}

func (s Select) MergeClause(clause *Clause) {
	if s.Expression != nil {
		if s.Distinct {
			if expr, ok := s.Expression.(Expr); ok {
				expr.SQL = "DISTINCT " + expr.SQL
				clause.Expression = expr
				return
			}
		}

		clause.Expression = s.Expression
	} else {
		clause.Expression = s
	}
}

// CommaExpression represents a group of expressions separated by commas.
type CommaExpression struct {

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

import org.codehaus.plexus.component.configurator.expression.ExpressionEvaluationException;
import org.codehaus.plexus.component.configurator.expression.TypeAwareExpressionEvaluator;

/**
 * Evaluator for plugin parameters expressions. Content surrounded by <code>${</code> and <code>}</code> is evaluated.
 * Recognized values are:
 * <table border="1">
 * <caption>Expression matrix</caption>

    static class Tokenizer {
        final String expression;

        int idx;

        Tokenizer(String expression) {
            this.expression = expression;
        }

        public int peekChar() {
            return idx < expression.length() ? expression.charAt(idx) : EOF;
        }

        public int skipChar() {
            return idx < expression.length() ? expression.charAt(idx++) : EOF;
        }

    @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.";

Container Enhancements

* ExpressionEvaluator

  Currently, the expression evaluator used to resolve configuration values
  is the DefaultExpressionEvaluator, which is a local variable within the
  implementation of the BasicComponentConfigurator. This ExpressionEvaluator
  simply returns the expression itself as the resolved value, which adds
  very little value to the container. Things like ${project.build.resources}

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:

Syntax      = { Production } .
Production  = production_name "=" [ Expression ] "." .
Expression  = Term { "|" Term } .
Term        = Factor { Factor } .
Factor      = production_name | token [ "…" token ] | Group | Option | Repetition .
Group       = "(" Expression ")" .
Option      = "[" Expression "]" .
Repetition  = "{" Expression "}" .
</pre>

<p>
Productions are expressions constructed from terms and the following

 * An instance of this object is bound to the {@link org.apache.maven.api.di.MojoExecutionScoped}
 * and available as {@code mojoExecution} within {@link org.apache.maven.api.plugin.annotations.Parameter}
 * expressions.
 *
 * @since 4.0.0
 */
@Experimental
public interface MojoExecution {

    @Nonnull
    Plugin getPlugin();

    @Nonnull
    PluginExecution getModel();

    @Nonnull

## Add regular expressions { #add-regular-expressions }

You can define a <abbr title="A regular expression, regex or regexp is a sequence of characters that define a search pattern for strings.">regular expression</abbr> `pattern` that the parameter should match:

{* ../../docs_src/query_params_str_validations/tutorial004_an_py310.py hl[11] *}

This specific regular expression pattern checks that the received parameter value: