528 lines
16 KiB
C#
528 lines
16 KiB
C#
using System.Diagnostics.CodeAnalysis;
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using Nub.Lang.Frontend.Lexing;
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namespace Nub.Lang.Frontend.Parsing;
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public class Parser
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{
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private List<Token> _tokens = [];
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private int _index;
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public ModuleNode ParseModule(List<Token> tokens, string path)
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{
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_index = 0;
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_tokens = tokens;
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List<DefinitionNode> definitions = [];
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List<string> imports = [];
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while (Peek().HasValue)
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{
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if (TryExpectSymbol(Symbol.Import))
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{
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var name = ExpectIdentifier();
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TryExpectSymbol(Symbol.Semicolon);
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imports.Add(name.Value);
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}
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else
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{
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definitions.Add(ParseDefinition());
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}
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}
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return new ModuleNode(path, imports, definitions);
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}
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private DefinitionNode ParseDefinition()
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{
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List<Modifier> modifiers = [];
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while (TryExpectModifier(out var modifier))
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{
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modifiers.Add(modifier);
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}
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var keyword = ExpectSymbol();
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return keyword.Symbol switch
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{
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Symbol.Func => ParseFuncDefinition(modifiers),
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Symbol.Struct => ParseStruct(modifiers),
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_ => throw new Exception("Unexpected symbol: " + keyword.Symbol)
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};
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}
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private DefinitionNode ParseFuncDefinition(List<Modifier> modifiers)
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{
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var name = ExpectIdentifier();
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List<FuncParameter> parameters = [];
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ExpectSymbol(Symbol.OpenParen);
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if (!TryExpectSymbol(Symbol.CloseParen))
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{
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while (!TryExpectSymbol(Symbol.CloseParen))
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{
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parameters.Add(ParseFuncParameter());
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TryExpectSymbol(Symbol.Comma);
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}
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}
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var returnType = Optional<NubType>.Empty();
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if (TryExpectSymbol(Symbol.Colon))
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{
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returnType = ParseType();
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}
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if (modifiers.Remove(Modifier.Extern))
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{
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if (modifiers.Count != 0)
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{
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throw new Exception($"Modifiers: {string.Join(", ", modifiers)} is not valid for an extern function");
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}
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ExpectSymbol(Symbol.Semicolon);
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return new ExternFuncDefinitionNode(name.Value, parameters, returnType);
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}
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var body = ParseBlock();
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var global = modifiers.Remove(Modifier.Global);
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if (modifiers.Count != 0)
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{
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throw new Exception($"Modifiers: {string.Join(", ", modifiers)} is not valid for a local function");
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}
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return new LocalFuncDefinitionNode(name.Value, parameters, body, returnType, global);
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}
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private StructDefinitionNode ParseStruct(List<Modifier> modifiers)
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{
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var name = ExpectIdentifier().Value;
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ExpectSymbol(Symbol.OpenBrace);
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List<StructField> variables = [];
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while (!TryExpectSymbol(Symbol.CloseBrace))
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{
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var variableName = ExpectIdentifier().Value;
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ExpectSymbol(Symbol.Colon);
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var variableType = ParseType();
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var variableValue = Optional<ExpressionNode>.Empty();
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if (TryExpectSymbol(Symbol.Assign))
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{
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variableValue = ParseExpression();
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}
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ExpectSymbol(Symbol.Semicolon);
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variables.Add(new StructField(variableName, variableType, variableValue));
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}
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return new StructDefinitionNode(name, variables);
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}
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private FuncParameter ParseFuncParameter()
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{
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var variadic = false;
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if (TryExpectSymbol(Symbol.Period))
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{
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ExpectSymbol(Symbol.Period);
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ExpectSymbol(Symbol.Period);
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variadic = true;
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}
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var name = ExpectIdentifier();
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ExpectSymbol(Symbol.Colon);
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var type = ParseType();
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return new FuncParameter(name.Value, type, variadic);
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}
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private StatementNode ParseStatement()
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{
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var token = ExpectToken();
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switch (token)
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{
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case IdentifierToken identifier:
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{
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var symbol = ExpectSymbol();
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switch (symbol.Symbol)
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{
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case Symbol.OpenParen:
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{
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var parameters = new List<ExpressionNode>();
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while (!TryExpectSymbol(Symbol.CloseParen))
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{
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parameters.Add(ParseExpression());
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TryExpectSymbol(Symbol.Comma);
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}
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ExpectSymbol(Symbol.Semicolon);
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return new FuncCallStatementNode(new FuncCall(identifier.Value, parameters));
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}
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case Symbol.Assign:
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{
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var value = ParseExpression();
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ExpectSymbol(Symbol.Semicolon);
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return new VariableAssignmentNode(identifier.Value, value);
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}
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default:
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{
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throw new Exception($"Unexpected symbol {symbol.Symbol}");
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}
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}
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}
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case SymbolToken symbol:
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{
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return symbol.Symbol switch
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{
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Symbol.Return => ParseReturn(),
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Symbol.If => ParseIf(),
