What's this?
A lightweight configurable condition rule check lib. Support simple condtion query syntax , just like mongo json query. eg:

{
	"a": "123",
	"a.b": {"$gt":0, "$lt":10},
	"$or": [{"a":1},{"c":{"$ne": "123"}}],
	"c": {"$in": ["1", "2", "3"]},
	"$and": [{"a.c": 100.001}, {"d": {"$regex": "go|home"}}]
}

(You can find more examples in unit test file: cond_test.go)

You can use it as a rule engine for condition check (run conditon check over the runtime data). Normally the Cond is a config data from config file or DB or API query.

Supports operators now:

operators	dsc
$eq	eg: {"a": 123}, {"a": {"$eq": 123}}
$ne	{"a": {"$ne": 123}}
$gt	{"a": {"$gt": 123}}
$gte	{"a": {"$gte": 123}}
$lt	{"a": {"$lt": 123}}
$lte	{"a": {"$lte": 123}}
$and	{"$and": [{"a": 123}, {"b": 125}]}
$or	{"$or": [{"a": 123}, {"b": 125}]}
$in	{"a": {"$in": [1,2,3,4,5]}
$nin	{"b": {"$nin": [1,2,3,4,5]}
$regex	{"a": "$regex": "hello
$contain	{"a": {"$contain": "abc"}}

How to use?

import (
	"fmt"

	"github.com/pozen/cond"
)

func main() {
	// define a condition:
	// { "key1": "123", "key2": {"$gt": 100} } ,
	c := cond.Cond{
		"key1": "123",
		"key2": cond.Cond{"$gt": 100},
	}

	// create a cond state
	s := cond.NewState().SetCond(c)

	// example1:  expect false
	val_to_check := map[string]interface{}{
		"key1": "123",
		"key2": 99,
	}
	check_result := s.Exec(val_to_check)
	fmt.Printf("check_result is: %v\n", check_result)

	// example2: expect true
	val_to_check = map[string]interface{}{
		"key1": "123",
		"key2": 200,
	}
	check_result = s.Exec(val_to_check)
	fmt.Printf("check_result is: %v\n", check_result)

	// example3: regex
	c2 := cond.Cond{
		"Key1.Key2": cond.Cond{"$regex": "hello|go"},
	}
	// struct as the value to check
	type TVal struct {
		Key1 struct {
			Key2 string
		}
	}
	var val_to_check2 TVal
	val_to_check2.Key1.Key2 = "let's go!"
	// reset cond & check
	check_result = s.SetCond(c2).Exec(&val_to_check2)
	fmt.Printf("regex check_result is: %v\n", check_result)

	// example4: varible
	val_to_check = map[string]interface{}{
		"key1": 123,
		"key2": 200,
	}
	c3 := cond.Cond{
		"key1": cond.Cond{"$lt": "&key2"},
	}
	check_result = s.SetCond(c3).Exec(val_to_check)
	fmt.Printf("variable check_result is: %v\n", check_result)
}