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webbjuwebbju
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Preprocessor scope/tree parser.
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5 files changed

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‎ServerCodeExciser/PreprocessorParser.cs‎

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using System;
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using System.Collections.Generic;
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using System.Linq;
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using Antlr4.Runtime;
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using ServerCodeExcisionCommon;
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namespace ServerCodeExciser
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{
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public class PreprocessorParser
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{
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public static List<PreprocessorScope> Parse(BufferedTokenStream tokenStream)
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{
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var directives = tokenStream
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.GetTokens()
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.Where(t => t.Channel == UnrealAngelscriptLexer.PREPROCESSOR_CHANNEL)
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.Where(t => t.Type == UnrealAngelscriptLexer.Directive)
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.OrderBy(t => t.StartIndex)
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.ToList();
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var rootScopes = new List<PreprocessorScope>();
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var ifStack = new Stack<PreprocessorScope>();
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foreach (var token in directives)
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{
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switch (token.Text)
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{
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case var t when t.StartsWith("#if", StringComparison.Ordinal): // #if, #ifdef, #ifndef
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{
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var scope = CreateScope(token);
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if (ifStack.TryPeek(out var parent))
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{
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parent.Children.Add(scope);
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}
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else
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{
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rootScopes.Add(scope);
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}
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ifStack.Push(scope);
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}
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break;
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case var t when t.StartsWith("#elif", StringComparison.Ordinal) || t.StartsWith("#else", StringComparison.Ordinal): // #elif, #elifdef, #elifndef, #else
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{
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var scope = CreateScope(token);
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if (ifStack.TryPeek(out var parent))
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{
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parent.Children.Add(scope);
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// adjust #if / #elif scope for closing bounds.
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parent.Span = new SourceSpan
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{
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Start = parent.Span.Start,
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StartIndex = parent.Span.StartIndex,
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End = new SourcePosition(token.Line, token.Column),
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EndIndex = token.StartIndex,
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};
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}
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}
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break;
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case var t when t.StartsWith("#endif", StringComparison.Ordinal):
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{
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if (ifStack.TryPop(out var parent))
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{
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// close parent (#if) to the range of the entire block.
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parent.Span = new SourceSpan
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{
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Start = parent.Span.Start,
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StartIndex = parent.Span.StartIndex,
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End = new SourcePosition(token.Line, token.Column),
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EndIndex = token.StopIndex,
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};
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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 rootScopes;
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}
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private static PreprocessorScope CreateScope(IToken token)
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{
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return new PreprocessorScope(
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token.Text,
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new SourceSpan(
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token.Line,
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token.Column,
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token.Line,
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token.Column,
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token.StartIndex,
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token.StopIndex
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)
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);
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}
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}
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}

‎ServerCodeExciser/PreprocessorScope.cs‎

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using System.Collections.Generic;
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using ServerCodeExcisionCommon;
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namespace ServerCodeExciser
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{
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public sealed class PreprocessorScope
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{
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public PreprocessorScope(string directive, SourceSpan span)
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{
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Directive = directive;
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Span = span;
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}
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public string Directive { get; set; }
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public SourceSpan Span { get; set; }
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public List<PreprocessorScope> Children { get; set; } = new();
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}
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}

‎ServerCodeExciserTest/PreprocessorParserTests.cs‎

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using Antlr4.Runtime;
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using Microsoft.VisualStudio.TestTools.UnitTesting;
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namespace ServerCodeExciser.Tests
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{
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[TestClass]
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public class PreprocessorParserTests
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{
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[TestMethod]
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public void ConditionalBranchTest()
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{
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var script = "#ifdef WITH_SERVER\r\n" +
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"#elif RELEASE\r\n" +
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"#elif DEBUG\r\n" +
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"#else\r\n" +
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"#endif // WITH_SERVER\r\n";
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var lexer = new UnrealAngelscriptLexer(new AntlrInputStream(script));
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var tokenStream = new CommonTokenStream(lexer);
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tokenStream.Fill();
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var nodes = PreprocessorParser.Parse(tokenStream);
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Assert.HasCount(1, nodes);
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Assert.AreEqual("#ifdef WITH_SERVER", nodes[0].Directive);
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Assert.AreEqual("#elif RELEASE", nodes[0].Children[0].Directive);
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Assert.AreEqual("#elif DEBUG", nodes[0].Children[1].Directive);
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Assert.AreEqual("#else", nodes[0].Children[2].Directive);
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Assert.AreEqual(1, nodes[0].Span.Start.Line);
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Assert.AreEqual(0, nodes[0].Span.Start.Column);
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Assert.AreEqual(0, nodes[0].Span.StartIndex);
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Assert.AreEqual(5, nodes[0].Span.End.Line);
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Assert.AreEqual(0, nodes[0].Span.End.Column);
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Assert.AreEqual(script.Length - "\r\n".Length - 1, nodes[0].Span.EndIndex);
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}
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[TestMethod]
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public void NestedTest()
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{
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var script = "#ifdef WITH_SERVER\r\n" +
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" #if RELEASE\r\n" +
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" #elif DEBUG\r\n" +
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" #endif // !RELEASE\r\n" +
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"#endif // WITH_SERVER\r\n";
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var lexer = new UnrealAngelscriptLexer(new AntlrInputStream(script));
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var tokenStream = new CommonTokenStream(lexer);
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tokenStream.Fill();
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var nodes = PreprocessorParser.Parse(tokenStream);
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Assert.HasCount(1, nodes);
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Assert.AreEqual("#ifdef WITH_SERVER", nodes[0].Directive);
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Assert.AreEqual("#if RELEASE", nodes[0].Children[0].Directive);
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Assert.AreEqual("#elif DEBUG", nodes[0].Children[0].Children[0].Directive);
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Assert.AreEqual(0, nodes[0].Span.End.Column);
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Assert.AreEqual(script.Length - "\r\n".Length - 1, nodes[0].Span.EndIndex);
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}
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}
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}

‎ServerCodeExcisionCommon/SourcePosition.cs‎

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namespace ServerCodeExcisionCommon
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{
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/// <summary>
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/// Represents a position in source code (line and column).
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/// Lines and columns are 1-based to match editor conventions.
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/// </summary>
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public readonly struct SourcePosition
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{
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public int Line { get; }
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public int Column { get; }
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public SourcePosition(int line, int column)
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{
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Line = line;
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Column = column;
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}
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public override string ToString() => $"({Line}:{Column})";
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}
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}

‎ServerCodeExcisionCommon/SourceSpan.cs‎

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using System;
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namespace ServerCodeExcisionCommon
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{
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/// <summary>
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/// Represents a span of source code from a start position to an end position.
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/// </summary>
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public struct SourceSpan
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{
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public SourcePosition Start { get; set; }
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public SourcePosition End { get; set; }
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/// <summary>
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/// The absolute start index in the source text (0-based).
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/// </summary>
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public int StartIndex { get; set; }
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/// <summary>
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/// The absolute end index in the source text (0-based, exclusive).
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/// </summary>
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public int EndIndex { get; set; }
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public SourceSpan(SourcePosition start, SourcePosition end, int startIndex, int endIndex)
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{
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if (startIndex > endIndex)
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{
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throw new ArgumentException($"{nameof(startIndex)} is greater than {nameof(endIndex)}");
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}
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Start = start;
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End = end;
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StartIndex = startIndex;
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EndIndex = endIndex;
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}
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public SourceSpan(int startLine, int startColumn, int endLine, int endColumn, int startIndex, int endIndex)
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: this(new SourcePosition(startLine, startColumn), new SourcePosition(endLine, endColumn), startIndex, endIndex)
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{
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}
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}
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}

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