github.com/joomcode/pegomock@v2.9.2-0.20220414140958-14f53b6b2a6c+incompatible/modelgen/gomock/reflect.go (about)

     1  // Copyright 2012 Google Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package gomock
    16  
    17  // This file contains the model construction by reflection.
    18  
    19  import (
    20  	"bytes"
    21  	"encoding/gob"
    22  	"flag"
    23  	"fmt"
    24  	"io"
    25  	"io/ioutil"
    26  	"os"
    27  	"os/exec"
    28  	"path/filepath"
    29  	"runtime"
    30  	"text/template"
    31  
    32  	"github.com/petergtz/pegomock/model"
    33  )
    34  
    35  var (
    36  	progOnly = flag.Bool("prog_only", false, "(reflect mode) Only generate the reflection program; write it to stdout.")
    37  	execOnly = flag.String("exec_only", "", "(reflect mode) If set, execute this reflection program.")
    38  )
    39  
    40  func Reflect(importPath string, symbols []string) (*model.Package, error) {
    41  	// TODO: sanity check arguments
    42  	progPath := *execOnly
    43  	if *execOnly == "" {
    44  		workingDir, err := os.Getwd()
    45  		if err != nil {
    46  			return nil, err
    47  		}
    48  		tmpDir, err := ioutil.TempDir(workingDir, ".tmp_gomock_reflect_")
    49  		if err != nil {
    50  			return nil, err
    51  		}
    52  		defer func() { os.RemoveAll(tmpDir) }()
    53  		const progSource = "prog.go"
    54  		var progBinary = "prog.bin"
    55  		if runtime.GOOS == "windows" {
    56  			// Windows won't execute a program unless it has a ".exe" suffix.
    57  			progBinary += ".exe"
    58  		}
    59  
    60  		// Generate program.
    61  		var program bytes.Buffer
    62  		data := reflectData{
    63  			ImportPath: importPath,
    64  			Symbols:    symbols,
    65  		}
    66  		if err := reflectProgram.Execute(&program, &data); err != nil {
    67  			return nil, err
    68  		}
    69  		if *progOnly {
    70  			io.Copy(os.Stdout, &program)
    71  			os.Exit(0)
    72  		}
    73  		if err := ioutil.WriteFile(filepath.Join(tmpDir, progSource), program.Bytes(), 0600); err != nil {
    74  			return nil, err
    75  		}
    76  
    77  		// Build the program.
    78  		cmd := exec.Command("go", "build", "-o", progBinary, progSource)
    79  		cmd.Dir = tmpDir
    80  		stderr := &bytes.Buffer{}
    81  		cmd.Stderr = stderr
    82  		if err := cmd.Run(); err != nil {
    83  			return nil, fmt.Errorf("%v caused by:\n%v", err, stderr.String())
    84  		}
    85  		progPath = filepath.Join(tmpDir, progBinary)
    86  	}
    87  
    88  	// Run it.
    89  	cmd := exec.Command(progPath)
    90  	var stdout bytes.Buffer
    91  	cmd.Stdout = &stdout
    92  	cmd.Stderr = os.Stderr
    93  	if err := cmd.Run(); err != nil {
    94  		return nil, err
    95  	}
    96  
    97  	// Process output.
    98  	var pkg model.Package
    99  	if err := gob.NewDecoder(&stdout).Decode(&pkg); err != nil {
   100  		return nil, err
   101  	}
   102  	return &pkg, nil
   103  }
   104  
   105  type reflectData struct {
   106  	ImportPath string
   107  	Symbols    []string
   108  }
   109  
   110  // This program reflects on an interface value, and prints the
   111  // gob encoding of a model.Package to standard output.
   112  // JSON doesn't work because of the model.Type interface.
   113  var reflectProgram = template.Must(template.New("program").Parse(`
   114  package main
   115  
   116  import (
   117  	"encoding/gob"
   118  	"fmt"
   119  	"os"
   120  	"path"
   121  	"reflect"
   122  
   123  	"github.com/petergtz/pegomock/model"
   124  	"github.com/petergtz/pegomock/modelgen/gomock"
   125  
   126  	pkg_ {{printf "%q" .ImportPath}}
   127  )
   128  
   129  func main() {
   130  	its := []struct{
   131  		sym string
   132  		typ reflect.Type
   133  	}{
   134  		{{range .Symbols}}
   135  		{ {{printf "%q" .}}, reflect.TypeOf((*pkg_.{{.}})(nil)).Elem()},
   136  		{{end}}
   137  	}
   138  	pkg := &model.Package{
   139  		// NOTE: This behaves contrary to documented behaviour if the
   140  		// package name is not the final component of the import path.
   141  		// The reflect package doesn't expose the package name, though.
   142  		Name: path.Base({{printf "%q" .ImportPath}}),
   143  	}
   144  
   145  	for _, it := range its {
   146  		intf, err := gomock.InterfaceFromInterfaceType(it.typ)
   147  		if err != nil {
   148  			fmt.Fprintf(os.Stderr, "Reflection: %v\n", err)
   149  			os.Exit(1)
   150  		}
   151  		intf.Name = it.sym
   152  		pkg.Interfaces = append(pkg.Interfaces, intf)
   153  	}
   154  	if err := gob.NewEncoder(os.Stdout).Encode(pkg); err != nil {
   155  		fmt.Fprintf(os.Stderr, "gob encode: %v\n", err)
   156  		os.Exit(1)
   157  	}
   158  }
   159  `))