mirror of https://github.com/miniflux/v2.git
340 lines
7.9 KiB
Go
340 lines
7.9 KiB
Go
package minify // import "github.com/tdewolff/minify"
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import (
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"bytes"
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"encoding/base64"
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"net/url"
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"github.com/tdewolff/parse"
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"github.com/tdewolff/parse/strconv"
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)
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// Epsilon is the closest number to zero that is not considered to be zero.
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var Epsilon = 0.00001
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// ContentType minifies a given mediatype by removing all whitespace.
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func ContentType(b []byte) []byte {
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j := 0
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start := 0
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inString := false
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for i, c := range b {
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if !inString && parse.IsWhitespace(c) {
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if start != 0 {
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j += copy(b[j:], b[start:i])
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} else {
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j += i
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}
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start = i + 1
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} else if c == '"' {
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inString = !inString
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}
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}
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if start != 0 {
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j += copy(b[j:], b[start:])
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return parse.ToLower(b[:j])
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}
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return parse.ToLower(b)
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}
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// DataURI minifies a data URI and calls a minifier by the specified mediatype. Specifications: https://www.ietf.org/rfc/rfc2397.txt.
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func DataURI(m *M, dataURI []byte) []byte {
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if mediatype, data, err := parse.DataURI(dataURI); err == nil {
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dataURI, _ = m.Bytes(string(mediatype), data)
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base64Len := len(";base64") + base64.StdEncoding.EncodedLen(len(dataURI))
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asciiLen := len(dataURI)
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for _, c := range dataURI {
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if 'A' <= c && c <= 'Z' || 'a' <= c && c <= 'z' || '0' <= c && c <= '9' || c == '-' || c == '_' || c == '.' || c == '~' || c == ' ' {
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asciiLen++
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} else {
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asciiLen += 2
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}
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if asciiLen > base64Len {
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break
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}
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}
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if asciiLen > base64Len {
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encoded := make([]byte, base64Len-len(";base64"))
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base64.StdEncoding.Encode(encoded, dataURI)
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dataURI = encoded
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mediatype = append(mediatype, []byte(";base64")...)
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} else {
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dataURI = []byte(url.QueryEscape(string(dataURI)))
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dataURI = bytes.Replace(dataURI, []byte("\""), []byte("\\\""), -1)
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}
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if len("text/plain") <= len(mediatype) && parse.EqualFold(mediatype[:len("text/plain")], []byte("text/plain")) {
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mediatype = mediatype[len("text/plain"):]
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}
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for i := 0; i+len(";charset=us-ascii") <= len(mediatype); i++ {
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// must start with semicolon and be followed by end of mediatype or semicolon
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if mediatype[i] == ';' && parse.EqualFold(mediatype[i+1:i+len(";charset=us-ascii")], []byte("charset=us-ascii")) && (i+len(";charset=us-ascii") >= len(mediatype) || mediatype[i+len(";charset=us-ascii")] == ';') {
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mediatype = append(mediatype[:i], mediatype[i+len(";charset=us-ascii"):]...)
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break
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}
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}
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dataURI = append(append(append([]byte("data:"), mediatype...), ','), dataURI...)
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}
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return dataURI
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}
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const MaxInt = int(^uint(0) >> 1)
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const MinInt = -MaxInt - 1
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// Number minifies a given byte slice containing a number (see parse.Number) and removes superfluous characters.
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func Number(num []byte, prec int) []byte {
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// omit first + and register mantissa start and end, whether it's negative and the exponent
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neg := false
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start := 0
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dot := -1
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end := len(num)
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origExp := 0
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if 0 < end && (num[0] == '+' || num[0] == '-') {
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if num[0] == '-' {
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neg = true
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}
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start++
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}
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for i, c := range num[start:] {
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if c == '.' {
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dot = start + i
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} else if c == 'e' || c == 'E' {
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end = start + i
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i += start + 1
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if i < len(num) && num[i] == '+' {
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i++
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}
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if tmpOrigExp, n := strconv.ParseInt(num[i:]); n > 0 && tmpOrigExp >= int64(MinInt) && tmpOrigExp <= int64(MaxInt) {
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// range checks for when int is 32 bit
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origExp = int(tmpOrigExp)
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} else {
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return num
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}
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break
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}
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}
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if dot == -1 {
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dot = end
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}
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// trim leading zeros but leave at least one digit
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for start < end-1 && num[start] == '0' {
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start++
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}
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// trim trailing zeros
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i := end - 1
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for ; i > dot; i-- {
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if num[i] != '0' {
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end = i + 1
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break
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}
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}
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if i == dot {
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end = dot
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if start == end {
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num[start] = '0'
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return num[start : start+1]
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}
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} else if start == end-1 && num[start] == '0' {
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return num[start:end]
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}
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// n is the number of significant digits
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// normExp would be the exponent if it were normalised (0.1 <= f < 1)
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n := 0
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normExp := 0
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if dot == start {
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for i = dot + 1; i < end; i++ {
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if num[i] != '0' {
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n = end - i
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normExp = dot - i + 1
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break
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}
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}
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} else if dot == end {
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normExp = end - start
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for i = end - 1; i >= start; i-- {
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if num[i] != '0' {
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n = i + 1 - start
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end = i + 1
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break
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}
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}
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} else {
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n = end - start - 1
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normExp = dot - start
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}
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if origExp < 0 && (normExp < MinInt-origExp || normExp-n < MinInt-origExp) || origExp > 0 && (normExp > MaxInt-origExp || normExp-n > MaxInt-origExp) {
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return num
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}
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normExp += origExp
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// intExp would be the exponent if it were an integer
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intExp := normExp - n
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lenIntExp := 1
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if intExp <= -10 || intExp >= 10 {
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lenIntExp = strconv.LenInt(int64(intExp))
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}
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// there are three cases to consider when printing the number
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// case 1: without decimals and with an exponent (large numbers)
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// case 2: with decimals and without an exponent (around zero)
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// case 3: without decimals and with a negative exponent (small numbers)
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if normExp >= n {
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// case 1
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if dot < end {
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if dot == start {
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start = end - n
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} else {
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// TODO: copy the other part if shorter?
