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Port of jsonata.js to Java to enable rules for JSON content
/**
* (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.functions;
import com.api.jsonata4java.expressions.EvaluateRuntimeException;
import com.api.jsonata4java.expressions.ExpressionsVisitor;
import com.api.jsonata4java.expressions.generated.MappingExpressionParser.Function_callContext;
import com.api.jsonata4java.expressions.utils.Constants;
import com.api.jsonata4java.expressions.utils.FunctionUtils;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.node.ArrayNode;
import com.fasterxml.jackson.databind.node.JsonNodeFactory;
/**
* From http://docs.jsonata.org/aggregation-functions.html
*
* $min(array)
*
* Returns the minimum number in an array of numbers. It is an error if the
* input array contains an item which isn’t a number.
*
* Example
*
* $min([5,1,3,7,4])==1
*
*/
public class MinFunction extends FunctionBase implements Function {
public static String ERR_BAD_CONTEXT = String.format(Constants.ERR_MSG_BAD_CONTEXT, Constants.FUNCTION_MIN);
public static String ERR_ARG1BADTYPE = String.format(Constants.ERR_MSG_ARG1_BAD_TYPE, Constants.FUNCTION_MIN);
public static String ERR_ARG2BADTYPE = String.format(Constants.ERR_MSG_ARG2_BAD_TYPE, Constants.FUNCTION_MIN);
public static final String ERR_ARG_TYPE = String.format(Constants.ERR_MSG_ARG1_MUST_BE_ARRAY_OF_NUMBER,
Constants.FUNCTION_MIN);
public JsonNode invoke(ExpressionsVisitor expressionVisitor, Function_callContext ctx) {
// Create the variable to return
JsonNode result = null;
// Retrieve the number of arguments
JsonNode argArray = JsonNodeFactory.instance.nullNode();
boolean useContext = FunctionUtils.useContextVariable(this, ctx, getSignature());
int argCount = getArgumentCount(ctx);
if (useContext) {
argArray = FunctionUtils.getContextVariable(expressionVisitor);
if (argArray != null && argArray.isNull() == false) {
argCount++;
} else {
useContext = false;
}
}
// Make sure that we have the right number of arguments
if (argCount == 1) {
if (!useContext) {
argArray = FunctionUtils.getValuesListExpression(expressionVisitor, ctx, 0);
}
if (argArray == null) {
return null;
}
if (argArray.isArray() == false) {
argArray = ExpressionsVisitor.ensureArray(argArray);
}
// Convert the input node to an ArrayNode and make check that the
// array is not empty
ArrayNode items = (ArrayNode) argArray;
if (items.size() > 0) {
JsonNode min = null;
for (JsonNode item : items) {
if (item.isNumber()) {
// Check whether the current item is less than the
// current min
if (min == null || item.asDouble() < min.asDouble()) {
min = item;
}
} else {
/*
* The input array contains an item that is not a number. Throw a suitable
* exception
*/
throw new EvaluateRuntimeException(ERR_ARG_TYPE);
}
} // FOR
// Return the node that represents the minimum value
result = min;
} else {
/*
* The input array is empty. Signal returning null
*/
// throw new EvaluateRuntimeException(ERR_ARG_TYPE);
return null;
}
} else {
throw new EvaluateRuntimeException(argCount == 0 ? ERR_ARG1BADTYPE : ERR_ARG2BADTYPE);
}
return result;
}
@Override
public int getMaxArgs() {
return 1;
}
@Override
public int getMinArgs() {
return 0; // account for context variable
}
@Override
public String getSignature() {
// accepts an array of numbers, returns a number
return ":n>";
}
}