initial commit

errorTypes.go

@@ -0,0 +1,10 @@
+package sortedList
+
+//List is empty
+type ErrListEmpty struct {
+	S string
+}
+
+func (err ErrListEmpty) Error() string {
+	return err.S
+}

sortedList.go

@@ -0,0 +1,76 @@
+package sortedList
+
+type num float64
+type elem interface{}
+
+type SortedList struct {
+	elems []*listElem
+}
+
+type listElem struct {
+	value num
+	elem  elem
+}
+
+func (sl *SortedList) Insert(elem elem, value num) {
+	newElem := listElem{
+		value,
+		elem,
+	}
+
+	if len(sl.elems) == 0 {
+		sl.elems = append(sl.elems, &newElem)
+	} else {
+
+		//find i such that sl.elems[i].value < newElen.value
+		var i int
+		for i = 0; i < len(sl.elems) && sl.elems[i].value < newElem.value; i++ {
+		}
+
+		//actual instertion at index = i
+		previousElems := sl.elems[:i]
+		forwardElems := make([]*listElem, len(sl.elems[i:]))
+		copy(forwardElems, sl.elems[i:])
+
+		sl.elems = append(previousElems, &newElem)
+		sl.elems = append(sl.elems, forwardElems...)
+	}
+}
+
+func (sl *SortedList) Nearest(value num) (elem, error) {
+
+	if len(sl.elems) == 0 {
+		return listElem{}, &ErrListEmpty{"List has no nearest element"}
+	}
+
+	if sl.elems[0].value > value {
+		return sl.elems[0].elem, nil
+	} else if len(sl.elems) == 1 {
+		return sl.elems[0].elem, nil
+	} else {
+		//Find i such that sl.elems[i].value > value
+		var i int
+		for i = 1; i < len(sl.elems) && sl.elems[i].value < value; i++ {
+		}
+		//If there is no bigger elemet return last element
+		if i == len(sl.elems) {
+			return sl.elems[i-1].elem, nil
+
+		}
+		biggerElem := sl.elems[i]
+		smallerElem := sl.elems[i-1]
+
+		//Return the element closer to value
+		switch {
+		case (value - smallerElem.value) <= (biggerElem.value - value):
+			return smallerElem.elem, nil
+		case (value - smallerElem.value) > (biggerElem.value - value):
+			return biggerElem.elem, nil
+		}
+	}
+	panic("reached unreachable statement")
+}
+
+func (sl *SortedList) Elems() []*listElem {
+	return sl.elems
+}

sortedList_test.go

@@ -0,0 +1,27 @@
+package sortedList
+
+import (
+	"testing"
+
+	tools "gitlab.com/Pixdigit/goTestTools"
+)
+
+func TestSortedList(t *testing.T) {
+	list := SortedList{}
+	list.Insert("a", 1)
+	list.Insert("b", 2)
+	list.Insert("c", 3)
+	list.Insert("d", 5)
+	list.Insert("e", 4)
+	value, err := list.Nearest(3.2);	if err != nil {tools.WrapErr(err, "could not get element from list", t)}
+	tools.Test(value == "c", "did not get corrent element", t)
+	value, err = list.Nearest(3.8);	if err != nil {tools.WrapErr(err, "could not get element from list", t)}
+	tools.Test(value == "e", "did not get corrent element", t)
+	value, err = list.Nearest(8);	if err != nil {tools.WrapErr(err, "could not get element from list", t)}
+	tools.Test(value == "d", "did not get corrent element", t)
+	value, err = list.Nearest(-2);	if err != nil {tools.WrapErr(err, "could not get element from list", t)}
+	tools.Test(value == "a", "did not get corrent element", t)
+	value, err = list.Nearest(2);	if err != nil {tools.WrapErr(err, "could not get element from list", t)}
+	tools.Test(value == "b", "did not get corrent element", t)
+
+}