com.jaregu.database.queries.compiling.AssignmentFeature Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of queries Show documentation

Java based SQL templating project. Store your queries in *.sql files and build queries for execution. Supports simple expressions and conditional clauses and interface proxying for java-sql bridge.

There is a newer version: 1.4.1

Show newest version

package com.jaregu.database.queries.compiling;

import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;

import com.jaregu.database.queries.building.ParametersResolver;
import com.jaregu.database.queries.compiling.expr.Expression;
import com.jaregu.database.queries.compiling.expr.Expression.ExpressionResult;
import com.jaregu.database.queries.compiling.expr.ExpressionParser;
import com.jaregu.database.queries.parsing.ParsedQueryPart;

/**
 * Assignment feature
 * 
 * Example SQL:
 * 
 *  * -- attr_name_1 = value_expression_1[; attr_name_2 = value_expression_2 ...]
 * 
 */
final class AssignmentFeature implements QueryCompilerFeature {

	private final ExpressionParser expressionParser;

	AssignmentFeature(ExpressionParser expressionParser) {
		this.expressionParser = expressionParser;
	}

	@Override
	public boolean isCompilable(Source source) {
		List parts = source.getParts();
		ParsedQueryPart part;
		return parts.size() == 1 && (part = parts.get(0)).isComment()
				&& expressionParser.isLikeExpression(part.getCommentContent());
	}

	@Override
	public Result compile(Source source, Compiler compiler) {
		List expressions = expressionParser.parse(source.getParts().get(0).getCommentContent());

		return new Result() {
			@Override
			public List getParts() {
				return Collections.singletonList(new AssignmentVariablePart(expressions));
			}
		};
	}

	private static final class AssignmentVariablePart implements PreparedQueryPart {

		private List expressions;

		private AssignmentVariablePart(List expressions) {
			this.expressions = expressions;
		}

		@Override
		public Result build(ParametersResolver resolver) {
			Map attributes = new LinkedHashMap<>();
			for (Expression expression : expressions) {
				ExpressionResult expressionResult = expression.eval(resolver);
				attributes.putAll(expressionResult.getOutputVariables());
			}
			return new PreparedQueryPartResultImpl(Optional.empty(), Collections.emptyList(), attributes);
		}

		@Override
		public String toString() {
			return "AssignmentVariablePart" + expressions;
		}

		@Override
		public boolean equals(Object obj) {
			if (obj == this)
				return true;

			return false;
		}

		@Override
		public int hashCode() {
			return Objects.hash(expressions);
		}
	}
}