Weekly GitHub Project "Phase II" govaluate

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Evaluation of arbitrary expressions in Golang environment//arbitrary expression evaluation for Golang

name	govaluate
Address	Github
Author	Knetic, etc.
Brief intro	Arbitrary expression evaluation for Golang
Brief introduction	Evaluation of arbitrary expressions in Golang environment
LICENSE	MIT
Stars	245

Govaluate provides an evaluation of any arithmetic/string expression similar to the C language.

Why you should not write an expression directly in your code

There are times when you have no way of knowing what an expression looks like, or you want the expression to be set. This library is useful if you have a bunch of data running on your app, or if you want to allow your users to customize something, or if you're writing a monitoring framework that can get a lot of metrics information and then do some formula calculations.

How to use

You can create a new evaluableexpression, and then call its "Evaluate" method.

123	expression, err: = Govaluate. Newevaluableexpression ("> 0"); result, err: = expression. Evaluate (nil); //result is now set to "true", the bool value.

So, how do I use parameters?

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expression, err: = Govaluate. Newevaluableexpression ("foo > 0"make (map[string]interface8 ) parameters["foo"-1; result, err: = expression. Evaluate (parameters); //result is now set to "false", the bool value.

This is great, but these can be basically implemented directly using code. So what if the calculations involve some mathematical calculations?

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expression, err: = Govaluate. Newevaluableexpression ("(Requests_made * requests_succeeded/100) >=");p arameters: = Make (map[string]interface{ }, 8) parameters["Requests_made"] = 100;parameters["requests_succeeded"] = 80;result, err: = expression. Evaluate (parameters);//result is today set to "false", the bool value.

The above example returns a Boolean value, in fact, it can return a number.

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expression, err: = Govaluate. Newevaluableexpression ("(mem_used/total_mem) *"make (map[string] Interface8) parameters["Total_mem"1024x768;p arameters["mem_used"512 ; result, err: = expression. Evaluate (parameters); //result is now set to "50.0", the float64 value.

You can also do some date conversions, as long as you meet Rf3339,iso8061,unix date, or ruby dates format standard. If you're still unsure, take a look at the supported date standards.

1234	expression, err: = Govaluate. Newevaluableexpression ("' 2014-01-02 ' > ' 2014-01-01 23:59:59 '); result, err: = expression. Evaluate (nil); //Result is now set to True

The expression requires only one syntactic analysis and can be reused multiple times.

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expression, err: = Govaluate. Newevaluableexpression ("Response_time <="make (map[string] Interface8) for {parameters["response_time"] = pingsomething (); result, err: = Expression. Evaluate (Parameters)}

With respect to execution order, this library supports the normal C standard execution order. When writing an expression, make sure that you write the operator correctly, or use parentheses to clarify which parts of the expression should run first.

Govaluate uses \ or [] to complete the escape.

Support for custom functions

Support for simple structures (accessors)

Operator support

The Ruleplatform expression engine supports the following operations:
Binary calculator: +-/ & | ^ * % >> <<
Binary comparators: > >= < <= = = = =~!~
Logical operators: | | &&
Brackets: ()
Array-Related:, in (Example 1 in (1, 2, ' foo '), return value TRUE)
Unary calculator:! - ~
Ternary operator:? :
Null-value aggregator:??

For more information, please see https://github.com/Knetic/govaluate