fixed bugs and revolutionized the universe

1 files changed, 177 insertions, 0 deletions

diff --git a/Compiler/visitors/FlowControl.cs b/Compiler/visitors/FlowControl.cs
new file mode 100644
index 0000000..944595d
--- /dev/null
+++ b/Compiler/visitors/FlowControl.cs
@@ -0,0 +1,177 @@
+namespace Q1.Compiler.visitors;
+
+public partial class CCompilerVisitor
+{
+    public override string? VisitBlock(CGrammarParser.BlockContext context)
+    {
+        this.EnterScope();
+
+        this.VisitChildren(context);
+
+        this.ExitScope();
+
+        return null;
+    }
+    public override string? VisitReturnStatement(CGrammarParser.ReturnStatementContext context)
+    {
+        if (context.expression() != null)
+        {
+            string expression = this.VisitExpression(context.expression());
+            this.Instruction($"mov {expression}, V0", "return value");
+            this.Instruction($"ret");
+        }
+        else
+            this.Instruction("ret");
+
+        return null;
+    }
+    public override string? VisitIfStatement(CGrammarParser.IfStatementContext context)
+    {
+        string cond = this.VisitExpression(context.expression());
+        string endBranch = this.GenerateBranchLabel("end");
+
+        if (context.@else != null)
+        {
+            this.Instruction($"bz {cond}", "check if condition");
+            // Else branch is first since it saves us from having to perform a NOT operation.
+            // If cond, jump to then, else fall through to else, then jump to end
+
+            string thenBranch = this.GenerateBranchLabel("then");
+
+            this.Instruction($"jmp {thenBranch}");
+
+            this.GeneratedComment("if failed");
+            if (context.@else != null)
+                this.Visit(context.@else);
+            this.Instruction($"jmp {endBranch}");
+
+            this.Branch(thenBranch, "if succeeded");
+            this.Visit(context.then);
+        }
+        else
+        {
+            this.Instruction($"not {cond}");
+            this.Instruction($"bz", "check if condition");
+            this.Instruction($"jmp {endBranch}", "if succeeds, continue, else jump to end");
+            this.Visit(context.then);
+        }
+
+        this.Branch(endBranch);
+
+        return null;
+    }
+    public override string? VisitForExprStatement(CGrammarParser.ForExprStatementContext context)
+    {
+        string bodyBranch = this.GenerateBranchLabel("body");
+        string endBranch = this.GenerateBranchLabel("end");
+
+        context.LoopBodyBranch = bodyBranch;
+        context.LoopEndBranch  = endBranch;
+
+        this.EnterScope();
+        this.Visit(context.initializer);
+
+        this.Branch(bodyBranch);
+        string cond = this.VisitExpression(context.cond);
+
+        this.Instruction($"not {cond}");
+        this.Instruction($"bz");
+        this.Instruction($"jmp {endBranch}", "if for condition fails, jump to end");
+
+        this.Visit(context.body);
+        this.Visit(context.post);
+
+        this.Branch(endBranch);
+        this.ExitScope();
+
+        return null;
+    }
+    public override string? VisitForDeclStatement(CGrammarParser.ForDeclStatementContext context)
+    {
+        string bodyBranch = this.GenerateBranchLabel("body");
+        string endBranch = this.GenerateBranchLabel("end");
+
+        context.LoopBodyBranch = bodyBranch;
+        context.LoopEndBranch  = endBranch;
+
+        this.EnterScope();
+        this.Visit(context.initializer);
+
+        this.Branch(bodyBranch);
+        string cond = this.VisitExpression(context.cond);
+
+        this.Instruction($"not {cond}");
+        this.Instruction($"bz");
+        this.Instruction($"jmp {endBranch}", "if for condition fails, jump to end");
+
+        this.Visit(context.body);
+        this.Visit(context.post);
+        
+        this.Instruction($"jmp {bodyBranch}");
+
+        this.Branch(endBranch);
+        this.ExitScope();
+
+        return null;
+    }
+    public override string? VisitWhileStatement(CGrammarParser.WhileStatementContext context)
+    {
+        string bodyBranch = this.GenerateBranchLabel("body");
+        string endBranch = this.GenerateBranchLabel("end");
+
+        context.LoopBodyBranch = bodyBranch;
+        context.LoopEndBranch  = endBranch;
+
+        this.Branch(bodyBranch);
+        string cond = this.VisitExpression(context.cond);
+
+        this.Instruction($"not {cond}");
+        this.Instruction($"bz");
+        this.Instruction($"jmp {endBranch}", "if while condition fails, jump to end");
+
+        this.Visit(context.body);
+        this.Instruction($"jmp {bodyBranch}");
+
+        this.Branch(endBranch);
+
+        return null;
+    }
+    public override string? VisitDoWhileStatement(CGrammarParser.DoWhileStatementContext context)
+    {
+        string bodyBranch = this.GenerateBranchLabel("body");
+        string endBranch = this.GenerateBranchLabel("end");
+
+        context.LoopBodyBranch = bodyBranch;
+        context.LoopEndBranch  = endBranch;
+
+        this.Branch(bodyBranch);
+        this.Visit(context.body);
+
+        string cond = this.VisitExpression(context.cond);
+
+        this.Instruction($"bz {cond}");
+        this.Instruction($"jmp {bodyBranch}", "if while condition succeeds, jump back to start");
+
+        this.Branch(endBranch);
+
+        return null;
+    }
+    public override string? VisitBreakStatement(CGrammarParser.BreakStatementContext context)
+    {
+        if (context.LoopEndBranch == null)
+            throw new CompilerException("Cannot break, not inside loop with end");
+
+        this.Instruction($"jmp {context.LoopEndBranch}", "break");
+
+        return null;
+    }
+    public override string? VisitContinueStatement(CGrammarParser.ContinueStatementContext context)
+    {
+        if (context.LoopBodyBranch == null)
+            throw new CompilerException("Cannot skip body (continue), not inside loop with body");
+
+        this.Instruction($"jmp {context.LoopBodyBranch}", "continue");
+
+        return null;
+    }
+}
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