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Symbol.While => ParseWhile(),
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Symbol.Break => ParseBreak(),
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Symbol.Continue => ParseContinue(),
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_ => throw new Exception($"Unexpected symbol {symbol.Symbol}")
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};
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}
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default:
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{
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throw new Exception($"Unexpected token type {token.GetType().Name}");
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}
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}
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}
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private ReturnNode ParseReturn()
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{
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var value = Optional<ExpressionNode>.Empty();
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if (!TryExpectSymbol(Symbol.Semicolon))
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{
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value = ParseExpression();
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ExpectSymbol(Symbol.Semicolon);
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}
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return new ReturnNode(value);
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}
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private IfNode ParseIf()
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{
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var condition = ParseExpression();
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var body = ParseBlock();
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var elseStatement = Optional<Variant<IfNode, BlockNode>>.Empty();
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if (TryExpectSymbol(Symbol.Else))
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{
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elseStatement = TryExpectSymbol(Symbol.If)
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? (Variant<IfNode, BlockNode>)ParseIf()
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: (Variant<IfNode, BlockNode>)ParseBlock();
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}
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return new IfNode(condition, body, elseStatement);
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}
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private WhileNode ParseWhile()
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{
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var condition = ParseExpression();
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var body = ParseBlock();
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return new WhileNode(condition, body);
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}
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private BreakNode ParseBreak()
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{
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ExpectSymbol(Symbol.Semicolon);
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return new BreakNode();
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}
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private ContinueNode ParseContinue()
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{
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ExpectSymbol(Symbol.Semicolon);
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return new ContinueNode();
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}
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private ExpressionNode ParseExpression(int precedence = 0)
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{
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var left = ParsePrimaryExpression();
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while (true)
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{
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var token = Peek();
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if (!token.HasValue || token.Value is not SymbolToken symbolToken || !TryGetBinaryOperator(symbolToken.Symbol, out var op) ||
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GetBinaryOperatorPrecedence(op.Value) < precedence)
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break;
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Next();
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var right = ParseExpression(GetBinaryOperatorPrecedence(op.Value) + 1);
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left = new BinaryExpressionNode(left, op.Value, right);
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}
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return left;
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}
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private static int GetBinaryOperatorPrecedence(BinaryExpressionOperator binaryExpressionOperator)
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{
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return binaryExpressionOperator switch
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{
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BinaryExpressionOperator.Multiply => 3,
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BinaryExpressionOperator.Divide => 3,
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BinaryExpressionOperator.Plus => 2,
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BinaryExpressionOperator.Minus => 2,
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BinaryExpressionOperator.GreaterThan => 1,
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BinaryExpressionOperator.GreaterThanOrEqual => 1,
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BinaryExpressionOperator.LessThan => 1,
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BinaryExpressionOperator.LessThanOrEqual => 1,
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BinaryExpressionOperator.Equal => 0,
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BinaryExpressionOperator.NotEqual => 0,
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_ => throw new ArgumentOutOfRangeException(nameof(binaryExpressionOperator), binaryExpressionOperator, null)
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};
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}
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private static bool TryGetBinaryOperator(Symbol symbol, [NotNullWhen(true)] out BinaryExpressionOperator? binaryExpressionOperator)
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{
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switch (symbol)
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{
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case Symbol.Equal:
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binaryExpressionOperator = BinaryExpressionOperator.Equal;
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return true;
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case Symbol.NotEqual:
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binaryExpressionOperator = BinaryExpressionOperator.NotEqual;
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return true;
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case Symbol.LessThan:
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binaryExpressionOperator = BinaryExpressionOperator.LessThan;
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return true;
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case Symbol.LessThanOrEqual:
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binaryExpressionOperator = BinaryExpressionOperator.LessThanOrEqual;
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return true;
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case Symbol.GreaterThan:
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binaryExpressionOperator = BinaryExpressionOperator.GreaterThan;
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return true;
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case Symbol.GreaterThanOrEqual:
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binaryExpressionOperator = BinaryExpressionOperator.GreaterThanOrEqual;
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return true;
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case Symbol.Plus:
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binaryExpressionOperator = BinaryExpressionOperator.Plus;
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return true;
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case Symbol.Minus:
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binaryExpressionOperator = BinaryExpressionOperator.Minus;
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return true;
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case Symbol.Star:
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binaryExpressionOperator = BinaryExpressionOperator.Multiply;
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return true;
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case Symbol.ForwardSlash:
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binaryExpressionOperator = BinaryExpressionOperator.Divide;
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return true;
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default:
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binaryExpressionOperator = null;
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return false;
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}
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}
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private ExpressionNode ParsePrimaryExpression()
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{
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var token = ExpectToken();
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switch (token)
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{
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case LiteralToken literal:
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{
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return new LiteralNode(literal.Value, literal.Type);
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}
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case IdentifierToken identifier:
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{
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return ParseExpressionIdentifier(identifier);
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}
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case SymbolToken symbolToken:
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{
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switch (symbolToken.Symbol)
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{
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case Symbol.OpenParen:
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{
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var expression = ParseExpression();
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ExpectSymbol(Symbol.CloseParen);
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return expression;
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}
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case Symbol.New:
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{
