package html import ( "bytes" "io" ) // SmartyPants rendering // SPRenderer is a struct containing state of a Smartypants renderer. type SPRenderer struct { inSingleQuote bool inDoubleQuote bool callbacks [256]smartCallback } func wordBoundary(c byte) bool { return c == 0 || isSpace(c) || isPunctuation(c) } func tolower(c byte) byte { if c >= 'A' && c <= 'Z' { return c - 'A' + 'a' } return c } func isdigit(c byte) bool { return c >= '0' && c <= '9' } func smartQuoteHelper(out *bytes.Buffer, previousChar byte, nextChar byte, quote byte, isOpen *bool, addNBSP bool) bool { // edge of the buffer is likely to be a tag that we don't get to see, // so we treat it like text sometimes // enumerate all sixteen possibilities for (previousChar, nextChar) // each can be one of {0, space, punct, other} switch { case previousChar == 0 && nextChar == 0: // context is not any help here, so toggle *isOpen = !*isOpen case isSpace(previousChar) && nextChar == 0: // [ "] might be [ "foo...] *isOpen = true case isPunctuation(previousChar) && nextChar == 0: // [!"] hmm... could be [Run!"] or [("...] *isOpen = false case /* isnormal(previousChar) && */ nextChar == 0: // [a"] is probably a close *isOpen = false case previousChar == 0 && isSpace(nextChar): // [" ] might be [...foo" ] *isOpen = false case isSpace(previousChar) && isSpace(nextChar): // [ " ] context is not any help here, so toggle *isOpen = !*isOpen case isPunctuation(previousChar) && isSpace(nextChar): // [!" ] is probably a close *isOpen = false case /* isnormal(previousChar) && */ isSpace(nextChar): // [a" ] this is one of the easy cases *isOpen = false case previousChar == 0 && isPunctuation(nextChar): // ["!] hmm... could be ["$1.95] or ["!...] *isOpen = false case isSpace(previousChar) && isPunctuation(nextChar): // [ "!] looks more like [ "$1.95] *isOpen = true case isPunctuation(previousChar) && isPunctuation(nextChar): // [!"!] context is not any help here, so toggle *isOpen = !*isOpen case /* isnormal(previousChar) && */ isPunctuation(nextChar): // [a"!] is probably a close *isOpen = false case previousChar == 0 /* && isnormal(nextChar) */ : // ["a] is probably an open *isOpen = true case isSpace(previousChar) /* && isnormal(nextChar) */ : // [ "a] this is one of the easy cases *isOpen = true case isPunctuation(previousChar) /* && isnormal(nextChar) */ : // [!"a] is probably an open *isOpen = true default: // [a'b] maybe a contraction? *isOpen = false } // Note that with the limited lookahead, this non-breaking // space will also be appended to single double quotes. if addNBSP && !*isOpen { out.WriteString(" ") } out.WriteByte('&') if *isOpen { out.WriteByte('l') } else { out.WriteByte('r') } out.WriteByte(quote) out.WriteString("quo;") if addNBSP && *isOpen { out.WriteString(" ") } return true } func (r *SPRenderer) smartSingleQuote(out *bytes.Buffer, previousChar byte, text []byte) int { if len(text) >= 2 { t1 := tolower(text[1]) if t1 == '\'' { nextChar := byte(0) if len(text) >= 3 { nextChar = text[2] } if smartQuoteHelper(out, previousChar, nextChar, 'd', &r.inDoubleQuote, false) { return 1 } } if (t1 == 's' || t1 == 't' || t1 == 'm' || t1 == 'd') && (len(text) < 3 || wordBoundary(text[2])) { out.WriteString("’") return 0 } if len(text) >= 3 { t2 := tolower(text[2]) if ((t1 == 'r' && t2 == 'e') || (t1 == 'l' && t2 == 'l') || (t1 == 'v' && t2 == 'e')) && (len(text) < 4 || wordBoundary(text[3])) { out.WriteString("’") return 0 } } } nextChar := byte(0) if len(text) > 1 { nextChar = text[1] } if smartQuoteHelper(out, previousChar, nextChar, 's', &r.inSingleQuote, false) { return 0 } out.WriteByte(text[0]) return 0 } func (r *SPRenderer) smartParens(out *bytes.Buffer, previousChar byte, text []byte) int { if len(text) >= 3 { t1 := tolower(text[1]) t2 := tolower(text[2]) if t1 == 'c' && t2 == ')' { out.WriteString("©") return 2 } if t1 == 'r' && t2 == ')' { out.WriteString("®") return 2 } if len(text) >= 4 && t1 == 't' && t2 == 'm' && text[3] == ')' { out.WriteString("™") return 3 } } out.WriteByte(text[0]) return 0 } func (r *SPRenderer) smartDash(out *bytes.Buffer, previousChar byte, text []byte) int { if len(text) >= 2 { if text[1] == '-' { out.WriteString("—") return 1 } if wordBoundary(previousChar) && wordBoundary(text[1]) { out.WriteString("–") return 0 } } out.WriteByte(text[0]) return 0 } func (r *SPRenderer) smartDashLatex(out *bytes.Buffer, previousChar byte, text []byte) int { if len(text) >= 3 && text[1] == '-' && text[2] == '-' { out.WriteString("—") return 2 } if len(text) >= 2 && text[1] == '-' { out.WriteString("–") return 1 } out.WriteByte(text[0]) return 0 } func (r *SPRenderer) smartAmpVariant(out *bytes.Buffer, previousChar byte, text []byte, quote byte, addNBSP bool) int { if bytes.HasPrefix(text, []byte(""")) { nextChar := byte(0) if len(text) >= 7 { nextChar = text[6] } if smartQuoteHelper(out, previousChar, nextChar, quote, &r.inDoubleQuote, addNBSP) { return 5 } } if bytes.HasPrefix(text, []byte("�")) { return 3 } out.WriteByte('&') return 0 } func (r *SPRenderer) smartAmp(angledQuotes, addNBSP bool) func(*bytes.Buffer, byte, []byte) int { var quote byte = 'd' if angledQuotes { quote = 'a' } return func(out *bytes.Buffer, previousChar byte, text []byte) int { return r.smartAmpVariant(out, previousChar, text, quote, addNBSP) } } func (r *SPRenderer) smartPeriod(out *bytes.Buffer, previousChar byte, text []byte) int { if len(text) >= 3 && text[1] == '.' && text[2] == '.' { out.WriteString("…") return 2 } if len(text) >= 5 && text[1] == ' ' && text[2] == '.' && text[3] == ' ' && text[4] == '.' { out.WriteString("…") return 4 } out.WriteByte(text[0]) return 0 } func (r *SPRenderer) smartBacktick(out *bytes.Buffer, previousChar byte, text []byte) int { if len(text) >= 2 && text[1] == '`' { nextChar := byte(0) if len(text) >= 3 { nextChar = text[2] } if smartQuoteHelper(out, previousChar, nextChar, 'd', &r.inDoubleQuote, false) { return 1 } } out.WriteByte(text[0]) return 0 } func (r *SPRenderer) smartNumberGeneric(out *bytes.Buffer, previousChar byte, text []byte) int { if wordBoundary(previousChar) && previousChar != '/' && len(text) >= 3 { // is it of the form digits/digits(word boundary)?, i.e., \d+/\d+\b // note: check for regular slash (/) or fraction slash (⁄, 0x2044, or 0xe2 81 84 in utf-8) // and avoid changing dates like 1/23/2005 into fractions. numEnd := 0 for len(text) > numEnd && isdigit(text[numEnd]) { numEnd++ } if numEnd == 0 { out.WriteByte(text[0]) return 0 } denStart := numEnd + 1 if len(text) > numEnd+3 && text[numEnd] == 0xe2 && text[numEnd+1] == 0x81 && text[numEnd+2] == 0x84 { denStart = numEnd + 3 } else if len(text) < numEnd+2 || text[numEnd] != '/' { out.WriteByte(text[0]) return 0 } denEnd := denStart for len(text) > denEnd && isdigit(text[denEnd]) { denEnd++ } if denEnd == denStart { out.WriteByte(text[0]) return 0 } if len(text) == denEnd || wordBoundary(text[denEnd]) && text[denEnd] != '/' { out.WriteString("") out.Write(text[:numEnd]) out.WriteString("") out.Write(text[denStart:denEnd]) out.WriteString("") return