fix: reduce Context code

[yusukebe]

This PR reduces the code size of src/context.ts and fixes some bugs.

Reducing the code size

The current implementation uses #preparedHeaders and #isFresh to avoid generating Headers and Response objects as much as possible. This increases the amount of code and makes the code more complex.

In this PR, we have removed them and shortened the code.

This change has reduced the bundle size by about 900B with a minified minimum app using the hono/tiny.

Fixes weird behaviors

There are some bugs in the current implementation of context.ts that cause weird behaviors. The following tests have failed. This PR allows those tests to succeed.

f4cb6ac

Therefore, the following Issues are fixed.

Fixes honojs/node-server#226
Fixes #3736 (maybe)

Performance

This PR shows a slight decrease in performance related to application speed. Benchmark results using this script are as follows.

Performance is very important to us. So we are not sure if we can accept this PR or not. However, the difference is slight, and the smaller file size is expected to improve performance in a serverless environment.

The author should do the following, if applicable

• Add tests
• Run tests
• bun run format:fix && bun run lint:fix to format the code
• Add TSDoc/JSDoc to document the code

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.27%. Comparing base (548d73f) to head (50b7819).
Report is 21 commits behind head on next.

Additional details and impacted files

@@            Coverage Diff             @@
##             next    #4100      +/-   ##
==========================================
- Coverage   91.32%   91.27%   -0.06%     
==========================================
  Files         168      168              
  Lines       10802    10723      -79     
  Branches     3073     3043      -30     
==========================================
- Hits         9865     9787      -78     
+ Misses        936      935       -1     
  Partials        1        1              

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[yusukebe]

Whether we merge this or not is a difficult thing. In the c.header(), using c.res to store the header values will introduce a significant decrease in performance when using c.header(). Hmm.

[yusukebe]

Hello @usualoma @sushichan044 !

What do you think of this? If this makes sense to you, can you review it?

[usualoma]

Great, I think it's wonderful work!

[sushichan044]

I had the same concern as @usualoma .
Since it has already been corrected, I think it looks good now!

I did a quick check on my end, and it seemed to handle common corner cases without any issues.

[sushichan044]

@yusukebe
As a nitpick, it might be good to have a test like this to demonstrate the behavior when we input empty array as header value.
This test isn't essential, as the behavior is predictable from the implementation.

  it('Should remove existing header when new value is empty array', async () => {
    c.header('X-Test', 'existing')
    const res = c.json({ test: 'data' }, 200, {
      'X-Test': [],
    })
    expect(res.headers.get('X-Test')).toBeNull()
  })

[usualoma]

Thank you!

[github-actions]

Bundle size check

	main (4a1dd5f)	#4100 (36744c6)	+/-
Bundle Size (B)	19,027B	18,157B	-870B
Bundle Size (KB)	18.58K	17.73K	-0.85K

Compiler Diagnostics (typescript-go)

	main (4a1dd5f)	#4100 (36744c6)	+/-
Files	231	231	0
Lines	106,340	106,248	-92
Identifiers	106,183	106,137	-46
Symbols	371,551	371,525	-26
Types	293,004	292,994	-10
Instantiations	3,568,489	3,568,491	2
Memory used	229,864K	229,650K	-214K
Memory allocs	10,003,691	10,003,331	-360
Parse time	0.066s	0.068s	0.002s
Bind time	0.014s	0.04s	0.026s
Check time	1.343s	1.39s	0.047s
Emit time	0s	0s	0s
Total time	1.425s	1.5s	0.075s

---

Reported by octocov

[github-actions]

Bundle size check

	main (4a1dd5f)	#4100 (36744c6)	+/-
Bundle Size (B)	19,027B	18,157B	-870B
Bundle Size (KB)	18.58K	17.73K	-0.85K

Compiler Diagnostics (tsc)

	main (4a1dd5f)	#4100 (36744c6)	+/-
Files	261	261	0
Lines	116,441	116,349	-92
Identifiers	114,443	114,397	-46
Symbols	259,900	259,888	-12
Types	162,567	162,559	-8
Instantiations	3,039,293	3,039,295	2
Memory used	272,070K	273,661K	1,591K
I/O read	0.02s	0.02s	0s
I/O write	0s	0s	0s
Parse time	0.65s	0.72s	0.07s
Bind time	0.27s	0.28s	0.01s
Check time	3.74s	3.7s	-0.04s
Emit time	0s	0s	0s
Total time	4.66s	4.7s	0.04s

---

Reported by octocov

[yusukebe]

@usualoma @sushichan044 Thanks!

@sushichan044 Yes. The test you mentioned is good. I added it.

I'll include this in the next minor release.