= Exercise 5.7 // Refs: :url-base: https://github.com/fenegroni/TGPL-exercise-solutions :workflow: workflows/Exercise 5.7 :action: actions/workflows/ch5ex7.yml :url-workflow: {url-base}/{workflow} :url-action: {url-base}/{action} :badge-exercise: image:{url-workflow}/badge.svg?branch=main[link={url-action}]

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Develop startElement and endElement into a general HTML pretty-printer. Print comment nodes, text nodes, and attributes of each element (<a href='...'>). Use short forms like <img/> instead of <img></img> when an element has no children. Write a test to ensure the output can be parsed successfully. (See Chapter 11.)

== Test

We test the implementation of PrettyPrint, which reads from input, writes to output, and performs the task in our exercise.

The implementation is a little flaky:

. it uses global variables to keep track of state.

. startElement prints the start tag of an HTML element by relying on being called the first time an element is encountered, before all child elements are visited.

. endElement prints the end tag of the element by relying on being called after all child nodes are visited.

. indenting the output requires a global depth, incremented by startElement and decremented by endElement.

=== The image element

The image element uses the tag <img> without an end tag and without the / character at the end.

We handle that case which corrects the exercise requirement.

=== Parsing the output

The html.Parse function does not seem to return an error when the html is malformed.

We use the outline function from the book to build an outline of the document and ensure that the output is correctly parsed.