494 lines
12 KiB
Go
494 lines
12 KiB
Go
package minify
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import (
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"encoding/base64"
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"github.com/tdewolff/parse/v2"
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"github.com/tdewolff/parse/v2/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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// Mediatype minifies a given mediatype by removing all whitespace.
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func Mediatype(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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origData := parse.Copy(dataURI)
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mediatype, data, err := parse.DataURI(dataURI)
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if err != nil {
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return dataURI
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}
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data, _ = m.Bytes(string(mediatype), data)
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base64Len := len(";base64") + base64.StdEncoding.EncodedLen(len(data))
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asciiLen := len(data)
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for _, c := range data {
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if parse.URLEncodingTable[c] {
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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 len(origData) < base64Len && len(origData) < asciiLen {
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return origData
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}
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if base64Len < asciiLen {
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encoded := make([]byte, base64Len-len(";base64"))
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base64.StdEncoding.Encode(encoded, data)
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data = encoded
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mediatype = append(mediatype, []byte(";base64")...)
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} else {
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data = parse.EncodeURL(data, parse.URLEncodingTable)
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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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return append(append(append([]byte("data:"), mediatype...), ','), data...)
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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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// Decimal minifies a given byte slice containing a number (see parse.Number) and removes superfluous characters.
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// 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.
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func Decimal(num []byte, prec int) []byte {
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if len(num) <= 1 {
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return num
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}
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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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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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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 ; dot < i; 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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// apply precision
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if 0 < prec && dot <= start+prec {
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precEnd := start + prec + 1 // include dot
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if dot == start { // for numbers like .012
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digit := start + 1
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for digit < end && num[digit] == '0' {
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digit++
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}
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precEnd = digit + prec
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}
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if precEnd < end {
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end = precEnd
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// process either an increase from a lesser significant decimal (>= 5)
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// or remove trailing zeros after the dot, or both
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i := end - 1
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inc := '5' <= num[end]
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for ; start < i; i-- {
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if i == dot {
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// no-op
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} else if inc && num[i] != '9' {
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num[i]++
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inc = false
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break
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} else if inc && i < dot { // end inc for integer
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num[i] = '0'
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} else if !inc && (i < dot || num[i] != '0') {
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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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} else {
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end = i + 1
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}
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if inc {
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if dot == start && end == start+1 {
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num[start] = '1'
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} else if num[start] == '9' {
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num[start] = '1'
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num[start+1] = '0'
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end++
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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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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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// 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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if len(num) <= 1 {
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return num
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}
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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 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:]); 0 < n && int64(MinInt) <= tmpOrigExp && 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 ; dot < i; 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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// apply precision
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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
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precEnd := start + prec
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if dot == start { // for numbers like .012
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digit := start + 1
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for digit < end && num[digit] == '0' {
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digit++
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}
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precEnd = digit + prec
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} else if dot < precEnd { // for numbers where precision will include the dot
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precEnd++
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}
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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
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end = precEnd
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inc := '5' <= num[end]
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if dot == end {
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inc = end+1 < len(num) && '5' <= num[end+1]
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}
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if precEnd < dot {
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origExp += dot - precEnd
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dot = precEnd
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}
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// process either an increase from a lesser significant decimal (>= 5)
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// and remove trailing zeros
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i := end - 1
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for ; start < i; i-- {
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if i == dot {
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// no-op
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} else if inc && num[i] != '9' {
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num[i]++
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inc = false
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break
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} else if !inc && num[i] != '0' {
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break
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}
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}
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end = i + 1
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if end < dot {
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origExp += dot - end
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dot = end
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}
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if inc { // single digit left
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if dot == start {
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num[start] = '1'
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dot = start + 1
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} else if num[start] == '9' {
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num[start] = '1'
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origExp++
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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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// 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; start <= i; 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) || 0 < origExp && (MaxInt-origExp < normExp || MaxInt-origExp < normExp-n) {
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return num // exponent overflow
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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 := strconv.LenInt(int64(intExp))
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lenNormExp := strconv.LenInt(int64(normExp))
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// there are three cases to consider when printing the number
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// case 1: without decimals and with a positive exponent (large numbers: 5e4)
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// case 2: with decimals and with a negative exponent (small numbers with many digits: .123456e-4)
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// case 3: with decimals and without an exponent (around zero: 5.6)
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// case 4: without decimals and with a negative exponent (small numbers: 123456e-9)
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if n <= normExp {
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// case 1: print number with positive exponent
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if dot < end {
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// remove dot, either from the front or copy the smallest part
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if dot == start {
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start = end - n
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} else if dot-start < end-dot-1 {
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copy(num[start+1:], num[start:dot])
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start++
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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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if n+3 <= normExp {
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num[end] = 'e'
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end++
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for i := end + lenIntExp - 1; end <= i; 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 n+2 == normExp {
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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 n+1 == normExp {
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num[end] = '0'
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end++
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}
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} else if normExp < -3 && lenNormExp < lenIntExp {
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// case 2: print normalized number (0.1 <= f < 1)
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zeroes := -normExp + origExp
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if 0 < zeroes {
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copy(num[start+1:], num[start+1+zeroes:end])
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end -= zeroes
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} else if zeroes < 0 {
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copy(num[start+1:], num[start:dot])
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num[start] = '.'
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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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for i := end + lenNormExp - 1; end <= i; i-- {
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num[i] = -byte(normExp%10) + '0'
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normExp /= 10
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}
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end += lenNormExp
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} else if -lenIntExp-1 <= normExp {
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// case 3: print number without exponent
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zeroes := -normExp
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if 0 < zeroes {
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// dot placed at the front and negative exponent, adding 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 0 < d {
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if dot < end {
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// copy original digits after the dot towards the end
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copy(num[dot+1+d:], num[dot+1:end])
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if start < dot {
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// copy original digits before the dot towards the end
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copy(num[start+d+1:], num[start:dot])
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}
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} else if start < dot {
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// copy original digits before the dot towards the end
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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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// dot placed in the middle of the number
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if dot == start {
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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 end <= dot {
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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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// move digits between dot and newDot towards the end
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if dot < newDot {
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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(num[newDot+1:], num[newDot:dot])
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}
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num[newDot] = '.'
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}
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} else {
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// case 4: print number with negative exponent
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// find new end, considering moving numbers to the front, removing the dot and increasing the length of the exponent
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newEnd := end
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if dot == start {
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newEnd = start + n
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} else {
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newEnd--
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}
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newEnd += 2 + lenIntExp
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exp := intExp
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lenExp := lenIntExp
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if newEnd < len(num) {
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// it saves space to convert the decimal to an integer and decrease the exponent
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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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} else {
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// it does not save space and will panic, so we revert to the original representation
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exp = origExp
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lenExp = 1
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if origExp <= -10 || 10 <= origExp {
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lenExp = strconv.LenInt(int64(origExp))
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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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for i := end + lenExp - 1; end <= i; i-- {
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num[i] = -byte(exp%10) + '0'
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exp /= 10
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}
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end += lenExp
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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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