[New Exercise]: Dot DSL (#351)

* [New Exercise]: Dot DSL

* Update DotDsl.ps1

-Remove the extra constructor in template

config.json

@@ -960,6 +960,14 @@
         "prerequisites": [],
         "difficulty": 5
       },
+      {
+        "slug": "dot-dsl",
+        "name": "DOT DSL",
+        "uuid": "79c56891-bb51-4de9-acb1-13edfa14573e",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "connect",
         "name": "Connect",

exercises/practice/dot-dsl/.docs/instructions.md

@@ -0,0 +1,30 @@
+# Instructions
+
+A [Domain Specific Language (DSL)][dsl] is a small language optimized for a specific domain.
+Since a DSL is targeted, it can greatly impact productivity/understanding by allowing the writer to declare _what_ they want rather than _how_.
+
+One problem area where they are applied are complex customizations/configurations.
+
+For example the [DOT language][dot-language] allows you to write a textual description of a graph which is then transformed into a picture by one of the [Graphviz][graphviz] tools (such as `dot`).
+A simple graph looks like this:
+
+    graph {
+        graph [bgcolor="yellow"]
+        a [color="red"]
+        b [color="blue"]
+        a -- b [color="green"]
+    }
+
+Putting this in a file `example.dot` and running `dot example.dot -T png -o example.png` creates an image `example.png` with red and blue circle connected by a green line on a yellow background.
+
+Write a Domain Specific Language similar to the Graphviz dot language.
+
+Our DSL is similar to the Graphviz dot language in that our DSL will be used to create graph data structures.
+However, unlike the DOT Language, our DSL will be an internal DSL for use only in our language.
+
+More information about the difference between internal and external DSLs can be found [here][fowler-dsl].
+
+[dsl]: https://en.wikipedia.org/wiki/Domain-specific_language
+[dot-language]: https://en.wikipedia.org/wiki/DOT_(graph_description_language)
+[graphviz]: https://graphviz.org/
+[fowler-dsl]: https://martinfowler.com/bliki/DomainSpecificLanguage.html

exercises/practice/dot-dsl/.meta/DotDsl.example.ps1

@@ -0,0 +1,97 @@
+<#
+.SYNOPSIS
+    Write a Domain Specific Language similar to the Graphviz dot language.
+
+.DESCRIPTION
+    Implement the classes to stimulate a DSL similar to the Graphviz dot language.
+
+    Node class : represent the nodes inside the graph.
+    Edge class : represent the relationship between two nodes.
+    Attr class : represent the attributes of other objects (node, edge or graph).
+    Graph class: represent the graph, contains info about nodes, edges and attributes.
+
+    Node, Edge and Attr should have the 'Equals' method implemented for the purpose of comparison in the test suite.
+#>
+
+Class Node {
+    [string] $Name
+    [Attr] $Attrs
+
+    Node([string] $name){
+        $this.Name = $name
+        $this.Attrs = [Attr]::new()
+    }
+
+    Node([string] $name, [hashtable] $attrs){
+        $this.Name = $name
+        $this.Attrs = [Attr]::new($attrs)
+    }
+
+    [bool] Equals([object] $other) {
+        return $this.Name -eq $other.Name -and $this.Attrs -eq $other.Attrs
+    }
+}
+
+Class Edge {
+    [string] $Source
+    [string] $Target
+    [Attr] $Attrs
+
+    Edge([string] $from, [string] $to){
+        $this.Source = $from
+        $this.Target = $to
+        $this.Attrs  = [Attr]::new()
+    }
+
+    Edge([string] $from, [string] $to, [hashtable] $attr){
+        $this.Source = $from
+        $this.Target = $to
+        $this.Attrs  = [Attr]::new($attr)
+    }
+
+    [bool] Equals([object] $other) {
+        return $this.Source -eq $other.Source 
+        -and $this.Target -eq $other.Target 
+        -and $this.Attrs -eq $other.Attrs
+    }
+}
+
+Class Attr {
+    [hashtable] hidden $Data
+
+    Attr() {
+        $this.Data = @{}
+    }
+
+    Attr([hashtable] $attr){
+        $this.Data = @{}
+        $this.Data += $attr
+    }
+
+    [bool] Equals( $other) {
+        $equalsKey = Compare-Object $this.Data.Keys $other.Data.Keys
+        $equalsVal = Compare-Object $this.Data.Values $other.Data.Values
+        return -not ($equalsKey -or $equalsVal)
+    }
+}
+
+Class Graph {
+    [Node[]] $Nodes
+    [Edge[]] $Edges
+    [Attr[]] $Attrs
+
+    Graph(){
+        $this.Nodes = @()
+        $this.Edges = @()
+        $this.Attrs = @()
+    }
+
+    Graph([object[]] $Data){
+        switch ($Data) {
+            {$_ -is [Node]} { $this.Nodes += $_ }
+            {$_ -is [Edge]} { $this.Edges += $_ }
+            {$_ -is [Attr]} { $this.Attrs += $_ }
+            Default { Throw "Graph can only contain node, egde or attribute"}
+        }
+    }
+}

exercises/practice/dot-dsl/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "glaxxie"
+  ],
+  "files": {
+    "solution": [
+      "DotDsl.ps1"
+    ],
+    "test": [
+      "DotDsl.tests.ps1"
+    ],
+    "example": [
+      ".meta/DotDsl.example.ps1"
+    ]
+  },
+  "blurb": "Write a Domain Specific Language similar to the Graphviz dot language.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/DOT_(graph_description_language)"
+}

