Исходники и презентации

lessons/strings/conversion_optimizations/main.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+)
+
+func rangeWithoutAllocation() {
+	var str = "world"
+	for range []byte(str) { // no allocation with copy
+	}
+}
+
+func workWithMapsWithoutAllocation() {
+	key := []byte{'k', 'e', 'y'}
+
+	data := map[string]string{}
+
+	data[string(key)] = "value" // allocation with copy
+	_ = data[string(key)]       // no allocation with copy
+}
+
+func comparisonAndConcatenation1() {
+	var x = []byte{1023: 'x'}
+	var y = []byte{1023: 'y'}
+
+	if string(x) != string(y) { // no allocation with copy
+		s := (" " + string(x) + string(y))[1:] // no allocation with copy
+		_ = s
+	}
+}
+
+func comparisonAndConcatenation2() {
+	var x = []byte{1023: 'x'}
+	var y = []byte{1023: 'y'}
+
+	if string(x) != string(y) { // no allocation with copy
+		s := string(x) + string(y) // allocation with copy
+		_ = s
+	}
+}
+
+func main() {
+	fmt.Println(testing.AllocsPerRun(1, comparisonAndConcatenation1)) // 1
+	fmt.Println(testing.AllocsPerRun(1, comparisonAndConcatenation2)) // 3
+}