Tokenizers, parsers and expression calculators in Node.js / ES2017

This module is a part of the Pip.Services polyglot microservices toolkit.
It provides syntax and lexical analyzers and expression calculator optimized for repeated calculations.

The module contains the following packages:
- Calculator - Expression calculator
- CSV - CSV tokenizer
- IO - input/output utility classes to support lexical analysis
- Mustache - Mustache templating engine
- Tokenizers - lexical analyzers to break incoming character streams into tokens
- Variants - dynamic objects that can hold any values and operators for them

Quick links:

* API Reference
* Change Log
* Get Help
* Contribute

Use

Install the NPM package as
``bash
npm install pip-services3-expressions-nodex --save
`

The example below shows how to use expression calculator to dynamically
calculate user-defined expressions.

`typescript
import { IConfigurable } from 'pip-services3-commons-nodex';
import { ConfigParams } from 'pip-services3-commons-nodex';
import { IReferenceable } from 'pip-services3-commons-nodex';
import { IReferences } from 'pip-services3-commons-nodex';
import { Descriptor } from 'pip-services3-commons-nodex';
import { IOpenable } from 'pip-services3-commons-nodex';

...
let calculator = new ExpressionCalculator();

calculator.expression = "A + b / (3 - Max(-123, 1)*2)";

let vars = new VariableCollection();
vars.add(new Variable("A", new Variant(1)));
vars.add(new Variable("B", new Variant("3")));

let result = await calculator.evaluateWithVariables(vars);
console.log("The result of the expression is " + result.asString);
...
`

This is an example to process mustache templates.

`typescript
let mustache = new MustacheTemplate();
mustache.template = "Hello, {{{NAME}}}{{#ESCLAMATION}}!{{/ESCLAMATION}}{{#unless ESCLAMATION}}.{{/unless}}";
let result = mustache.evaluateWithVariables({ NAME: 'Mike', ESCLAMATION: true });
console.log("The result of template evaluation is '" + result + "'");
`

Develop

For development you shall install the following prerequisites:
* Node.js 8+
* Visual Studio Code or another IDE of your choice
* Docker
* Typescript

Install dependencies:
`bash
npm install
`

Compile the code:
`bash
tsc
`

Run automated tests:
`bash
npm test
`

Generate API documentation:
`bash
./docgen.ps1
`

Before committing changes run dockerized build and test as:
`bash
./build.ps1
./test.ps1
./clear.ps1
``

Contacts

The module is created and maintained by Sergey Seroukhov.