dictyBase/modware-annotation

package arangodb

import (
    "errors"

    "github.com/dictyBase/modware-annotation/internal/model"
)

// StringPairWiseIterator is the container for iterator.
type StringPairWiseIterator struct {
    slice []string
    // keeps track of the first index
    firstIdx int
    // keeps track of the next index in the pair
    secondIdx int
    // last index of the slice
    lastIdx int
    // toogle the state for fetching the first pair
    firstPair bool
}

// NewStringPairWiseIterator is the constructor, returns error in case of empty or
// slice with single element.
func NewStringPairWiseIterator(mdl []string) (StringPairWiseIterator, error) {
    if len(mdl) <= 1 {
        return StringPairWiseIterator{}, errors.New("not enough element to fetch pairs")
    }

    return StringPairWiseIterator{
        slice:     mdl,
        firstIdx:  0,
        secondIdx: 1,
        lastIdx:   len(mdl) - 1,
        firstPair: true,
    }, nil
}

// NextStringPair moves the iteration to the next pair. If NextStringPair() returns true
// the pair could be retrieved by Pair() method. If it is called for the first
// time it points to the first pair.
func (p *StringPairWiseIterator) NextStringPair() bool {
    if p.firstPair {
        p.firstPair = false

        return true
    }
    if p.secondIdx == p.lastIdx {
        return false
    }
    p.firstIdx++
    p.secondIdx++

    return true
}

// StringPair retrieves the pair of elements from the slice.
func (p *StringPairWiseIterator) StringPair() (string, string) {
    return p.slice[p.firstIdx], p.slice[p.secondIdx]
}

// ModelAnnoDocPairWiseIterator is the container for iterator.
type ModelAnnoDocPairWiseIterator struct {
    slice []*model.AnnoDoc
    // keeps track of the first index
    firstIdx int
    // keeps track of the next index in the pair
    secondIdx int
    // last index of the slice
    lastIdx int
    // toogle the state for fetching the first pair
    firstPair bool
}

// NewModelAnnoDocPairWiseIterator is the constructor, returns error in case of empty or
// slice with single element.
func NewModelAnnoDocPairWiseIterator(mdl []*model.AnnoDoc) (ModelAnnoDocPairWiseIterator, error) {
    if len(mdl) <= 1 {
        return ModelAnnoDocPairWiseIterator{}, errors.New("not enough element to fetch pairs")
    }

    return ModelAnnoDocPairWiseIterator{
        slice:     mdl,
        firstIdx:  0,
        secondIdx: 1,
        lastIdx:   len(mdl) - 1,
        firstPair: true,
    }, nil
}

// NextModelAnnoDocPair moves the iteration to the next pair. If NextModelAnnoDocPair() returns true
// the pair could be retrieved by Pair() method. If it is called for the first
// time it points to the first pair.
func (p *ModelAnnoDocPairWiseIterator) NextModelAnnoDocPair() bool {
    if p.firstPair {
        p.firstPair = false

        return true
    }
    if p.secondIdx == p.lastIdx {
        return false
    }
    p.firstIdx++
    p.secondIdx++

    return true
}

// ModelAnnoDocPair retrieves the pair of elements from the slice.
func (p *ModelAnnoDocPairWiseIterator) ModelAnnoDocPair() (*model.AnnoDoc, *model.AnnoDoc) {
    return p.slice[p.firstIdx], p.slice[p.secondIdx]
}