RTF parsing — pure AILANG, no Office required

The Problem

RTF was specified by Microsoft in 1987 and never went away. It's still a default "Save As" option in Word, it's what TextEdit produces on macOS, and it's the lingua franca of legacy government and legal pipelines. Yet most parsing libraries either skip RTF entirely or shell out to a 200 MB LibreOffice install just to read a 50 KB form.

How It Works

The RTF parser is a char-by-char state machine that walks the source via std/string.foldChars. It tracks { } group nesting, recognizes control words and control symbols, and decodes Unicode/CP1252 escapes. The output is the same Block ADT as every other AILANG Parse format — TextBlock per paragraph, no new variants.

# Parse an RTF file from the CLI
./bin/docparse contract.rtf

# Or via API
curl -X POST https://docparse.ailang.sunholo.com/api/v1/parse \
  -F "filepath=@contract.rtf" \
  -F "outputFormat=markdown" \
  -F "apiKey=YOUR_API_KEY"

Encoding Support

RTF uses two parallel escape mechanisms for non-ASCII characters. AILANG Parse decodes both correctly.

The CP1252 decoder includes the full Windows-1252 translation table for the 0x80–0x9F range — euro sign (0x80 → €), smart quotes (0x91–0x94 → ' ' " "), em/en dashes (0x96–0x97 → – —), ellipsis (0x85 → …), trademark (0x99 → ™), and all the other punctuation Microsoft tucked into the C1 control space. Bytes 0xA0–0xFF map directly to Unicode U+00A0–U+00FF.

Skipped Destinations

RTF mixes content with header tables — fonts, colors, stylesheets, list definitions, generator strings, theme data. The parser skips these wholesale so they never pollute extracted text. Nested skip groups (e.g. {\*\panose ...} inside \fonttbl) are tracked correctly: the outer skip context wins, so leaving a nested group doesn't accidentally re-enable text capture.

• \fonttbl, \filetbl, \colortbl, \stylesheet, \listtable, \listoverridetable — definition tables
• \info, \generator, \themedata, \latentstyles, \datastore — document metadata blobs
• \pict, \shppict, \nonshppict — embedded image data (not yet extracted)
• \field, \fldinst, \fldrslt — field codes and hyperlink internals
• \bkmkstart, \bkmkend, \panose, \xmlnstbl — minor structural markers
• Any {\*\foo …} — RTF specifies that starred destinations are "optional" and consumers free to skip; we do

Example Output

Each \par closes a TextBlock. Tab-separated form fields show up as \t-joined text within a single block, which preserves the row layout when re-rendered as Markdown or HTML.

{
  "blocks": [
    {"kind": "TextBlock", "style": "normal", "text": "Sample RTF Document"},
    {"kind": "TextBlock", "style": "normal", "text": "Danish words: Købsaftale, økonomi, smørrebrød, fjærkræ, ål."},
    {"kind": "TextBlock", "style": "normal", "text": "French phrases: café au lait, première classe, naïveté."},
    {"kind": "TextBlock", "style": "normal", "text": "Currency: 50£ pounds sterling, 100€ euro, 250¥ yen, copyright © 1999."},
    {"kind": "TextBlock", "style": "normal", "text": "Smart quotes: “like these” and ‘these’."},
    {"kind": "TextBlock", "style": "normal", "text": "Name:\tJane Doe"},
    {"kind": "TextBlock", "style": "normal", "text": "Email:\tjane@example.com"}
  ]
}

Use Cases

Try It

RTF is one of 16 supported input formats. The parser is pure AILANG — zero model calls, zero subprocess, fully deterministic.

# CLI
./bin/docparse contract.rtf --convert contract.md

# API
curl -X POST https://docparse.ailang.sunholo.com/api/v1/parse \
  -F "filepath=@contract.rtf" \
  -F "outputFormat=markdown" \
  -F "apiKey=YOUR_API_KEY"

Parse in Browser    API Reference