Function estimateStringSplitCost

ext/strings.go:989–1002

estimateStringSplitCost estimates cost for string split operations. Split creates a list of substrings, so cost includes both traversal and list allocation proportional to the input size.

(estimator checker.CostEstimator, target *checker.AstNode, args []checker.AstNode)

// Split creates a list of substrings, so cost includes both traversal and
// list allocation proportional to the input size.
func estimateStringSplitCost(estimator checker.CostEstimator, target *checker.AstNode, args []checker.AstNode) *checker.CallEstimate {
	if target == nil || len(args) < 1 {
		return nil
	}
	targetSize := estimateSize(estimator, *target)
	// Traversal cost proportional to input size.
	traversalCost := targetSize.Add(fixedSizeEstimate(1)).MultiplyByCostFactor(stringCostFactor)
	// Worst case: split("") produces N elements for a string of size N.
	resultSize := rangedSizeEstimate(0, targetSize.Max)
	// Include list creation base cost plus allocation for each element.
	allocationCost := resultSize.MultiplyByCostFactor(1).Add(checker.FixedCostEstimate(common.ListCreateBaseCost))
	cost := traversalCost.Add(allocationCost).Add(callCostEstimate)
	return callEstimate(cost, &resultSize)
}

// estimateStringJoinCost estimates cost for string join operations.
// Join iterates over all list elements and concatenates them, so cost is