https://github.com/kasperosterbye/stringutilities

String slices and string builder for pharo
https://github.com/kasperosterbye/stringutilities

pharo

Last synced: 18 days ago
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String slices and string builder for pharo

• Host: GitHub
• URL: https://github.com/kasperosterbye/stringutilities
• Owner: kasperosterbye
• Created: 2020-02-04T08:55:11.000Z (almost 5 years ago)
• Default Branch: master
• Last Pushed: 2020-05-15T05:55:24.000Z (over 4 years ago)
• Last Synced: 2024-11-06T01:54:51.635Z (2 months ago)
• Topics: pharo
• Language: Smalltalk
• Homepage:
• Size: 59.6 KB
• Stars: 4
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# StringSlice

A string slice a substring obtained by a `start` and an `end` index into an existing string. It is thus possible to get substrings without copying the bytes of the original string - at least for a large number of operations.

The package adds one extra method to class String: the `sliceFrom: a to: b`. 

```smalltalk

slice := 'aaabbbccc' sliceFrom: 4 to: 6.

slice = 'bbb' >>> true.

slice size >>> 3.

(slice at: 2) >>> $b.

slice hash = 'bbb' hash >>> true.

```

**This library also contains a [StringBuilder](StringBuilder.md)**

## Metacello call

```smalltalk

Metacello new

   baseline: 'StringUtilities';

   repository: 'github://kasperosterbye/StringUtilities';

   load.

```

## Implementation notes

### Imutable

StringSlice does not allow changes to the original string. 

* Some mutatation operations will give an error - `at:put:` is not allowed.

* Other mutation operations already have copy semantics for String, for example asUppercase. These copying methods do not return a slice, but a String.

### Complete

I have tried my best to make sure slices respond to the same protocol as String.

While the Metacello expression above do not load the tests, I have ported all the non-destructive tests from string to make sure all string methods work on slices. Any missing issue - please raise them. 

### Effecient 

A large number of methods return slices if used on a slice. For example:

* The substrings: method return slices if the original is a slice.

* Regular expression matching returns slices if the original is a slice.

```smalltalk

slice := 'aaa bbb ccc' sliceFrom: 1 to: 11.

((slice substrings: ' ') collect: [:s | s class]) >>>

    {StringSlice. StringSlice. StringSlice}.

    

'(a+|c+)' asRegex  matchesIn: slice. "returns slices"

```

The slice has three instance variables, the original string, start and end. Making them is therefore rather fast. In fact my timings show it is faster to make a zero length slice than a zero length string copy. There are some timing methods in the StringSlice class side. Perhaps yours computer is different than mine.

### Comments onString

While I have been testing Slice, I have come across a number of issues with the class String. They are summarized in [StringIssues](StringIssues.md).