README
¶
Expr Engine · 表达式引擎
基于 expr-lang/expr 的轻量级表达式引擎
概述
Expr 引擎使用 expr-lang/expr 库，提供快速、类型安全的表达式求值。支持变量、函数和丰富的内置运算符，适用于业务表达式、模板引擎、数据筛选等场景。
引擎特性
| 特性 | 说明 |
|---|---|
| 底层库 | github.com/expr-lang/expr v1.17.0 |
| 语言 | Expr DSL |
| 类型系统 | Duck typing，编译时类型检查 |
| 环境快照 | 每次编译/执行时创建环境快照，保证一致性 |
| 线程安全 | 双锁模式（RWMutex + execMutex） |
| 热更新 | 支持 StartWatch / StopWatch |
| 类型常量 | scriptEngine.ExprType |
安装
go get github.com/tx7do/go-scripts/expr
快速开始
package main
import (
"context"
"fmt"
"log"
scriptEngine "github.com/tx7do/go-scripts"
_ "github.com/tx7do/go-scripts/expr" // 注册 Expr 引擎
)
func main() {
eng, _ := scriptEngine.NewScriptEngine(scriptEngine.ExprType)
defer eng.Close()
ctx := context.Background()
eng.Init(ctx)
// 注入变量
_ = eng.RegisterGlobal("name", "world")
_ = eng.RegisterGlobal("items", []int{1, 2, 3, 4, 5})
// 注册函数
_ = eng.RegisterFunction("double", func(x int) int { return x * 2 })
// 求值表达式
result, _ := eng.ExecuteString(ctx, "filter", `items | filter(# > 2) | map(double(#))`)
fmt.Println(result) // [6, 8, 10]
}
API 参考
| 方法 | 说明 |
|---|---|
Init(ctx) |
初始化引擎环境 |
Close() |
释放引擎资源 |
LoadString(ctx, name, code) |
编译 Expr 表达式并加入队列 |
Execute(ctx) |
顺序求值队列中所有表达式，返回最后一个结果 |
ExecuteString(ctx, name, code) |
编译并立即求值内联 Expr 表达式 |
RegisterGlobal(name, value) |
注册全局变量到表达式环境 |
RegisterFunction(name, fn) |
注册 Go 函数到表达式环境 |
CallFunction(ctx, name, args...) |
命令式调用已注册的宿主函数 |
RegisterModule(name, module) |
注册命名空间模块 |
StartWatch(ctx, key) |
启动表达式热更新监听 |
StopWatch(key) |
停止热更新监听 |
测试
cd expr && go test -v ./...
相关文档
License
Documentation
¶
Overview ¶
Package expr provides a script engine implementation using the Expr expression language (https://github.com/expr-lang/expr). Expr is a fast, type-safe expression evaluator that supports variables, functions, and a rich set of built-in operators.
Construction:
eng, _ := expr.New(ctx)
eng.Init(ctx)
eng.RegisterGlobal("name", "world")
result, _ := eng.ExecuteString(ctx, "greet", `"Hello " + name`)
The engine supports hot-reload via StartWatch/StopWatch when the bound Source implements the Watcher interface.
Index ¶
Constants ¶
This section is empty.
Variables ¶
View Source
var ( // ErrExprEngineNotInitialized is returned when an operation is invoked // before Init or after Close. ErrExprEngineNotInitialized = errors.New("expr engine not initialized") // ErrExprEngineAlreadyInitialized is returned when Init is called on an // already-initialized engine. ErrExprEngineAlreadyInitialized = errors.New("expr engine already initialized") // ErrExprCompileFailed is returned when compiling an expression fails. ErrExprCompileFailed = errors.New("expr compile failed") // ErrExprNoExpressionLoaded is returned when Execute is called but no // expression has been loaded. ErrExprNoExpressionLoaded = errors.New("expr no expression loaded") // ErrExprRunFailed is returned when evaluating an expression fails. ErrExprRunFailed = errors.New("expr run failed") // ErrExprFunctionNotFound is returned when CallFunction cannot find the // named function. ErrExprFunctionNotFound = errors.New("expr function not found") // ErrExprGlobalNotFound is returned when GetGlobal cannot find the named // variable. ErrExprGlobalNotFound = errors.New("expr global not found") )
Sentinel errors returned by the Expr engine.
Functions ¶
This section is empty.
Types ¶
This section is empty.
Source Files
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