Ensure shuffled bits get cleared out in "modifying" operations #33
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Fixes #32. The core issue here is we're taking a few shortcuts in some operations like chop, chomp, first, last where we just shuffle the bits around and OR the new length. The problem is there can be "extra bits" in the inline string that can then affect operations like `==`. So we need to ensure in these optimized "modifying" operations, these extra bits get zeroed out to ensure a consistent bit representation.
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Let's add tests?
some things which were failing before:
abc = InlineString3("abc")
@test first(abc, 2) == InlineString3("ab")
@test last(abc, 2) == InlineString3("bc")
@test chop(abc; head=0, tail=1) == InlineString3("ab")
@test chomp(InlineString3("ab\n")) == InlineString3("ab")
src/InlineStrings.jl
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| newlen = nextind(s, min(lastindex(s), nextind(s, 0, n))) - 1 | ||
| i = sizeof(T) - newlen | ||
| # clear out any bits we're not keeping | ||
| s = Base.shl_int(Base.lshr_int(s, 8 * i), 8 * i) |
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is it worth putting this in a little helper function for clarity, rather than repeating it with comment?
@inline clear_last(s, n) = Base.shl_int(Base.lshr_int(s, 8 * n), 8 * n)
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Fixes #32. The core issue here is we're taking a few shortcuts in some operations
like chop, chomp, first, last where we just shuffle the bits around and OR the
new length. The problem is there can be "extra bits" in the inline string that
can then affect operations like
==. So we need to ensure in these optimized"modifying" operations, these extra bits get zeroed out to ensure a consistent
bit representation.