Raise ValueError for truncated path commands instead of a bare IndexError - #246
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eeshsaxena wants to merge 1 commit into
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Raise ValueError for truncated path commands instead of a bare IndexError#246eeshsaxena wants to merge 1 commit into
eeshsaxena wants to merge 1 commit into
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A path string that ends mid-command (e.g. 'M 0 0 L', 'C 1 2', a bare 'H') popped past the end of the token list in _parse_path, surfacing a bare IndexError: pop from empty list. Add a per-command argument-count check so these raise a descriptive ValueError like other malformed paths. Also fix a leading smooth command (a path starting with S/s or T/t): the reflection check compared last_command (None) with 'in "CS"', raising TypeError. Compare against a tuple so a missing previous command is handled.
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I was feeding some machine-generated d-strings through parse_path and hit a couple of confusing crashes when a string happened to be cut off mid-command.
Anything that ends before a command has all its numbers, like
M 0 0 L,C 1 2, or a loneH, pops past the end of the token list in_parse_pathand comes back asIndexError: pop from empty list, which doesn't tell you much about what was wrong with the path. I added a small per-command argument-count check right after a command is read, so a short command now raises a ValueError naming the command and how many values it expected, matching how the parser already reports other malformed input (theZ 100 200case).While testing that I also ran into a second one: a path that starts with a smooth command, e.g.
S 1 1 2 2orT 1 1, raisesTypeError: 'in <string>' requires string as left operand, not NoneType. On the first commandlast_commandis still None and the reflection check doeslast_command not in 'CS', andNone in 'CS'throws. Per the SVG spec, when there's no preceding curve the first control point should just coincide with the current point, so I switched the two membership tests to tuples (('C', 'S')/('Q', 'T')), which handles None and parses these as you'd expect.Added tests for both under test_parsing.py; they fail on master (IndexError / TypeError) and pass with the change, and the rest of the parsing suite still passes.