StringIO line readers, fresh-literal bytes, Integer/Float exception: false, Array#inject/minmax, zip with a Range by Largo · Pull Request #114 · Largo/ironruby

Largo · 2026-11-05T15:50:24Z

This PR picks up more items from #89 after #111. All figures compare against CRuby 3.3.

1. StringIO, and the byte side of fresh string literals (`9a2f2c8`)

StringIO. Times are µs for a 20k-line string.

	before	after	CRuby
`gets` loop	3496	1288	1646
`readlines(chomp: true)`	8651	~2300	1274
`puts` ×10k	4168	2740	2858

Bare gets. A call with no arguments now has its own overload.
One-byte separators are searched for with IndexOf(byte).
chomp: compares bytes and cuts the line in place. It no longer goes through EndsWith and a second slice.
Fix: lineno no longer counts the nil that gets returns at the end. This matches MRI's strio_gets.

Fresh string literals. A literal starts as a CLR string. It used to switch to bytes through the escaping encoder, even for ASCII text. "hello world\n".bytesize took ~420 ns, against ~62 ns in CRuby.

StringContent now handles this in two places:

GetByteCount and GetByte first find out whether the string is ASCII, using a cached, vectorized scan, before switching to bytes.
DataToBytes and its helpers convert ASCII with Ascii.FromUtf16.

Results:

bytesize on a fresh literal: ~420 → ~200 ns.
IO#puts ×10k: 3386 → 1871 µs (CRuby 2784).

2. Kernel conversions, Array#inject/minmax, zip with a Range (`19c6386`)

	before	after	CRuby
`Integer("x", exception: false)`	54.8 µs	0.9 µs	0.17 µs
`Integer(1.5)`	1.5 µs	0.9 µs	0.09 µs
`(1..100).to_a.inject(:+)`	7.7 µs	2.2 µs	0.25 µs
`(1..100).to_a.minmax`	7.5 µs	0.5 µs	0.22 µs
`(1..100).zip(1..100)`	1620 µs	164 µs	42 µs

exception: false. The prelude used to rescue the ArgumentError the parser raised. New built-ins __ir_try_Integer__ and __ir_try_Float__ now return nil for unreadable text. An invalid radix still raises, as in MRI; before this change it returned nil.
inject over a plain Array loops over the list directly. While Integer#+ is the built-in, it adds Fixnums in C#, as MRI's ary_inject_op does.
Array#minmax is [min, max]. That is exactly what MRI's ary_minmax calls, so a custom <=> sees the same comparisons.
zip with an Integer Range reads the element from the index, when the Range's #each is the built-in. Before, each element went through Enumerator#next, at about 15 µs per element. Range#zip(Range) was Performance gaps found while optimizing 2016-era code (not yet addressed) #89's "Enumerable#zip through Enumerator#next" item (~38×). It is now ~4×; the rest is the cost of the prelude's per-row loop.

Also fixed, all already wrong in master:

Integer and Float of a String in an ASCII-incompatible encoding now raise Encoding::CompatibilityError, whether or not exception: false is given. Before, Integer("12".encode("UTF-16LE")) returned 12.
Float("1\0") now raises "string for Float contains null byte".

Testing

Spec sweeps with no failures:
- spec/core/kernel, enumerable, range, float, struct, hash, enumerator;
- library/stringio, library/stringscanner;
- core/io, core/file, core/encoding, core/symbol, core/regexp, core/matchdata, core/marshal, core/array/pack;
- library/zlib, library/digest.
Known errors in core/string, core/array and core/integer: these are only errors from mspec's fixnum_max()/fixnum_min() helper, which has no IronRuby case. core/string shows the same errors on master.
IronRuby.Tests passes, with two new tests whose expected output is CRuby's: StringIO_LineReaders1 and Kernel_ConversionsInjectZip1.

Still open:

StringIO#read of the whole buffer still copies it; that is the copy-on-write item in Performance gaps found while optimizing 2016-era code (not yet addressed) #89.
Creating a literal costs ~100 ns, against 51 ns in CRuby.
inject(:+) keeps ~1.5 µs of prelude wrapper per call.

🤖 Generated with Claude Code

https://claude.ai/code/session_013PQjtzmBTstQR8oqifXLX6

Summary by CodeRabbit

New Features
- Added Array#minmax support.
- Improved Enumerable#zip for integer ranges.
- Added non-raising string conversions with exception: false for Kernel.Integer and Kernel.Float.
- Improved Kernel.Integer conversion of finite floats when exceptions are enabled.
Bug Fixes
- Improved StringIO line reading with default and custom separators, limits, and chomp: true.
- Improved ASCII string byte handling while preserving behavior for other encodings.
- Improved Array#inject behavior, including integer summation.

