Patterned expressions

[unlessgames]

I've implemented patterns on the right side of expression * / and %.

While the same thing for Bjorklund parameters still has to be done, these seem to work fine.

[github-actions]

Benchmark for 59aa142

Click to view benchmark

Test	Base	PR	%
Cycle/Generate	58.5±0.80µs	62.7±0.43µs	+7.18%
Cycle/Parse	330.2±6.55µs	325.0±4.94µs	-1.57%
Rust Phrase/Clone	432.4±3.56ns	432.9±6.85ns	+0.12%
Rust Phrase/Create	67.9±1.25µs	66.0±1.09µs	-2.80%
Rust Phrase/Run	682.8±4.27µs	684.4±7.64µs	+0.23%
Rust Phrase/Seek	161.0±304.47µs	153.6±290.00µs	-4.60%
Scripted Phrase/Clone	669.4±14.06ns	658.1±4.12ns	-1.69%
Scripted Phrase/Create	901.2±11.50µs	893.5±14.02µs	-0.85%
Scripted Phrase/Run	1853.6±17.12µs	1848.5±21.57µs	-0.28%
Scripted Phrase/Seek	365.6±708.67µs	252.4±513.49µs	-30.96%

[github-actions]

Benchmark for e66ef7d

Click to view benchmark

Test	Base	PR	%
Cycle/Generate	58.9±0.86µs	57.9±0.71µs	-1.70%
Cycle/Parse	323.2±11.59µs	332.1±7.26µs	+2.75%
Rust Phrase/Clone	434.2±19.86ns	454.4±5.40ns	+4.65%
Rust Phrase/Create	66.0±0.72µs	67.1±1.07µs	+1.67%
Rust Phrase/Run	685.8±10.17µs	670.3±6.60µs	-2.26%
Rust Phrase/Seek	164.7±340.90µs	159.7±301.55µs	-3.04%
Scripted Phrase/Clone	686.5±7.42ns	651.1±9.53ns	-5.16%
Scripted Phrase/Create	895.5±39.98µs	888.6±22.10µs	-0.77%
Scripted Phrase/Run	1857.3±24.24µs	1875.4±58.30µs	+0.97%
Scripted Phrase/Seek	366.9±711.55µs	250.8±508.47µs	-31.64%

[emuell]

Looks good to me. Given this a quick try and things works fine so far.

While testing, I've noticed that negative numbers are allowed in the right side expressions for * and /. I can't make things crash when using them, but they likely will do weird things?

Example:

  emit = cycle("c8*<0 -1>")

Let me know if you want to merge this now or if you want to add support for bjorklunds as well.

[unlessgames]

I was thinking of adding support for bjorklund but the fact that there are three arguments there that would need to be combined in multiple ways got me a bit stuck. We'd need a more general function here that could merge event streams into each other.

Something like (a: Vec<(Span, Vec<Value>)>, b: Vec<Vec<Event>>) -> Vec<(Span, Vec<Value>)> that would fold events from b into a (creating new events when the stream is denser) and appending values. This could be applied any number of times to get like a (Span, [Value, Value, Value]) for each step (in case of the bjorklund).

In strudel, negative numbers will silently apply zero basically, resulting in empty chunks. I wonder how hard it could be to implement a reverse functionality that could be used when the multiplier is negative.

[emuell]

Just wanted to report this issue here:

Right side expressions of * / and % currently can't be padded with white-space.

This works:
cycle("[c4]*2")

This fails to parse:
cycle("[c4]* 2")

Seems to be fixed in this branch too.

The changes are useful already. Let's clear and merge them, and deal with the Bjorklund parameters in a new PR?

[unlessgames]

Let's do that!

[github-actions]

Benchmark for 4639dbe

Click to view benchmark

Test	Base	PR	%
Cycle/Generate	59.2±1.14µs	58.0±0.56µs	-2.03%
Cycle/Parse	323.5±9.13µs	326.0±9.74µs	+0.77%
Rust Phrase/Clone	445.3±7.79ns	433.7±4.28ns	-2.60%
Rust Phrase/Create	67.2±1.27µs	67.1±1.37µs	-0.15%
Rust Phrase/Run	677.4±6.12µs	676.5±6.28µs	-0.13%
Rust Phrase/Seek	164.1±311.05µs	160.6±304.04µs	-2.13%
Scripted Phrase/Clone	625.2±9.68ns	627.7±5.87ns	+0.40%
Scripted Phrase/Create	935.5±8.77µs	945.2±14.96µs	+1.04%
Scripted Phrase/Run	1840.5±13.26µs	1805.1±49.19µs	-1.92%
Scripted Phrase/Seek	230.4±466.41µs	229.1±463.98µs	-0.56%

[emuell]

Wanted to update the limitations in the API docs, but am a bit unsure here:

bd(3, 8)*2 or bd(3, 8)*<2, 2> does not work, so:

Does that make sense?

REMOVE
* Operators currently only accept numbers on the right side (`a3*2` is valid, `a3*<1 2>` is not)

ADD
* Operators on the right side of bjorklund expressions are not yet supported (e.g. `bd(3, 8)*2` is not)

[unlessgames]

That doesn't sound right. Operators should work for Bjorklund, what is not supported is patterned parameters for it.

These should be fine:

bd(3,8)*2
bd(3,8)*<1 2>

This is not supported:

bd(<3 6>, 8)

[emuell]

These should be fine

Currently doesn't work.

Also fine with me to postpone a fix for this. decide you...

[unlessgames]

Oh true, I've missed that. Unfortunately operators are read right recursively (to satisfy the peg parser spec) and that's also how they are applied so stacking operators is actually not working properly. Note, this is not specific to Bjorklund, things like [a b]*2/2 don't work as they should either. This will not be an easy/fast fix though, so maybe we should merge this for now.

[github-actions]

Benchmark for 89b4997

Click to view benchmark

Test	Base	PR	%
Cycle/Generate	58.8±0.92µs	58.0±0.73µs	-1.36%
Cycle/Parse	322.3±7.49µs	327.6±3.75µs	+1.64%
Rust Phrase/Clone	439.5±35.66ns	436.5±5.23ns	-0.68%
Rust Phrase/Create	65.6±1.58µs	66.0±1.47µs	+0.61%
Rust Phrase/Run	685.9±11.03µs	682.0±10.28µs	-0.57%
Rust Phrase/Seek	164.7±295.60µs	162.8±309.35µs	-1.15%
Scripted Phrase/Clone	651.6±6.31ns	623.6±11.23ns	-4.30%
Scripted Phrase/Create	954.9±7.61µs	960.8±26.46µs	+0.62%
Scripted Phrase/Run	1798.7±11.65µs	1802.0±23.01µs	+0.18%
Scripted Phrase/Seek	229.7±463.72µs	227.7±463.62µs	-0.87%