Function exercise8

codelab/solution/codelab.go:343–381

exercise8 covers some useful features of CEL-Go which can be used to improve performance and better understand evaluation behavior. Turn on the optimization, exhaustive eval, and state tracking `cel.ProgramOption` flags to see the impact on evaluation behavior.

()

// Turn on the optimization, exhaustive eval, and state tracking
// `cel.ProgramOption` flags to see the impact on evaluation behavior.
func exercise8() {
	fmt.Println("=== Exercise 8: Tuning ===\n")
	// Declare the `x` and 'y' variables as input into the expression.
	env, _ := cel.NewEnv(
		cel.Variable("x", cel.IntType),
		cel.Variable("y", cel.UintType),
	)
	ast := compile(env,
		`x in [1, 2, 3, 4, 5] && type(y) == uint`,
		cel.BoolType)
	// Turn on optimization.
	trueVars := map[string]any{"x": int64(4), "y": uint64(2)}
	program, _ := env.Program(ast, cel.EvalOptions(cel.OptOptimize))
	// Try benchmarking this evaluation with the optimization flag on and off.
	eval(program, trueVars)

	// Turn on exhaustive eval to see what the evaluation state looks like.
	// The input is structure to show a false on the first branch, and true
	// on the second.
	falseVars := map[string]any{"x": int64(6), "y": uint64(2)}
	program, _ = env.Program(ast, cel.EvalOptions(cel.OptExhaustiveEval))
	eval(program, falseVars)

	// Turn on optimization and state tracking to see the typical eval
	// behavior, but with partial input.
	xVar := map[string]any{"x": int64(3)}
	partialVars, _ := cel.PartialVars(xVar, cel.AttributePattern("y"))
	program, _ = env.Program(ast,
		cel.EvalOptions(cel.OptPartialEval, cel.OptOptimize, cel.OptTrackState))
	_, details, _ := eval(program, partialVars)

	// Convert the unknown parts of the expression to a new AST and format it back
	// to a human-readable expression.
	residualAst, _ := env.ResidualAst(ast, details)
	residual, _ := cel.AstToString(residualAst)
	fmt.Printf("------ residual ------\n%s\n", residual)

	fmt.Println()
}

// Functions to assist with CEL execution.