logical-compiler
v0.1.0
Published
Compile MongoDB-like boolean expressions based on boolean operators AND and OR
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logical-compiler
Compile MongoDB-like boolean expressions based on boolean operators AND
and OR
Installation
Use one of the two based on your project's dependency manager.
$ npm install logical-compiler --save
$ yarn add logical-compiler
Getting started
import compile from 'logical-compiler';
compile(expression, options); // false
Arguments:
expression
- the boolean expression to be executed.options
- an optional object specifying options.fns
- an optional attribute specifying any function(s) used on the expression.
Operators
AND operator
let expression = { $and: [true, true] };
compile(expression); // true
expression = { $and: [true, false] };
compile(expression); // false
expression = { $and: [false, true] };
compile(expression); // false
expression = { $and: [false, false] };
compile(expression); // false
OR operator
let expression = { $or: [true, true] };
compile(expression); // true
expression = { $or: [true, false] };
compile(expression); // true
expression = { $or: [false, true] };
compile(expression); // true
expression = { $or: [false, false] };
compile(expression); // false
Unrecognized operator
const expression = { $someOp: ['x', 'y'] };
compile(expression); // Error: Unrecognized operator: '$someOp'
Primitives
undefined
compile(); // Error: Expected an expression
boolean
compile(true); // true
compile(false); // false
string
const expression = 'test';
compile(expression); // Error: Unexpected token 'test'
number
const expression = 201;
compile(expression); // Error: Unexpected token '201'
Callbacks
Simple callback
let cb = () => true;
compile(cb); // true
cb = () => false;
compile(cb); // false
Promise callback
cb = () => Promise.resolve(true);
await compile(cb); //true
cb = () => Promise.resolve(false);
await compile(cb); // false
Nested promise callback
const expression = {
$and: [true, () => Promise.resolve(true)],
};
compile(expression); // Error: Unexpected nested promise callback
Functions
Simple function
const options = {
fns: {
isEven: (number) => number % 2 === 0,
},
};
let expression = { isEven: 7 };
compile(expression, options); // false
expression = { isEven: 6 };
compile(expression, options); // true
Note that the function is defined on the
fns
attribute of theoptions
argument.
Promise function
const options = {
fns: {
isEqual: (num1, num2) => Promise.resolve(num1 === num2),
},
};
expression = { isEqual: [3, 3] };
await compile(expression, options); // true
expression = { isEqual: [3, 5] };
await compile(expression, options); // false
Nested promise function
const options = {
fns: {
authenticated: () => Promise.resolve(true),
},
};
const expression = {
$or: [false, { authenticated: null }],
};
compile(expression, options); // Error: Unexpected nested promise function
Undefined function
const expression = { someFn: ['x', 'y'] };
compile(expression, options); // Error: Undefined function: 'someFn'
Compound expressions
let expression = {
$or: [{ $and: [true, true] }, false],
};
compile(expression); // true
expression = {
$or: [() => false, () => false],
};
compile(expression); // false
expression = {
$and: [() => true, true],
};
compile(expression); // true
expression = {
$or: [
() => false,
false,
{
$and: [true, { $or: [() => true, false] }],
},
],
};
compile(expression); // true
const options = {
fns: {
any: (target, values) => values.includes(target),
all: (targets, values) => targets.every((target) => values.includes(target)),
},
};
expression = {
$and: [
() => true,
{ $or: [true, false] },
{ any: [5, [1, 3, 4, 6, 7]] }
],
};
compile(expression, options); // false
expression = {
$or: [
() => false,
false,
{ $and: [true, false] },
{
all: [
[3, 4, 7],
[2, 3, 4, 5, 6, 7],
],
},
],
};
compile(expression, options); // true
Operators can be nested in any fashion to achieve the desired logical check.
IMPORTANT NOTES
An asynchronous call can be made inside a callback or function. Currently, the library does not support promise returning callbacks or functions on nested expressions. If one is found, an exception is thrown. Promise returning executables are only allowed ALONE. The clean workaround is to resolve values resulting from asynchronous calls before invoking the compiler.
Callbacks and functions must explicitly return boolean values to avoid the ambiguity of relying on truthiness. Relying on truthiness would pose a serious loophole because the executable might accidentally resolve to true on a non-boolean value. If the library encounters a callback that resolves to a non-boolean value, it throws an exception. See MDN documentation on truthy values.
Licence
MIT © Mutai Mwiti | GitHub | GitLab
DISCLAIMER: All opinions expressed in this repository are mine and do not reflect any company or organisation I'm involved with.