# `Text.Extract.Boundary`
[🔗](https://github.com/kipcole9/text/blob/v0.6.1/lib/extract/boundary.ex#L1)

Phase 3 of the URL / email extraction pipeline: trim spurious
trailing punctuation from a candidate span.

Real-world prose embeds URLs into sentences. The text
`"See http://example.com."` should yield the URL `http://example.com`
with the sentence-final period dropped, while
`"https://en.wikipedia.org/wiki/URI_(disambiguation)"` should keep
the closing parenthesis because it has a matching opener inside the
span.

This module produces a (possibly shorter) `{start, length}` span by:

1. Stripping trailing characters from a fixed punctuation set
   (`.,;:!?'"`).

2. Stripping trailing closing brackets (`)`, `]`, `}`, `>`) that have
   no matching opener inside the span.

Steps repeat until no further trimming is possible.

### Examples

    iex> Text.Extract.Boundary.shrink("http://example.com.")
    "http://example.com"

    iex> Text.Extract.Boundary.shrink("http://example.com)")
    "http://example.com"

    iex> Text.Extract.Boundary.shrink("http://en.wikipedia.org/wiki/URI_(disambiguation)")
    "http://en.wikipedia.org/wiki/URI_(disambiguation)"

    iex> Text.Extract.Boundary.shrink("http://x.com/path......")
    "http://x.com/path"

# `shrink`

```elixir
@spec shrink(String.t()) :: String.t()
```

Trims trailing punctuation and unbalanced closers from a candidate
string.

### Arguments

* `candidate` is the candidate substring (e.g. as emitted by
  `Text.Extract.Scanner.scan/1`).

### Returns

* The candidate with trailing junk removed. Never grows; only the
  end of the string is trimmed.

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*Consult [api-reference.md](api-reference.md) for complete listing*