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var type = ParseType();
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Dictionary<string, ExpressionNode> initializers = [];
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ExpectSymbol(Symbol.OpenBrace);
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while (!TryExpectSymbol(Symbol.CloseBrace))
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{
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var name = ExpectIdentifier().Value;
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ExpectSymbol(Symbol.Assign);
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var value = ParseExpression();
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TryExpectSymbol(Symbol.Semicolon);
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initializers.Add(name, value);
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}
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return new StructInitializerNode(type, initializers);
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}
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default:
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{
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throw new Exception($"Unknown symbol: {symbolToken.Symbol}");
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}
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}
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}
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default:
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throw new Exception($"Unexpected token type {token.GetType().Name}");
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}
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}
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private ExpressionNode ParseExpressionIdentifier(IdentifierToken identifier)
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{
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var token = Peek();
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if (!token.HasValue)
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{
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return new IdentifierNode(identifier.Value);
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}
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switch (token.Value)
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{
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case SymbolToken symbolToken:
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{
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switch (symbolToken.Symbol)
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{
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case Symbol.Period:
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{
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Next();
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ExpressionNode result = new IdentifierNode(identifier.Value);
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do
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{
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var field = ExpectIdentifier();
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result = new StructFieldAccessorNode(result, field.Value);
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} while (TryExpectSymbol(Symbol.Period));
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return result;
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}
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case Symbol.OpenParen:
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{
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Next();
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List<ExpressionNode> parameters = [];
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while (!TryExpectSymbol(Symbol.CloseParen))
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{
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parameters.Add(ParseExpression());
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TryExpectSymbol(Symbol.Comma);
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}
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return new FuncCallExpressionNode(new FuncCall(identifier.Value, parameters));
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}
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}
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break;
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}
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}
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return new IdentifierNode(identifier.Value);
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}
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private BlockNode ParseBlock()
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{
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ExpectSymbol(Symbol.OpenBrace);
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List<StatementNode> statements = [];
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while (!TryExpectSymbol(Symbol.CloseBrace))
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{
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statements.Add(ParseStatement());
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}
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return new BlockNode(statements);
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}
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private NubType ParseType()
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{
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var name = ExpectIdentifier().Value;
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return NubType.Parse(name);
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}
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private Token ExpectToken()
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{
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var token = Peek();
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if (!token.HasValue)
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{
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throw new Exception("Reached end of tokens");
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}
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Next();
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return token.Value;
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}
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private SymbolToken ExpectSymbol()
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{
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var token = ExpectToken();
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if (token is not SymbolToken symbol)
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{
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throw new Exception($"Expected {nameof(SymbolToken)} but got {token.GetType().Name}");
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}
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return symbol;
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}
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private void ExpectSymbol(Symbol symbol)
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{
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var token = ExpectSymbol();
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if (token.Symbol != symbol)
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{
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throw new Exception($"Expected symbol {symbol} but got {token.Symbol}");
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}
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}
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private bool TryExpectSymbol(Symbol symbol)
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{
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var result = Peek() is { HasValue: true, Value: SymbolToken symbolToken } && symbolToken.Symbol == symbol;
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if (result) Next();
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return result;
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}
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private bool TryExpectModifier(out Modifier modifier)
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{
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if (Peek() is { HasValue: true, Value: ModifierToken modifierToken })
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{
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modifier = modifierToken.Modifier;
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Next();
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return true;
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}
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modifier = default;
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return false;
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}
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private IdentifierToken ExpectIdentifier()
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{
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var token = ExpectToken();
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if (token is not IdentifierToken identifier)
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{
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throw new Exception($"Expected {nameof(IdentifierToken)} but got {token.GetType().Name}");
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}
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return identifier;
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}
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private LiteralToken ExpectLiteral()
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{
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var token = ExpectToken();
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if (token is not LiteralToken literal)
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{
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throw new Exception($"Expected {nameof(LiteralToken)} but got {token.GetType().Name}");
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}
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return literal;
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}
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private Optional<Token> Peek()
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{
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while (_index < _tokens.Count && _tokens.ElementAt(_index) is SymbolToken { Symbol: Symbol.Whitespace })
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{
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Next();
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}
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if (_index < _tokens.Count)
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{
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return _tokens.ElementAt(_index);
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}
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return Optional<Token>.Empty();
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}
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private void Next()
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{
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_index++;
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}
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} |