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diff --git a/docs/Component docs/HTML Parser updates.md b/docs/Component docs/HTML Parser updates.md new file mode 100644 index 000000000..7a2c76e94 --- /dev/null +++ b/docs/Component docs/HTML Parser updates.md @@ -0,0 +1,63 @@ +# Updating HTML5 parser code + +Our html5 parser is based on the java html5 parser from [Validator.nu](http://about.validator.nu/htmlparser/) by Henri Sivonen. It has been adopted by Mozilla and further updated, and has been imported as a whole into the UXP tree to have an independent and maintainable source of it that doesn't rely on external sources. + +## Stages +Updating the parser code consists of 3 stages: +- Making updates to the html parser source in java +- Let the java parser regenerate part of its own code after the change +- Translate the java source to C++ + +This process was best explained in the [following Bugzilla comment](https://bugzilla.mozilla.org/show_bug.cgi?id=1378079#c6), which explain how to add a new attribute name to html5, inserted in this document for convenience: + +>> Is +>> there any documentation on how to add a new nsHtml5AttributeName? +> +> I don't recall. I should get around to writing it. +> +>> Looks like +>> I need to clone hg.mozilla.org/projects/htmlparser/ and generate a hash with +>> it? +> +> Yes. Here's how: +> +> `cd parser/html/java/` +> `make sync` +> +> Now you have a clone of [https://hg.mozilla.org/projects/htmlparser/](https://hg.mozilla.org/projects/htmlparser/) in > parser/html/java/htmlparser/ +> +> `cd htmlparser/src/` +> `$EDITOR nu/validator/htmlparser/impl/AttributeName.java` +> +> Search for the word "uncomment" and uncomment stuff according to the two comments that talk about uncommenting +> Duplicate the declaration a normal attribute (nothings special in SVG mode, etc.). Let's use "alt", since it's the first one. +> In the duplicate, replace ALT with IS and "alt" with "is". +> Search for "ALT,", duplicate that line and change the duplicate to say "IS," +> Save. +> +> `javac nu/validator/htmlparser/impl/AttributeName.java` +> `java nu.validator.htmlparser.impl.AttributeName` +> +> Copy and paste the output into nu/validator/htmlparser/impl/AttributeName.java replacing the text below the comment "START GENERATED CODE" and above the very last "}". +> Recomment the bits that you uncommented earlier. +> Save. +> +> `cd ../..` - Back to parser/html/java/ +> `make translate` + +## Organizing commits + +**The html5 parser code is fragile due to its generation and translation before being used as C++ in our tree. Do not touch or commit anything without a code peer nearby with knowledge of the parser and the commit process (at this moment that means Gaming4JC (@g4jc)), and communicate the changes thoroughly.** + +To organize this properly in our repo, commits should be split up when making these kinds of changes: +1. Commit your code edits to the html parser +2. Regenerate java into a translation-ready source +3. Commit +4. Translate and regenerate C++ code +5. Check a build to make sure the changes have the intended result +6. Commit + +This is needed because the source edit will sometimes be in parts that are self-generated and may otherwise be lost in generation noise, and because we want to keep a strict separation between commits resulting from developer work and those resulting from running scripts/automated processes. + + + |