feat: add String::concat_view

[Lampese]

• Make String::concat take ArrayView[T] #1148

[coveralls]

Pull Request Test Coverage Report for Build 3978

Details

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.003%) to 80.132%

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Totals
Change from base Build 3975:	0.003%
Covered Lines:	4360
Relevant Lines:	5441

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💛 - Coveralls

[bobzhang]

what's the rationale to make it a plain function istead of a method?

[peter-jerry-ye]

How about:

pub(open) trait IterString {
  iter(Self) -> Iter[String]
}

pub fn concat[T : IterString](strings : T, separator~ : String = "") -> String {
  let buf = StringBuilder::new()
  let mut str : String? = None
  for s in strings {
    if str.is_empty().not() {
      buf.write_string(str.unwrap())
      buf.write_string(separator)
    }
    str = Some(s)
  } else {
    if str.is_empty().not() {
      buf.write_string(str.unwrap())
    }
  }
  buf.to_string()
}

test {
  inspect!(concat(([] : Array[String])), content="")
  inspect!(concat(["a", "b", "c"]), content="abc")
  inspect!(concat(["a", "b", "c"], separator="|"), content="a|b|c")
  inspect!(concat(["a", "b", "c"][1:], separator="|"), content="b|c")
  inspect!(
    concat((["a", "b", "c"] : FixedArray[String]), separator="|"),
    content="a|b|c",
  )
}

[Lampese]

How about:

pub(open) trait IterString {
  iter(Self) -> Iter[String]
}

pub fn concat[T : IterString](strings : T, separator~ : String = "") -> String {
  let buf = StringBuilder::new()
  let mut str : String? = None
  for s in strings {
    if str.is_empty().not() {
      buf.write_string(str.unwrap())
      buf.write_string(separator)
    }
    str = Some(s)
  } else {
    if str.is_empty().not() {
      buf.write_string(str.unwrap())
    }
  }
  buf.to_string()
}

test {
  inspect!(concat(([] : Array[String])), content="")
  inspect!(concat(["a", "b", "c"]), content="abc")
  inspect!(concat(["a", "b", "c"], separator="|"), content="a|b|c")
  inspect!(concat(["a", "b", "c"][1:], separator="|"), content="b|c")
  inspect!(
    concat((["a", "b", "c"] : FixedArray[String]), separator="|"),
    content="a|b|c",
  )
}

It is a quite feasible plan

[peter-jerry-ye]

We are now considering moving it to Iter[String]::join

[Yoorkin]

String::concat was a mistake. In the self parameter, the types in the type constructor can be a concrete type like String. After discussing offline, we will move to Iter[String]::join and make String::concat a function. The join method will be added later because users can always use other methods instead.

[Lampese]

• add Iter[String]::join #1257