defer Remove(f.Name())
	defer f.Close()

	checkSize(t, f, 0)
	f.Write([]byte("hello, world\n"))
	checkSize(t, f, 13)
	f.Truncate(10)
	checkSize(t, f, 10)
	f.Truncate(1024)
	checkSize(t, f, 1024)
	f.Truncate(0)
	checkSize(t, f, 0)
	_, err := f.Write([]byte("surprise!"))
	if err == nil {
		checkSize(t, f, 13+9) // wrote at offset past where hello, world was.
	}
}

		delete(p.height, re)
	}
	re.Sub0[0] = p.free
	p.free = re
}

func (p *parser) checkLimits(re *Regexp) {
	if p.numRunes > maxRunes {
		panic(ErrLarge)
	}
	p.checkSize(re)
	p.checkHeight(re)
}

func (p *parser) checkSize(re *Regexp) {
	if p.size == nil {
		// We haven't started tracking size yet.
		// Do a relatively cheap check to see if we need to start.