Editing Pretty-printing (section)

==Pretty-printing markup and tag-based code==
[[File:HTML source code example.svg|thumb|HTML source code, pretty-printed to better show the hierarchical relationships of its elements (called tags)]]
Pretty-printing in markup language instances is most typically associated with [[indentation (typesetting)|indentation]] of tags and string content to visually determine hierarchy and nesting. Although the syntactical structures of tag-based languages do not significantly vary, the indentation may vary significantly due to how a markup language is interpreted or due to the data it describes.

In [[MathML]], [[whitespace character]]s do not reflect data, meaning, or syntax above what is required by [[XML]] syntax. In [[HTML]], whitespace characters between tags are considered text and are parsed as text nodes into the parsed result.<ref>{{cite web |url=https://developer.mozilla.org/en-US/docs/Whitespace_in_the_DOM |title=Whitespace in the DOM |first=L. David |last=Baron |publisher=Mozilla Developer Network |accessdate=27 August 2012}}</ref> While indentation may be generously applied to a MathML document, sufficient additional care must be taken in pretty-printing an HTML document to ensure additional text nodes are not created or destroyed in general proximity to the content or content-reflective tag elements. This difference in complexity is non-trivial from the perspective of an automated pretty-print operation where no special rules or edge cases are necessary, as in the more simple MathML example. The HTML example may require a series of progressive interrelated algorithms to account for various patterns of tag elements and content that conforms to a uniform style and is consistent in application across various instances, as evidenced by the markup.ts<ref>[https://github.com/prettydiff/prettydiff/blob/master/beautify/markup.ts markup.ts]</ref> application component used to beautify HTML, XML, and related technologies for the [[Pretty Diff]] tool.