92 lines
3 KiB
JavaScript
92 lines
3 KiB
JavaScript
// This tokenizer is highly inspired by the one found in rxi's lite.
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// I highly recommend checking it out!
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// https://github.com/rxi/lite/blob/master/data/core/tokenizer.lua
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// There's also a mirror of it in the static generator, to enable highlighting of code blocks which
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// are *not* JavaScript-powered.
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export function compileSyntax(def) {
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for (let pattern of def.patterns) {
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let flags = "dy";
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if (pattern.flags != null) {
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if ("dotMatchesNewline" in pattern.flags) {
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flags += "s";
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}
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}
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pattern.regex = new RegExp(pattern.regex, flags);
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}
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def.keywords = new Map(Object.entries(def.keywords));
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return def;
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}
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function pushToken(tokens, kind, string) {
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let previousToken = tokens[tokens.length - 1];
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if (previousToken != null && previousToken.kind == kind) {
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previousToken.string += string;
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} else {
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tokens.push({ kind, string });
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}
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}
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function tokenize(text, syntax) {
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let tokens = [];
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let i = 0;
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while (i < text.length) {
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let hadMatch = false;
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for (let pattern of syntax.patterns) {
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let match;
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pattern.regex.lastIndex = i;
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if ((match = pattern.regex.exec(text)) != null) {
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if (typeof pattern.is == "object") {
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let lastMatchEnd = i;
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for (let i = 1; i < match.indices.length; ++i) {
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let [start, end] = match.indices[i];
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if (match.indices[i] != null) {
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pushToken(tokens, pattern.is.default, text.substring(lastMatchEnd, start));
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pushToken(tokens, pattern.is.captures[i], text.substring(start, end));
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}
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}
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} else {
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pushToken(tokens, pattern.is, match[0]);
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}
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i = pattern.regex.lastIndex;
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hadMatch = true;
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break;
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}
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}
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// Base case: no pattern matched, just add the current character to the output.
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if (!hadMatch) {
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pushToken(tokens, "default", text.substring(i, i + 1));
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++i;
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}
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}
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for (let token of tokens) {
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let replacement = syntax.keywords.get(token.string);
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if (replacement != null) {
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if (replacement.onlyReplaces == null || token.kind == replacement.onlyReplaces) {
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token.kind = replacement.into;
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}
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}
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}
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return tokens;
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}
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export function highlight(element, syntax, customize = null) {
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let tokens = tokenize(element.textContent, syntax);
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element.textContent = "";
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element.classList.add("th-syntax-highlighting");
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for (let token of tokens) {
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let span = document.createElement("span");
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span.textContent = token.string;
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span.classList.add(token.kind);
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if (customize != null) {
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customize(token, span);
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}
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element.appendChild(span);
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}
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}
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