#zerkel An adzerk-based query-ish language.
###Language Zerkel provides primitive integer and string literals, identifiers, sets, and a selection of boolean operators:
| operator/type | comment | examples |
|---|---|---|
| integers | syntax |
42, -7
|
| strings | syntax |
"foo", "C:\\\\Windows\\System32", `"^(foo |
| variables | syntax |
count, _foo_bar, $location.postalCode
|
| . | property accessor |
$location.postalCode, foo.bar.baz
|
| [, ] | set construction | [42, "foo"] |
| (, ) | expression grouping | x < 100 AND (y < 50 OR z < 10) |
| = | foo = 42 |
|
| <> | not equal | foo <> "bar" |
| =~ | regex match | `foo =~ "^(some |
| !~ | not regex match | `foo !~ "^(some |
| > | foo > 42 |
|
| < | foo < 42 |
|
| >= | foo >= 42 |
|
| <= | foo <= 42 |
|
| AND | foo = 42 AND bar < 100 |
|
| OR | foo = 42 OR bar < 100 |
|
| NOT | NOT (bar =~ "^foo") |
|
| LIKE | wildcard match | foo LIKE "ba*" |
| CONTAINS | set membership / substring |
["foo", "bar"] CONTAINS "foo", "foobar" CONTAINS "foo"
|
Thus, queries may be written like:
count > 43 and (user = "bob" or user = "alice")
keywords contains "awesome"All operators are available in upper and lowercase forms.
###Demo
Check out the live Zerkel scratchpad demo app and try some zerkel queries in your browser.
###Usage Queries can executed in coffeescript/javascript using the zerkel module, like so:
zerkel = require 'zerkel'
query = 'count > 43 and (user = "bob" or user = "alice")'
matchFn = zerkel.compile query
matchFn {count: 50, user: 'bob'} # true
matchFn {count: 12, user: 'alice'} # false
matchFn {count: 50, user: 'George Michael'} # terribly, unfortunately, falseYou can also access properties on passed in objects, like so:
zerkel = require 'zerkel'
query = 'user.location = "open field west of a white house"'
matchFn = zerkel.compile query
matchFn {user: {name: 'bob', location: 'open field west of a white house'}} # true
matchFn {user: {name: 'alice', location: 'middle earth'}} # false###Gzip
Set the parser.MIN_GZIP_SIZE to a number, and if the length of the compiled
JavaScript is greater than that it will be gzipped and base64 encoded, with
GZ: prepended. The zerkel#makePredicate function will unzip automatically
as necessary.
parser = require 'zerkel-parser'
parser.MIN_GZIP_SIZE = 50
parser.parse 'foo = 42' # _helpers['getIn'](_env, 'foo')==42'
parser.parse '[42, 43] contains foo' # GZ:H4sIAAAAAAAAA9OINjHSMTGOVVODMvQy81JSK/zTNOIzUnMKUouKo9XTU0s889RjNeJT88p0FNTT8vPVNTUV7GwVDDQBm8CsuD8AAAA=###Status
###License Apache 2.0