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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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