Update kjol website with C documentation

go/lexer/lexer_go.go

@@ -0,0 +1,99 @@
+package lexer
+
+import (
+	"html"
+	"strings"
+)
+
+var goKeywords = map[string]bool{
+	"break": true, "case": true, "chan": true, "const": true, "continue": true,
+	"default": true, "defer": true, "else": true, "fallthrough": true, "for": true,
+	"func": true, "go": true, "goto": true, "if": true, "import": true,
+	"interface": true, "map": true, "package": true, "range": true, "return": true,
+	"select": true, "struct": true, "switch": true, "type": true, "var": true,
+	// Not keywords to the Go spec — predeclared identifiers — but every editor colours
+	// them, and a reader looking for `nil` is looking for the same kind of thing.
+	"nil": true, "true": true, "false": true, "iota": true,
+	"string": true, "int": true, "int64": true, "float64": true, "bool": true,
+	"byte": true, "rune": true, "any": true, "error": true,
+}
+
+// HighlightGo turns Go source into HTML with the tokens wrapped in coloured spans.
+func HighlightGo(src string) string {
+	var b strings.Builder
+	b.Grow(len(src) * 2)
+
+	i := 0
+	for i < len(src) {
+		c := src[i]
+
+		switch {
+		// Line comment — including the //gowasm: directives, which are the most important
+		// line in several of the snippets this was written for.
+		case c == '/' && i+1 < len(src) && src[i+1] == '/':
+			end := strings.IndexByte(src[i:], '\n')
+			if end < 0 {
+				end = len(src)
+			} else {
+				end += i
+			}
+			span(&b, CommentClass, src[i:end])
+			i = end
+
+		// Block comment.
+		case c == '/' && i+1 < len(src) && src[i+1] == '*':
+			end := strings.Index(src[i+2:], "*/")
+			if end < 0 {
+				end = len(src)
+			} else {
+				end = i + 2 + end + 2
+			}
+			span(&b, CommentClass, src[i:end])
+			i = end
+
+		// Interpreted string. Ends at the closing quote or the line's end — an unterminated
+		// string is a typo in a snippet, not a reason to paint the rest of the file green.
+		case c == '"':
+			i = quoted(&b, src, i, '"', true)
+
+		// Raw string: no escapes, and it may span lines.
+		case c == '`':
+			i = quoted(&b, src, i, '`', false)
+
+		// Rune literal.
+		case c == '\'':
+			i = quoted(&b, src, i, '\'', true)
+
+		case isDigit(c):
+			j := i
+			for j < len(src) && (isDigit(src[j]) || isHexish(src[j])) {
+				j++
+			}
+			span(&b, NumberClass, src[i:j])
+			i = j
+
+		case isIdentStart(c):
+			j := i
+			for j < len(src) && isIdentPart(src[j]) {
+				j++
+			}
+			word := src[i:j]
+			switch {
+			case goKeywords[word]:
+				span(&b, KeywordClass, word)
+			case callAhead(src, j):
+				// Colouring the callee is what makes the shape of a snippet readable at a
+				// glance: you see what it DOES before you read what it says.
+				span(&b, FuncClass, word)
+			default:
+				b.WriteString(html.EscapeString(word))
+			}
+			i = j
+
+		default:
+			b.WriteString(html.EscapeString(string(c)))
+			i++
+		}
+	}
+	return b.String()
+}