749 lines
25 KiB
C#
749 lines
25 KiB
C#
using System.Diagnostics.CodeAnalysis;
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using Nub.Lang.Frontend.Diagnostics;
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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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private List<Diagnostic> _diagnostics = [];
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public DiagnosticsResult<ModuleNode> ParseModule(List<Token> tokens, string rootFilePath)
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{
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_index = 0;
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_tokens = tokens;
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_diagnostics = [];
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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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try
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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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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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catch (ParseException ex)
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{
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_diagnostics.Add(ex.Diagnostic);
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RecoverToNextDefinition();
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}
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}
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return new DiagnosticsResult<ModuleNode>(_diagnostics, new ModuleNode(GetTokensForNode(0), rootFilePath, imports, definitions));
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}
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private DefinitionNode ParseDefinition()
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{
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var startIndex = _index;
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List<ModifierToken> modifiers = [];
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List<string> documentationParts = [];
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while (_index < _tokens.Count && _tokens[_index] is DocumentationToken commentToken)
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{
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documentationParts.Add(commentToken.Documentation);
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_index++;
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}
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var documentation = documentationParts.Count == 0 ? null : string.Join('\n', documentationParts);
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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(startIndex, modifiers, Optional.OfNullable(documentation)),
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Symbol.Struct => ParseStruct(startIndex, modifiers, Optional.OfNullable(documentation)),
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_ => throw new ParseException(Diagnostic
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.Error($"Expected 'func' or 'struct', but found '{keyword.Symbol}'")
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.WithHelp("Valid definition keywords are 'func' and 'struct'")
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.At(keyword)
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.Build())
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};
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}
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private DefinitionNode ParseFuncDefinition(int startIndex, List<ModifierToken> modifiers, Optional<string> documentation)
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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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if (!TryExpectSymbol(Symbol.Comma) && Peek().TryGetValue(out var token) && token is not SymbolToken { Symbol: Symbol.CloseParen })
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{
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_diagnostics.Add(Diagnostic
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.Warning("Missing comma between function parameters")
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.WithHelp("Add a ',' to separate parameters")
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.At(token)
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.Build());
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}
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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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var isExtern = modifiers.RemoveAll(x => x.Modifier == Modifier.Extern) > 0;
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if (isExtern)
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{
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if (modifiers.Count != 0)
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{
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throw new ParseException(Diagnostic
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.Error($"Invalid modifier for extern function: {modifiers[0].Modifier}")
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.WithHelp($"Extern functions cannot use the '{modifiers[0].Modifier}' modifier")
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.At(modifiers[0])
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.Build());
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}
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return new ExternFuncDefinitionNode(GetTokensForNode(startIndex), documentation, name.Value, parameters, returnType);
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}
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var body = ParseBlock();
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var isGlobal = modifiers.RemoveAll(x => x.Modifier == Modifier.Global) > 0;
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if (modifiers.Count != 0)
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{
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throw new ParseException(Diagnostic
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.Error($"Invalid modifiers for function: {modifiers[0].Modifier}")
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.WithHelp($"Functions cannot use the '{modifiers[0].Modifier}' modifier")
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.At(modifiers[0])
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.Build());
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}
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return new LocalFuncDefinitionNode(GetTokensForNode(startIndex), documentation, name.Value, parameters, body, returnType, isGlobal);
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}
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private StructDefinitionNode ParseStruct(int startIndex, List<ModifierToken> _, Optional<string> documentation)
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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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variables.Add(new StructField(variableName, variableType, variableValue));
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}
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return new StructDefinitionNode(GetTokensForNode(startIndex), documentation, 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 startIndex = _index;
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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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return new FuncCallStatementNode(GetTokensForNode(startIndex), 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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return new VariableAssignmentNode(GetTokensForNode(startIndex), identifier.Value, Optional<NubType>.Empty(), value);
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}
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case Symbol.Colon:
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{
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var type = ParseType();
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ExpectSymbol(Symbol.Assign);
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var value = ParseExpression();
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return new VariableAssignmentNode(GetTokensForNode(startIndex), identifier.Value, type, value);
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}
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default:
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{
