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Copy pathcommon.go
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500 lines (475 loc) · 12 KB
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Copy pathcommon.go
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500 lines (475 loc) · 12 KB
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package minify
import (
"encoding/base64"
"github.com/tdewolff/parse/v2"
"github.com/tdewolff/parse/v2/strconv"
)
var (
textMimeBytes = []byte("text/plain")
charsetAsciiBytes = []byte("charset=us-ascii")
dataBytes = []byte("data:")
base64Bytes = []byte(";base64")
)
// Epsilon is the closest number to zero that is not considered to be zero.
var Epsilon = 0.00001
// Mediatype minifies a given mediatype by removing all whitespace.
func Mediatype(b []byte) []byte {
j := 0
start := 0
inString := false
for i, c := range b {
if !inString && parse.IsWhitespace(c) {
if start != 0 {
j += copy(b[j:], b[start:i])
} else {
j += i
}
start = i + 1
} else if c == '"' {
inString = !inString
}
}
if start != 0 {
j += copy(b[j:], b[start:])
return parse.ToLower(b[:j])
}
return parse.ToLower(b)
}
// DataURI minifies a data URI and calls a minifier by the specified mediatype. Specifications: https://www.ietf.org/rfc/rfc2397.txt.
func DataURI(m *M, dataURI []byte) []byte {
origData := parse.Copy(dataURI)
mediatype, data, err := parse.DataURI(dataURI)
if err != nil {
return dataURI
}
data, _ = m.Bytes(string(mediatype), data)
base64Len := len(";base64") + base64.StdEncoding.EncodedLen(len(data))
asciiLen := len(data)
for _, c := range data {
if parse.URLEncodingTable[c] {
asciiLen += 2
}
if asciiLen > base64Len {
break
}
}
if len(origData) < base64Len && len(origData) < asciiLen {
return origData
}
if base64Len < asciiLen {
encoded := make([]byte, base64Len-len(";base64"))
base64.StdEncoding.Encode(encoded, data)
data = encoded
mediatype = append(mediatype, base64Bytes...)
} else {
data = parse.EncodeURL(data, parse.URLEncodingTable)
}
if len("text/plain") <= len(mediatype) && parse.EqualFold(mediatype[:len("text/plain")], textMimeBytes) {
mediatype = mediatype[len("text/plain"):]
}
for i := 0; i+len(";charset=us-ascii") <= len(mediatype); i++ {
// must start with semicolon and be followed by end of mediatype or semicolon
if mediatype[i] == ';' && parse.EqualFold(mediatype[i+1:i+len(";charset=us-ascii")], charsetAsciiBytes) && (i+len(";charset=us-ascii") >= len(mediatype) || mediatype[i+len(";charset=us-ascii")] == ';') {
mediatype = append(mediatype[:i], mediatype[i+len(";charset=us-ascii"):]...)
break
}
}
return append(append(append(dataBytes, mediatype...), ','), data...)
}
const MaxInt = int(^uint(0) >> 1)
const MinInt = -MaxInt - 1
// Decimal minifies a given byte slice containing a number (see parse.Number) and removes superfluous characters.
// It does not parse or output exponents. prec is the number of significant digits. When prec is zero it will keep all digits. Only digits after the dot can be removed to reach the number of significant digits. Very large number may thus have more significant digits.
func Decimal(num []byte, prec int) []byte {
if len(num) <= 1 {
return num
}
// omit first + and register mantissa start and end, whether it's negative and the exponent
neg := false
start := 0
dot := -1
end := len(num)
if 0 < end && (num[0] == '+' || num[0] == '-') {
if num[0] == '-' {
neg = true
}
start++
}
for i, c := range num[start:] {
if c == '.' {
dot = start + i
break
}
}
if dot == -1 {
dot = end
}
// trim leading zeros but leave at least one digit
for start < end-1 && num[start] == '0' {
start++
}
// trim trailing zeros
i := end - 1
for ; dot < i; i-- {
if num[i] != '0' {
end = i + 1
break
}
}
if i == dot {
end = dot
if start == end {
num[start] = '0'
return num[start : start+1]
}
} else if start == end-1 && num[start] == '0' {
return num[start:end]
}
// apply precision
if 0 < prec && dot <= start+prec {
precEnd := start + prec + 1 // include dot
if dot == start { // for numbers like .012
digit := start + 1
for digit < end && num[digit] == '0' {
digit++
}
precEnd = digit + prec
}
if precEnd < end {
end = precEnd
// process either an increase from a lesser significant decimal (>= 5)
// or remove trailing zeros after the dot, or both
i := end - 1
inc := '5' <= num[end]
for ; start < i; i-- {
if i == dot {
// no-op
} else if inc && num[i] != '9' {
num[i]++
inc = false
break
} else if inc && i < dot { // end inc for integer
num[i] = '0'
} else if !inc && (i < dot || num[i] != '0') {
break
}
}
if i < dot {
end = dot
} else {
end = i + 1
}
if inc {
if dot == start && end == start+1 {
num[start] = '1'
} else if num[start] == '9' {
num[start] = '1'
num[start+1] = '0'
end++
} else {
num[start]++
}
}
}
}
if neg {
start--
num[start] = '-'
}
return num[start:end]
}
// Number minifies a given byte slice containing a number (see parse.Number) and removes superfluous characters.
