When finding or extracting text in EPUB/KEPUB DOM trees, inline
formatting elements like <em>, <strong>, <i>, <b>, <span>, etc. should
not break text continuity. A reader sees 'Vokalia and Consonantia' as
one phrase regardless of the <em> wrappers around each word.
Add inline formatting element set and helper functions:
- isInlineFormatting: checks if an element is an inline phrasing element
- collectInlineText: flattens text across formatting elements within
a block-level parent, returning segments that map back to original
text nodes
- findBlockParent: walks up from a text node to find the nearest
block-level ancestor (used to scope text collection)
- findTextAcrossInlineElements: fallback for findTextInNode that
concatenates text within each block element (transparently crossing
formatting elements) and maps match positions back to actual nodes
- collectBlockElements: gathers all block-level elements containing text
The key invariant: text collection NEVER crosses block-level element
boundaries (<p>, <div>, <h1>-<h6>, <li>, etc.) to avoid concatenating
text from different paragraphs.
The findTextInNode function now tries single-text-node matching first
(fast path, unchanged), then falls back to cross-element matching only
when needed. This preserves performance for the common case.
Implements ConvertCREToStandard which converts CREngine XPointers
(e.g. /body/DocFragment[6]/body/div/p[47]/text().2399) to standard
epubcfi format (e.g. epubcfi(/6/12!/4/2[id]/4/1:7)).
Key components:
- indexChildNodes: faithful port of foliate-js's epubcfi.js algorithm
for computing CFI-compatible child node indices including virtual
positions, null positions between adjacent elements, and text chunks
- preprocessXHTML: converts XHTML self-closing tags (e.g. <a id="x"/>)
to open/close pairs so Go's HTML parser produces the same DOM as the
browser's XHTML parser
- buildCFI: walks up from a text node to body, computing CFI indices
at each level using indexChildNodes
- findTextInNode: regex-based whitespace-flexible text search for
context_text fallback positioning
- convertByPercentageOffset: estimates position via book-wide character
counts when no context_text is available
- ConvertCREToStandard: orchestrates text search → percentage fallback
Supports CREngine XPointer format, CREngine fragment ID format
(#_doc_fragment_N_anchor), and includes round-trip test coverage for
1984 and Crime and Punishment EPUBs.
john-okeefe