Add support for block-style if/else and while loop statements with tests

SYNTAX_V2.md

@@ -19,18 +19,6 @@ This document describes the current, word-based YesNt syntax.
 
 ## Quick Example
 
-v1:
-
-```ynt
-<name = world
-fnc greet
-cwl Hello >name
-ret
-cal greet
-```
-
-v2:
-
 ```ynt
 let name = world
 func greet:
@@ -39,6 +27,26 @@ return
 call greet
 ```
 
+## Block Conditionals
+
+```ynt
+if 10 > 5:
+print_line yes
+else:
+print_line no
+end_if
+```
+
+## While Loops
+
+```ynt
+let i = 3
+while ${i} > 0:
+print_line ${i}
+let i = ${i} - 1 calc
+end_while
+```
+
 ## Full v1 -> v2 Mapping
 
 | Area | v1 Syntax | v2 Syntax | Notes |

YesNt.Interpreter.Tests/CodeFowStatementsTests.cs

@@ -34,4 +34,106 @@ public class CodeFlowTests
         ];
         YesNtAssert.IsLastLineEqual(lines, "1");
     }
+
+    [TestMethod]
+    public void IfBlockTrueTest()
+    {
+        List<string> lines =
+        [
+            "let result = low",
+            "if 6 > 5:",
+            "let result = high",
+            "end_if",
+            "${result}"
+        ];
+
+        YesNtAssert.IsLastLineEqual(lines, "high");
+    }
+
+    [TestMethod]
+    public void IfElseFalseBranchTest()
+    {
+        List<string> lines =
+        [
+            "let result = low",
+            "if 6 < 5:",
+            "let result = high",
+            "else:",
+            "let result = medium",
+            "end_if",
+            "${result}"
+        ];
+
+        YesNtAssert.IsLastLineEqual(lines, "medium");
+    }
+
+    [TestMethod]
+    public void NestedIfElseTest()
+    {
+        List<string> lines =
+        [
+            "let result = 0",
+            "if 1 == 1:",
+            "if 2 == 3:",
+            "let result = 1",
+            "else:",
+            "let result = 2",
+            "end_if",
+            "end_if",
+            "${result}"
+        ];
+
+        YesNtAssert.IsLastLineEqual(lines, "2");
+    }
+
+    [TestMethod]
+    public void WhileLoopTest()
+    {
+        List<string> lines =
+        [
+            "let i = 3",
+            "while ${i} > 0:",
+            "let i = ${i} - 1 calc",
+            "end_while",
+            "${i}"
+        ];
+
+        YesNtAssert.IsLastLineEqual(lines, "0");
+    }
+
+    [TestMethod]
+    public void WhileSkipBodyWhenFalseTest()
+    {
+        List<string> lines =
+        [
+            "let i = 0",
+            "while ${i} > 0:",
+            "let i = 99",
+            "end_while",
+            "${i}"
+        ];
+
+        YesNtAssert.IsLastLineEqual(lines, "0");
+    }
+
+    [TestMethod]
+    public void NestedWhileLoopTest()
+    {
+        List<string> lines =
+        [
+            "let outer = 2",
+            "let count = 0",
+            "while ${outer} > 0:",
+            "let inner = 2",
+            "while ${inner} > 0:",
+            "let count = ${count} + 1 calc",
+            "let inner = ${inner} - 1 calc",
+            "end_while",
+            "let outer = ${outer} - 1 calc",
+            "end_while",
+            "${count}"
+        ];
+
+        YesNtAssert.IsLastLineEqual(lines, "4");
+    }
 }

YesNt.Interpreter/Statements/CodeFlowStatements.cs

@@ -140,6 +140,105 @@ internal class CodeFlowStatements : StatementRuntimeInformation
         }
     }
 
