/
map.ts
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/
map.ts
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import * as cdk from '@aws-cdk/core';
import { Chain } from '../chain';
import { StateGraph } from '../state-graph';
import { CatchProps, IChainable, INextable, RetryProps } from '../types';
import { StateType } from './private/state-type';
import { renderJsonPath, State } from './state';
/**
* Properties for defining a Map state
*/
export interface MapProps {
/**
* An optional description for this state
*
* @default No comment
*/
readonly comment?: string;
/**
* JSONPath expression to select part of the state to be the input to this state.
*
* May also be the special value DISCARD, which will cause the effective
* input to be the empty object {}.
*
* @default $
*/
readonly inputPath?: string;
/**
* JSONPath expression to select part of the state to be the output to this state.
*
* May also be the special value DISCARD, which will cause the effective
* output to be the empty object {}.
*
* @default $
*/
readonly outputPath?: string;
/**
* JSONPath expression to indicate where to inject the state's output
*
* May also be the special value DISCARD, which will cause the state's
* input to become its output.
*
* @default $
*/
readonly resultPath?: string;
/**
* JSONPath expression to select the array to iterate over
*
* @default $
*/
readonly itemsPath?: string;
/**
* The JSON that you want to override your default iteration input
*
* @default $
*/
readonly parameters?: { [key: string]: any };
/**
* MaxConcurrency
*
* An upper bound on the number of iterations you want running at once.
*
* @default - full concurrency
*/
readonly maxConcurrency?: number;
}
/**
* Returns true if the value passed is a positive integer
* @param value the value ti validate
*/
export const isPositiveInteger = (value: number) => {
const isFloat = Math.floor(value) !== value;
const isNotPositiveInteger = value < 0 || value > Number.MAX_SAFE_INTEGER;
return !isFloat && !isNotPositiveInteger;
};
/**
* Define a Map state in the state machine
*
* A `Map` state can be used to run a set of steps for each element of an input array.
* A Map state will execute the same steps for multiple entries of an array in the state input.
*
* While the Parallel state executes multiple branches of steps using the same input, a Map state
* will execute the same steps for multiple entries of an array in the state input.
*
* @see https://docs.aws.amazon.com/step-functions/latest/dg/amazon-states-language-map-state.html
*/
export class Map extends State implements INextable {
public readonly endStates: INextable[];
private readonly maxConcurrency: number | undefined;
private readonly itemsPath?: string;
constructor(scope: cdk.Construct, id: string, props: MapProps = {}) {
super(scope, id, props);
this.endStates = [this];
this.maxConcurrency = props.maxConcurrency;
this.itemsPath = props.itemsPath;
}
/**
* Add retry configuration for this state
*
* This controls if and how the execution will be retried if a particular
* error occurs.
*/
public addRetry(props: RetryProps = {}): Map {
super._addRetry(props);
return this;
}
/**
* Add a recovery handler for this state
*
* When a particular error occurs, execution will continue at the error
* handler instead of failing the state machine execution.
*/
public addCatch(handler: IChainable, props: CatchProps = {}): Map {
super._addCatch(handler.startState, props);
return this;
}
/**
* Continue normal execution with the given state
*/
public next(next: IChainable): Chain {
super.makeNext(next.startState);
return Chain.sequence(this, next);
}
/**
* Define iterator state machine in Map
*/
public iterator(iterator: IChainable): Map {
const name = `Map ${this.stateId} Iterator`;
super.addIterator(new StateGraph(iterator.startState, name));
return this;
}
/**
* Return the Amazon States Language object for this state
*/
public toStateJson(): object {
return {
Type: StateType.MAP,
Comment: this.comment,
ResultPath: renderJsonPath(this.resultPath),
...this.renderNextEnd(),
...this.renderInputOutput(),
...this.renderRetryCatch(),
...this.renderIterator(),
...this.renderItemsPath(),
MaxConcurrency: this.maxConcurrency,
};
}
/**
* Validate this state
*/
protected validate(): string[] {
const errors: string[] = [];
if (this.iteration === undefined) {
errors.push('Map state must have a non-empty iterator');
}
if (this.maxConcurrency !== undefined && !isPositiveInteger(this.maxConcurrency)) {
errors.push('maxConcurrency has to be a positive integer');
}
return errors;
}
private renderItemsPath(): any {
return {
ItemsPath: renderJsonPath(this.itemsPath),
};
}
}