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
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
|
package main
import (
"encoding/json"
"fmt"
"io/ioutil"
"os"
"runtime/debug"
"github.com/nihei9/vartan/driver"
"github.com/nihei9/vartan/spec"
"github.com/spf13/cobra"
)
var parseFlags = struct {
source *string
onlyParse *bool
cst *bool
disableLAC *bool
}{}
func init() {
cmd := &cobra.Command{
Use: "parse <grammar file path>",
Short: "Parse a text stream",
Example: ` cat src | vartan parse grammar.json`,
Args: cobra.ExactArgs(1),
RunE: runParse,
}
parseFlags.source = cmd.Flags().StringP("source", "s", "", "source file path (default stdin)")
parseFlags.onlyParse = cmd.Flags().Bool("only-parse", false, "when this option is enabled, the parser performs only parse and doesn't semantic actions")
parseFlags.cst = cmd.Flags().Bool("cst", false, "when this option is enabled, the parser generates a CST")
parseFlags.disableLAC = cmd.Flags().Bool("disable-lac", false, "disable LAC (lookahead correction)")
rootCmd.AddCommand(cmd)
}
func runParse(cmd *cobra.Command, args []string) (retErr error) {
defer func() {
panicked := false
v := recover()
if v != nil {
err, ok := v.(error)
if !ok {
retErr = fmt.Errorf("an unexpected error occurred: %v", v)
fmt.Fprintf(os.Stderr, "%v:\n%v", retErr, string(debug.Stack()))
return
}
retErr = err
panicked = true
}
if retErr != nil {
if panicked {
fmt.Fprintf(os.Stderr, "%v:\n%v", retErr, string(debug.Stack()))
} else {
fmt.Fprintf(os.Stderr, "%v\n", retErr)
}
}
}()
if *parseFlags.onlyParse && *parseFlags.cst {
return fmt.Errorf("You cannot enable --only-parse and --cst at the same time")
}
cgram, err := readCompiledGrammar(args[0])
if err != nil {
return fmt.Errorf("Cannot read a compiled grammar: %w", err)
}
var p *driver.Parser
var treeAct *driver.SyntaxTreeActionSet
{
src := os.Stdin
if *parseFlags.source != "" {
f, err := os.Open(*parseFlags.source)
if err != nil {
return fmt.Errorf("Cannot open the source file %s: %w", *parseFlags.source, err)
}
defer f.Close()
src = f
}
var opts []driver.ParserOption
{
switch {
case *parseFlags.cst:
treeAct = driver.NewSyntaxTreeActionSet(cgram, false, true)
case !*parseFlags.onlyParse:
treeAct = driver.NewSyntaxTreeActionSet(cgram, true, false)
}
if treeAct != nil {
opts = append(opts, driver.SemanticAction(treeAct))
}
if *parseFlags.disableLAC {
opts = append(opts, driver.DisableLAC())
}
}
p, err = driver.NewParser(cgram, src, opts...)
if err != nil {
return err
}
}
err = p.Parse()
if err != nil {
return err
}
synErrs := p.SyntaxErrors()
for _, synErr := range synErrs {
tok := synErr.Token
var msg string
switch {
case tok.EOF:
msg = "<eof>"
case tok.Invalid:
msg = fmt.Sprintf("'%v' (<invalid>)", tok.Text())
default:
msg = fmt.Sprintf("'%v' (%v)", tok.Text(), tok.KindName)
}
fmt.Fprintf(os.Stderr, "%v:%v: %v: %v", synErr.Row+1, synErr.Col+1, synErr.Message, msg)
if len(synErrs) > 0 {
fmt.Fprintf(os.Stderr, "; expected: %v", synErr.ExpectedTerminals[0])
for _, t := range synErr.ExpectedTerminals[1:] {
fmt.Fprintf(os.Stderr, ", %v", t)
}
}
fmt.Fprintf(os.Stderr, "\n")
}
if len(synErrs) == 0 && !*parseFlags.onlyParse {
var tree *driver.Node
if *parseFlags.cst {
tree = treeAct.CST()
} else {
tree = treeAct.AST()
}
driver.PrintTree(os.Stdout, tree)
}
return nil
}
func readCompiledGrammar(path string) (*spec.CompiledGrammar, error) {
f, err := os.Open(path)
if err != nil {
return nil, err
}
data, err := ioutil.ReadAll(f)
if err != nil {
return nil, err
}
cgram := &spec.CompiledGrammar{}
err = json.Unmarshal(data, cgram)
if err != nil {
return nil, err
}
return cgram, nil
}
|
