ozanh/ugo

// Copyright (c) 2020-2023 Ozan Hacıbekiroğlu.
// Use of this source code is governed by a MIT License
// that can be found in the LICENSE file.

package ugo

import (
    "sync"
    "unicode/utf8"
)

// Iterator wraps the methods required to iterate Objects in VM.
type Iterator interface {
    // Next returns true if there are more elements to iterate.
    Next() bool

    // Key returns the key or index value of the current element.
    Key() Object

    // Value returns the value of the current element.
    Value() Object
}

// iteratorObject is used in VM to make an iterable Object.
type iteratorObject struct {
    ObjectImpl
    Iterator
}

var _ Object = (*iteratorObject)(nil)

// ArrayIterator represents an iterator for the array.
type ArrayIterator struct {
    V Array
    i int
}

var _ Iterator = (*ArrayIterator)(nil)

// Next implements Iterator interface.
func (it *ArrayIterator) Next() bool {
    it.i++
    return it.i-1 < len(it.V)
}

// Key implements Iterator interface.
func (it *ArrayIterator) Key() Object {
    return Int(it.i - 1)
}

// Value implements Iterator interface.
func (it *ArrayIterator) Value() Object {
    i := it.i - 1
    if i > -1 && i < len(it.V) {
        return it.V[i]
    }
    return Undefined
}

// BytesIterator represents an iterator for the bytes.
type BytesIterator struct {
    V Bytes
    i int
}

var _ Iterator = (*BytesIterator)(nil)

// Next implements Iterator interface.
func (it *BytesIterator) Next() bool {
    it.i++
    return it.i-1 < len(it.V)
}

// Key implements Iterator interface.
func (it *BytesIterator) Key() Object {
    return Int(it.i - 1)
}

// Value implements Iterator interface.
func (it *BytesIterator) Value() Object {
    i := it.i - 1
    if i > -1 && i < len(it.V) {
        return Int(it.V[i])
    }
    return Undefined
}

// MapIterator represents an iterator for the map.
type MapIterator struct {
    V    Map
    keys []string
    i    int
}

var _ Iterator = (*MapIterator)(nil)

// Next implements Iterator interface.
func (it *MapIterator) Next() bool {
    it.i++
    return it.i-1 < len(it.keys)
}

// Key implements Iterator interface.
func (it *MapIterator) Key() Object {
    return String(it.keys[it.i-1])
}

// Value implements Iterator interface.
func (it *MapIterator) Value() Object {
    v, ok := it.V[it.keys[it.i-1]]
    if !ok {
        return Undefined
    }
    return v
}

// SyncIterator represents an iterator for the SyncMap.
type SyncIterator struct {
    mu sync.Mutex
    Iterator
}

// Next implements Iterator interface.
func (it *SyncIterator) Next() bool {
    it.mu.Lock()
    defer it.mu.Unlock()
    return it.Iterator.Next()
}

// Key implements Iterator interface.
func (it *SyncIterator) Key() Object {
    it.mu.Lock()
    defer it.mu.Unlock()
    return it.Iterator.Key()
}

// Value implements Iterator interface.
func (it *SyncIterator) Value() Object {
    it.mu.Lock()
    defer it.mu.Unlock()
    return it.Iterator.Value()
}

// StringIterator represents an iterator for the string.
type StringIterator struct {
    V String
    i int
    k int
    r rune
}

var _ Iterator = (*StringIterator)(nil)

// Next implements Iterator interface.
func (it *StringIterator) Next() bool {
    if it.i > len(it.V)-1 {
        return false
    }

    r, s := utf8.DecodeRuneInString(string(it.V)[it.i:])
    if r == utf8.RuneError || s == 0 {
        return false
    }

    it.k = it.i
    it.r = r
    it.i += s
    return true
}

// Key implements Iterator interface.
func (it *StringIterator) Key() Object {
    return Int(it.k)
}

// Value implements Iterator interface.
func (it *StringIterator) Value() Object {
    return Char(it.r)
}