add `length()` and `is_empty()` to `Buffer`

[rami3l]

As required in the Markdown parser implementation.

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[coveralls]

Pull Request Test Coverage Report for Build 3825

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 5 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.007%) to 80.214%

---

Files with Coverage Reduction	New Missed Lines	%
/Users/runner/work/core/core/buffer/buffer.mbt	5	70.0%
<!--	Total:	5

Totals
Change from base Build 3821:	0.007%
Covered Lines:	4346
Relevant Lines:	5418

---

💛 - Coveralls

[hackwaly]

related https://github.com/moonbitlang/core/pull/1084

[bobzhang]

@rami3l can you cherry pick these APIs into the new buffer package

[peter-jerry-ye-code-review[bot]]

Based on the provided git diff output, here are three potential issues or suggestions in the MoonBit code:

1. Documentation Comments:

   • The new functions length and is_empty have triple-slash (///) documentation comments. According to the context provided, MoonBit uses double-slash (//) for comments and triple-slash (///) for doc comments followed by markdown text and pragmas. Ensure that the documentation comments are formatted correctly and contain the necessary information and pragmas.

   /// Return the given buffer's length in bytes.
   pub fn length(self : Buffer) -> Int {
     self.len
   }
   
   /// Return whether the given buffer is empty.
   pub fn is_empty(self : Buffer) -> Bool {
     self.len == 0
   }
   

2. Function Parameter Naming:

   • In the length and is_empty functions, the parameter self is used, which is typical for object-oriented languages. However, in MoonBit, it might be more consistent to use self as the first parameter in method definitions, but it's worth ensuring that this is the correct convention in MoonBit, especially if it supports method definitions in a more functional style.

3. Testing Values:

   • In the test blocks for length and is_empty, the inspect! macro is used to check the values. Ensure that the inspect! macro is correctly defined or imported and that the content strings ("0", "8", "true", "false") match the expected output types (Int and Bool). It's important to verify that the macro correctly interprets these values as strings for comparison.

   test "length method" {
     let buf = @buffer.new(size_hint=100)
     inspect!(buf.length(), content="0")
     buf.write_string("Test")
     inspect!(buf.length(), content="8")
   }
   
   test "is_empty method" {
     let buf = @buffer.new(size_hint=100)
     inspect!(buf.is_empty(), content="true")
     buf.write_string("Test")
     inspect!(buf.is_empty(), content="false")
   }
   

These suggestions aim to ensure code clarity, consistency with MoonBit's conventions, and accuracy in testing.

[rami3l]

@rami3l can you cherry pick these APIs into the new buffer package

@bobzhang Rebased.

[rami3l]

May I ask what is blocking this PR from being merged? Many thanks in advance :)

[rami3l]

lgtm @rami3l sorry for the delay

@bobzhang Thanks again! The PR is now rebased.