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
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
|
package main
import (
"io"
"log"
"strconv"
)
type tokenType byte
const (
tokenEOF tokenType = iota
// no explicit keyword type
tokenIdent // e.g. set, ratios, 1:2:3
tokenColon // :
tokenPrefix // $, %, !, &
tokenLBraces // {{
tokenRBraces // }}
tokenCommand // in between a prefix to \n or between {{ and }}
tokenSemicolon // ;
// comments are stripped
)
type scanner struct {
buf []byte // input buffer
off int // current offset in buf
chr byte // current character in buf
sem bool // insert semicolon
nln bool // insert newline
eof bool // buffer ended
key bool // scanning keys
blk bool // scanning block
cmd bool // scanning command
typ tokenType // scanned token type
tok string // scanned token value
// TODO: pos
}
func newScanner(r io.Reader) *scanner {
buf, err := io.ReadAll(r)
if err != nil {
log.Printf("scanning: %s", err)
}
var eof bool
var chr byte
if len(buf) == 0 {
eof = true
} else {
eof = false
chr = buf[0]
}
return &scanner{
buf: buf,
eof: eof,
chr: chr,
}
}
func (s *scanner) next() {
if s.off+1 < len(s.buf) {
s.off++
s.chr = s.buf[s.off]
return
}
s.off = len(s.buf)
s.chr = 0
s.eof = true
}
func (s *scanner) peek() byte {
if s.off+1 < len(s.buf) {
return s.buf[s.off+1]
}
return 0
}
func isSpace(b byte) bool {
switch b {
case '\t', '\n', '\v', '\f', '\r', ' ':
return true
}
return false
}
func isDigit(b byte) bool {
return '0' <= b && b <= '9'
}
func isPrefix(b byte) bool {
switch b {
case '$', '%', '!', '&':
return true
}
return false
}
func (s *scanner) scan() bool {
scan:
switch {
case s.eof:
s.next()
if s.sem {
s.typ = tokenSemicolon
s.tok = "\n"
s.sem = false
return true
}
if s.nln {
s.typ = tokenSemicolon
s.tok = "\n"
s.nln = false
return true
}
s.typ = tokenEOF
s.tok = "EOF"
return false
case s.key:
beg := s.off
for !s.eof && !isSpace(s.chr) {
s.next()
}
s.typ = tokenIdent
s.tok = string(s.buf[beg:s.off])
s.key = false
case s.blk:
// return here by setting s.cmd to false
// after scanning the command in the loop below
if !s.cmd {
s.next()
s.next()
s.typ = tokenRBraces
s.tok = "}}"
s.blk = false
s.sem = true
return true
}
beg := s.off
for !s.eof {
s.next()
if s.chr == '}' {
if !s.eof && s.peek() == '}' {
s.typ = tokenCommand
s.tok = string(s.buf[beg:s.off])
s.cmd = false
return true
}
}
}
s.typ = tokenEOF
s.tok = "EOF"
return false
case s.cmd:
for !s.eof && isSpace(s.chr) {
s.next()
}
if !s.eof && s.chr == '{' {
if s.peek() == '{' {
s.next()
s.next()
s.typ = tokenLBraces
s.tok = "{{"
s.blk = true
return true
}
}
beg := s.off
for !s.eof && s.chr != '\n' {
s.next()
}
s.typ = tokenCommand
s.tok = string(s.buf[beg:s.off])
s.cmd = false
s.sem = true
case s.chr == '\n':
if s.sem {
s.typ = tokenSemicolon
s.tok = "\n"
s.sem = false
return true
}
s.next()
if s.nln {
s.typ = tokenSemicolon
s.tok = "\n"
s.nln = false
return true
}
goto scan
case isSpace(s.chr):
for !s.eof && isSpace(s.chr) && s.chr != '\n' {
s.next()
}
goto scan
case s.chr == ';':
s.typ = tokenSemicolon
s.tok = ";"
s.sem = false
s.next()
case s.chr == '#':
for !s.eof && s.chr != '\n' {
s.next()
}
goto scan
case s.chr == '"':
s.next()
var buf []byte
for !s.eof && s.chr != '"' {
if s.chr == '\\' {
s.next()
switch {
case s.chr == '"' || s.chr == '\\':
buf = append(buf, s.chr)
case s.chr == 'a':
buf = append(buf, '\a')
case s.chr == 'b':
buf = append(buf, '\b')
case s.chr == 'f':
buf = append(buf, '\f')
case s.chr == 'n':
buf = append(buf, '\n')
case s.chr == 'r':
buf = append(buf, '\r')
case s.chr == 't':
buf = append(buf, '\t')
case s.chr == 'v':
buf = append(buf, '\v')
case isDigit(s.chr):
var oct []byte
for isDigit(s.chr) {
oct = append(oct, s.chr)
s.next()
}
n, err := strconv.ParseInt(string(oct), 8, 0)
if err != nil {
log.Printf("scanning: %s", err)
}
buf = append(buf, byte(n))
continue
default:
buf = append(buf, '\\', s.chr)
}
s.next()
continue
}
buf = append(buf, s.chr)
s.next()
}
s.typ = tokenIdent
s.tok = string(buf)
s.next()
case s.chr == '\'':
s.next()
beg := s.off
|