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throw new ParseException(Diagnostic
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.Error($"Unexpected symbol '{symbol.Symbol}' after identifier")
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.WithHelp("Expected '(', '=', or ':' after identifier")
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.At(symbol)
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.Build());
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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(startIndex),
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Symbol.If => ParseIf(startIndex),
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Symbol.While => ParseWhile(startIndex),
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Symbol.Break => new BreakNode(GetTokensForNode(startIndex)),
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Symbol.Continue => new ContinueNode(GetTokensForNode(startIndex)),
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_ => throw new ParseException(Diagnostic
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.Error($"Unexpected symbol '{symbol.Symbol}' at start of statement")
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.WithHelp("Expected identifier, 'return', 'if', 'while', 'break', or 'continue'")
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.At(symbol)
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.Build())
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};
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}
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default:
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{
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throw new ParseException(Diagnostic
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.Error($"Unexpected token '{token.GetType().Name}' at start of statement")
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.WithHelp("Statements must start with an identifier or keyword")
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.At(token)
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.Build());
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}
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}
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}
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private ReturnNode ParseReturn(int startIndex)
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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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}
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return new ReturnNode(GetTokensForNode(startIndex), value);
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}
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private IfNode ParseIf(int startIndex)
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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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var newStartIndex = _index;
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elseStatement = TryExpectSymbol(Symbol.If)
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? (Variant<IfNode, BlockNode>)ParseIf(newStartIndex)
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: (Variant<IfNode, BlockNode>)ParseBlock();
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}
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return new IfNode(GetTokensForNode(startIndex), condition, body, elseStatement);
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}
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private WhileNode ParseWhile(int startIndex)
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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(GetTokensForNode(startIndex), condition, body);
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}
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private ExpressionNode ParseExpression(int precedence = 0)
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{
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var startIndex = _index;
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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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{
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break;
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}
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Next();
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var right = ParseExpression(GetBinaryOperatorPrecedence(op.Value) + 1);
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left = new BinaryExpressionNode(GetTokensForNode(startIndex), 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 startIndex = _index;
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ExpressionNode expr;
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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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expr = new LiteralNode(GetTokensForNode(startIndex), literal.Value, literal.Type);
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break;
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}
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case IdentifierToken identifier:
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{
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var next = Peek();
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switch (next.Value)
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{
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case SymbolToken { Symbol: 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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if (!TryExpectSymbol(Symbol.Comma) && Peek().TryGetValue(out var nextToken) && nextToken is not SymbolToken { Symbol: Symbol.CloseParen })
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{
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_diagnostics.Add(Diagnostic
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.Warning("Missing comma between function arguments")
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.WithHelp("Add a ',' to separate arguments")
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.At(nextToken)
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.Build());
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}
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}
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expr = new FuncCallExpressionNode(GetTokensForNode(startIndex), new FuncCall(identifier.Value, parameters));
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break;
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}
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default:
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{
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expr = new IdentifierNode(GetTokensForNode(startIndex), identifier.Value);
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break;
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}
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}
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break;
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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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expr = expression;
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break;
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}
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case Symbol.LessThan:
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{
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var type = ParseType();
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ExpectSymbol(Symbol.GreaterThan);
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ExpectSymbol(Symbol.OpenParen);
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var expressionToCast = ParseExpression();
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ExpectSymbol(Symbol.CloseParen);
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expr = new CastNode(GetTokensForNode(startIndex), type, expressionToCast);
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break;
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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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initializers.Add(name, value);
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}
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expr = new StructInitializerNode(GetTokensForNode(startIndex), type, initializers);
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break;
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}
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case Symbol.Ampersand:
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{
