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//go:generate re2go $INPUT -o $OUTPUT
package main
import "fmt"
import "os"
/*!max:re2c*/
var SIZE uint = 11
type YYCTYPE = byte
type Input struct {
file *os.File
data []YYCTYPE
cursor uint
marker uint
token uint
limit uint
eof bool
}
func fill(in *Input, need uint) int {
// End of input has already been reached, nothing to do.
if in.eof {
fmt.Println("fill error: unexpected EOF")
return 1
}
// Check if after moving the current lexeme to the beginning
// of buffer there will be enough free space.
if SIZE-(in.cursor-in.token) < need {
fmt.Println("fill error: lexeme too long")
return 2
}
// Discard everything up to the start of the current lexeme,
// shift buffer contents and adjust offsets.
copy(in.data[0:], in.data[in.token:in.limit])
in.cursor -= in.token
in.marker -= in.token
in.limit -= in.token
in.token = 0
// Read new data (as much as possible to fill the buffer).
n, _ := in.file.Read(in.data[in.limit:SIZE])
in.limit += uint(n)
fmt.Printf("fill(%d): %v '%s'\n", need, in.data[:in.limit+1],
string(in.data[:in.limit]))
// If read less than expected, this is the end of input.
in.eof = in.limit < SIZE
// If end of input, add padding so that the lexer can read
// the remaining characters at the end of buffer.
if in.eof {
for i := uint(0); i < YYMAXFILL; i += 1 {
in.data[in.limit+i] = 0
}
in.limit += YYMAXFILL
}
return 0
}
func Lex(in *Input) int {
YYPEEK := func() YYCTYPE { return in.data[in.cursor] }
YYSKIP := func() { in.cursor++ }
YYBACKUP := func() { in.marker = in.cursor }
YYRESTORE := func() { in.cursor = in.marker }
YYLESSTHAN := func(n uint) bool { return in.limit-in.cursor < n }
YYFILL := func(n uint) int { return fill(in, n) }
in.token = in.cursor
/*!re2c
re2c:define:YYFILL = "if YYFILL(@@) != 0 { return -2 }";
re2c:define:YYFILL:naked = 1;
re2c:api:style = functions;
* {
fmt.Println("error")
return -1
}
"\x00" {
fmt.Println("end")
return 0
}
[0-9]+ {
fmt.Printf("number-1: %v\n", string(in.data[in.token:in.cursor]))
return 1
}
[0-9]+ [-] [0-9]+ {
fmt.Printf("number-2: %v\n", string(in.data[in.token:in.cursor]))
return 2
}
[ ] {
return 3
}
*/
}
func test(data string) (result int) {
tmpfile := "input.txt"
f, _ := os.Create(tmpfile)
f.WriteString(data)
f.WriteString("\000") // lexer expects NULL-terminator
f.Seek(0, 0)
defer func() {
f.Close()
os.Remove(tmpfile)
}()
in := &Input{
file: f,
data: make([]byte, SIZE+YYMAXFILL),
cursor: SIZE,
marker: SIZE,
token: SIZE,
limit: SIZE,
eof: false,
}
result = 9999
for result > 0 {
result = Lex(in)
}
return
}
func main() {
var s string
// Succeeds, the lexer has enough characters ahead.
s = " 123456789 "
if test(s) != 0 {
panic("expected 'number: 123456789'")
}
// Fails, there is no space for the needed characters.
s = " 1234567890 "
if test(s) != -2 {
panic("expected 'fill error: lexeme too long'")
}
// Succeeds, the lexer has enough characters ahead
// (although the same lexeme length as the previous case,
// YYFILL argument is smaller in this state).
s = " 12345-6789 "
if test(s) != 0 {
panic("expected 'number: 12345-6789'")
}
// Fails, there is no space for any characters.
s = " 12345-67890 "
if test(s) != -2 {
panic("expected 'fill error: lexeme too long'")
}
// Fails, invalid input.
s = "?#!*"
if test(s) != -1 {
panic("expected 'error'")
}
fmt.Println("OK")
}
|