exercises/practice/dot-dsl/DotDsl.ps1

@@ -0,0 +1,56 @@
+<#
+.SYNOPSIS
+    Write a Domain Specific Language similar to the Graphviz dot language.
+
+.DESCRIPTION
+    Implement the classes to stimulate a DSL similar to the Graphviz dot language.
+
+    Node class : represent the nodes inside the graph.
+    Edge class : represent the relationship between two nodes.
+    Attr class : represent the attributes of other objects (node, edge or graph).
+    Graph class: represent the graph, contains info about nodes, edges and attributes.
+
+    Node, Edge and Attr should have the 'Equals' method implemented for the purpose of comparison in the test suite.
+#>
+
+Class Node {
+    Node(){
+        Throw "Please implement this class"
+    }
+
+    [bool] Equals() {
+        Throw "Please implement this fucntion"
+    }
+}
+
+Class Edge {
+    Edge(){
+        Throw "Please implement this class"
+    }
+
+    [bool] Equals() {
+        Throw "Please implement this fucntion"
+    }
+}
+
+Class Attr {
+    Attr() {
+        Throw "Please implement this class"
+    }
+
+    [bool] Equals() {
+        Throw "Please implement this fucntion"
+    }
+}
+
+Class Graph {
+    [Node[]] $Nodes
+    [Edge[]] $Edges
+    [Attr[]] $Attrs
+
+    Graph($data){
+        Throw "Please implement this class"
+    }
+}
+
+

exercises/practice/dot-dsl/DotDsl.tests.ps1

@@ -0,0 +1,111 @@
+BeforeAll {
+    . "./DotDsl.ps1"
+}
+
+Describe "DotDsl test cases" {
+    It "empty graph" {
+        $graph = [Graph]::new()
+
+        $graph.Nodes | Should -BeNullOrEmpty
+        $graph.Edges | Should -BeNullOrEmpty
+        $graph.Attrs | Should -BeNullOrEmpty
+    }
+
+    It "graph with one node" {
+        $graph = [Graph]::new( 
+            @(
+                [Node]::new("a")   
+            )
+        )
+
+        $graph.Nodes | Should -BeExactly @([Node]::new("a"))
+        $graph.Edges | Should -BeNullOrEmpty
+        $graph.Attrs | Should -BeNullOrEmpty
+    }
+
+    It "graph with one node with keywords" {
+        $graph = [Graph]::new( 
+            @(
+                [Node]::new("a", @{Color = "green"})   
+            )
+        )
+
+        $graph.Nodes | Should -BeExactly @([Node]::new("a", @{Color = "green"}))
+        $graph.Edges | Should -BeNullOrEmpty
+        $graph.Attrs | Should -BeNullOrEmpty
+    }
+
+    It "graph with one edge" {
+        $graph = [Graph]::new( 
+            @(
+                [Edge]::new("a", "b")   
+            )
+        )
+
+        $graph.Nodes | Should -BeNullOrEmpty
+        $graph.Edges | Should -BeExactly @([Edge]::new("a", "b"))
+        $graph.Attrs | Should -BeNullOrEmpty
+    }
+
+    It "graph with one edge with attribute" {
+        $graph = [Graph]::new( 
+            @(
+                [Edge]::new("a", "b", @{Style = "dotted"})   
+            )
+        )
+
+        $graph.Nodes | Should -BeNullOrEmpty
+        $graph.Edges | Should -BeExactly @([Edge]::new("a", "b", @{Style = "dotted"}))
+        $graph.Attrs | Should -BeNullOrEmpty
+    }
+
+    It "graph with one attribute" {
+        $graph = [Graph]::new( 
+            @(
+                [Attr]::new(@{Title = "mygraph"})   
+            )
+        )
+
+        $graph.Nodes | Should -BeNullOrEmpty
+        $graph.Edges | Should -BeNullOrEmpty
+        $graph.Attrs | Should -BeExactly @([Attr]::new(@{Title = "mygraph"}))
+    }
+
+    It "graph with attributes" {
+        $graph = [Graph]::new( 
+            @(
+                [Attr]::new(@{Title = "mygraph"}),
+                [Attr]::new(@{Author = "exercism"}),
+                [Node]::new("a", @{Color = "green"}),
+                [Node]::new("c"),
+                [Node]::new("b", @{Label = "beta"}),
+                [Edge]::new("b", "c"),
+                [Edge]::new("a", "b", @{Style = "solid"; Color = "yellow"}),
+                [Attr]::new(@{Version = 1.0})
+            )
+        )
+
+        $nodes = @(
+                [Node]::new("a", @{Color = "green"}), 
+                [Node]::new("c"), 
+                [Node]::new("b", @{Label = "beta"})
+            )
+        $edges = @(
+                [Edge]::new("b", "c"), 
+                [Edge]::new("a", "b", @{Style = "solid"; Color = "yellow"})
+            )
+        $attrs = @(
+                [Attr]::new(@{Title = "mygraph"}), 
+                [Attr]::new(@{Author = "exercism"}), 
+                [Attr]::new(@{Version = 1.0})
+            )
+
+        $graph.Nodes | Should -BeExactly $nodes
+        $graph.Edges | Should -BeExactly $edges
+        $graph.Attrs | Should -BeExactly $attrs
+    }
+
+    It "unknown item in graph throw error" {
+        {[Graph]::new("hello")} | Should -Throw "*Graph can only contain node, egde or attribute*"
+    }
+}