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var expression = ParsePrimaryExpression();
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expr = new AddressOfNode(GetTokensForNode(startIndex), expression);
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break;
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}
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case Symbol.Minus:
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{
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var expression = ParsePrimaryExpression();
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expr = new UnaryExpressionNode(GetTokensForNode(startIndex), UnaryExpressionOperator.Negate, expression);
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break;
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}
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case Symbol.Bang:
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{
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var expression = ParsePrimaryExpression();
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expr = new UnaryExpressionNode(GetTokensForNode(startIndex), UnaryExpressionOperator.Invert, expression);
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break;
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}
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default:
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{
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throw new ParseException(Diagnostic
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.Error($"Unexpected symbol '{symbolToken.Symbol}' in expression")
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.WithHelp("Expected literal, identifier, or '(' to start expression")
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.At(symbolToken)
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.Build());
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}
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}
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break;
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}
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default:
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{
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throw new ParseException(Diagnostic
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.Error($"Unexpected token '{token.GetType().Name}' in expression")
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.WithHelp("Expected literal, identifier, or parenthesized expression")
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.At(token)
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.Build());
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}
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}
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return ParsePostfixOperators(startIndex, expr);
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}
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private ExpressionNode ParsePostfixOperators(int startIndex, ExpressionNode expr)
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{
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while (true)
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{
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if (TryExpectSymbol(Symbol.Caret))
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{
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expr = new DereferenceNode(GetTokensForNode(startIndex), expr);
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continue;
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}
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|
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if (TryExpectSymbol(Symbol.Period))
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{
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var structMember = ExpectIdentifier().Value;
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expr = new MemberAccessNode(GetTokensForNode(startIndex), expr, structMember);
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continue;
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}
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|
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if (TryExpectSymbol(Symbol.OpenBracket))
|
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{
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var index = ParseExpression();
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ExpectSymbol(Symbol.CloseBracket);
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expr = new ArrayIndexNode(GetTokensForNode(startIndex), expr, index);
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continue;
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}
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break;
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}
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|
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return expr;
|
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}
|
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|
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private BlockNode ParseBlock()
|
|
{
|
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var startIndex = _index;
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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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|
try
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|
{
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statements.Add(ParseStatement());
|
|
}
|
|
catch (ParseException ex)
|
|
{
|
|
_diagnostics.Add(ex.Diagnostic);
|
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RecoverToNextStatement();
|
|
}
|
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}
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return new BlockNode(GetTokensForNode(startIndex), statements);
|
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}
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|
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private NubType ParseType()
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|
{
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if (TryExpectIdentifier(out var name))
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{
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return NubType.Parse(name);
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|
}
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|
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if (TryExpectSymbol(Symbol.Caret))
|
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{
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var baseType = ParseType();
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return new NubPointerType(baseType);
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}
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|
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if (TryExpectSymbol(Symbol.OpenBracket))
|
|
{
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ExpectSymbol(Symbol.CloseBracket);
|
|
var baseType = ParseType();
|
|
return new NubArrayType(baseType);
|
|
}
|
|
|
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if (!Peek().TryGetValue(out var token))
|
|
{
|
|
throw new ParseException(Diagnostic
|
|
.Error("Unexpected end of file while parsing type")
|
|
.WithHelp("Expected a type name")
|
|
.At(_tokens.Last().SourceFile, SourceLocationCalculator.GetSpan(_tokens.Last()))
|
|
.Build());
|
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}
|
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|
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throw new ParseException(Diagnostic
|
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.Error("Invalid type syntax")
|
|
.WithHelp("Expected type name, '^' for pointer, or '[]' for array")
|
|
.At(token)
|
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.Build());
|
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}
|
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|
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private Token ExpectToken()
|
|
{
|
|
if (!Peek().TryGetValue(out var token))
|
|
{
|
|
throw new ParseException(Diagnostic
|
|
.Error("Unexpected end of file")
|
|
.WithHelp("Expected more tokens to complete the syntax")
|
|
.At(_tokens.Last().SourceFile, SourceLocationCalculator.GetSpan(_tokens.Last()))
|
|
.Build());
|
|
}
|
|
|
|
Next();
|
|
return token;
|
|
}
|
|
|
|
private SymbolToken ExpectSymbol()
|
|
{
|
|
var token = ExpectToken();
|
|
if (token is not SymbolToken symbol)
|
|
{
|
|
throw new ParseException(Diagnostic
|
|
.Error($"Expected symbol, but found {token.GetType().Name}")
|
|
.WithHelp("This position requires a symbol like '(', ')', '{', '}', etc.")
