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298 lines
8.9 KiB
298 lines
8.9 KiB
using System;
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using System.Collections.Generic;
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using System.Text;
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using System.IO;
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using System.Text.RegularExpressions;
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namespace SuperBASIC
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{
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class Parser
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{
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[Serializable]
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public class ParseException : Exception
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{
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public ParseException() { }
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public ParseException(string message) : base(message) { }
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public ParseException(string message, Exception inner) : base(message, inner) { }
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protected ParseException(
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System.Runtime.Serialization.SerializationInfo info,
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System.Runtime.Serialization.StreamingContext context) : base(info, context) { }
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}
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readonly Library library;
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readonly Runtime runtime;
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Dictionary<string, int> namedLabels;
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List<Tuple<string, int>> positionedLabels;
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public Parser(Runtime rt)
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{
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runtime = rt;
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library = rt.lib;
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}
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internal enum Controls
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{
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If, Then, Else, EndIf,
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For, To, Step, Next,
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While, Wend,
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Repeat, Until,
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Do, LoopCond
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}
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internal struct FlowControlTag
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{
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public Controls ctrl;
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public int index;
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}
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private void ParseExpression(Bytecode c, string[] components, int idx, List<int> lineSpans)
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{
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if (library.nameResolution.ContainsKey(components[0]))
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{
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int opcode = library.nameResolution[components[0]];
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int arity = library.arities[opcode];
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if (arity != components.Length - 1)
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{
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int lineIndex = 0;
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foreach (int cnt in lineSpans.GetRange(0, idx + 1)) lineIndex += cnt;
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throw new ParseException($"Operation {components[0]} was provided with the wrong number of arguments\n\tExpected {arity} found {components.Length - 1}\n\tat line {lineIndex}");
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}
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c.bytecode.Add(new BasicNumber(runtime, opcode));
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foreach (string elem in components.AsSpan(1))
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{
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#if MEMORY
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if (elem.StartsWith("M"))
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{
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try
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{
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Int16 v = Int16.Parse(elem[1..]);
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c.bytecode.Add(new BasicNumber(runtime, v, NumberType.Memory));
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}
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catch (Exception)
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{
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int lineIndex = 0;
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foreach (int cnt in lineSpans.GetRange(0, idx + 1)) lineIndex += cnt;
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throw new ParseException($"Cannot parse {elem} as argument to memory address\n\tExpected 'M' followed by an integer lower than {Int16.MaxValue}\n\tat line {lineIndex}");
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}
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}
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else
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#endif
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if (namedLabels.ContainsKey(elem))
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{
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positionedLabels.Add(new Tuple<string, int>(elem, c.bytecode.Count));
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c.bytecode.Add(new BasicNumber(runtime, (float)namedLabels[elem]));
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}
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else if (elem == "$")
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{
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c.bytecode.Add(new BasicNumber(runtime));
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}
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else
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{
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try
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{
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float v = float.Parse(elem);
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c.bytecode.Add(new BasicNumber(runtime, v));
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}
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catch (Exception)
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{
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int lineIndex = 0;
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foreach (int cnt in lineSpans.GetRange(0, idx + 1)) lineIndex += cnt;
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throw new ParseException($"Cannot parse {elem} as argument\n\tExpected floating point number or '$' or memory argument\n\tat line {lineIndex}");
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}
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}
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}
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}
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else
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{
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int lineIndex = 0;
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foreach (int cnt in lineSpans.GetRange(0, idx + 1)) lineIndex += cnt;
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throw new ParseException($"Unknown operation \"{components[0]}\"\n\tat line {lineIndex}");
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}
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}
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public Bytecode ParseFile(string filepath)
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{
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Bytecode c = new Bytecode();
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string[] sourceLines = File.ReadAllLines(filepath);
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Regex lws = new Regex(@"\s+");
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Regex leadings = new Regex(@"^\s+");
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Regex trailings = new Regex(@"\s+$");
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List<string> codeLines = new List<string>();
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List<int> lineSpans = new List<int>();
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Stack<FlowControlTag> labelStack = new Stack<FlowControlTag>();
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namedLabels = new Dictionary<string, int>();
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positionedLabels = new List<Tuple<string, int>>();
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int a = 0;
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foreach (string line in sourceLines)
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{
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a++;
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string l = lws.Replace(line, " ");
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l = leadings.Replace(l, "");
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l = trailings.Replace(l, "");
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if (l != String.Empty)
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{
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lineSpans.Add(a);
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a = 0;
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codeLines.Add(l);
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}
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}
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for (int idx = 0; idx < codeLines.Count; idx++)
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{
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string line = codeLines[idx];
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var components = line.Split(' ');
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if (components[0] == "LABEL")
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{
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if (components.Length != 2)
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{
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int lineIndex = 0;
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foreach (int cnt in lineSpans.GetRange(0, idx + 1)) lineIndex += cnt;
