	count := 0
+
+	if array, isArray := row.([]RowType); isArray {
+		for _, item := range array {
+			value := c.getFieldValue(selectExpression, item)
+			if value != nil {
+				count++
+			}
+		}
+	}
+
+	return count
+}
+
+func (c memoryExecutorContext) aggregate_Max(arguments []interface{}, row RowType) interface{} {
+	selectExpression := arguments[0].(parsers.SelectItem)
+	max := 0.0
+	count := 0
+
+	if array, isArray := row.([]RowType); isArray {
+		for _, item := range array {
+			value := c.getFieldValue(selectExpression, item)
+			if numericValue, ok := value.(float64); ok {
+				if numericValue > max {
+					max = numericValue
+				}
+				count++
+			} else if numericValue, ok := value.(int); ok {
+				if float64(numericValue) > max {
+					max = float64(numericValue)
+				}
+				count++
+			}
+		}
+	}
+
+	if count > 0 {
+		return max
+	} else {
+		return nil
+	}
+}
+
+func (c memoryExecutorContext) aggregate_Min(arguments []interface{}, row RowType) interface{} {
+	selectExpression := arguments[0].(parsers.SelectItem)
+	min := math.MaxFloat64
+	count := 0
+
+	if array, isArray := row.([]RowType); isArray {
+		for _, item := range array {
+			value := c.getFieldValue(selectExpression, item)
+			if numericValue, ok := value.(float64); ok {
+				if numericValue < min {
+					min = numericValue
+				}
+				count++
+			} else if numericValue, ok := value.(int); ok {
+				if float64(numericValue) < min {
+					min = float64(numericValue)
+				}
+				count++
+			}
+		}
+	}
+
+	if count > 0 {
+		return min
+	} else {
+		return nil
+	}
+}
+
+func (c memoryExecutorContext) aggregate_Sum(arguments []interface{}, row RowType) interface{} {
+	selectExpression := arguments[0].(parsers.SelectItem)
+	sum := 0.0
+	count := 0
+
+	if array, isArray := row.([]RowType); isArray {
+		for _, item := range array {
+			value := c.getFieldValue(selectExpression, item)
+			if numericValue, ok := value.(float64); ok {
+				sum += numericValue
+				count++
+			} else if numericValue, ok := value.(int); ok {
+				sum += float64(numericValue)
+				count++
+			}
+		}
+	}
+
+	if count > 0 {
+		return sum
+	} else {
+		return nil
+	}
+}