+    [Statement("if", SearchMode.StartOfLine, SpaceAround.End, ConsoleColor.Green, Priority = Priority.VeryLow, Separator = ":")]
+    public void IfBlock(string args)
+    {
+        args = args.Trim();
+        if (!args.EndsWith(':'))
+        {
+            RuntimeInfo.Exit("Invalid syntax", true);
+            return;
+        }
+
+        string condition = args[..^1].Trim();
+        bool? result = Evaluator.EvaluateCondition(condition);
+
+        if (result is null)
+        {
+            RuntimeInfo.Exit("Invalid operation", true);
+            return;
+        }
+
+        if (result == true)
+        {
+            return;
+        }
+
+        (int targetLine, _) = FindElseOrEndIf(RuntimeInfo.LineNumber);
+        if (targetLine < 0)
+        {
+            RuntimeInfo.Exit("No matching end_if found", true);
+            return;
+        }
+
+        RuntimeInfo.LineNumber = targetLine;
+    }
+
+    [Statement("else:", SearchMode.Exact, SpaceAround.None, ConsoleColor.Green)]
+    public void Else(string _)
+    {
+        int targetLine = FindEndIf(RuntimeInfo.LineNumber);
+        if (targetLine < 0)
+        {
+            RuntimeInfo.Exit("No matching end_if found", true);
+            return;
+        }
+
+        RuntimeInfo.LineNumber = targetLine;
+    }
+
+    [Statement("end_if", SearchMode.Exact, SpaceAround.None, ConsoleColor.Green)]
+    public void EndIf(string _)
+    {
+    }
+
+    [Statement("while", SearchMode.StartOfLine, SpaceAround.End, ConsoleColor.Green, Priority = Priority.VeryLow, Separator = ":")]
+    public void While(string args)
+    {
+        args = args.Trim();
+        if (!args.EndsWith(':'))
+        {
+            RuntimeInfo.Exit("Invalid syntax", true);
+            return;
+        }
+
+        string condition = args[..^1].Trim();
+        bool? result = Evaluator.EvaluateCondition(condition);
+
+        if (result is null)
+        {
+            RuntimeInfo.Exit("Invalid operation", true);
+            return;
+        }
+
+        if (result == true)
+        {
+            return;
+        }
+
+        int endWhileLine = FindEndWhile(RuntimeInfo.LineNumber);
+        if (endWhileLine < 0)
+        {
+            RuntimeInfo.Exit("No matching end_while found", true);
+            return;
+        }
+
+        RuntimeInfo.LineNumber = endWhileLine;
+    }
+
+    [Statement("end_while", SearchMode.Exact, SpaceAround.None, ConsoleColor.Green)]
+    public void EndWhile(string _)
+    {
+        int whileLine = FindWhile(RuntimeInfo.LineNumber);
+        if (whileLine < 0)
+        {
+            RuntimeInfo.Exit("No matching while found", true);
+            return;
+        }
+
+        RuntimeInfo.LineNumber = whileLine - 1;
+    }
+
     [Statement("exit", SearchMode.Exact, SpaceAround.None, ConsoleColor.Red, ExecuteInSearchMode = true)]
     public void End(string _)
     {
@@ -198,4 +297,132 @@ internal class CodeFlowStatements : StatementRuntimeInformation
     {
         return value.Trim().TrimEnd(':').Trim();
     }
+
+    private (int TargetLine, bool IsElse) FindElseOrEndIf(int currentLine)
+    {
+        int depth = 0;
+
+        for (int i = currentLine + 1; i < RuntimeInfo.Lines.Count; i++)
+        {
+            string line = RuntimeInfo.Lines[i].Content.Trim().Replace("\r", string.Empty);
+
+            if (IsIfStart(line))
+            {
+                depth++;
+                continue;
+            }
+
+            if (line == "end_if")
+            {
+                if (depth == 0)
+                {
+                    return (i, false);
+                }
+
+                depth--;
+                continue;
+            }
+
+            if (line == "else:" && depth == 0)
+            {
+                return (i, true);
+            }
+        }
+
+        return (-1, false);
+    }
+
+    private int FindEndIf(int currentLine)
+    {
+        int depth = 0;
+
+        for (int i = currentLine + 1; i < RuntimeInfo.Lines.Count; i++)
+        {
+            string line = RuntimeInfo.Lines[i].Content.Trim().Replace("\r", string.Empty);
+
+            if (IsIfStart(line))
+            {
+                depth++;
+                continue;
+            }
+
+            if (line == "end_if")
+            {
+                if (depth == 0)
+                {
+                    return i;
+                }
+
+                depth--;
+            }
+        }
+
+        return -1;
+    }
+
+    private static bool IsIfStart(string line)
+    {
+        return line.StartsWith("if ", StringComparison.Ordinal) && line.EndsWith(':');
+    }
+
+    private int FindEndWhile(int currentLine)
+    {
+        int depth = 0;
+
+        for (int i = currentLine + 1; i < RuntimeInfo.Lines.Count; i++)
+        {
+            string line = RuntimeInfo.Lines[i].Content.Trim().Replace("\r", string.Empty);
+
+            if (IsWhileStart(line))
+            {
+                depth++;
+                continue;
+            }
+
+            if (line == "end_while")
+            {
+                if (depth == 0)
+                {
+                    return i;
+                }
+
+                depth--;
+            }
+        }
+
+        return -1;
+    }
+
+    private int FindWhile(int currentLine)
+    {
+        int depth = 0;
+
+        for (int i = currentLine - 1; i >= 0; i--)
+        {
+            string line = RuntimeInfo.Lines[i].Content.Trim().Replace("\r", string.Empty);
+
+            if (line == "end_while")
+            {
+                depth++;
+                continue;
+            }
+
+            if (IsWhileStart(line))
+            {
+                if (depth == 0)
+                {
+                    return i;
+                }
+
+                depth--;
+            }
+        }
+
+        return -1;
+    }
+
+    private static bool IsWhileStart(string line)
+    {
+        return line.StartsWith("while ", StringComparison.Ordinal) && line.EndsWith(':');
+    }
 }