github.com/Comcast/plax@v0.8.32/subst/js.go (about)

     1  /*
     2   * Copyright 2021 Comcast Cable Communications Management, LLC
     3   *
     4   * Licensed under the Apache License, Version 2.0 (the "License");
     5   * you may not use this file except in compliance with the License.
     6   * You may obtain a copy of the License at
     7   *
     8   * http://www.apache.org/licenses/LICENSE-2.0
     9   *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   *
    16   * SPDX-License-Identifier: Apache-2.0
    17   */
    18  
    19  package subst
    20  
    21  import (
    22  	"fmt"
    23  	"strings"
    24  	"time"
    25  
    26  	"github.com/Comcast/sheens/match"
    27  	"github.com/dop251/goja"
    28  )
    29  
    30  // JSExec executes the javascript source with the given context and environment mappings
    31  func JSExec(ctx *Ctx, src string, env map[string]interface{}) (interface{}, error) {
    32  	x, err := jsExec(ctx, src, env)
    33  	if err != nil {
    34  		return nil, fmt.Errorf("JavaScript problem: %w", err)
    35  	}
    36  	return x, nil
    37  }
    38  
    39  func jsExec(ctx *Ctx, src string, env map[string]interface{}) (interface{}, error) {
    40  
    41  	js := goja.New()
    42  
    43  	js.Set("print", func(args ...interface{}) {
    44  		acc := make([]string, 0, len(args))
    45  		for _, x := range args {
    46  			acc = append(acc, JSON(x))
    47  		}
    48  		fmt.Printf("%s\n", strings.Join(acc, ","))
    49  	})
    50  
    51  	js.Set("now", func() interface{} {
    52  		return time.Now().UTC().Format(time.RFC3339Nano)
    53  	})
    54  
    55  	js.Set("match", func(pat, msg interface{}, bs map[string]interface{}) []map[string]interface{} {
    56  		if bs == nil {
    57  			bs = match.NewBindings()
    58  		}
    59  		bss, err := match.Match(pat, msg, bs)
    60  		if err != nil {
    61  			panic(js.ToValue(err.Error()))
    62  		}
    63  		// Strip type (match.Bindings) to enable standard
    64  		// Javascript access to the maps.
    65  		acc := make([]map[string]interface{}, len(bss))
    66  		for i, bs := range bss {
    67  			acc[i] = map[string]interface{}(bs)
    68  		}
    69  		return acc
    70  	})
    71  
    72  	js.Set("tsMs", func(s string) int64 {
    73  		t, err := time.Parse(time.RFC3339Nano, s)
    74  		if err != nil {
    75  			return 0
    76  		}
    77  		return t.UnixNano() / 1000 / 1000
    78  	})
    79  
    80  	for k, v := range env {
    81  		js.Set(k, v)
    82  	}
    83  
    84  	v, err := js.RunString(src)
    85  	if err != nil {
    86  		return nil, err
    87  	}
    88  
    89  	return v.Export(), nil
    90  }