#200 - new ast node + parsing

Author: Stepami

src/Domain/HydraScript.Domain.FrontEnd/Parser/Impl/Ast/Nodes/Statements/InputStatement.cs

@@ -0,0 +1,21 @@
+using HydraScript.Domain.FrontEnd.Parser.Impl.Ast.Nodes.Expressions.PrimaryExpressions;
+
+namespace HydraScript.Domain.FrontEnd.Parser.Impl.Ast.Nodes.Statements;
+
+[AutoVisitable<IAbstractSyntaxTreeNode>]
+public partial class InputStatement : Statement
+{
+    protected override IReadOnlyList<IAbstractSyntaxTreeNode> Children { get; }
+
+    public IdentifierReference Destination { get; }
+
+    public InputStatement(IdentifierReference destination)
+    {
+        Destination = destination;
+        Destination.Parent = this;
+
+        Children = [Destination];
+    }
+
+    protected override string NodeRepresentation() => "input";
+}

src/Domain/HydraScript.Domain.FrontEnd/Parser/Impl/TopDownParser.cs

@@ -83,7 +83,8 @@ private ScriptBody Script() =>
     private List<StatementListItem> StatementList()
     {
         var statementList = new List<StatementListItem>();
-        while (CurrentIsDeclaration() || CurrentIsExpression() || CurrentIs("Output") ||
+        while (CurrentIsDeclaration() || CurrentIsExpression() ||
+               CurrentIs("Output") || CurrentIs("Input") ||
                CurrentIsKeyword("return") || CurrentIsKeyword("break") || CurrentIsKeyword("continue") ||
                CurrentIsKeyword("if") || CurrentIsKeyword("while"))
         {
@@ -115,6 +116,7 @@ private StatementListItem StatementListItem()
     ///              BreakStatement
     ///              ReturnStatement
     ///              OutputStatement
+    ///              InputStatement
     /// </summary>
     private Statement Statement()
     {
@@ -149,6 +151,9 @@ private Statement Statement()
         if (CurrentIs("Output"))
             return OutputStatement();
 
+        if (CurrentIs("Input"))
+            return InputStatement();
+
         return null!;
     }
 
@@ -228,6 +233,32 @@ private OutputStatement OutputStatement()
         return new OutputStatement(Expression());
     }
 
+    /// <summary>
+    /// InputStatement -> '&lt;&lt;&lt;' (Ident | EnvVar)
+    /// </summary>
+    private InputStatement InputStatement()
+    {
+        var input = Expect("Input");
+        if (CurrentIsOperator("$"))
+        {
+            var dollar = Expect("Operator");
+            var envIdent = Expect("Ident");
+            return new InputStatement(new EnvVarReference(envIdent.Value)
+            {
+                Segment = dollar.Segment + envIdent.Segment
+            })
+            {
+                Segment = input.Segment + envIdent.Segment
+            };
+        }
+
+        var ident = Expect("Ident");
+        return new InputStatement(new IdentifierReference(ident.Value) { Segment = ident.Segment })
+        {
+            Segment = input.Segment + ident.Segment
+        };
+    }
+
     /// <summary>
     /// TypeDeclaration -> 'type' "Ident" = TypeValue
     /// </summary>