/
codegen.go
126 lines (106 loc) · 2.51 KB
/
codegen.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package main
import (
"errors"
"fmt"
"go/types"
"log"
"os"
"strings"
"text/template"
"golang.org/x/tools/go/packages"
)
func main() {
argsWithoutProg := os.Args[1:]
if len(argsWithoutProg) != 1 {
fmt.Println("Usage: go run codegen.go <FunctionPackage>")
os.Exit(1)
}
pkg := argsWithoutProg[0]
triggers, err := extractTriggers(pkg)
if err != nil {
log.Fatalln(err)
}
code, err := generateEntrypoint(pkg, triggers)
if err != nil {
log.Fatalln(err)
}
fmt.Println(code)
}
func extractTriggers(pkg string) ([]string, error) {
exports, err := loadExports(pkg)
if err != nil {
return nil, err
}
var triggers []string
for _, exp := range exports {
triggers = append(triggers, exp.Name())
}
return triggers, nil
}
func loadExports(pkg string) ([]types.Object, error) {
cfg := &packages.Config{Mode: packages.LoadTypes}
pkgs, err := packages.Load(cfg, pkg)
if err != nil {
return nil, err
}
if packages.PrintErrors(pkgs) > 0 {
return nil, fmt.Errorf("one or mor errors")
}
var results []types.Object
scope := pkgs[0].Types.Scope()
for _, symbol := range scope.Names() {
typeInfo := scope.Lookup(symbol)
if typeInfo.Exported() {
results = append(results, typeInfo)
}
}
if results == nil {
return nil, errors.New("no exported member")
}
return results, nil
}
const mainTemplate = `
package main
import (
alias "{{ .Pkg }}"
"github.com/FirebaseExtended/firebase-functions-go/support/runtime"
)
func main() {
runtime.Serve(map[string]interface{}{
{{- range .Triggers }}
"{{ . }}": alias.{{ . }},
{{- end }}
})
}
`
func generateEntrypoint(pkg string, triggers []string) (string, error) {
tmpl, err := template.New("main").Parse(mainTemplate)
if err != nil {
return "", err
}
b := new(strings.Builder)
info := struct {
Pkg string
Triggers []string
}{
Pkg: pkg,
Triggers: triggers,
}
if err := tmpl.Execute(b, info); err != nil {
return "", err
}
return b.String(), nil
}