func Number(num []byte, prec int) []byte {
if len(num) <= 1 {
return num
}
// omit first + and register mantissa start and end, whether it's negative and the exponent
neg := false
start := 0
dot := -1
end := len(num)
origExp := 0
if num[0] == '+' || num[0] == '-' {
if num[0] == '-' {
neg = true
}
start++
}
for i, c := range num[start:] {
if c == '.' {
dot = start + i
} else if c == 'e' || c == 'E' {
end = start + i
i += start + 1
if i < len(num) && num[i] == '+' {
i++
}
if tmpOrigExp, n := strconv.ParseInt(num[i:]); 0 < n && int64(MinInt) <= tmpOrigExp && tmpOrigExp <= int64(MaxInt) {
// range checks for when int is 32 bit
origExp = int(tmpOrigExp)
} else {
return num
}
break
}
}
if dot == -1 {
dot = end
}
// trim leading zeros but leave at least one digit
for start < end-1 && num[start] == '0' {
start++
}
// trim trailing zeros
i := end - 1
for ; dot < i; i-- {
if num[i] != '0' {
end = i + 1
break
}
}
if i == dot {
end = dot
if start == end {
num[start] = '0'
return num[start : start+1]
}
} else if start == end-1 && num[start] == '0' {
return num[start:end]
}
// apply precision
if 0 < prec { //&& (dot <= start+prec || start+prec+1 < dot || 0 < origExp) { // don't minify 9 to 10, but do 999 to 1e3 and 99e1 to 1e3
precEnd := start + prec
if dot == start { // for numbers like .012
digit := start + 1
for digit < end && num[digit] == '0' {
digit++
}
precEnd = digit + prec
} else if dot < precEnd { // for numbers where precision will include the dot
precEnd++
}
if precEnd < end && (dot < end || 1 < dot-precEnd+origExp) { // do not minify 9=>10 or 99=>100 or 9e1=>1e2 (but 90), but 999=>1e3 and 99e1=>1e3
end = precEnd
inc := '5' <= num[end]
if dot == end {
inc = end+1 < len(num) && '5' <= num[end+1]
}
if precEnd < dot {
origExp += dot - precEnd
dot = precEnd
}
// process either an increase from a lesser significant decimal (>= 5)
// and remove trailing zeros
i := end - 1
for ; start < i; i-- {
if i == dot {
// no-op
} else if inc && num[i] != '9' {
num[i]++
inc = false
break
} else if !inc && num[i] != '0' {
break
}
}
end = i + 1
if end < dot {
origExp += dot - end
dot = end
}
if inc { // single digit left
if dot == start {
num[start] = '1'
dot = start + 1
} else if num[start] == '9' {
num[start] = '1'
origExp++
} else {
num[start]++
}
}
}
}
// n is the number of significant digits
// normExp would be the exponent if it were normalised (0.1 <= f < 1)
n := 0
normExp := 0
if dot == start {
for i = dot + 1; i < end; i++ {
if num[i] != '0' {
n = end - i
normExp = dot - i + 1
break
}
}
} else if dot == end {
normExp = end - start
for i = end - 1; start <= i; i-- {
if num[i] != '0' {
n = i + 1 - start
end = i + 1
break
}
}
} else {
n = end - start - 1
normExp = dot - start
}
if origExp < 0 && (normExp < MinInt-origExp || normExp-n < MinInt-origExp) || 0 < origExp && (MaxInt-origExp < normExp || MaxInt-origExp < normExp-n) {
return num // exponent overflow
}
normExp += origExp
// intExp would be the exponent if it were an integer
intExp := normExp - n
lenIntExp := strconv.LenInt(int64(intExp))
lenNormExp := strconv.LenInt(int64(normExp))
// there are three cases to consider when printing the number
// case 1: without decimals and with a positive exponent (large numbers: 5e4)
// case 2: with decimals and with a negative exponent (small numbers with many digits: .123456e-4)