StringIO (20k-line string, us; before -> after, CRuby 3.3): - gets: 3496 -> 1288 (1646). The bare call has its own overload, so it binds without the optional arguments' conversions; and a one-byte separator is looked for with IndexOf(byte), with no copy of the separator per line. - readlines(chomp: true): 8651 -> ~2300 (1274). Chomp compared the separator with MutableString.EndsWith and sliced a second string. It now compares bytes and cuts the line, a fresh slice, where it is. - lineno no longer counts the nil gets answers at the end (MRI's strio_gets); every read that answers a line still counts, limit or no. Fresh string literals start as a CLR string and switch to bytes the first time something wants bytes, through the encoding's escaping encoder, even when the text is ASCII. "hello world\n".bytesize took ~420 ns (CRuby ~62), and writing a fresh literal to an IO or a StringIO paid that on every call. StringContent now: - finds out whether the data is ASCII (a vectorized scan, cached in the flags) before switching to bytes in GetByteCount and GetByte; - narrows ASCII data in an ASCII-compatible encoding with Ascii.FromUtf16 in DataToBytes, GetDataByteCount and GetDataBytes. Literal bytesize ~420 -> ~200 ns. IO#puts x10k 3386 -> 1871 us (CRuby 2784); StringIO#puts x10k 4168 -> 2740 (2858). spec/core/string (2 errors from mspec's fixnum_max(), as on master), library/stringio, library/stringscanner, core/io, core/file, core/encoding, core/symbol, core/regexp, core/matchdata, core/marshal, core/array/pack, library/zlib and library/digest: no failures. IronRuby.Tests passes, with the new StringIO_LineReaders1, whose expected output is CRuby's. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_013PQjtzmBTstQR8oqifXLX6

coderabbitai · 2026-11-05T15:50:45Z

Walkthrough

StringIO line-reading behavior and MutableString byte handling change. Kernel conversions and Enumerable operations also change. New runtime tests cover these behaviors.

Changes: StringIO and byte handling

Layer / File(s)	Summary
StringIO reader behavior `Src/Libraries/StringIO/StringIO.cs`, `Src/IronRuby.Tests/Runtime/MiscTests.cs`	`Chomp` compares separator bytes and truncates the line in place. `gets` has an overload for calls without optional arguments and a shared implementation for separator, limit, and `chomp:` options. One-byte separators use a direct byte search. Tests cover line readers, separators, limits, and chomping.
ASCII byte handling `Src/Ruby/Builtins/MutableString.StringContent.cs`	MutableString converts and copies eligible ASCII data directly. Byte-count and byte-index paths detect single-byte characters on demand.

Kernel conversions and Enumerable operations

Layer / File(s)	Summary
Kernel conversions `Src/Libraries/Builtins/KernelOps.cs`, `Src/Ruby/Runtime/RubyOps.cs`, `Src/StdLib/ironruby/ruby4.rb`, `Src/IronRuby.Tests/Runtime/MiscTests.cs`	Kernel adds try-conversion methods and ASCII-compatibility checks. `Kernel.Integer` and `Kernel.Float` use the try-conversion paths for String inputs with `exception: false`. `TryParseRubyFloat` becomes public. Tests cover conversion results and errors.
Enumerable operations `Src/Libraries/Builtins/Enumerable.cs`, `Src/Libraries/Extensions/IListOps.cs`, `Src/StdLib/ironruby/ruby4.rb`, `Src/IronRuby.Tests/Runtime/MiscTests.cs`, `Src/IronRuby.Tests/RubyTests.cs`	Array inject uses a direct list path for eligible `RubyArray` values. `IListOps` adds `minmax`. `Enumerable#zip` indexes qualifying integer ranges. Tests cover inject, minmax, and range zip.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Possibly related issues

Largo/ironruby issue 89: The issue describes StringIO line-reading and byte-handling work. This PR changes StringIO line readers and MutableString byte conversion.

Possibly related PRs

Largo/ironruby#111: This PR changes IO line-reader argument handling, chomping, and line-number accounting; this PR changes corresponding StringIO reader behavior.
Largo/ironruby#95: This PR adds IsPlainList, which this PR uses to select the direct inject implementation.
Largo/ironruby#76: This PR optimizes escaping-encoding byte conversion; this PR adds a direct path for eligible ASCII data and retains the encoder path for other data.

Suggested reviewers: claude

Merge Risk: Minimal · up to f6145

No merge-blocking issue is established from the available evidence.

