tagexpr

package
v0.1.4 Latest Latest
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 Go to latest Published: May 12, 2025 License: Apache-2.0, Apache-2.0 Imports: 11 Imported by: 0

README

go-tagexpr

originally from https://github.com/bytedance/go-tagexpr

Documentation

Overview

Example 
package main

import (
	"fmt"

	"github.com/telecom-cloud/client-go/internal/tagexpr"
)

func main() {
	type T struct {
		A  int             `tagexpr:"$<0||$>=100"`
		B  string          `tagexpr:"len($)>1 && regexp('^\\w*$')"`
		C  bool            `tagexpr:"expr1:(f.g)$>0 && $; expr2:'C must be true when T.f.g>0'"`
		d  []string        `tagexpr:"@:len($)>0 && $[0]=='D'; msg:sprintf('invalid d: %v',$)"`
		e  map[string]int  `tagexpr:"len($)==$['len']"`
		e2 map[string]*int `tagexpr:"len($)==$['len']"`
		f  struct {
			g int `tagexpr:"$"`
		}
		h int `tagexpr:"$>minVal"`
	}

	vm := tagexpr.New("tagexpr")
	t := &T{
		A:  107,
		B:  "abc",
		C:  true,
		d:  []string{"x", "y"},
		e:  map[string]int{"len": 1},
		e2: map[string]*int{"len": new(int)},
		f: struct {
			g int `tagexpr:"$"`
		}{1},
		h: 10,
	}

	tagExpr, err := vm.Run(t)
	if err != nil {
		panic(err)
	}

	fmt.Println(tagExpr.Eval("A"))
	fmt.Println(tagExpr.Eval("B"))
	fmt.Println(tagExpr.Eval("C@expr1"))
	fmt.Println(tagExpr.Eval("C@expr2"))
	if !tagExpr.Eval("d").(bool) {
		fmt.Println(tagExpr.Eval("d@msg"))
	}
	fmt.Println(tagExpr.Eval("e"))
	fmt.Println(tagExpr.Eval("e2"))
	fmt.Println(tagExpr.Eval("f.g"))
	fmt.Println(tagExpr.EvalWithEnv("h", map[string]interface{}{"minVal": 9}))
	fmt.Println(tagExpr.EvalWithEnv("h", map[string]interface{}{"minVal": 11}))

}

Output:

true
true
true
C must be true when T.f.g>0
invalid d: [x y]
true
false
1
true
false

Index

Examples

Constants

View Source 
const (
	// FieldSeparator in the expression selector,
	// the separator between field names
	FieldSeparator = "."
	// ExprNameSeparator in the expression selector,
	// the separator of the field name and expression name
	ExprNameSeparator = "@"
	// DefaultExprName the default name of single model expression
	DefaultExprName = ExprNameSeparator
)

Variables

This section is empty.

Functions

func FakeBool 

func FakeBool(v interface{}) bool

FakeBool fakes any type as a boolean.

func MustRegFunc 

func MustRegFunc(funcName string, fn func(...interface{}) interface{}, force ...bool)

MustRegFunc registers function expression. NOTE: 

example: len($), regexp("\\d") or regexp("\\d",$);
If @force=true, allow to cover the existed same @funcName;
The go number types always are float64;
The go string types always are string;
Panic if there is an error.

func RegFunc 

func RegFunc(funcName string, fn func(...interface{}) interface{}, force ...bool) error

RegFunc registers function expression. NOTE: 

example: len($), regexp("\\d") or regexp("\\d",$);
If @force=true, allow to cover the existed same @funcName;
The go number types always are float64;
The go string types always are string.

Types

type Boolean 

type Boolean = bool

Internally unified data types

type Expr 

type Expr struct {
	// contains filtered or unexported fields
}

Expr expression

type ExprHandler 

type ExprHandler struct {
	// contains filtered or unexported fields
}

ExprHandler expr handler

func (*ExprHandler) Eval 

func (e *ExprHandler) Eval() interface{}

Eval evaluate the value of the struct tag expression. NOTE: 

result types: float64, string, bool, nil

func (*ExprHandler) EvalBool 

func (e *ExprHandler) EvalBool() bool

EvalBool evaluates the value of the struct tag expression. NOTE: 

If the expression value is not 0, '' or nil, return true.

func (*ExprHandler) EvalFloat 

func (e *ExprHandler) EvalFloat() float64

EvalFloat evaluates the value of the struct tag expression. NOTE: 

If the expression value type is not float64, return 0.

func (*ExprHandler) EvalString 

func (e *ExprHandler) EvalString() string

EvalString evaluates the value of the struct tag expression. NOTE: 

If the expression value type is not string, return "".

func (*ExprHandler) ExprSelector 

func (e *ExprHandler) ExprSelector() ExprSelector

ExprSelector returns the expression selector of ExprSelector type.

func (*ExprHandler) Path 

func (e *ExprHandler) Path() string

Path returns the path description of the expression.

func (*ExprHandler) StringSelector 

func (e *ExprHandler) StringSelector() string

StringSelector returns the expression selector of string type.

func (*ExprHandler) TagExpr 

func (e *ExprHandler) TagExpr() *TagExpr

TagExpr returns the *TagExpr.

type ExprNode 

type ExprNode interface {
	SetParent(ExprNode)
	Parent() ExprNode
	LeftOperand() ExprNode
	RightOperand() ExprNode
	SetLeftOperand(ExprNode)
	SetRightOperand(ExprNode)
	String() string
	Run(context.Context, string, *TagExpr) interface{}
}