|
|
.At(token)
|
|
.Build());
|
|
}
|
|
|
|
return symbol;
|
|
}
|
|
|
|
private void ExpectSymbol(Symbol expectedSymbol)
|
|
{
|
|
var token = ExpectSymbol();
|
|
if (token.Symbol != expectedSymbol)
|
|
{
|
|
throw new ParseException(Diagnostic
|
|
.Error($"Expected '{expectedSymbol}', but found '{token.Symbol}'")
|
|
.WithHelp($"Insert '{expectedSymbol}' here")
|
|
.At(token)
|
|
.Build());
|
|
}
|
|
}
|
|
|
|
private bool TryExpectSymbol(Symbol symbol)
|
|
{
|
|
if (Peek() is { Value: SymbolToken symbolToken } && symbolToken.Symbol == symbol)
|
|
{
|
|
Next();
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
private bool TryExpectModifier([NotNullWhen(true)] out ModifierToken? modifier)
|
|
{
|
|
if (Peek() is { Value: ModifierToken modifierToken })
|
|
{
|
|
modifier = modifierToken;
|
|
Next();
|
|
return true;
|
|
}
|
|
|
|
modifier = null;
|
|
return false;
|
|
}
|
|
|
|
private bool TryExpectIdentifier([NotNullWhen(true)] out string? identifier)
|
|
{
|
|
if (Peek() is { Value: IdentifierToken identifierToken })
|
|
{
|
|
identifier = identifierToken.Value;
|
|
Next();
|
|
return true;
|
|
}
|
|
|
|
identifier = null;
|
|
return false;
|
|
}
|
|
|
|
private IdentifierToken ExpectIdentifier()
|
|
{
|
|
var token = ExpectToken();
|
|
if (token is not IdentifierToken identifier)
|
|
{
|
|
throw new ParseException(Diagnostic
|
|
.Error($"Expected identifier, but found {token.GetType().Name}")
|
|
.WithHelp("Provide a valid identifier name here")
|
|
.At(token)
|
|
.Build());
|
|
}
|
|
|
|
return identifier;
|
|
}
|
|
|
|
private void RecoverToNextDefinition()
|
|
{
|
|
while (Peek().HasValue)
|
|
{
|
|
var token = Peek().Value;
|
|
if (token is SymbolToken { Symbol: Symbol.Func or Symbol.Struct })
|
|
{
|
|
break;
|
|
}
|
|
|
|
Next();
|
|
}
|
|
}
|
|
|
|
private void RecoverToNextStatement()
|
|
{
|
|
while (Peek().TryGetValue(out var token))
|
|
{
|
|
if (token is SymbolToken { Symbol: Symbol.CloseBrace } or IdentifierToken or SymbolToken
|
|
{
|
|
Symbol: Symbol.Return or Symbol.If or Symbol.While or Symbol.Break or Symbol.Continue
|
|
})
|
|
{
|
|
break;
|
|
}
|
|
|
|
Next();
|
|
}
|
|
}
|
|
|
|
private Optional<Token> Peek()
|
|
{
|
|
var peekIndex = _index;
|
|
while (peekIndex < _tokens.Count && _tokens[peekIndex] is DocumentationToken)
|
|
{
|
|
peekIndex++;
|
|
}
|
|
|
|
if (peekIndex < _tokens.Count)
|
|
{
|
|
return _tokens[peekIndex];
|
|
}
|
|
|
|
return Optional<Token>.Empty();
|
|
}
|
|
|
|
private void Next()
|
|
{
|
|
while (_index < _tokens.Count && _tokens[_index] is DocumentationToken)
|
|
{
|
|
_index++;
|
|
}
|
|
|
|
_index++;
|
|
}
|
|
|
|
private IReadOnlyList<Token> GetTokensForNode(int startIndex)
|
|
{
|
|
return _tokens[startIndex..Math.Min(_index, _tokens.Count - 1)];
|
|
}
|
|
}
|
|
|
|
public class ParseException : Exception
|
|
{
|
|
public Diagnostic Diagnostic { get; }
|
|
|
|
public ParseException(Diagnostic diagnostic) : base(diagnostic.Message)
|
|
{
|
|
Diagnostic = diagnostic;
|
|
}
|
|
} |