2c2fcff4f8
This PR removes all uses of `String.Iterator` from core, preferring `String.ValidPos` instead. In an upcoming PR, `String.Iterator` will be renamed to `String.Legacy.Iterator`.
88 lines
2.6 KiB
Text
88 lines
2.6 KiB
Text
/-
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Copyright (c) 2016 Microsoft Corporation. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Author: Leonardo de Moura, Mario Carneiro
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-/
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module
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prelude
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public import Init.Data.String.Substring
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public section
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/--
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Interprets a string as the decimal representation of an integer, returning it. Returns `none` if
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the string does not contain a decimal integer.
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A string can be interpreted as a decimal integer if it only consists of at least one decimal digit
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and optionally `-` in front. Leading `+` characters are not allowed.
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Use `String.isInt` to check whether `String.toInt?` would return `some`. `String.toInt!` is an
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alternative that panics instead of returning `none` when the string is not an integer.
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Examples:
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* `"".toInt? = none`
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* `"-".toInt? = none`
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* `"0".toInt? = some 0`
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* `"5".toInt? = some 5`
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* `"-5".toInt? = some (-5)`
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* `"587".toInt? = some 587`
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* `"-587".toInt? = some (-587)`
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* `" 5".toInt? = none`
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* `"2-3".toInt? = none`
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* `"0xff".toInt? = none`
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-/
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def String.toInt? (s : String) : Option Int := do
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if s.front = '-' then do
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let v ← (s.toSubstring.drop 1).toNat?;
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pure <| - Int.ofNat v
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else
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Int.ofNat <$> s.toNat?
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/--
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Checks whether the string can be interpreted as the decimal representation of an integer.
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A string can be interpreted as a decimal integer if it only consists of at least one decimal digit
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and optionally `-` in front. Leading `+` characters are not allowed.
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Use `String.toInt?` or `String.toInt!` to convert such a string to an integer.
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Examples:
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* `"".isInt = false`
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* `"-".isInt = false`
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* `"0".isInt = true`
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* `"-0".isInt = true`
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* `"5".isInt = true`
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* `"587".isInt = true`
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* `"-587".isInt = true`
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* `"+587".isInt = false`
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* `" 5".isInt = false`
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* `"2-3".isInt = false`
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* `"0xff".isInt = false`
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-/
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def String.isInt (s : String) : Bool :=
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if s.front = '-' then
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(s.toSubstring.drop 1).isNat
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else
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s.isNat
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/--
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Interprets a string as the decimal representation of an integer, returning it. Panics if the string
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does not contain a decimal integer.
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A string can be interpreted as a decimal integer if it only consists of at least one decimal digit
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and optionally `-` in front. Leading `+` characters are not allowed.
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Use `String.isInt` to check whether `String.toInt!` would return a value. `String.toInt?` is a safer
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alternative that returns `none` instead of panicking when the string is not an integer.
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Examples:
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* `"0".toInt! = 0`
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* `"5".toInt! = 5`
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* `"587".toInt! = 587`
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* `"-587".toInt! = -587`
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-/
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def String.toInt! (s : String) : Int :=
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match s.toInt? with
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| some v => v
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| none => panic "Int expected"
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