README.md

ksql  

Is a JSON data expression lexer, parser, cli and library.

How to install CLI

~ cargo install ksql

Usage

use ksql::parser::{Parser, Value};
use std::error::Error;

fn main() -> Result<(), Box<dyn Error>>{
    let src = r#"{"name":"MyCompany", "properties":{"employees": 50}"#.as_bytes();
    let expression = ".properties.employees > 20";
    let ex = Parser::parse(expression.as_bytes())?;
    let result = ex.calculate(src)?;
    assert_eq!(Value::Bool(true), result);
    Ok(())
}

CLI Usage

~ ksql '(.field1 + 1) /2' '{"field1": 1}'
or
echo '{"field1": 1}' | ksql '(.field1 + 1) /2'

Expressions

Expressions support most mathematical and string expressions see below for details:

Syntax & Rules

Token	Example	Syntax Rules
Equals	==	supports both == and =.
Add	+	N/A
Subtract	-	N/A
Multiply	*	N/A
Divide	/	N/A
Gt	>	N/A
Gte	>=	N/A
Lt	<	N/A
Lte	<=	N/A
OpenParen	(	N/A
CloseParen	)	N/A
OpenBracket	[	N/A
CloseBracket	]	N/A
Comma	,	N/A
QuotedString	"sample text"	Must start and end with an unescaped " character
Number	123.45	Must start and end with a space or '+' or '-' when hard coded value in expression and supports 0-9 +- e characters for numbers and exponent notation.
BooleanTrue	true	Accepts true as a boolean only.
BooleanFalse	false	Accepts false as a boolean only.
SelectorPath	.selector_path	Starts with a . and ends with whitespace blank space. This crate currently uses gjson and so the full gjson syntax for identifiers is supported.
And	&&	N/A
Not	!	Must be before Boolean identifier or expression or be followed by an operation
Or	||	N/A
Contains	CONTAINS	Ends with whitespace blank space.
ContainsAny	CONTAINS_ANY	Ends with whitespace blank space.
ContainsAll	CONTAINS_ALL	Ends with whitespace blank space.
In	IN	Ends with whitespace blank space.
Between	BETWEEN	Starts & ends with whitespace blank space. example 1 BETWEEN 0 10
StartsWith	STARTSWITH	Ends with whitespace blank space.
EndsWith	ENDSWITH	Ends with whitespace blank space.
NULL	NULL	N/A
Coerce	COERCE	Coerces one data type into another using in combination with 'Identifier'. Syntax is COERCE <expression> _identifer_.
Identifier	_identifier_	Starts and end with an _ used with 'COERCE' to cast data types, see table below with supported values. You can combine multiple coercions if separated by a COMMA.
Colon	:	N/A

COERCE Types

Type	Description
_datetime_	This attempts to convert the type into a DateTime.
_lowercase_	This converts the text into lowercase.
_uppercase_	This converts the text into uppercase.
_title_	This converts the text into title case, when the first letter is capitalized but the rest lower cased.
_string_	This converts the value into a string and supports the Value's String, Number, Bool, DateTime with nanosecond precision.
_number_	This converts the value into an f64 number and supports the Value's Null, String, Number, Bool and DateTime.
_substr_[n:n]	This allows taking a substring of a string value. this returns Null if no match at specified indices exits.

License

^{Licensed under either of Apache License, Version 2.0 or MIT license at your option.}
_{Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in Proteus by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.}