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Passed checks: 4 passed

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Title check		The title identifies the main areas changed, including StringIO, conversions, array operations, and Range-based zip.
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Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

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…a Range Before -> after, CRuby 3.3: - Integer("x", exception: false): 54.8 -> 0.9 us (0.17). The prelude rescued the ArgumentError the C# parser raised. __ir_try_Integer__ and __ir_try_Float__ now answer nil for a String that does not read as a number. An invalid radix still raises, as in MRI; it used to answer nil. - Integer(1.5): 1.5 -> 0.9 us. A finite Float is truncated before the block and its rescue frame. - [1..100].inject(:+): 7.7 -> 2.2 us (0.25). Over a plain Array, inject loops over the list and not through #each with a splatting Proc, and while Integer#+ is the built-in it adds Fixnums in C#, as MRI's ary_inject_op does. - [1..100].minmax: 7.5 -> 0.5 us (0.22). Array#minmax is [min, max], which is what MRI's ary_minmax calls, so a custom <=> sees the same comparisons, and it uses min's and max's Fixnum fast paths. With a block it is Enumerable#minmax. - (1..100).zip(1..100): 1620 -> 164 us (42). An Integer Range whose #each is the built-in is read from the index; going through Enumerator#next cost ~15 us an element. Fixed as well, all already in master: Integer and Float of a String in an ASCII-incompatible encoding raise Encoding::CompatibilityError whether or not exception: false is given (Integer("12" in UTF-16LE) was 12), and Float("1\0") says "string for Float contains null byte". spec/core/kernel, enumerable, range, float, struct, hash and enumerator: no failures. core/array and core/integer: only the errors from mspec's fixnum_max()/fixnum_min() helper, which has no IronRuby case (core/string has the same on master). IronRuby.Tests passes, with the new Kernel_ConversionsInjectZip1, whose expected output is CRuby's. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_013PQjtzmBTstQR8oqifXLX6

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Inline comments:
Review comments at @Src/StdLib/ironruby/ruby4.rb:
- Around line 3170-3171: Update the String conversion path around
__ir_try_Integer__ so radix coercion runs within the existing non-raising rescue
when exception: false, returning nil if base cannot convert to an Integer while
preserving the intended error for an invalid numeric radix.
- Around line 806-807: Update the Range fast-path guard in zip to account for
the `each` method resolved on `other`: use the indexed path only when the
instance does not override Range’s `each`, and otherwise use the enumerator path
so values yielded by the singleton method are preserved.

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Conflicts: StringIO#gets keeps the PR's shared helper and takes #112's rule that gets(0) does not count a line; MiscTests keeps master's tests and the PR's two new ones. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01KPwZf7MsYwQdhLBCZCkH2C

…he built-in A Range that is not frozen - (1..3).dup - can have a singleton #each or extend a module with one; MRI's zip goes through it, so the guard now asks for the method the argument resolves, not Range's instance method. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01KPwZf7MsYwQdhLBCZCkH2C

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Review comments at @Src/StdLib/ironruby/ruby4.rb:
- Around line 806-807: The indexed zip fast path can use overridden Range
endpoint readers while built-in iteration uses the stored endpoints. Update the
Range eligibility and indexing logic near the `other.method(:each).unbind ==
RANGE_EACH__` check to use built-in endpoint values, or fall back to enumeration
when an endpoint reader is overridden, so indexed results match Range iteration.

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`Src/IronRuby.Tests/Runtime/MiscTests.cs`

`Src/Libraries/Builtins/Enumerable.cs`

`Src/Libraries/Builtins/KernelOps.cs`

`Src/Libraries/Extensions/IListOps.cs`

`Src/Libraries/StringIO/StringIO.cs`

`Src/Ruby/Builtins/MutableString.StringContent.cs`

`Src/Ruby/Runtime/RubyOps.cs`

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Range#each reads the stored endpoints, so a Range that overrides one of the readers - (1..3).dup can - must not be zipped from the index the readers describe. The method checks also come before the readers are called, as MRI never calls them here. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01KPwZf7MsYwQdhLBCZCkH2C

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Largo mentioned this pull request Nov 5, 2026

Performance gaps found while optimizing 2016-era code (not yet addressed) #89

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Largo changed the title ~~StringIO line readers, and the byte side of fresh string literals~~ StringIO line readers, fresh-literal bytes, Integer/Float exception: false, Array#inject/minmax, zip with a Range Nov 5, 2026

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Comment thread Src/StdLib/ironruby/ruby4.rb Resolved

Comment thread Src/StdLib/ironruby/ruby4.rb Resolved

claude added 2 commits November 6, 2026 00:09

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Comment thread Src/StdLib/ironruby/ruby4.rb Resolved

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Largo merged commit 75a2d00 into master Nov 6, 2026
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Integer()/Float() in C#, JIT for optional positionals before keywords, Fixnum rounding, Range#first/last, Float#step #115

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Windows pipes: blocked reads look blocked and give way to close; nonblocking I/O does not wait #116

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StringIO line readers, fresh-literal bytes, Integer/Float exception: false, Array#inject/minmax, zip with a Range - #114

StringIO line readers, fresh-literal bytes, Integer/Float exception: false, Array#inject/minmax, zip with a Range#114
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1. StringIO, and the byte side of fresh string literals (9a2f2c8)

2. Kernel conversions, Array#inject/minmax, zip with a Range (19c6386)

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1. StringIO, and the byte side of fresh string literals (`9a2f2c8`)

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