github.com/anycable/anycable-go@v1.5.1/mrb/mrb.go (about)

     1  //go:build (darwin && mrb) || (linux && mrb)
     2  // +build darwin,mrb linux,mrb
     3  
     4  package mrb
     5  
     6  import (
     7  	"fmt"
     8  	"io/ioutil"
     9  	"strings"
    10  	"sync"
    11  
    12  	nanoid "github.com/matoous/go-nanoid"
    13  	"github.com/mitchellh/go-mruby"
    14  )
    15  
    16  // Supported returns true iff mruby scripting is available
    17  func Supported() bool {
    18  	return true
    19  }
    20  
    21  // Engine represents one running mruby VM
    22  type Engine struct {
    23  	VM *mruby.Mrb
    24  	mu sync.Mutex
    25  }
    26  
    27  var (
    28  	defaultEngine     *Engine
    29  	defaultEngineSync sync.Mutex
    30  )
    31  
    32  // NewEngine builds new mruby VM and return new engine
    33  func NewEngine() *Engine {
    34  	return &Engine{VM: mruby.NewMrb()}
    35  }
    36  
    37  // DefaultEngine returns a default mruby engine
    38  func DefaultEngine() *Engine {
    39  	defaultEngineSync.Lock()
    40  	defer defaultEngineSync.Unlock()
    41  
    42  	if defaultEngine == nil {
    43  		defaultEngine = NewEngine()
    44  	}
    45  
    46  	return defaultEngine
    47  }
    48  
    49  func Version() (v string, err error) {
    50  	mrbv, err := DefaultEngine().Eval("MRUBY_DESCRIPTION")
    51  	if err != nil {
    52  		return
    53  	}
    54  
    55  	v = strings.TrimSpace(mrbv.String())
    56  	return
    57  }
    58  
    59  // LoadFile loads, parses and eval Ruby file within a vm
    60  func (engine *Engine) LoadFile(path string) error {
    61  	contents, err := ioutil.ReadFile(path)
    62  
    63  	if err != nil {
    64  		return err
    65  	}
    66  
    67  	return engine.LoadString(string(contents))
    68  }
    69  
    70  // LoadString loads, parses and eval Ruby code within a vm
    71  func (engine *Engine) LoadString(contents string) error {
    72  	engine.mu.Lock()
    73  	defer engine.mu.Unlock()
    74  
    75  	ctx := mruby.NewCompileContext(engine.VM)
    76  	defer ctx.Close()
    77  
    78  	filename, err := nanoid.Nanoid()
    79  
    80  	if err != nil {
    81  		return err
    82  	}
    83  
    84  	ctx.SetFilename(fmt.Sprintf("%s.rb", filename))
    85  
    86  	parser := mruby.NewParser(engine.VM)
    87  	defer parser.Close()
    88  
    89  	if _, err = parser.Parse(contents, ctx); err != nil {
    90  		return err
    91  	}
    92  
    93  	parsed := parser.GenerateCode()
    94  
    95  	if _, err = engine.VM.Run(parsed, nil); err != nil {
    96  		return err
    97  	}
    98  
    99  	return nil
   100  }
   101  
   102  // Eval runs arbitrary code within a vm
   103  func (engine *Engine) Eval(code string) (*mruby.MrbValue, error) {
   104  	return engine.VM.LoadString(code)
   105  }