10 releases
Uses old Rust 2015
0.4.3 | Aug 24, 2018 |
---|---|
0.4.2 | Jan 17, 2018 |
0.4.1 | Dec 6, 2017 |
0.4.0 | Feb 13, 2017 |
0.1.1 | Nov 16, 2016 |
#23 in #expr
1,383 downloads per month
Used in 13 crates
(12 directly)
76KB
2K
SLoC
eval
Eval is a powerful expression evaluator.
Document
Features
Supported operators: !
!=
""
''
()
[]
,
>
<
>=
<=
==
+
-
*
/
%
&&
||
n..m
.
Built-in functions: min()
max()
len()
is_empty()
array()
.
Where can eval be used?
- Template engine
- ...
Usage
Add dependency to Cargo.toml
[dependencies]
eval = "^0.4"
In your main.rs
or lib.rs
:
extern crate eval;
Examples
You can do mathematical calculations with supported operators:
use eval::{eval, to_value};
assert_eq!(eval("1 + 2 + 3"), Ok(to_value(6)));
assert_eq!(eval("2 * 2 + 3"), Ok(to_value(7)));
assert_eq!(eval("2 / 2 + 3"), Ok(to_value(4.0)));
assert_eq!(eval("2 / 2 + 3 / 3"), Ok(to_value(2.0)));
You can eval with context:
use eval::{Expr, to_value};
assert_eq!(Expr::new("foo == bar")
.value("foo", true)
.value("bar", true)
.exec(),
Ok(to_value(true)));
You can access data like javascript by using .
and []
. []
supports expression.
use eval::{Expr, to_value};
use std::collections::HashMap;
let mut object = HashMap::new();
object.insert("foos", vec!["Hello", "world", "!"]);
assert_eq!(Expr::new("object.foos[1-1] == 'Hello'")
.value("object", object)
.exec(),
Ok(to_value(true)));
You can eval with function:
use eval::{Expr, to_value};
assert_eq!(Expr::new("say_hello()")
.function("say_hello", |_| Ok(to_value("Hello world!")))
.exec(),
Ok(to_value("Hello world!")));
You can create an array with array()
:
use eval::{eval, to_value};
assert_eq!(eval("array(1, 2, 3, 4, 5)"), Ok(to_value(vec![1, 2, 3, 4, 5])));
You can create an integer array with n..m
:
use eval::{eval, to_value};
assert_eq!(eval("0..5"), Ok(to_value(vec![0, 1, 2, 3, 4])));
License
eval is primarily distributed under the terms of the MIT license. See LICENSE for details.
Dependencies
~0.8–1MB
~23K SLoC