67 lines
1.9 KiB
Python
67 lines
1.9 KiB
Python
"""Page fingerprints, scienting-page/1, and download-stamp rules, scienting-stamps/1.
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Non-normative; see spec/07-geometry.md.
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"""
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import math
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import re
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import unicodedata
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from . import jcs
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from .notation import fold_plain_text
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from .text import is_ws, norm, sha256_hex
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def round_point(x):
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"""Round half up to a whole point."""
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return int(math.floor(x + 0.5))
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def _in_margin(box, size, margin):
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x0, y0, x1, y1 = box
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w, h = size
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return x1 <= margin or x0 >= w - margin or y1 <= margin or y0 >= h - margin
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def is_stamp(line, size, rules):
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text = norm(line["text"])
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for r in rules:
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if r.get("where", "any") == "margin":
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if "box" not in line or not _in_margin(line["box"], size, r.get("margin", 36)):
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continue
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if re.search(r["pattern"], text, re.IGNORECASE | re.ASCII):
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return r["id"]
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return None
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def _strip(s):
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return "".join(c for c in s if not is_ws(c) and unicodedata.category(c) not in ("Cc", "Cf"))
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def fp_text(text):
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"""Steps 3 and 4 of spec/07 §7.1: whitespace and control characters go first, so that "10 -20" and "10-20"
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fold alike; then scripts and dashes fold as in the strict projection, then NFKC."""
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return _strip(unicodedata.normalize("NFKC", fold_plain_text(_strip(text))))
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def fingerprint(page, rules):
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"""`page`: {"size": [w, h], "lines": [{"text", "box"?}], "images": [sha256...]}.
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Returns (fingerprint, removed stamp rule IDs in line order).
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"""
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size = page["size"]
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kept, removed = [], []
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for line in page.get("lines", []):
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rid = is_stamp(line, size, rules)
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if rid:
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removed.append(rid)
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else:
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kept.append(line["text"])
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payload = {
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"format": "scienting-page/1",
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"size": [round_point(size[0]), round_point(size[1])],
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"text": fp_text(" ".join(kept)),
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"images": sorted(page.get("images", [])),
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}
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return sha256_hex(jcs.dumpb(payload)), removed
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