FA-70718 / GIS polygon topology / Member archive

WKT polygon and multipolygon ring structure: keyword case folding · case 03

Lower-case WKT from some databases is rejected.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input: a WKT string. The keyword (case-insensitive) must be POLYGON or MULTIPOLYGON, else None; "<keyword> EMPTY" returns []. Otherwise parse the parenthesised body into polygons -> rings -> positions, keeping only x and y of every position (Z/M ordinates are dropped). Every ring must have at least 4 positions and be closed in x/y, else None. Return a list of polygons (a POLYGON gives a one-element list).

Why this case matters

WKT is the lingua franca between databases and GIS tools; losing a dimension or nesting level corrupts rings.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
boundary #6	`null`	`[]`	Failed

MEMBER ARCHIVE

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