A naive YAML lexer.

Does not try to be smart in anyway. Instead, just highlights what it
can. Used this reference: https://learnxinyminutes.com/docs/yaml/

Fixes #13.

lexers/yaml.go

@@ -0,0 +1,75 @@
+package lexers
+
+import (
+	. "github.com/alecthomas/chroma" // nolint
+)
+
+// Prism.languages.yaml = {
+// 	'scalar': {
+// 		pattern: /([\-:]\s*(![^\s]+)?[ \t]*[|>])[ \t]*(?:((?:\r?\n|\r)[ \t]+)[^\r\n]+(?:\3[^\r\n]+)*)/,
+// 		lookbehind: true,
+// 		alias: 'string'
+// 	},
+// 	'comment': /#.*/,
+// 	'key': {
+// 		pattern: /(\s*(?:^|[:\-,[{\r\n?])[ \t]*(![^\s]+)?[ \t]*)[^\r\n{[\]},#\s]+?(?=\s*:\s)/,
+// 		lookbehind: true,
+// 		alias: 'atrule'
+// 	},
+// 	'directive': {
+// 		pattern: /(^[ \t]*)%.+/m,
+// 		lookbehind: true,
+// 		alias: 'important'
+// 	},
+// 	'datetime': {
+// 		pattern: /([:\-,[{]\s*(![^\s]+)?[ \t]*)(\d{4}-\d\d?-\d\d?([tT]|[ \t]+)\d\d?:\d{2}:\d{2}(\.\d*)?[ \t]*(Z|[-+]\d\d?(:\d{2})?)?|\d{4}-\d{2}-\d{2}|\d\d?:\d{2}(:\d{2}(\.\d*)?)?)(?=[ \t]*($|,|]|}))/m,
+// 		lookbehind: true,
+// 		alias: 'number'
+// 	},
+// 	'boolean': {
+// 		pattern: /([:\-,[{]\s*(![^\s]+)?[ \t]*)(true|false)[ \t]*(?=$|,|]|})/im,
+// 		lookbehind: true,
+// 		alias: 'important'
+// 	},
+// 	'null': {
+// 		pattern: /([:\-,[{]\s*(![^\s]+)?[ \t]*)(null|~)[ \t]*(?=$|,|]|})/im,
+// 		lookbehind: true,
+// 		alias: 'important'
+// 	},
+// 	'string': {
+// 		pattern: /([:\-,[{]\s*(![^\s]+)?[ \t]*)("(?:[^"\\]|\\.)*"|'(?:[^'\\]|\\.)*')(?=[ \t]*($|,|]|}))/m,
+// 		lookbehind: true,
+// 		greedy: true
+// 	},
+// 	'number': {
+// 		pattern: /([:\-,[{]\s*(![^\s]+)?[ \t]*)[+\-]?(0x[\da-f]+|0o[0-7]+|(\d+\.?\d*|\.?\d+)(e[\+\-]?\d+)?|\.inf|\.nan)[ \t]*(?=$|,|]|})/im,
+// 		lookbehind: true
+// 	},
+// 	'tag': /![^\s]+/,
+// 	'important': /[&*][\w]+/,
+// 	'punctuation': /---|[:[\]{}\-,|>?]|\.\.\./
+
+var YAML = Register(MustNewLexer(
+	&Config{
+		Name:      "YAML",
+		Aliases:   []string{"yaml"},
+		Filenames: []string{"*.yaml", "*.yml"},
+		MimeTypes: []string{"text/x-yaml"},
+	},
+	Rules{
+		"root": {
+			{`\s+`, Whitespace, nil},
+			{`#.*`, Comment, nil},
+			{`!![^\s]+`, CommentPreproc, nil},
+			{`&[^\s]+`, CommentPreproc, nil},
+			{`\*[^\s]+`, CommentPreproc, nil},
+			{Words(``, `\b`, "true", "false", "null"), KeywordConstant, nil},
+			{`"(?:\\.|[^"])+"`, StringDouble, nil},
+			{`\d\d\d\d-\d\d-\d\d([T ]\d\d:\d\d:\d\d(\.\d+)?(Z|\s+[-+]\d+)?)?`, LiteralDate, nil},
+			{`([>|])(\s+)((?:(?:.*?$)(?:[\n\r]*?\2)?)*)`, ByGroups(StringDoc, StringDoc, StringDoc), nil},
+			{`[+\-]?(0x[\da-f]+|0o[0-7]+|(\d+\.?\d*|\.?\d+)(e[\+\-]?\d+)?|\.inf|\.nan)\b`, Number, nil},
+			{`[?:,\[\]]`, Punctuation, nil},
+			{`.`, Text, nil},
+		},
+	},
+))

styles/swapoff.go

@@ -20,4 +20,5 @@ var SwapOff = Register(chroma.MustNewStyle("swapoff", map[chroma.TokenType]strin
 	chroma.NameAttribute:     "#ansiteal",
 	chroma.NameVariable:      "bold",
 	chroma.Error:             "#ansired",
+	chroma.LiteralDate:       "bold #ansiyellow",
 }))