// case 3: with decimals and without an exponent (around zero: 5.6)
// case 4: without decimals and with a negative exponent (small numbers: 123456e-9)
if n <= normExp {
// case 1: print number with positive exponent
if dot < end {
// remove dot, either from the front or copy the smallest part
if dot == start {
start = end - n
} else if dot-start < end-dot-1 {
copy(num[start+1:], num[start:dot])
start++
} else {
copy(num[dot:], num[dot+1:end])
end--
}
}
if n+3 <= normExp {
num[end] = 'e'
end++
for i := end + lenIntExp - 1; end <= i; i-- {
num[i] = byte(intExp%10) + '0'
intExp /= 10
}
end += lenIntExp
} else if n+2 == normExp {
num[end] = '0'
num[end+1] = '0'
end += 2
} else if n+1 == normExp {
num[end] = '0'
end++
}
} else if normExp < -3 && lenNormExp < lenIntExp {
// case 2: print normalized number (0.1 <= f < 1)
zeroes := -normExp + origExp
if 0 < zeroes {
copy(num[start+1:], num[start+1+zeroes:end])
end -= zeroes
} else if zeroes < 0 {
copy(num[start+1:], num[start:dot])
num[start] = '.'
}
num[end] = 'e'
num[end+1] = '-'
end += 2
for i := end + lenNormExp - 1; end <= i; i-- {
num[i] = -byte(normExp%10) + '0'
normExp /= 10
}
end += lenNormExp
} else if -lenIntExp-1 <= normExp {
// case 3: print number without exponent
zeroes := -normExp
if 0 < zeroes {
// dot placed at the front and negative exponent, adding zeroes
newDot := end - n - zeroes - 1
if newDot != dot {
d := start - newDot
if 0 < d {
if dot < end {
// copy original digits after the dot towards the end
copy(num[dot+1+d:], num[dot+1:end])
if start < dot {
// copy original digits before the dot towards the end
copy(num[start+d+1:], num[start:dot])
}
} else if start < dot {
// copy original digits before the dot towards the end
copy(num[start+d:], num[start:dot])
}
newDot = start
end += d
} else {
start += -d
}
num[newDot] = '.'
for i := 0; i < zeroes; i++ {
num[newDot+1+i] = '0'
}
}
} else {
// dot placed in the middle of the number
if dot == start {
// when there are zeroes after the dot
dot = end - n - 1
start = dot
} else if end <= dot {
// when input has no dot in it
dot = end
end++
}
newDot := start + normExp
// move digits between dot and newDot towards the end
if dot < newDot {
copy(num[dot:], num[dot+1:newDot+1])
} else if newDot < dot {
copy(num[newDot+1:], num[newDot:dot])
}
num[newDot] = '.'
}
} else {
// case 4: print number with negative exponent
// find new end, considering moving numbers to the front, removing the dot and increasing the length of the exponent
newEnd := end
if dot == start {
newEnd = start + n
} else {
newEnd--
}
newEnd += 2 + lenIntExp
exp := intExp
lenExp := lenIntExp
if newEnd < len(num) {
// it saves space to convert the decimal to an integer and decrease the exponent
if dot < end {
if dot == start {
copy(num[start:], num[end-n:end])
end = start + n
} else {
copy(num[dot:], num[dot+1:end])
end--
}
}
} else {
// it does not save space and will panic, so we revert to the original representation
exp = origExp
lenExp = 1
if origExp <= -10 || 10 <= origExp {
lenExp = strconv.LenInt(int64(origExp))
}
}
num[end] = 'e'
num[end+1] = '-'
end += 2
for i := end + lenExp - 1; end <= i; i-- {
num[i] = -byte(exp%10) + '0'
exp /= 10
}
end += lenExp
}
if neg {
start--
num[start] = '-'
}
return num[start:end]
}