/
generator.go
204 lines (173 loc) · 3.97 KB
/
generator.go
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package ohyeah
import (
"fmt"
"net/url"
"math/big"
)
type Int64F func() int64
// RandomFunc returns a simple int64 random number generator based
// on the given seed. The idea here is not to produce a great series
// of random numbers but rather a highly reproducable one, over differnt
// programming languages.
func RandomFunc(seed int64) Int64F {
current := seed
modValue := int64((1 << 31) - 1)
g := int64(16807)
return func() int64 {
result := current
current = (g * result) % modValue
return result
}
}
type Generator func() interface{}
func ConstantGen(x interface{}) Generator {
return func() interface{} {
return x
}
}
func IntGen(r Int64F) Generator {
return func() interface{} {
return r()
}
}
func IntN(r Int64F, n int) int {
return int(r() % int64(n))
}
func BoolGen(r Int64F) Generator {
return func() interface{} {
i := IntN(r, 2)
return i == 0
}
}
var runes = "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz01234567890"
func RuneGen(r Int64F) Generator {
return func() interface{} {
i := IntN(r, len(runes))
return runes[i]
}
}
func Float64Gen(r Int64F) Generator {
return func() interface{} {
i := r()
j := r()
return float64(i) / float64(j)
}
}
func BigIntGen(r Int64F) Generator {
return func() interface{} {
x := big.NewInt(r())
x = x.Mul(x, x)
return x
}
}
func BigFloatGen(r Int64F) Generator {
return func() interface{} {
a := float64(r())
b := float64(r()) + 1.0
x := big.NewFloat(a)
y := big.NewFloat(b)
y = y.Quo(x, y)
return y
}
}
func BigRatGen(r Int64F) Generator {
return func() interface{} {
d := r()
for d == 0 {
d = r()
}
r := big.NewRat(r(), d)
return r
}
}
func StringGen(r Int64F) Generator {
return func() interface{} {
l := IntN(r, 10)
ba := make([]byte, l)
for i := 0; i < l; i++ {
ba[i] = byte(IntN(r, 100) + 12)
}
return string(ba)
}
}
// UrlGen takes two generators, one that generates host names and
// the other that generates the path part of the url and returns
// a generator that produces urls.
func UrlGen(hostGen, pathGen Generator) Generator {
return func() interface{} {
host := hostGen()
path := pathGen()
s := fmt.Sprintf("http://%s/%s", host, path)
u, _ := url.Parse(s)
return u
}
}
func PatternedStringGen(prefix string) Generator {
i := 0
return func() interface{} {
i++
return fmt.Sprintf("%s%d", prefix, i)
}
}
// RandomGen picks a random generator from generators and evaluates it.
func RandomGen(r Int64F, generators ...Generator) Generator {
return func() interface{} {
i := IntN(r, len(generators))
return generators[i]()
}
}
// CycleGen cycles thru all of the generators.
func CycleGen(generators ...Generator) Generator {
if len(generators) == 0 {
panic("No generators supplied to CycleGen")
}
i := 0
return func() interface{} {
result := generators[i]()
i = (i + 1) % len(generators)
return result
}
}
// RepeatGen generates a repeated pattern of values. The first n times
// the repeat gen is called it will call g and return the values. On
// call n+1 the generator will return the first value, then the second
// and so on.
func RepeatGen(g Generator, n int) Generator {
i := 0
savedValues := make([]interface{}, n)
return func() interface{} {
if i < n {
savedValues[i] = g()
}
result := savedValues[i%n]
i++
return result
}
}
func ArrayGen(r Int64F, g Generator, maxLen int) Generator {
return func() interface{} {
l := IntN(r, maxLen+1)
result := make([]interface{}, l)
for i, _ := range result {
result[i] = g()
}
return result
}
}
func MapGen(r Int64F, k Generator, v Generator, maxLen int) Generator {
return func() interface{} {
l := IntN(r, maxLen+1)
result := map[interface{}]interface{}{}
for i := 0; i < l; i++ {
result[k()] = v()
}
return result
}
}
// ElementGen returns a generator that will produce random elements from the array.
func ElementGen(r Int64F, array []interface{}) Generator {
return func() interface{} {
i := IntN(r, len(array))
return array[i]
}
}