eb01aaeee4
This PR renames `String.Iterator` to `String.Legacy.Iterator`. From the docstring of `String.Legacy.Iterator`: > This is a no-longer-supported legacy API that will be removed in a future release. You should use > `String.ValidPos` instead, which is similar, but safer. To iterate over a string `s`, start with > `p : s.startValidPos`, advance it using `p.next`, access the current character using `p.get` and > check if the position is at the end using `p = s.endValidPos` or `p.IsAtEnd`.
44 lines
900 B
Text
44 lines
900 B
Text
/--
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info: Try this:
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[apply] termination_by xs.length / 2 - i
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-/
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#guard_msgs in
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def foo (xs : String) (i : Nat) (a b : String.Legacy.Iterator) : Bool :=
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if xs.length / 2 ≤ i then
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true
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else if a.curr ≠ b.curr then
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false
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else
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foo xs (i + 1) a.next b.prev
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termination_by?
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/--
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info: Try this:
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[apply] termination_by xs.length / 2 - i
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-/
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#guard_msgs in
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def bar (xs : String) (i : Nat) (a b : String.Legacy.Iterator) : Bool :=
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if i < xs.length / 2 then
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if a.curr ≠ b.curr then
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false
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else
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bar xs (i + 1) a.next b.prev
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else
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true
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termination_by?
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/--
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info: Try this:
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[apply] termination_by xs.length / 2 - i
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-/
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#guard_msgs in
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def baz (xs : String) (i : Nat) (a b : String.Legacy.Iterator) : Bool :=
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if ¬ (i < xs.length / 2) then
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true
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else
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if a.curr ≠ b.curr then
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false
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else
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baz xs (i + 1) a.next b.prev
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termination_by?
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