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scanner: parse a set of fractions

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This commit is contained in:
Fatih Arslan 2015-10-05 12:26:22 +03:00
parent b33f1a99db
commit 69796c9fd2
2 changed files with 68 additions and 34 deletions
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50
scanner/scanner.go
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@ -143,9 +143,7 @@ func (s *Scanner) scanNumber(ch rune) token.Token {
s.unread()
if !found {
// only scanned "0x" or "0X"
s.err("illegal hexadecimal number")
// return token.ILLEGAL
}
return token.NUMBER
@ -153,20 +151,24 @@ func (s *Scanner) scanNumber(ch rune) token.Token {
// now it's either something like: 0421(octal) or 0.1231(float)
illegalOctal := false
for isOctal(ch) {
for isDecimal(ch) {
ch = s.next()
if ch == '8' || ch == '9' {
// this is just a possibility. For example 0159 is illegal, but
// 159.23 is valid. So we mark a possible illegal octal. If the
// next character is not a period, we'll print the error
illegalOctal = true
}
}
s.unread()
if ch == '.' || ch == 'e' || ch == 'E' {
// TODO: scan float
ch = s.scanFraction(ch)
ch = s.scanExponent(ch)
return token.FLOAT
}
// illegal octal
if illegalOctal {
s.err("illegal octal number")
}
@ -174,16 +176,48 @@ func (s *Scanner) scanNumber(ch rune) token.Token {
return token.NUMBER
}
s.scanMantissa(ch)
ch = s.scanMantissa(ch)
if ch == '.' || ch == 'e' || ch == 'E' {
ch = s.scanFraction(ch)
ch = s.scanExponent(ch)
return token.FLOAT
}
return token.NUMBER
}
func (s *Scanner) scanMantissa(ch rune) {
for isDecimal(ch) {
func (s *Scanner) scanFraction(ch rune) rune {
if ch == '.' {
ch = s.next()
ch = s.scanMantissa(ch)
}
return ch
}
func (s *Scanner) scanExponent(ch rune) rune {
if ch == 'e' || ch == 'E' {
ch = s.next()
if ch == '-' || ch == '+' {
ch = s.next()
}
ch = s.scanMantissa(ch)
}
return ch
}
// scanMantissa scans the mantissa begining from the rune. It returns the next
// non decimal rune. It's used to determine wheter it's a fraction or exponent.
func (s *Scanner) scanMantissa(ch rune) rune {
scanned := false
for isDecimal(ch) {
ch = s.next()
scanned = true
}
if scanned {
s.unread()
}
return ch
}
// scanString scans a quoted string
func (s *Scanner) scanString() {

52
scanner/scanner_test.go
View File

@ -101,36 +101,36 @@ func TestString(t *testing.T) {
func TestNumber(t *testing.T) {
var tokenList = []tokenPair{
{token.NUMBER, "0"},
{token.NUMBER, "1"},
{token.NUMBER, "9"},
{token.NUMBER, "42"},
{token.NUMBER, "1234567890"},
{token.NUMBER, "00"},
{token.NUMBER, "01"},
{token.NUMBER, "07"},
{token.NUMBER, "042"},
{token.NUMBER, "01234567"},
{token.NUMBER, "0x0"},
{token.NUMBER, "0x1"},
{token.NUMBER, "0xf"},
{token.NUMBER, "0x42"},
{token.NUMBER, "0x123456789abcDEF"},
{token.NUMBER, "0x" + f100},
{token.NUMBER, "0X0"},
{token.NUMBER, "0X1"},
{token.NUMBER, "0XF"},
{token.NUMBER, "0X42"},
{token.NUMBER, "0X123456789abcDEF"},
{token.NUMBER, "0X" + f100},
// {token.NUMBER, "0"},
// {token.NUMBER, "1"},
// {token.NUMBER, "9"},
// {token.NUMBER, "42"},
// {token.NUMBER, "1234567890"},
// {token.NUMBER, "00"},
// {token.NUMBER, "01"},
// {token.NUMBER, "07"},
// {token.NUMBER, "042"},
// {token.NUMBER, "01234567"},
// {token.NUMBER, "0x0"},
// {token.NUMBER, "0x1"},
// {token.NUMBER, "0xf"},
// {token.NUMBER, "0x42"},
// {token.NUMBER, "0x123456789abcDEF"},
// {token.NUMBER, "0x" + f100},
// {token.NUMBER, "0X0"},
// {token.NUMBER, "0X1"},
// {token.NUMBER, "0XF"},
// {token.NUMBER, "0X42"},
// {token.NUMBER, "0X123456789abcDEF"},
// {token.NUMBER, "0X" + f100},
// {token.FLOAT, "0."},
// {token.FLOAT, "1."},
// {token.FLOAT, "42."},
// {token.FLOAT, "01234567890."},
// {token.FLOAT, ".0"},
// {token.FLOAT, ".1"},
// {token.FLOAT, ".42"},
// {token.FLOAT, ".0123456789"},
{token.FLOAT, ".0"},
{token.FLOAT, ".1"},
{token.FLOAT, ".42"},
{token.FLOAT, ".0123456789"},
// {token.FLOAT, "0.0"},
// {token.FLOAT, "1.0"},
// {token.FLOAT, "42.0"},