| 🛟 Updated. 28d5985 k33g 14h ago | 1 | package syntax |
| 2 | |
| 3 | // highlightXML colours an XML document, one slice of spans per line. |
| 4 | // |
| 5 | // XML gets its own scanner rather than borrowing HTML's, for one reason that |
| 6 | // matters and two that follow from it. The one that matters is CDATA: the whole |
| 7 | // point of `<![CDATA[ … ]]>` is that its contents are *not* markup, and HTML's |
| 8 | // scanner would colour the tags inside one as tags — which is exactly backwards |
| 9 | // in the files most likely to contain any. The other two are the `<?xml ?>` |
| 10 | // declaration and namespaced names, neither of which HTML has. |
| 11 | func highlightXML(src string) [][]Span { |
| 12 | return ScanLines(src, scanXMLLine) |
| 13 | } |
| 14 | |
| 15 | // xmlCarry is what a line can leave open. Two things can: a comment and a CDATA |
| 16 | // section, and they close on different delimiters. |
| 17 | type xmlCarry uint8 |
| 18 | |
| 19 | const ( |
| 20 | xmlGround xmlCarry = iota |
| 21 | xmlInComment |
| 22 | xmlInCDATA |
| 23 | ) |
| 24 | |
| 25 | // closer returns the text that ends whatever is open. |
| 26 | func (c xmlCarry) closer() string { |
| 27 | if c == xmlInCDATA { |
| 28 | return "]]>" |
| 29 | } |
| 30 | return "-->" |
| 31 | } |
| 32 | |
| 33 | // class returns the class the open construct is drawn in. A CDATA section is a |
| 34 | // string because that is what it is: text that happens to sit inside markup. |
| 35 | func (c xmlCarry) class() Class { |
| 36 | if c == xmlInCDATA { |
| 37 | return ClassString |
| 38 | } |
| 39 | return ClassComment |
| 40 | } |
| 41 | |
| 42 | // scanXMLLine returns the spans of one line, and what it leaves open. |
| 43 | func scanXMLLine(line []rune, carry xmlCarry) ([]Span, xmlCarry) { |
| 44 | s := &LineScanner{line: line} |
| 45 | |
| 46 | if carry != xmlGround && !FinishBlockComment(s, carry.closer(), carry.class()) { |
| 47 | return s.spans, carry |
| 48 | } |
| 49 | |
| 50 | for !s.AtEnd() { |
| 51 | if open := stepXML(s); open != xmlGround { |
| 52 | return s.spans, open |
| 53 | } |
| 54 | } |
| 55 | return s.spans, xmlGround |
| 56 | } |
| 57 | |
| 58 | // stepXML colours whatever starts at the current position, and reports anything |
| 59 | // it left open at the end of the line. |
| 60 | func stepXML(s *LineScanner) xmlCarry { |
| 61 | switch { |
| 62 | case s.HasPrefix(0, "<!--"): |
| 63 | if !OpenBlockComment(s, "<!--", "-->", ClassComment) { |
| 64 | return xmlInComment |
| 65 | } |
| 66 | case s.HasPrefix(0, "<![CDATA["): |
| 67 | if !OpenBlockComment(s, "<![CDATA[", "]]>", ClassString) { |
| 68 | return xmlInCDATA |
| 69 | } |
| 70 | case s.HasPrefix(0, "<?"): |
| 71 | takeXMLProcessingInstruction(s) |
| 72 | case s.HasPrefix(0, "<!"): |
| 73 | takeXMLDeclaration(s) |
| 74 | case s.Peek(0) == '<': |
| 75 | takeXMLTag(s) |
| 76 | case s.Peek(0) == '&': |
| 77 | takeXMLEntity(s) |
| 78 | default: |
| 79 | s.Advance(1) |
| 80 | } |
| 81 | return xmlGround |
| 82 | } |
| 83 | |
| 84 | // takeXMLProcessingInstruction colours `<?xml version="1.0"?>` and the |
| 85 | // stylesheet instructions that follow it in real documents. |
| 86 | // |
| 87 | // The target and the `?>` are keyword; what is between them is coloured as |
| 88 | // attributes, because that is what it looks like and what a reader is scanning |
| 89 | // for. |
| 90 | func takeXMLProcessingInstruction(s *LineScanner) { |
| 91 | start := s.Pos() |
