column := "column-name"
	results := []struct {
		Expressions  []clause.Expression
		ExpectedVars []interface{}
		Result       string
	}{{
		Expressions: []clause.Expression{
			clause.Eq{Column: column, Value: "column-value"},
		},
		ExpectedVars: []interface{}{"column-value"},
		Result:       "`column-name` = ?",
	}, {
		Expressions: []clause.Expression{
			clause.Eq{Column: column, Value: nil},

	if !selectAST.Expression.All &&
		len(selectAST.Expression.Expressions) == 1 &&
		len(selectAST.Expression.Expressions[0].Expression.And) == 1 &&
		len(selectAST.Expression.Expressions[0].Expression.And[0].Condition) == 1 &&
		selectAST.Expression.Expressions[0].Expression.And[0].Condition[0].Operand != nil &&
		selectAST.Expression.Expressions[0].Expression.And[0].Condition[0].Operand.Operand.Left != nil &&

     * unprefixed expressions.
     * @param possiblePrefixes The possible prefixes.
     * @param root The root of the graph.
     * @param allowUnprefixedExpressions if we allow undefined expressions or not.
     */
    public PrefixedObjectValueSource(List<String> possiblePrefixes, Object root, boolean allowUnprefixedExpressions) {
        super(new PrefixedValueSourceWrapper(

    /**
     * Interpolates all expressions in the src parameter.
     * <p>
     * The algorithm used for each expression is:
     * <ul>
     *   <li>If it starts with either "pom." or "project.", the expression is evaluated against the model.</li>
     *   <li>If the value is null, get the value from the context.</li>
     *   <li>If the value is null, but the context contains the expression, don't replace the expression string

     * Finally, return the result of the last expression part's resolution.</p>
     *
     * <p><b>NOTE:</b> The object-graph navigation actually takes place via the
     * {@link ReflectionValueExtractor} class.</p>
     */
    @Override
    public Object getValue(String expression) {
        if (expression == null || expression.trim().isEmpty()) {
            return null;

        assertViolations(result, 0, 0, 2);

        assertEquals(
                "'profiles.profile[exists-project-version].activation.file.exists' "
                        + "Failed to interpolate profile activation property ${project.version}/test.txt: "
                        + "${project.version} expressions are not supported during profile activation.",

import org.apache.maven.project.path.PathTranslator;
import org.codehaus.plexus.interpolation.Interpolator;
import org.codehaus.plexus.interpolation.RegexBasedInterpolator;

/**
 * Use a regular expression search to find and resolve expressions within the POM.
 *
 * TODO Consolidate this logic with the PluginParameterExpressionEvaluator, minus deprecations/bans.
 */
@Deprecated

    @Override
    public Object getValue(String expression) {
        Object value = valueSource.getValue(expression);

        if (value != null && expression.startsWith(bannedPrefix)) {
            String msg = "The expression ${" + expression + "} is deprecated.";
            if (newPrefix != null && !newPrefix.isEmpty()) {
                msg += " Please use ${" + newPrefix + expression.substring(bannedPrefix.length()) + "} instead.";

Traditional retrieval of objects is always as whole entities, i.e GetObject for a 5 GiB object, will always return 5 GiB of data. S3 Select API allows us to retrieve a subset of data by using simple SQL expressions. By using Select API to retrieve only the data needed by the application, drastic performance improvements can be achieved.

You can use the Select API to query objects with following features:

</pre>

<p>
There are two forms: expression switches and type switches.
In an expression switch, the cases contain expressions that are compared
against the value of the switch expression.
In a type switch, the cases contain types that are compared against the
type of a specially annotated switch expression.
The switch expression is evaluated exactly once in a switch statement.
</p>