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|
package jsonparser
import (
"strconv"
"testing"
"unsafe"
)
type ParseIntTest struct {
in string
out int64
isErr bool
isOverflow bool
}
var parseIntTests = []ParseIntTest{
{
in: "0",
out: 0,
},
{
in: "1",
out: 1,
},
{
in: "-1",
out: -1,
},
{
in: "12345",
out: 12345,
},
{
in: "-12345",
out: -12345,
},
{
in: "9223372036854775807", // = math.MaxInt64
out: 9223372036854775807,
},
{
in: "-9223372036854775808", // = math.MinInt64
out: -9223372036854775808,
},
{
in: "-92233720368547758081",
out: 0,
isErr: true,
isOverflow: true,
},
{
in: "18446744073709551616", // = 2^64
out: 0,
isErr: true,
isOverflow: true,
},
{
in: "9223372036854775808", // = math.MaxInt64 - 1
out: 0,
isErr: true,
isOverflow: true,
},
{
in: "-9223372036854775809", // = math.MaxInt64 - 1
out: 0,
isErr: true,
isOverflow: true,
},
{
in: "",
isErr: true,
},
{
in: "abc",
isErr: true,
},
{
in: "12345x",
isErr: true,
},
{
in: "123e5",
isErr: true,
},
{
in: "9223372036854775807x",
isErr: true,
},
}
func TestBytesParseInt(t *testing.T) {
for _, test := range parseIntTests {
out, ok, overflow := parseInt([]byte(test.in))
if overflow != test.isOverflow {
t.Errorf("Test '%s' error return did not overflow expectation (obtained %t, expected %t)", test.in, overflow, test.isOverflow)
}
if ok != !test.isErr {
t.Errorf("Test '%s' error return did not match expectation (obtained %t, expected %t)", test.in, !ok, test.isErr)
} else if ok && out != test.out {
t.Errorf("Test '%s' did not return the expected value (obtained %d, expected %d)", test.in, out, test.out)
}
}
}
func BenchmarkParseInt(b *testing.B) {
bytes := []byte("123")
for i := 0; i < b.N; i++ {
parseInt(bytes)
}
}
// Alternative implementation using unsafe and delegating to strconv.ParseInt
func BenchmarkParseIntUnsafeSlower(b *testing.B) {
bytes := []byte("123")
for i := 0; i < b.N; i++ {
strconv.ParseInt(*(*string)(unsafe.Pointer(&bytes)), 10, 64)
}
}
// Old implementation that did not check for overflows.
func BenchmarkParseIntOverflows(b *testing.B) {
bytes := []byte("123")
for i := 0; i < b.N; i++ {
parseIntOverflows(bytes)
}
}
func parseIntOverflows(bytes []byte) (v int64, ok bool) {
if len(bytes) == 0 {
return 0, false
}
var neg bool = false
if bytes[0] == '-' {
neg = true
bytes = bytes[1:]
}
for _, c := range bytes {
if c >= '0' && c <= '9' {
v = (10 * v) + int64(c-'0')
} else {
return 0, false
}
}
if neg {
return -v, true
} else {
return v, true
}
}
|