| 92 | s.Advance(2) |
| 93 | for !s.AtEnd() && isXMLNameRune(s.Peek(0)) { |
| 94 | s.Advance(1) |
| 95 | } |
| 96 | s.Emit(start, s.Pos(), ClassKeyword) |
| 97 | |
| 98 | takeXMLAttributes(s, "?>") |
| 99 | |
| 100 | if s.HasPrefix(0, "?>") { |
| 101 | s.Take(2, ClassKeyword) |
| 102 | } |
| 103 | } |
| 104 | |
| 105 | // takeXMLDeclaration colours `<!DOCTYPE …>` and the other `<!` forms. |
| 106 | func takeXMLDeclaration(s *LineScanner) { |
| 107 | start := s.Pos() |
| 108 | for !s.AtEnd() && s.Peek(0) != '>' { |
| 109 | s.Advance(1) |
| 110 | } |
| 111 | s.Advance(1) // the closing angle bracket |
| 112 | s.Emit(start, s.Pos(), ClassKeyword) |
| 113 | } |
| 114 | |
| 115 | // takeXMLTag colours an element's opening or closing tag, with its attributes. |
| 116 | // |
| 117 | // The name may be namespaced — `<xsl:template>` — and the colon is part of it: |
| 118 | // splitting the prefix from the local name would be two colours for one name. |
| 119 | func takeXMLTag(s *LineScanner) { |
| 120 | start := s.Pos() |
| 121 | s.Advance(1) |
| 122 | if s.Peek(0) == '/' { |
| 123 | s.Advance(1) |
| 124 | } |
| 125 | for !s.AtEnd() && isXMLNameRune(s.Peek(0)) { |
| 126 | s.Advance(1) |
| 127 | } |
| 128 | s.Emit(start, s.Pos(), ClassTag) |
| 129 | |
| 130 | takeXMLAttributes(s, "/>") |
| 131 | |
| 132 | switch { |
| 133 | case s.HasPrefix(0, "/>"): |
| 134 | s.Take(2, ClassTag) |
| 135 | case s.Peek(0) == '>': |
| 136 | s.Take(1, ClassTag) |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | // takeXMLAttributes colours the name="value" pairs up to a tag's closing |
| 141 | // delimiter, which differs between an element and a processing instruction. |
| 142 | func takeXMLAttributes(s *LineScanner, closing string) { |
| 143 | for !s.AtEnd() { |
| 144 | switch r := s.Peek(0); { |
| 145 | case r == ' ' || r == '\t': |
| 146 | s.SkipSpaces() |
| 147 | case s.HasPrefix(0, closing) || r == '>': |
| 148 | return |
| 149 | case r == '=': |
| 150 | s.Take(1, ClassOperator) |
| 151 | case r == '"' || r == '\'': |
| 152 | TakeQuoted(s, r, ClassString) |
| 153 | case isXMLNameRune(r): |
| 154 | s.TakeWhile(ClassAttribute, isXMLNameRune) |
| 155 | default: |
| 156 | s.Advance(1) |
| 157 | } |
| 158 | } |
| 159 | } |
| 160 | |
| 161 | // takeXMLEntity colours `&` and `©`. |
| 162 | // |
| 163 | // A bare `&` with no semicolon soon after is left alone: it is legal text in |
| 164 | // plenty of documents, and colouring the rest of the line after it would be a |
| 165 | // bigger mistake than missing an entity. |
| 166 | func takeXMLEntity(s *LineScanner) { |
| 167 | for at := 1; at <= maxEntityLength; at++ { |
| 168 | switch s.Peek(at) { |
| 169 | case ';': |
| 170 | s.Take(at+1, ClassConstant) |
| 171 | return |
| 172 | case 0, ' ', '<', '&': |
| 173 | s.Advance(1) |
| 174 | return |
| 175 | } |
| 176 | } |
| 177 | s.Advance(1) |
| 178 | } |
| 179 | |
| 180 | // maxEntityLength is how far past an `&` a semicolon may sit for the two to be |
| 181 | // read as an entity. The longest named entity in common use is well inside it. |
| 182 | const maxEntityLength = 32 |
| 183 | |
| 184 | // isXMLNameRune reports whether a rune can appear in an element or attribute |
| 185 | // name. The colon is included because a namespace prefix is part of the name, |
| 186 | // and the dot and dash because XML allows them. |
| 187 | func isXMLNameRune(r rune) bool { |
| 188 | return IsWordRune(r) || r == ':' || r == '-' || r == '.' |
| 189 | } |