Added License, Readme and Changelog files. Remove Sort() from Intervals interface (not needed because it's called on each operation).

LICENSE

@@ -0,0 +1,9 @@
+The MIT License (MIT)
+
+Copyright (c) 2018 centraldereservas.com
+
+Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

README.md

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+# intervals [![License: MIT](https://img.shields.io/badge/License-MIT-yellow.svg)](https://opensource.org/licenses/MIT) [![GoDoc](https://godoc.org/github.com/centraldereservas/intervals?status.svg)](https://godoc.org/github.com/centraldereservas/intervals)
+
+Provides a helper to work with integer intervals detecting gaps, merged and overlapped sections.
+
+## Installation
+
+```sh
+go get github.com/centraldereservas/intervals
+```
+
+## Motivation
+
+Why we need to have control over a list of intervals?
+
+Because provider API's have product prices depending on the age, so they assign a price amount to different age bands.
+
+As a result we have a bunch of age bands (with its corresponding price) which can have:
+
+- overlapping ages (due to an error entering the data).
+- gaps in between age bands.
+- different maximal age (for adult) depending on the provider (e.g. one can specify [18,99] and another [18-999] meaning the same).
+- some providers do not create an age band for babies which has to be interpret as free entry, so we have a gap at the beginning.
+
+So we need a mechanism to enter a list of age bands and be able to analyse it to take future actions.
+
+## Documentation
+
+We define an interval as
+
+```go
+type Interval struct {
+   Low    int
+   High   int
+   Object interface{}
+}
+```
+
+where the `Low` and `High` values define a range and `Object` is any object to link to this range (in our case would be a Price object for the age band specified in the range).
+
+API documentation is available on [godoc.org][doc].
+
+## Usage
+
+### Initialization
+
+To use this package the first thing we have to do is create an instance:
+
+```go
+intvls := interval.NewIntervals(minLow, maxHigh, lowInclusive, highInclusive, selfAdjustMinLow, selfAdjustMaxHigh)
+```
+
+where `minLow` and `maxHigh` are integers that defines the accepted integer space to work with, anything else outside will be rejected. The booleans `lowInclusive` and `highInclusive` indicates if the values of a range (low, high) are inclusive or not. The booleans `selfAdjustMinLow`and `selfAdjustMaxHigh` indicates that we do not need to specify the minLow or maxHigh in the constructor, but those values will be self adjusted automatically taking the lower and greatest value  respectively of all intervals added.
+
+Here some examples of inclusiveness:
+
+- if both are inclusive for the interval [10, 17] means that a person with age 17 years old applies this interval
+- if the low is inclusive and the high exclusive for the same example [10, 17) then a person with age 17 do not apply this interval, but a person with 10 does.
+
+### Add intervals
+
+Once initialized, we can proced to add new intervals.
+
+We can add intervals by passing an `Interval` object:
+
+```go
+intvl := &interval.Interval{Low: ageFrom, High: ageTo, Object: myObject}
+err := intvls.AddInterval(intvl)
+if err != nil {
+   fmt.Printf("invalid interval discarded: %v\n", err)
+}
+```
+
+or directly the values `Low`, `High` and `Object`:
+
+```go
+err := intvls.Add(low: ageFrom, high: ageTo, obj: myObject)
+if err != nil {
+   fmt.Printf("invalid interval discarded: %v\n", err)
+}
+```
+
+### Get all intervals
+
+Returns all the intervals added sorted by the `Low` integer value.
+
+```go
+allIntervals := intvls.GetIntervals()
+```
+
+NOTE: any operation (get all, gaps, merge, overlap) apply a sort if needed.
+
+### Find value inside intervals
+
+Given an integer value we can retrieve all intervals which cointain it
+
+```go
+list := intvls.FindIntervalsForValue(tc.valueToFind)
+```
+
+### Calculate gaps
+
+Before getting the gaps, we could verify if exists any:
+
+```go
+existsGaps := intvls.HasGaps() 
+```
+
+Once we assure the gaps existance we can call `Gaps()`. This function scans all intervals searching for gaps in between and return a list of intervals corresponding to the gaps.
+
+```go
+gaps := intvls.Gaps()
+```
+
+### Calculate overlapping
+
+Before getting the overlapped elements, we could verify if exists any:
+
+```go
+existsOverlapping := intvls.HasOverlapped() 
+```
+
+Once we assure the existance overlapping we can call `Overlapped()`. This function scans all intervals searching for overlapping in between and return a list of intervals corresponding to the overlaped sections.
+
+```go
+overlapping := intvls.Overlapped()
+```
+
+### Calculate merging
+
+If we join together all the intervals we can fusion all them and as a result we will get a list of intervals merged, this is what the function `Merge` does:
+
+```go
+merging := intvls.Merge() 
+```
+
+
+## Example
+
+There is a complete example under the `/example/` folder in the source code that shows how the package is used.
+
+Output:
+
+```sh
+go run ./example/main.go
+```
+
+This example generates an output image file exposing the data analyzed:
+
+![alt text](./example/out.png)
+
+
+## References
+
+* [justforfunc #34: Plotting Data with gonum/plot](https://youtu.be/ihP7lQivA6M) by [Francesc Campoy](https://github.com/campoy)
+
+
+## License
+
+This project is under the [MIT License][mit].
+
+[mit]: https://github.com/centraldereservas/intervals/blob/master/LICENSE
+[doc]: https://godoc.org/github.com/centraldereservas/intervals

example/CHANGELOG.md

@@ -0,0 +1,4 @@
+# Changelog
+
+## [0.0.1] - 2018-06-28
+- First commit

intervals.go

@@ -21,9 +21,6 @@ type Intervals interface {
 	// AddInterval appends a new interval to the list. If the interval range (low, high) is invalid, it returns an error
 	AddInterval(itvl *Interval) error
 
-	// Sort sorts the intervals list by the Low property (ascending)
-	Sort()
-
 	// HasGaps returns true if exists gaps for the introduced intervals between MinLow and MaxHigh
 	HasGaps() bool