@emartech/data-aggregator-language

Data Aggregator

Execute aggregation expressions on a given data set.

What it Does

Given the following input data structure,

const input = [{ 
  date: '2017-09-16',
  reservations: {
    silver: 12,
    gold: 5
  }  
}, {
  date: '2017-09-17',
  reservations: {
    silver: 3,
    gold: 2
  }  
}]

the parser allows mixing aggregation expressions over the input with common arithmetic operators.

For example,

• an aggregation expression: SUM reservations.silver would yield 12 + 3 = 15.
• an aggregation expression mixed with arithmetic: SUM reservations.silver + 3 would yield (12 + 3) + 3 = 18

Usage

const aggregator = require('@emartech/data-aggregator-language')(input);
const result = aggregator('SUM reservations.silver')

Supported Syntax in Aggregation Expressions

Examples below are for the input defined above.

Constants

• LENGTH
  • LENGTH (yields 2)
  • LENGTH + 3 (yields 5)
• Any number literal
  • 5 (yields 5)

Unary Operators

• SUM
  • SUM reservations.silver (yields 15)
• LAST
  • LAST reservations.silver (yields 3)
• AVERAGE
  • AVERAGE reservations.silver (yields 7.5)

Binary Operators

+, -, *, /

For example, (LAST reservations.silver + 3) * 2 / 2 (yields 6)

Commit Convention

Semantic release depends on the Angular commit message conventions. Please follow these.

Credit

Uses SAP/chevrotain for parsing.