fileinfo.go

Documentation: github.com/bazelbuild/bazel-gazelle/language/proto

     1  /* Copyright 2018 The Bazel Authors. All rights reserved.
     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  
    16  package proto
    17  
    18  import (
    19  	"bytes"
    20  	"log"
    21  	"os"
    22  	"path/filepath"
    23  	"regexp"
    24  	"sort"
    25  	"strconv"
    26  	"strings"
    27  )
    28  
    29  // FileInfo contains metadata extracted from a .proto file.
    30  type FileInfo struct {
    31  	Path, Name string
    32  
    33  	PackageName string
    34  
    35  	Options []Option
    36  	Imports []string
    37  
    38  	HasServices bool
    39  }
    40  
    41  // Option represents a top-level option statement in a .proto file. Only
    42  // string options are supported for now.
    43  type Option struct {
    44  	Key, Value string
    45  }
    46  
    47  var protoRe = buildProtoRegexp()
    48  
    49  func protoFileInfo(dir, name string) FileInfo {
    50  	info := FileInfo{
    51  		Path: filepath.Join(dir, name),
    52  		Name: name,
    53  	}
    54  	content, err := os.ReadFile(info.Path)
    55  	if err != nil {
    56  		log.Printf("%s: error reading proto file: %v", info.Path, err)
    57  		return info
    58  	}
    59  
    60  	for _, match := range protoRe.FindAllSubmatch(content, -1) {
    61  		switch {
    62  		case match[importSubexpIndex] != nil:
    63  			imp := unquoteProtoString(match[importSubexpIndex])
    64  			info.Imports = append(info.Imports, imp)
    65  
    66  		case match[packageSubexpIndex] != nil:
    67  			pkg := string(match[packageSubexpIndex])
    68  			if info.PackageName == "" {
    69  				info.PackageName = pkg
    70  			}
    71  
    72  		case match[optkeySubexpIndex] != nil:
    73  			key := string(match[optkeySubexpIndex])
    74  			value := unquoteProtoString(match[optvalSubexpIndex])
    75  			info.Options = append(info.Options, Option{key, value})
    76  
    77  		case match[serviceSubexpIndex] != nil:
    78  			info.HasServices = true
    79  
    80  		default:
    81  			// Comment matched. Nothing to extract.
    82  		}
    83  	}
    84  	sort.Strings(info.Imports)
    85  
    86  	return info
    87  }
    88  
    89  const (
    90  	importSubexpIndex  = 1
    91  	packageSubexpIndex = 2
    92  	optkeySubexpIndex  = 3
    93  	optvalSubexpIndex  = 4
    94  	serviceSubexpIndex = 5
    95  )
    96  
    97  // Based on https://developers.google.com/protocol-buffers/docs/reference/proto3-spec
    98  func buildProtoRegexp() *regexp.Regexp {
    99  	hexEscape := `\\[xX][0-9a-fA-f]{2}`
   100  	octEscape := `\\[0-7]{3}`
   101  	charEscape := `\\[abfnrtv'"\\]`
   102  	charValue := strings.Join([]string{hexEscape, octEscape, charEscape, "[^\x00\\'\\\"\\\\]"}, "|")
   103  	strLit := `'(?:` + charValue + `|")*'|"(?:` + charValue + `|')*"`
   104  	ident := `[A-Za-z][A-Za-z0-9_]*`
   105  	fullIdent := ident + `(?:\.` + ident + `)*`
   106  	importStmt := `\bimport\s*(?:public|weak)?\s*(?P<import>` + strLit + `)\s*;`
   107  	packageStmt := `\bpackage\s*(?P<package>` + fullIdent + `)\s*;`
   108  	optionStmt := `\boption\s*(?P<optkey>` + fullIdent + `)\s*=\s*(?P<optval>` + strLit + `)\s*;`
   109  	serviceStmt := `(?P<service>service\s*` + ident + `\s*{)`
   110  	comment := `//[^\n]*`
   111  	protoReSrc := strings.Join([]string{importStmt, packageStmt, optionStmt, serviceStmt, comment}, "|")
   112  	return regexp.MustCompile(protoReSrc)
   113  }
   114  
   115  func unquoteProtoString(q []byte) string {
   116  	// Adjust quotes so that Unquote is happy. We need a double quoted string
   117  	// without unescaped double quote characters inside.
   118  	noQuotes := bytes.Split(q[1:len(q)-1], []byte{'"'})
   119  	if len(noQuotes) != 1 {
   120  		for i := 0; i < len(noQuotes)-1; i++ {
   121  			if len(noQuotes[i]) == 0 || noQuotes[i][len(noQuotes[i])-1] != '\\' {
   122  				noQuotes[i] = append(noQuotes[i], '\\')
   123  			}
   124  		}
   125  		q = append([]byte{'"'}, bytes.Join(noQuotes, []byte{'"'})...)
   126  		q = append(q, '"')
   127  	}
   128  	if q[0] == '\'' {
   129  		q[0] = '"'
   130  		q[len(q)-1] = '"'
   131  	}
   132  
   133  	s, err := strconv.Unquote(string(q))
   134  	if err != nil {
   135  		log.Panicf("unquoting string literal %s from proto: %v", q, err)
   136  	}
   137  	return s
   138  }
   139
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