Method Eval

pkg/sql/sem/tree/eval.go:3159–3203

Eval implements the TypedExpr interface.

(ctx *EvalContext)

// Eval implements the TypedExpr interface.
func (expr *CaseExpr) Eval(ctx *EvalContext) (Datum, error) {
	if expr.Expr != nil {
		// CASE <val> WHEN <expr> THEN ...
		//
		// For each "when" expression we compare for equality to <val>.
		val, err := expr.Expr.(TypedExpr).Eval(ctx)
		if err != nil {
			return nil, err
		}

		for _, when := range expr.Whens {
			arg, err := when.Cond.(TypedExpr).Eval(ctx)
			if err != nil {
				return nil, err
			}
			d, err := evalComparison(ctx, EQ, val, arg)
			if err != nil {
				return nil, err
			}
			if v, err := GetBool(d); err != nil {
				return nil, err
			} else if v {
				return when.Val.(TypedExpr).Eval(ctx)
			}
		}
	} else {
		// CASE WHEN <bool-expr> THEN ...
		for _, when := range expr.Whens {
			d, err := when.Cond.(TypedExpr).Eval(ctx)
			if err != nil {
				return nil, err
			}
			if v, err := GetBool(d); err != nil {
				return nil, err
			} else if v {
				return when.Val.(TypedExpr).Eval(ctx)
			}
		}
	}

	if expr.Else != nil {
		return expr.Else.(TypedExpr).Eval(ctx)
	}
	return DNull, nil
}

// pgSignatureRegexp matches a Postgres function type signature, capturing the
// name of the function into group 1.