Basic parser

Nub.Lang/Nub.Lang/Input/program.nub

@@ -5,8 +5,6 @@ let STD_ERR = 2;
 
 func main() {
     write("test");
-    syscall(SYS_WRITE, STD_OUT, msg);
-    return 12;
 }
 
 func write(msg: void) {

Nub.Lang/Nub.Lang/Parsing/BlockNode.cs

@@ -1,6 +1,6 @@
 namespace Nub.Lang.Parsing;
 
-public class BlockNode(IEnumerable<StatementNode> statements) : StatementNode
+public class BlockNode(IEnumerable<StatementNode> statements) : Node
 {
     public IEnumerable<StatementNode> Statements { get; } = statements;
 }

Nub.Lang/Nub.Lang/Parsing/FuncCallNode.cs

@@ -0,0 +1,7 @@
+namespace Nub.Lang.Parsing;
+
+public class FuncCallNode(string name, IEnumerable<ExpressionNode> parameters) : StatementNode
+{
+    public string Name { get; } = name;
+    public IEnumerable<ExpressionNode> Parameters { get; } = parameters;
+}

Nub.Lang/Nub.Lang/Parsing/FuncDefinitionNode.cs

@@ -1,7 +1,8 @@
 namespace Nub.Lang.Parsing;
 
-public class FuncDefinitionNode(string name, IEnumerable<FuncParameter> parameters) : DefinitionNode
+public class FuncDefinitionNode(string name, IEnumerable<FuncParameter> parameters, BlockNode body) : DefinitionNode
 {
     public string Name { get; } = name;
     public IEnumerable<FuncParameter> Parameters { get; } = parameters;
+    public BlockNode Body { get; } = body;
 }

Nub.Lang/Nub.Lang/Parsing/IdentifierNode.cs

@@ -0,0 +1,6 @@
+namespace Nub.Lang.Parsing;
+
+public class IdentifierNode(string identifier) : ExpressionNode
+{
+    public string Identifier { get; } = identifier;
+}

Nub.Lang/Nub.Lang/Parsing/LiteralNode.cs

@@ -0,0 +1,6 @@
+namespace Nub.Lang.Parsing;
+
+public class LiteralNode(string value) : ExpressionNode
+{
+    public string Value { get; } = value;
+}

Nub.Lang/Nub.Lang/Parsing/Parser.cs

@@ -15,17 +15,130 @@ public class Parser
 
     public IEnumerable<DefinitionNode> Parse()
     {
+        _index = 0;
         List<DefinitionNode> definitions = [];
         while (Peek().HasValue)
         {
             definitions.Add(ParseDefinition());
         }
+
         return definitions;
     }
 
     private DefinitionNode ParseDefinition()
     {
-        throw new NotImplementedException();
+        var keyword = ExpectSymbol();
+        return keyword.Symbol switch
+        {
+            Symbol.Let => ParseGlobalVariableDefinition(),
+            Symbol.Func => ParseFuncDefinition(),
+            _ => throw new Exception("Unexpected symbol: " + keyword.Symbol)
+        };
+    }
+
+    private GlobalVariableDefinitionNode ParseGlobalVariableDefinition()
+    {
+        var name = ExpectIdentifier();
+        ExpectSymbol(Symbol.Assign);
+        var value = ParseExpression();
+        ExpectSymbol(Symbol.Semicolon);
+
+        return new GlobalVariableDefinitionNode(name.Value, value);
+    }
+
+    private FuncDefinitionNode ParseFuncDefinition()
+    {
+        var name = ExpectIdentifier();
+        List<FuncParameter> parameters = [];
+        ExpectSymbol(Symbol.OpenParen);
+        if (!TryExpectSymbol(Symbol.CloseParen))
+        {
+            while (!TryExpectSymbol(Symbol.CloseParen))
+            {
+                parameters.Add(ParseFuncParameter());
+            }
+        }
+
+        var body = ParseBlock();
+
+        return new FuncDefinitionNode(name.Value, parameters, body);
+    }
+
+    private FuncParameter ParseFuncParameter()
+    {
+        var name = ExpectIdentifier();
+        ExpectSymbol(Symbol.Colon);
+        var type = ParseType();
+
+        return new FuncParameter(name.Value, type);
+    }
+
+    private StatementNode ParseStatement()
+    {
+        var token = ExpectToken();
+        switch (token)
+        {
+            case IdentifierToken identifier:
+            {
+                var symbol = ExpectSymbol();
+                switch (symbol.Symbol)
+                {
+                    case Symbol.OpenParen:
+                    {
+                        var parameters = new List<ExpressionNode>();
+                        while (!TryExpectSymbol(Symbol.CloseParen))
+                        {
+                            parameters.Add(ParseExpression());
+                            TryExpectSymbol(Symbol.Comma);
+                        }
+
+                        ExpectSymbol(Symbol.Semicolon);
+
+                        if (identifier.Value == "syscall")
+                        {
+                            return new SyscallNode(parameters);
+                        }
+
+                        return new FuncCallNode(identifier.Value, parameters);
+                    }
+                    case Symbol.Assign:
+                        throw new NotImplementedException();
+                    default:
+                        throw new Exception($"Unexpected symbol {symbol.Symbol}");
+                }
+            }
+            default:
+                throw new Exception($"Unexpected token type {token.GetType().Name}");
+        }
+    }
+
+    private ExpressionNode ParseExpression()
+    {
+        var token = ExpectToken();
+        return token switch
+        {
+            LiteralToken literal => new LiteralNode(literal.Value),
+            IdentifierToken identifier => new IdentifierNode(identifier.Value),
+            _ => throw new Exception($"Unexpected token type {token.GetType().Name}")
+        };
+    }
+
+    private BlockNode ParseBlock()
+    {
+        ExpectSymbol(Symbol.OpenBrace);
+        List<StatementNode> statements = [];
+        while (!TryExpectSymbol(Symbol.CloseBrace))
+        {
+            statements.Add(ParseStatement());
+        }
+
+        return new BlockNode(statements);
+    }
+
+    private Type ParseType()
+    {
+        var name = ExpectIdentifier();
+        return new Type(name.Value);
     }
 
