git@github.com:stalniy/ucast.git
npm install @ucast/core
This package contains classes and functions that helps to create parsers, conditions AST, interpreters and translators.
``sh`
npm i @ucast/coreor
yarn add @ucast/coreor
pnpm add @ucast/core
Parser is a function that translates conditions from any language into conditions AST. For example, MongoQueryParser parses MongoQuery into AST which then can be interpreted by JavaScriptInterpreter that returns a boolean value based on passed in object.
Abstract Syntax Tree of any condition. What is condition?
x > 4 is a condition, x === 4 is a condition as well, { x: { $eq: 4 } } is a MongoQuery condition.
There are few types of AST nodes that allow us to represent any condition:
* FieldCondition. \
Depends on a field, operator and its value. For example, in condition x > 4, x is a field, 4 is a value and > is operator$where
* DocumentCondition. \
Any condition that test a document (or a row) as whole (e.g., in MongoDB Query, it's operator and in SQL it's EXISTS).
* CompoundCondition. \
Combines other conditions using logical operations like "and", "or", "not".
An interpreter is a function that interprets conditions AST in a specific way. For example, it can:
* interpret conditions in JavaScript runtime to return a boolean result
* or it can convert conditions into SQL WHERE statement
* or MongoDB query,
* or HTTP/REST query
* or GraphQL input
* or anything else you can imagine
Combines Parser and Interpreter and returns a factory function:
`js``
const parse = (query) => / to conditions AST /
const interpreter = createInterpreter({ / condition interpreters / });
const translate = (query, ...args) => interpreter.bind(null, parse(query));
Want to file a bug, contribute some code, or improve documentation? Excellent! Read up on guidelines for [contributing]
[contributing]: https://github.com/stalniy/ucast/blob/master/CONTRIBUTING.md