Example #1
0
func (this *Filter) Run() {
	defer close(this.outputChannel)

	// FIXME should ensure booleanFactors are sorted
	// from cheapest to most expensive to compute

	// start the source
	go this.source.Run()
DOCUMENT:
	for row := range this.source.GetOutputChannel() {
		var context ast.Context
		switch row := row.(type) {
		case datasource.Document:
			context = ast.NewContext(row)
		default:
			panic(fmt.Sprintf("Non-map rows not currently supported (saw %T)", row))
		}

		for _, booleanFactor := range this.booleanFactors {
			result, err := booleanFactor.EvaluateBoolean(context)
			if err != nil {
				log.Printf("Error evaluating boolean factor: %v", err)
				continue DOCUMENT
			}
			if !result {
				continue DOCUMENT
			}
		}
		this.outputChannel <- row
	}
}
Example #2
0
func (this *Project) Run() {
	defer close(this.outputChannel)

	// start the source
	go this.source.Run()
DOCUMENT:
	for row := range this.source.GetOutputChannel() {

		if this.projection != nil {
			var context ast.Context
			switch row := row.(type) {
			case datasource.Document:
				//log.Printf("creating context with %v", row)
				context = ast.NewContext(row)
			default:
				panic(fmt.Sprintf("Non-map rows not currently supported (saw %T)", row))
			}

			result, err := this.projection.Evaluate(context)
			if err != nil {
				log.Printf("Error evaluating projection: %v", err)
				continue DOCUMENT
			}
			this.outputChannel <- result
		} else {
			this.outputChannel <- row
		}
	}
}
Example #3
0
func (this *Order) Less(i, j int) bool {
	left := this.output[i]
	right := this.output[j]

	var leftContext, rightContext ast.Context
	switch left := left.(type) {
	case datasource.Document:
		leftContext = ast.NewContext(left)
		switch right := right.(type) {
		case datasource.Document:
			rightContext = ast.NewContext(right)
		default:
			panic(fmt.Sprintf("Non-map rows not currently supported (saw %T)", right))
		}
	default:
		panic(fmt.Sprintf("Non-map rows not currently supported (saw %T)", left))
	}

	for _, oe := range this.orderBy {
		leftVal, err := oe.Expression().Evaluate(leftContext)
		if err != nil {
			log.Printf("Error evaluating expression: %v", err)
			return false
		}
		rightVal, err := oe.Expression().Evaluate(rightContext)
		if err != nil {
			log.Printf("Error evaluating expression: %v", err)
			return false
		}

		result := ast.CollateJSON(leftVal, rightVal)
		if result != 0 {
			if oe.Order() && result < 0 {
				return true
			} else if !oe.Order() && result > 0 {
				return true
			} else {
				return false
			}
		}
		// at this level they are the same, keep going
	}

	// if we go to this point the order expressions could not differentiate between the elements
	return false
}