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throw new ParseException($"Bad LABEL statement\n\tat line {lineIndex}");
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}
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namedLabels[components[1]] = -1;
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}
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}
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for (int idx = 0; idx < codeLines.Count; idx++)
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{
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string line = codeLines[idx];
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var components = line.Split(' ');
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var label = new FlowControlTag();
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switch (components[0])
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{
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case "IF":
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// Role: manages the expression
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label.ctrl = Controls.If;
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label.index = c.bytecode.Count;
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labelStack.Push(label);
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ParseExpression(c, components[1..], idx, lineSpans);
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break;
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case "LABEL":
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if (components.Length != 2)
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{
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int lineIndex = 0;
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foreach (int cnt in lineSpans.GetRange(0, idx + 1)) lineIndex += cnt;
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throw new ParseException($"Bad LABEL statement\n\tat line {lineIndex}");
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}
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namedLabels[components[1]] = c.bytecode.Count;
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break;
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case "THEN":
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// Role: Jumps to the far block if false
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// 1. Adds the label to update the destination
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label.ctrl = Controls.Then;
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label.index = c.bytecode.Count;
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labelStack.Push(label);
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// 2. Adds the jumper
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c.bytecode.Add(new BasicNumber(runtime, library.nameResolution["JZ"]));
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c.bytecode.Add(new BasicNumber(runtime));
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c.bytecode.Add(new BasicNumber(runtime, 0f));
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break;
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case "ELSE":
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//Role: skips its section if encountered, marks the THEN for JZ
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//1. Gets the THEN label
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label = labelStack.Pop();
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if(label.ctrl != Controls.Then)
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{
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int lineIndex = 0;
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foreach (int cnt in lineSpans.GetRange(0, idx + 1)) lineIndex += cnt;
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throw new ParseException($"Orphaned ELSE\n\tat line {lineIndex}");
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}
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//2. Self tags for the ENDIF to complete the GOTO
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var label_self = new FlowControlTag
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{
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ctrl = Controls.Else,
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index = c.bytecode.Count
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};
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labelStack.Push(label_self);
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//3. Pushes the GOTO
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c.bytecode.Add(new BasicNumber(runtime, library.nameResolution["GOTO"]));
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c.bytecode.Add(new BasicNumber(runtime, 0f));
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//4. Place the THEN destination after the GOTO
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c.bytecode[label.index+2] = new BasicNumber(runtime, (float)c.bytecode.Count);
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break;
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case "ENDIF":
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//Role: Destination if depending on what is skipped
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label = labelStack.Pop();
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if (label.ctrl == Controls.Else)
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{
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//Case 1: update the GOTO
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c.bytecode[label.index + 1] = new BasicNumber(runtime, (float)c.bytecode.Count);
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}
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else if (label.ctrl == Controls.Then)
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{
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//Case 2: update the JZ
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c.bytecode[label.index + 2] = new BasicNumber(runtime, (float)c.bytecode.Count);
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}
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else
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{
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int lineIndex = 0;
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foreach (int cnt in lineSpans.GetRange(0, idx + 1)) lineIndex += cnt;
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throw new ParseException($"Orphaned ENDIF\n\tat line {lineIndex}");
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}
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// Controls the syntax
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if (labelStack.Pop().ctrl != Controls.If)
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{
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int lineIndex = 0;
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foreach (int cnt in lineSpans.GetRange(0, idx + 1)) lineIndex += cnt;
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throw new ParseException($"Orphaned ENDIF despite THEN\n\tat line {lineIndex}");
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}
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break;
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case "WHILE":
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// Role: manages the expression
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// 1. Deal with expression
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label.ctrl = Controls.While;
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label.index = c.bytecode.Count;
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labelStack.Push(label);
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ParseExpression(c, components[1..], idx, lineSpans);
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// 2. Adds the label to update the destination
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label.ctrl = Controls.Wend;
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label.index = c.bytecode.Count;
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labelStack.Push(label);
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// 3. Adds the jumper
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c.bytecode.Add(new BasicNumber(runtime, library.nameResolution["JZ"]));
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c.bytecode.Add(new BasicNumber(runtime));
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c.bytecode.Add(new BasicNumber(runtime, 0f));
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break;
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case "WEND":
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//Role: Destination if depending on what is skipped
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var labelA = labelStack.Pop();
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if (labelA.ctrl == Controls.Wend)
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{
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label = labelStack.Pop();
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if (label.ctrl == Controls.While)
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{
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c.bytecode.Add(new BasicNumber(runtime, library.nameResolution["GOTO"]));
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c.bytecode.Add(new BasicNumber(runtime, (float)label.index));
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c.bytecode[labelA.index + 2] = new BasicNumber(runtime, (float)c.bytecode.Count);
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}
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}
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else
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{
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int lineIndex = 0;
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foreach (int cnt in lineSpans.GetRange(0, idx + 1)) lineIndex += cnt;
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throw new ParseException($"Orphaned WEND\n\tat line {lineIndex}");
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}
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break;
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default:
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ParseExpression(c, components, idx, lineSpans);
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break;
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}
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}
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foreach(var lbl in positionedLabels)
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{
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c.bytecode[lbl.Item2] = new BasicNumber(runtime, (float)namedLabels[lbl.Item1]);
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}
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return c;
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}
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}
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}
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