com.api.jsonata4java.expressions.path.PathExpression Maven / Gradle / Ivy

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Port of jsonata.js to Java to enable rules for JSON content
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/**
 * (c) Copyright 2018, 2019 IBM Corporation
 * 1 New Orchard Road, 
 * Armonk, New York, 10504-1722
 * United States
 * +1 914 499 1900
 * support: Nathaniel Mills [email protected]
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package com.api.jsonata4java.expressions.path;

import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.CommonTokenStream;
import org.antlr.v4.runtime.RecognitionException;
import org.antlr.v4.runtime.tree.ParseTree;

import com.api.jsonata4java.expressions.BufferingErrorListener;
import com.api.jsonata4java.expressions.ParseException;
import com.api.jsonata4java.expressions.path.generated.PathExpressionLexer;
import com.api.jsonata4java.expressions.path.generated.PathExpressionParser;
import com.fasterxml.jackson.databind.JsonNode;

@SuppressWarnings("deprecation")
public class PathExpression {

	private String expression;
	private ParseTree tree;

	private PathExpression(String expr, ParseTree tree) {
		this.expression = expr;
		this.tree = tree;
	}

	public JsonNode get(JsonNode jsonToRead, Integer indexVarValue) {
		PathExpressionVisitor visitor = new PathExpressionVisitor.Getter(jsonToRead, indexVarValue);
		return visitor.visit(tree);
	}

	public JsonNode set(JsonNode jsonToModify, Integer indexVarValue, JsonNode valueToAssign) {
		PathExpressionVisitor visitor = new PathExpressionVisitor.Setter(jsonToModify, indexVarValue, valueToAssign);
		return visitor.visit(tree);
	}

	@Override
	public String toString() {
		return this.getExpression();
	}

	public String getExpression() {
		return expression;
	}

	public static PathExpression parse(final String expr) throws ParseException {

		ANTLRInputStream input = new ANTLRInputStream(expr);
		PathExpressionLexer lexer = new PathExpressionLexer(input);
		CommonTokenStream tokens = new CommonTokenStream(lexer);
		PathExpressionParser parser = new PathExpressionParser(tokens);
		ParseTree tree = null;

		BufferingErrorListener errorListener = new BufferingErrorListener();

		try {
			// remove the default error listeners which print to stderr
			parser.removeErrorListeners();
			lexer.removeErrorListeners();

			// replace with error listener that buffer errors and allow us to retrieve them
			// later
			parser.addErrorListener(errorListener);
			lexer.addErrorListener(errorListener);

			tree = parser.expr();
			if (errorListener.heardErrors()) {
				throw new ParseException(errorListener.getErrorsAsString());
			}
		} catch (RecognitionException e) {
			throw new ParseException(e.getMessage());
		}

		return new PathExpression(expr, tree);
	}

}