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package main
var testmap1 = map[string]int{"data": 3}
var testmap2 = map[string]int{
"one": 1,
"two": 2,
"three": 3,
"four": 4,
"five": 5,
"six": 6,
"seven": 7,
"eight": 8,
"nine": 9,
"ten": 10,
"eleven": 11,
"twelve": 12,
}
type ArrayKey [4]byte
var testMapArrayKey = map[ArrayKey]int{
ArrayKey([4]byte{1, 2, 3, 4}): 1234,
ArrayKey([4]byte{4, 3, 2, 1}): 4321,
}
var testmapIntInt = map[int]int{1: 1, 2: 4, 3: 9}
type namedFloat struct {
s string
f float32
}
func main() {
m := map[string]int{"answer": 42, "foo": 3}
readMap(m, "answer")
readMap(testmap1, "data")
readMap(testmap2, "three")
readMap(testmap2, "ten")
delete(testmap2, "six")
readMap(testmap2, "seven")
lookup(testmap2, "eight")
lookup(testmap2, "nokey")
// operations on nil maps
var nilmap map[string]int
println(m == nil, m != nil, len(m))
println(nilmap == nil, nilmap != nil, len(nilmap))
delete(nilmap, "foo")
println("nilmap:", nilmap["bar"])
println(testmapIntInt[2])
testmapIntInt[2] = 42
println(testmapIntInt[2])
for k := range nilmap {
println(k) // unreachable
}
arrKey := ArrayKey([4]byte{4, 3, 2, 1})
println(testMapArrayKey[arrKey])
testMapArrayKey[arrKey] = 5555
println(testMapArrayKey[arrKey])
// test maps with interface keys
itfMap := map[interface{}]int{
3.14: 3,
8: 8,
uint8(8): 80,
"eight": 800,
[2]int{5, 2}: 52,
true: 1,
}
println("itfMap[3]:", itfMap[3]) // doesn't exist
println("itfMap[3.14]:", itfMap[3.14])
println("itfMap[8]:", itfMap[8])
println("itfMap[uint8(8)]:", itfMap[uint8(8)])
println(`itfMap["eight"]:`, itfMap["eight"])
println(`itfMap[[2]int{5, 2}]:`, itfMap[[2]int{5, 2}])
println("itfMap[true]:", itfMap[true])
delete(itfMap, 8)
println("itfMap[8]:", itfMap[8])
// test map with float keys
floatMap := map[float32]int{
42: 84,
}
println("floatMap[42]:", floatMap[42])
println("floatMap[43]:", floatMap[43])
delete(floatMap, 42)
println("floatMap[42]:", floatMap[42])
// test maps with struct keys
structMap := map[namedFloat]int{
namedFloat{"tau", 6.28}: 5,
}
println(`structMap[{"tau", 6.28}]:`, structMap[namedFloat{"tau", 6.28}])
println(`structMap[{"Tau", 6.28}]:`, structMap[namedFloat{"Tau", 6.28}])
println(`structMap[{"tau", 3.14}]:`, structMap[namedFloat{"tau", 3.14}])
delete(structMap, namedFloat{"tau", 6.28})
println(`structMap[{"tau", 6.28}]:`, structMap[namedFloat{"tau", 6.28}])
// test preallocated map
squares := make(map[int]int, 200)
testBigMap(squares, 100)
println("tested preallocated map")
// test growing maps
squares = make(map[int]int, 0)
testBigMap(squares, 10)
squares = make(map[int]int, 20)
testBigMap(squares, 40)
println("tested growing of a map")
}
func readMap(m map[string]int, key string) {
println("map length:", len(m))
println("map read:", key, "=", m[key])
for k, v := range m {
println(" ", k, "=", v)
}
}
func lookup(m map[string]int, key string) {
value, ok := m[key]
println("lookup with comma-ok:", key, value, ok)
}
func testBigMap(squares map[int]int, n int) {
for i := 0; i < n; i++ {
if len(squares) != i {
println("unexpected length:", len(squares), "at i =", i)
}
squares[i] = i * i
for j := 0; j <= i; j++ {
if v, ok := squares[j]; !ok || v != j*j {
if !ok {
println("key not found in squares map:", j)
} else {
println("unexpected value read back from squares map:", j, v)
}
return
}
}
}
}
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