     private Token ExpectToken()
@@ -36,6 +149,7 @@ public class Parser
             throw new Exception("Reached end of tokens");
         }
 
+        Next();
         return token.Value;
     }
 
@@ -46,9 +160,10 @@ public class Parser
         {
             throw new Exception($"Expected {nameof(SymbolToken)} but got {token.GetType().Name}");
         }
+
         return symbol;
     }
-    
+
     private void ExpectSymbol(Symbol symbol)
     {
         var token = ExpectSymbol();
@@ -58,6 +173,13 @@ public class Parser
         }
     }
 
+    private bool TryExpectSymbol(Symbol symbol)
+    {
+        var result = Peek() is { HasValue: true, Value: SymbolToken symbolToken } && symbolToken.Symbol == symbol;
+        if (result) Next();
+        return result;
+    }
+
     private IdentifierToken ExpectIdentifier()
     {
         var token = ExpectToken();
@@ -65,9 +187,10 @@ public class Parser
         {
             throw new Exception($"Expected {nameof(IdentifierToken)} but got {token.GetType().Name}");
         }
+
         return identifier;
     }
-    
+
     private LiteralToken ExpectLiteral()
     {
         var token = ExpectToken();
@@ -75,19 +198,25 @@ public class Parser
         {
             throw new Exception($"Expected {nameof(LiteralToken)} but got {token.GetType().Name}");
         }
+
         return literal;
     }
-    
+
     private Optional<Token> Peek()
     {
+        while (_index < _tokens.Length && _tokens[_index] is SymbolToken { Symbol: Symbol.Whitespace })
+        {
+            Next();
+        }
+
         if (_index < _tokens.Length)
         {
             return _tokens[_index];
         }
-        
+
         return Optional<Token>.Empty();
     }
-    
+
     private void Next()
     {
         _index++;

Nub.Lang/Nub.Lang/Parsing/SyscallNode.cs

@@ -1,11 +1,6 @@
 namespace Nub.Lang.Parsing;
 
-public class ESyscallNode(IEnumerable<FuncParameter> parameters) : ExpressionNode
+public class SyscallNode(IEnumerable<ExpressionNode> parameters) : StatementNode
 {
-    public IEnumerable<FuncParameter> Parameters { get; } = parameters;
-}
-
-public class SSyscallNode(IEnumerable<FuncParameter> parameters) : StatementNode
-{
-    public IEnumerable<FuncParameter> Parameters { get; } = parameters;
+    public IEnumerable<ExpressionNode> Parameters { get; } = parameters;
 }

Nub.Lang/Nub.Lang/Program.cs

@@ -1,6 +1,12 @@
 using Nub.Lang.Lexing;
+using Nub.Lang.Parsing;
 
 var src = File.ReadAllText(args[0]);
 
 var lexer = new Lexer(src);
-var tokens = lexer.Lex();
+var tokens = lexer.Lex();
+
+var parser = new Parser(tokens);
+var definitions = parser.Parse();
+
+Console.Read();