Debug

DebugExpression injects a debug callback into an expression tree. The delegate is called at runtime when execution reaches the debug point, receiving the current argument values for inspection.

It is useful for tracing expression tree execution without modifying the surrounding code.

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Factory Methods

using static Hyperbee.Expressions.ExpressionExtensions;

Overload	Description
Debug( Delegate debugDelegate, Expression argument )	Unconditional – single argument
Debug( Delegate debugDelegate, Expression[] arguments )	Unconditional – multiple arguments
Debug( Delegate debugDelegate, Expression condition, Expression argument )	Conditional – single argument
Debug( Delegate debugDelegate, Expression condition, Expression[] arguments )	Conditional – multiple arguments

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Usage

Unconditional Debug Point

using static System.Linq.Expressions.Expression;
using static Hyperbee.Expressions.ExpressionExtensions;

Action<int> printer = value => Console.WriteLine( $"[debug] value={value}" );

var x = Variable( typeof(int), "x" );

var expr = Block(
    [x],
    Assign( x, Constant( 42 ) ),
    Debug( printer, x ),   // prints "[debug] value=42"
    x
);

var lambda = Lambda<Func<int>>( expr );
lambda.Compile()();

Conditional Debug Point

// Only fires when x > 10
Action<int> breakpoint = value => Console.WriteLine( $"[break] {value}" );

var expr = Block(
    [x],
    Assign( x, Constant( 15 ) ),
    Debug(
        breakpoint,
        GreaterThan( x, Constant( 10 ) ),  // condition
        x                                   // argument
    ),
    x
);

Multiple Arguments

Action<int, string> trace = (i, s) => Console.WriteLine( $"i={i} s={s}" );

var i = Variable( typeof(int), "i" );
var s = Variable( typeof(string), "s" );

var expr = Block(
    [i, s],
    Assign( i, Constant( 7 ) ),
    Assign( s, Constant( "hello" ) ),
    Debug( trace, [i, s] ),
    i
);

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Notes

• DebugExpression reduces to void – it does not change the stack value of the surrounding block.
• The debug delegate is embedded as a constant in the expression tree and is not serializable.
• Conditional debug points evaluate the condition at runtime; the delegate is only called when true.
• In production builds, simply remove Debug(...) calls – they have no effect on surrounding logic.