L-systems in Go

lsystems.go

package lsystems

import (
	"bytes"
)

func lsystem_buffer(s *bytes.Buffer, rules []string) {
	tmpbuf := bytes.NewBuffer(make([]byte, 0, 1e6))

	for _, b := range s.Bytes() {
		if rule := rules[b]; rule != "" {
			tmpbuf.WriteString(rule)
		} else {
			tmpbuf.WriteByte(b)
		}
	}

	*s = *tmpbuf
}

func lsystem_append(s *[]byte, rules []string) {
	tmpbuf := make([]byte, 0, 1e6)

	for _, b := range *s {
		if rule := rules[b]; rule != "" {
			tmpbuf = append(tmpbuf, rule...)
		} else {
			tmpbuf = append(tmpbuf, b)
		}
	}

	*s = tmpbuf
}

lsystems_test.go

package lsystems

import (
	"bytes"
	"encoding/json"
	"fmt"
	"testing"
)

type rule struct {
	key   []byte
	value []byte
}

func BenchmarkBuffer(b *testing.B) {
	b.StopTimer()
	rules_in := []byte("{\"X\": \"F-[[X]+X]+F[+FX]-X\", \"F\": \"FF\"}")
	rules_tmp := make(map[string]string)
	json.Unmarshal(rules_in, &rules_tmp)

	rules := make([]string, 256)
	for key, value := range rules_tmp {
		rules[byte(key[0])] = value
	}

	out := bytes.NewBuffer(make([]byte, 0, 1e8))

	b.StartTimer()
	for i := 0; i < b.N; i++ {
		out.Reset()
		out.WriteString("X")
		for x := 0; x < 9; x++ {
			lsystem_buffer(out, rules)
		}
	}

	fmt.Println(out.String())
}

func BenchmarkAppend(b *testing.B) {
	b.StopTimer()
	rules_in := []byte("{\"X\": \"F-[[X]+X]+F[+FX]-X\", \"F\": \"FF\"}")
	rules_tmp := make(map[string]string)
	json.Unmarshal(rules_in, &rules_tmp)

	rules := make([]string, 256)
	for key, value := range rules_tmp {
		rules[byte(key[0])] = value
	}

	out := make([]byte, 0, 1e8)

	b.StartTimer()
	for i := 0; i < b.N; i++ {
		out = []byte("X")
		for x := 0; x < 9; x++ {
			lsystem_append(&out, rules)
		}
	}

	fmt.Println(string(out))
}