fixed bugs and revolutionized the universe

1 files changed, 134 insertions, 0 deletions

diff --git a/Compiler/visitors/Expressions.cs b/Compiler/visitors/Expressions.cs
new file mode 100644
index 0000000..e67688d
--- /dev/null
+++ b/Compiler/visitors/Expressions.cs
@@ -0,0 +1,134 @@
+namespace Q1.Compiler.visitors;
+
+public partial class CCompilerVisitor
+{
+    private string VisitExpression(CGrammarParser.ExpressionContext expression)
+    {
+        string? expressionString = this.Visit(expression) as string;
+        if (expressionString == null)
+            throw new CompilerException("Expression did not return a string");
+
+        return expressionString;
+    }
+    
+    public override string VisitCallExpression(CGrammarParser.CallExpressionContext context)
+    {
+        string functionName = context.ID().GetText();
+
+        FunctionReference function = this.GetFunctionReference(functionName);
+        FunctionOverload overload = function.GetOverload(context._params.Count);
+
+        // We reverse arugments so when we perform pop, its in the right order
+        CGrammarParser.ExpressionContext[] argumentsReversed = context._params.Reverse().ToArray();
+
+        for (int i = 0; i < argumentsReversed.Length; i++)
+        {
+            CGrammarParser.ExpressionContext argument = argumentsReversed[i];
+            string result = this.VisitExpression(argument);
+
+            this.Instruction($"push {result}", $"arg {overload.ParameterTypes[i]} {overload.ParameterNames[i]}");
+        }
+
+        this.Instruction($"call {function.GetBranchName(overload)}", function.GetBranchFriendlyName(overload));
+
+        return "V0";
+    }
+    public override string VisitParenthesizedExpression(CGrammarParser.ParenthesizedExpressionContext context)
+    {
+        return this.VisitExpression(context.expression());
+    }
+    public override string VisitVariableExpression(CGrammarParser.VariableExpressionContext context)
+    {
+        string varName = context.ID().GetText();
+        VariableReference reference = this.FindVariable(varName);
+
+        return $"[${reference.Address:X4}]";
+    }
+    public override string VisitAssignmentExpression(CGrammarParser.AssignmentExpressionContext context)
+    {
+        Target target = this.VisitTarget(context.target());
+        string value = this.VisitExpression(context.expression());
+
+        this.DynamicMove(target.Type, value, target.Value, $"{target.Value} = {value}");
+        return target.Value;
+    }
+    public override string VisitTernaryExpression(CGrammarParser.TernaryExpressionContext context)
+    {
+        string cond = this.VisitExpression(context.cond);
+
+        string thenBranch = this.GenerateBranchLabel("then");
+        string endBranch = this.GenerateBranchLabel("end");
+        string result;
+
+        // Else branch is first since it saves us from having to perform a NOT operation.
+        // If cond, jump to then, else fall through to else, then jump to end
+
+        this.Instruction($"bz {cond}", "check ternary condition");
+        this.Instruction($"jmp {thenBranch}");
+
+        result = this.VisitExpression(context.@else);
+        this.Instruction($"mov {result}, V0", "store ternary fail result");
+        this.Instruction($"jmp {endBranch}");
+
+        this.Branch(thenBranch);
+        result = this.VisitExpression(context.then);
+        this.Instruction($"mov {result}, V0", "store ternary success result");
+
+        this.Branch(endBranch);
+
+        return "V0";
+    }
+    public override string VisitAddressOfExpression(CGrammarParser.AddressOfExpressionContext context)
+    {
+        Target target = this.VisitTarget(context.target());
+
+        return target.Address;
+    }
+    public override string VisitDereferenceExpression(CGrammarParser.DereferenceExpressionContext context)
+    {
+        string value = this.VisitExpression(context.expression());
+
+        this.Instruction($"mov {value}, V0", "move pointer into register for dereference");
+        return "[V0]";
+    }
+
+    public override object? VisitIndexExpression(CGrammarParser.IndexExpressionContext context)
+    {
+        Target obj = this.VisitTarget(context.obj);
+        if (obj.Type is not CTypePtr ptr)
+            throw new CompilerException("Indexer target was not a pointer!");
+        
+        this.Instruction($"push {obj.Value}", "store index obj");
+
+        string indexer = this.VisitExpression(context.indexer);
+
+        this.Instruction($"mov {indexer}, V1",      "store indexer");
+        this.Instruction($"pop V0",                 "restore index obj");
+        this.Instruction($"mul V1, {ptr.Sub.Size}", $"multiply indexer by {ptr.Sub.Size}");
+        this.Instruction($"add AX, V0",             "add indexer and index obj");
+        this.Instruction($"mov AX, V0",             "move to general purpose register");
+        return "[V0]";
+    }
+
+    public override object? VisitArrayExpression(CGrammarParser.ArrayExpressionContext context)
+    {
+        CType type = this.VisitCType(context.type());
+        int? arrPtr = null;
+
+        if (context._params.Count == 0)
+            throw new CompilerException("Cannot create empty array");
+        
+        foreach (CGrammarParser.ExpressionContext? param in context._params)
+        {
+            int itemPtr = Alloc(type.Size);
+            
+            if (arrPtr == null)
+                arrPtr = itemPtr;
+
+            string value = this.VisitExpression(param);
+            this.DynamicMove(type, value, $"[${itemPtr:X4}]");
+        }
+
+        return $"${arrPtr:X4}";
+    }
+}
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