denEnd - 1 } } out.WriteByte(text[0]) return 0 } func (r *SPRenderer) smartNumber(out *bytes.Buffer, previousChar byte, text []byte) int { if wordBoundary(previousChar) && previousChar != '/' && len(text) >= 3 { if text[0] == '1' && text[1] == '/' && text[2] == '2' { if len(text) < 4 || wordBoundary(text[3]) && text[3] != '/' { out.WriteString("½") return 2 } } if text[0] == '1' && text[1] == '/' && text[2] == '4' { if len(text) < 4 || wordBoundary(text[3]) && text[3] != '/' || (len(text) >= 5 && tolower(text[3]) == 't' && tolower(text[4]) == 'h') { out.WriteString("¼") return 2 } } if text[0] == '3' && text[1] == '/' && text[2] == '4' { if len(text) < 4 || wordBoundary(text[3]) && text[3] != '/' || (len(text) >= 6 && tolower(text[3]) == 't' && tolower(text[4]) == 'h' && tolower(text[5]) == 's') { out.WriteString("¾") return 2 } } } out.WriteByte(text[0]) return 0 } func (r *SPRenderer) smartDoubleQuoteVariant(out *bytes.Buffer, previousChar byte, text []byte, quote byte) int { nextChar := byte(0) if len(text) > 1 { nextChar = text[1] } if !smartQuoteHelper(out, previousChar, nextChar, quote, &r.inDoubleQuote, false) { out.WriteString(""") } return 0 } func (r *SPRenderer) smartDoubleQuote(out *bytes.Buffer, previousChar byte, text []byte) int { return r.smartDoubleQuoteVariant(out, previousChar, text, 'd') } func (r *SPRenderer) smartAngledDoubleQuote(out *bytes.Buffer, previousChar byte, text []byte) int { return r.smartDoubleQuoteVariant(out, previousChar, text, 'a') } func (r *SPRenderer) smartLeftAngle(out *bytes.Buffer, previousChar byte, text []byte) int { i := 0 for i < len(text) && text[i] != '>' { i++ } out.Write(text[:i+1]) return i } type smartCallback func(out *bytes.Buffer, previousChar byte, text []byte) int // NewSmartypantsRenderer constructs a Smartypants renderer object. func NewSmartypantsRenderer(flags Flags) *SPRenderer { var ( r SPRenderer smartAmpAngled = r.smartAmp(true, false) smartAmpAngledNBSP = r.smartAmp(true, true) smartAmpRegular = r.smartAmp(false, false) smartAmpRegularNBSP = r.smartAmp(false, true) addNBSP = flags&SmartypantsQuotesNBSP != 0 ) if flags&SmartypantsAngledQuotes == 0 { r.callbacks['"'] = r.smartDoubleQuote if !addNBSP { r.callbacks['&'] = smartAmpRegular } else { r.callbacks['&'] = smartAmpRegularNBSP } } else { r.callbacks['"'] = r.smartAngledDoubleQuote if !addNBSP { r.callbacks['&'] = smartAmpAngled } else { r.callbacks['&'] = smartAmpAngledNBSP } } r.callbacks['\''] = r.smartSingleQuote r.callbacks['('] = r.smartParens if flags&SmartypantsDashes != 0 { if flags&SmartypantsLatexDashes == 0 { r.callbacks['-'] = r.smartDash } else { r.callbacks['-'] = r.smartDashLatex } } r.callbacks['.'] = r.smartPeriod if flags&SmartypantsFractions == 0 { r.callbacks['1'] = r.smartNumber r.callbacks['3'] = r.smartNumber } else { for ch := '1'; ch <= '9'; ch++ { r.callbacks[ch] = r.smartNumberGeneric } } r.callbacks['<'] = r.smartLeftAngle r.callbacks['`'] = r.smartBacktick return &r } // Process is the entry point of the Smartypants renderer. func (r *SPRenderer) Process(w io.Writer, text []byte) { mark := 0 for i := 0; i < len(text); i++ { if action := r.callbacks[text[i]]; action != nil { if i > mark { w.Write(text[mark:i]) } previousChar := byte(0) if i > 0 { previousChar = text[i-1] } var tmp bytes.Buffer i += action(&tmp, previousChar, text[i:]) w.Write(tmp.Bytes()) mark = i + 1 } } if mark < len(text) { w.Write(text[mark:]) } }