logic-filter-strings
v0.0.2
Published
An algebraic expression parser for stream logic filters
Downloads
247
Maintainers
Readme
node-logic-filter-strings
A parser that transforms logical expression strings for filtering JSON objects into their equivalent logic filter structure.
#Example
var logicFilterString = require('logic-filter-strings');
var obj = logicFilterString('foo === "bar"&&bar === "baz qux"');
Obj will be:
[['foo', '===', 'bar'], '&&', ['bar', '===', 'baz qux']]
##Filter Language
This interpreter was desgined with the end goal of being able to provide rules for filtering JSON object streams. It was meant to be used by node-logic-filter
as the means of parsing filter rules. In general, strings on the left side of an equality represent keys in an object, and strings/numbers/arrays/objects on the right side of an equality represent values to compare against. You are also able to use &&, ||, and ! to combine conditions/expressions as you might expect.
###Case: foo exists in the comparison object
'foo'
###Case: foo does not exist in the comparison object
'!foo'
###Case: foo equals string
'foo === "bar"'
Note: The quotes around "bar" are required
###Case: foo equals array
'foo === [1, 2, 3]'
###Case: foo equals object
'foo === {bar: "baz"}'
###Case: foo equals string and bar equals string
'foo == "baz" && bar == "qux"'
Note: ==
and ===
are interchangeable
###Case: foo does not equal string
'foo !== "baz"'
###Case: field on a nested object equals string
'foo.bar.qux === "baz"'
###Case: Or-ing 3 or more conditions
'(foo == "baz" || bar == "qux") || a === "b"'
Note: Parentheses are necessary