anyreader/safe_reader.go

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2023-08-07 20:45:57 +02:00
package anyreader
import (
"git.milar.in/milarin/ds"
"git.milar.in/milarin/slices"
)
type SafeReader[T any] struct {
buf ds.Stack[T]
indices ds.Stack[uint64]
index uint64
src func() T
}
func NewSafeReaderFromSlice[T any](s []T) *SafeReader[T] {
return NewSafeReaderFromFunc(sliceToSafeFunc(s))
}
func NewSafeReaderFromFunc[T any](src func() T) *SafeReader[T] {
return &SafeReader[T]{
src: src,
buf: ds.NewArrayStack[T](),
index: 0,
indices: ds.NewArrayStack[uint64](),
}
}
func (r *SafeReader[T]) Read() T {
v := r.src()
r.buf.Push(v)
r.index++
return v
}
func (r *SafeReader[T]) Unread() {
if r.buf.Empty() {
return
}
v := r.buf.Pop()
r.index--
returned := false
oldSrc := r.src
r.src = func() T {
if returned {
return oldSrc()
}
returned = true
return v
}
}
func (r *SafeReader[T]) UnreadN(n int) {
for i := 0; i < n; i++ {
r.Unread()
}
}
func (r *SafeReader[T]) Peek() T {
value := r.Read()
r.Unread()
return value
}
func (r *SafeReader[T]) ReadWhile(f ...func(T) bool) []T {
res := make([]T, 0, 10)
for value := r.Read(); findFirstTrue(value, f); value = r.Read() {
res = append(res, value)
}
return res
}
func (r *SafeReader[T]) ReadUntil(f ...func(T) bool) []T {
return r.ReadWhile(func(v T) bool { return !findFirstTrue(v, f) })
}
func (r *SafeReader[T]) SkipUntil(f ...func(T) bool) {
r.ReadUntil(f...)
r.Unread()
}
func (r *SafeReader[T]) SkipWhile(f ...func(T) bool) {
r.ReadWhile(f...)
r.Unread()
}
func (r *SafeReader[T]) Expect(f ...func(T) bool) bool {
return findFirstTrue(r.Read(), f)
}
func (r *SafeReader[T]) Push() {
r.indices.Push(r.index)
}
func (r *SafeReader[T]) Pop() []T {
if r.indices.Empty() {
return []T{}
}
lastIndex := r.indices.Pop()
currentIndex := r.index
if lastIndex < currentIndex {
values := make([]T, 0, int(currentIndex-lastIndex))
for i := 0; i < int(currentIndex-lastIndex); i++ {
r.Unread()
values = append(values, r.Peek())
}
return slices.Reverse(values)
} else if lastIndex > currentIndex {
values := make([]T, 0, int(lastIndex-currentIndex))
for i := 0; i < int(lastIndex-currentIndex); i++ {
values = append(values, r.Read())
}
return values
}
return []T{}
}