| 🛟 Updated. 28d5985 k33g 20h ago | 1 | package syntax |
| 2 | |
| 3 | import "strings" |
| 4 | |
| 5 | // Keys and bare words: telling `image: nginx` from a scalar that merely |
| 6 | // contains a colon, which is most of what makes YAML awkward to scan. |
| 7 | |
| 8 | // takeYAMLKey colours a mapping key and its colon, when the line has one. |
| 9 | // |
| 10 | // The key is recognised only when a colon follows it before any space, which is |
| 11 | // what tells `image: nginx` from a bare scalar such as `nginx:latest` in a list |
| 12 | // entry — the second has no space after its colon and is a value, not a key. |
| 13 | func takeYAMLKey(s *LineScanner) { |
| 14 | end, ok := yamlKeyEnd(s) |
| 15 | if !ok { |
| 16 | return |
| 17 | } |
| 18 | |
| 19 | s.Emit(s.Pos(), end, ClassIdentifier) |
| 20 | s.Advance(end - s.Pos()) |
| 21 | s.Take(1, ClassPunctuation) // the colon |
| 22 | s.SkipSpaces() |
| 23 | } |
| 24 | |
| 25 | // yamlKeyEnd returns where a key ends, and whether the line starts with one. |
| 26 | func yamlKeyEnd(s *LineScanner) (int, bool) { |
| 27 | if quote := s.Peek(0); quote == '"' || quote == '\'' { |
| 28 | return quotedYAMLKeyEnd(s, quote) |
| 29 | } |
| 30 | |
| 31 | for at := s.Pos(); at < s.Len(); at++ { |
| 32 | switch s.line[at] { |
| 33 | case ':': |
| 34 | // A colon ends a key only when a space or the end of the line |
| 35 | // follows it. `http://x` is a value, not a key called `http`. |
| 36 | if at+1 >= s.Len() || s.line[at+1] == ' ' { |
| 37 | return at, at > s.Pos() |
| 38 | } |
| 39 | case '#': |
| 40 | return 0, false |
| 41 | } |
| 42 | } |
| 43 | return 0, false |
| 44 | } |
| 45 | |
| 46 | // quotedYAMLKeyEnd returns where a quoted key ends, and whether it is one. |
| 47 | func quotedYAMLKeyEnd(s *LineScanner, quote rune) (int, bool) { |
| 48 | for at := s.Pos() + 1; at < s.Len(); at++ { |
| 49 | if s.line[at] != quote { |
| 50 | continue |
| 51 | } |
| 52 | if at+1 < s.Len() && s.line[at+1] == ':' { |
| 53 | return at + 1, true |
| 54 | } |
| 55 | return 0, false |
| 56 | } |
| 57 | return 0, false |
| 58 | } |
| 59 | |
| 60 | // takeYAMLWord colours a bare word, which is a constant when YAML names it and |
| 61 | // plain text otherwise. |
| 62 | // |
| 63 | // A colon inside the word is taken with it unless a space follows, which is |
| 64 | // what keeps `nginx:1.27` and `http://example.com/x` one span each rather than |
| 65 | // three. |
| 66 | func takeYAMLWord(s *LineScanner) { |
| 67 | start := s.Pos() |
| 68 | for !s.AtEnd() { |
| 69 | switch { |
| 70 | case isYAMLNameRune(s.Peek(0)): |
| 71 | s.Advance(1) |
| 72 | case s.Peek(0) == ':' && !endsWord(s, 1): |
| 73 | s.Advance(1) |
| 74 | case s.Peek(0) == '/' && !endsWord(s, 1): |
| 75 | s.Advance(1) |
| 76 | default: |
| 77 | s.Emit(start, s.Pos(), yamlWordClass(s, start)) |
| 78 | return |
| 79 | } |
| 80 | } |
| 81 | |
| 82 | s.Emit(start, s.Pos(), yamlWordClass(s, start)) |
| 83 | } |
| 84 | |
| 85 | // yamlWordClass says whether the word running from start to the scanner's |
| 86 | // position is one the language names. |
| 87 | func yamlWordClass(s *LineScanner, start int) Class { |
| 88 | if yamlConstants[strings.ToLower(string(s.line[start:s.Pos()]))] { |
| 89 | return ClassConstant |
| 90 | } |
| 91 | return ClassIdentifier |
| 92 | } |
| 93 | |
| 94 | // endsWord reports whether the rune at an offset is a space or the end of the |
| 95 | // line — which is what tells a separator from a character inside a scalar. |
| 96 | func endsWord(s *LineScanner, offset int) bool { |
| 97 | r := s.Peek(offset) |
| 98 | return r == 0 || r == ' ' || r == '\t' |
| 99 | } |
| 100 | |
| 101 | // yamlConstants are the words YAML 1.1 reads as booleans and nulls. The |
| 102 | // spelling is generous on purpose: `yes` and `on` are still true to most YAML |
| 103 | // parsers in the wild, and a reader wants to see that they are not plain text. |
| 104 | var yamlConstants = map[string]bool{ |
| 105 | "true": true, "false": true, |
| 106 | "yes": true, "no": true, |
| 107 | "on": true, "off": true, |
| 108 | "null": true, "~": true, |
| 109 | } |