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copy(num[dot:], num[dot+1:end])
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end--
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}
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}
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if normExp >= n+3 {
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num[end] = 'e'
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end++
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for i := end + lenIntExp - 1; i >= end; i-- {
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num[i] = byte(intExp%10) + '0'
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intExp /= 10
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}
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end += lenIntExp
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} else if normExp == n+2 {
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num[end] = '0'
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num[end+1] = '0'
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end += 2
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} else if normExp == n+1 {
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num[end] = '0'
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end++
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}
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} else if normExp >= -lenIntExp-1 {
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// case 2
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zeroes := -normExp
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newDot := 0
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if zeroes > 0 {
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// dot placed at the front and add zeroes
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newDot = end - n - zeroes - 1
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if newDot != dot {
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d := start - newDot
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if d > 0 {
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if dot < end {
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// copy original digits behind the dot backwards
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copy(num[dot+1+d:], num[dot+1:end])
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if dot > start {
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// copy original digits before the dot backwards
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copy(num[start+d+1:], num[start:dot])
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}
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} else if dot > start {
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// copy original digits before the dot backwards
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copy(num[start+d:], num[start:dot])
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}
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newDot = start
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end += d
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} else {
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start += -d
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}
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num[newDot] = '.'
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for i := 0; i < zeroes; i++ {
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num[newDot+1+i] = '0'
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}
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}
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} else {
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// placed in the middle
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if dot == start {
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// TODO: try if placing at the end reduces copying
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// when there are zeroes after the dot
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dot = end - n - 1
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start = dot
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} else if dot >= end {
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// TODO: try if placing at the start reduces copying
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// when input has no dot in it
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dot = end
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end++
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}
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newDot = start + normExp
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if newDot > dot {
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// copy digits forwards
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copy(num[dot:], num[dot+1:newDot+1])
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} else if newDot < dot {
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// copy digits backwards
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copy(num[newDot+1:], num[newDot:dot])
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}
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num[newDot] = '.'
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}
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// apply precision
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dot = newDot
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if prec > -1 && dot+1+prec < end {
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end = dot + 1 + prec
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inc := num[end] >= '5'
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if inc || num[end-1] == '0' {
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for i := end - 1; i > start; i-- {
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if i == dot {
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end--
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} else if inc {
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if num[i] == '9' {
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if i > dot {
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end--
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} else {
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num[i] = '0'
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}
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} else {
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num[i]++
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inc = false
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break
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}
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} else if i > dot && num[i] == '0' {
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end--
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}
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}
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}
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if dot == start && end == start+1 {
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if inc {
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num[start] = '1'
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} else {
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num[start] = '0'
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}
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} else {
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if dot+1 == end {
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end--
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}
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if inc {
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if num[start] == '9' {
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num[start] = '0'
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copy(num[start+1:], num[start:end])
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end++
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num[start] = '1'
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} else {
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num[start]++
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}
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}
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}
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}
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} else {
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// case 3
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if dot < end {
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if dot == start {
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copy(num[start:], num[end-n:end])
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end = start + n
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} else {
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copy(num[dot:], num[dot+1:end])
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end--
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}
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}
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num[end] = 'e'
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num[end+1] = '-'
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end += 2
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intExp = -intExp
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for i := end + lenIntExp - 1; i >= end; i-- {
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num[i] = byte(intExp%10) + '0'
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intExp /= 10
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}
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end += lenIntExp
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}
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if neg {
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start--
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num[start] = '-'
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}
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return num[start:end]
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}
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