ExprNode expression interface

type ExprSelector 

type ExprSelector string

ExprSelector expression selector

func (ExprSelector) Field 

func (e ExprSelector) Field() string

Field returns the field selector it belongs to.

func (ExprSelector) Name 

func (e ExprSelector) Name() string

Name returns the name of the expression.

func (ExprSelector) ParentField 

func (e ExprSelector) ParentField() (string, bool)

ParentField returns the parent field selector it belongs to.

func (ExprSelector) Split 

func (e ExprSelector) Split() (field FieldSelector, name string)

Split returns the field selector and the expression name.

func (ExprSelector) String 

func (e ExprSelector) String() string

String returns string type value.

type FieldHandler 

type FieldHandler struct {
	// contains filtered or unexported fields
}

FieldHandler field handler

func (*FieldHandler) EvalFuncs 

func (f *FieldHandler) EvalFuncs() map[ExprSelector]func() interface{}

EvalFuncs returns the tag expression eval functions.

func (*FieldHandler) FieldSelector 

func (f *FieldHandler) FieldSelector() FieldSelector

FieldSelector returns the field selector of FieldSelector type.

func (*FieldHandler) StringSelector 

func (f *FieldHandler) StringSelector() string

StringSelector returns the field selector of string type.

func (*FieldHandler) StructField 

func (f *FieldHandler) StructField() reflect.StructField

StructField returns the field StructField object.

func (*FieldHandler) Value 

func (f *FieldHandler) Value(initZero bool) reflect.Value

Value returns the field value. NOTE: 

If initZero==true, initialize nil pointer to zero value

type FieldSelector 

type FieldSelector string

FieldSelector expression selector

func (FieldSelector) Name 

func (f FieldSelector) Name() string

Name returns the current field name.

func (FieldSelector) Parent 

func (f FieldSelector) Parent() (string, bool)

Parent returns the parent FieldSelector.

func (FieldSelector) Split 

func (f FieldSelector) Split() (paths []string, name string)

Split returns the path segments and the current field name.

func (FieldSelector) String 

func (f FieldSelector) String() string

String returns string type value.

type Null 

type Null = interface{}

Internally unified data types

type Number 

type Number = float64

Internally unified data types

type String 

type String = string

Internally unified data types

type TagExpr 

type TagExpr struct {
	// contains filtered or unexported fields
}

TagExpr struct tag expression evaluator

func (*TagExpr) Eval 

func (t *TagExpr) Eval(exprSelector string) interface{}

Eval evaluates the value of the struct tag expression by the selector expression. NOTE: 

format: fieldName, fieldName.exprName, fieldName1.fieldName2.exprName1
result types: float64, string, bool, nil

func (*TagExpr) EvalBool 

func (t *TagExpr) EvalBool(exprSelector string) bool

EvalBool evaluates the value of the struct tag expression by the selector expression. NOTE: 

If the expression value is not 0, '' or nil, return true.

func (*TagExpr) EvalFloat 

func (t *TagExpr) EvalFloat(exprSelector string) float64

EvalFloat evaluates the value of the struct tag expression by the selector expression. NOTE: 

If the expression value type is not float64, return 0.

func (*TagExpr) EvalString 

func (t *TagExpr) EvalString(exprSelector string) string

EvalString evaluates the value of the struct tag expression by the selector expression. NOTE: 

If the expression value type is not string, return "".

func (*TagExpr) EvalWithEnv 

func (t *TagExpr) EvalWithEnv(exprSelector string, env map[string]interface{}) interface{}

EvalWithEnv evaluates the value with the given env NOTE: 

format: fieldName, fieldName.exprName, fieldName1.fieldName2.exprName1
result types: float64, string, bool, nil

func (*TagExpr) Field 

func (t *TagExpr) Field(fieldSelector string) (fh *FieldHandler, found bool)

Field returns the field handler specified by the selector.

func (*TagExpr) Range 

func (t *TagExpr) Range(fn func(*ExprHandler) error) error

Range loop through each tag expression. When fn returns false, interrupt traversal and return false. NOTE: 

eval result types: float64, string, bool, nil

func (*TagExpr) RangeFields 

func (t *TagExpr) RangeFields(fn func(*FieldHandler) bool) bool

RangeFields loop through each field. When fn returns false, interrupt traversal and return false.

type VM 

type VM struct {
	// contains filtered or unexported fields
}

VM struct tag expression interpreter

func New 

func New(tagName ...string) *VM

New creates a tag expression interpreter that uses tagName as the tag name. NOTE: 

If no tagName is specified, no tag expression will be interpreted,
but still can operate the various fields.

func (*VM) MustRun 

func (vm *VM) MustRun(structOrStructPtrOrReflectValue interface{}) *TagExpr

MustRun is similar to Run, but panic when error.

func (*VM) Run 

func (vm *VM) Run(structPtrOrReflectValue interface{}) (*TagExpr, error)

Run returns the tag expression handler of the @structPtrOrReflectValue. NOTE: 

If the structure type has not been warmed up,
it will be slower when it is first called.

Disable new -d=checkptr behaviour for Go 1.14

func (*VM) RunAny 

func (vm *VM) RunAny(v interface{}, fn func(*TagExpr, error) error) error

RunAny returns the tag expression handler for the @v. NOTE: 

The @v can be structured data such as struct, map, slice, array, interface, reflcet.Value, etc.
If the structure type has not been warmed up,
it will be slower when it is first called.

Source Files

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Directories

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