Add String::replace_first and String::replace_last

[zachs18]

Rebase of #97977 (cc @WilliamVenner)

Convenience methods that use match_indices and replace_range to efficiently replace a substring in a string without reallocating, if capacity (and the implementation of Vec::splice) allows.

The intra-doc link to str::replacen is a direct url-based link to str::replacen in std's docs to work around #98941. This means that when building only alloc's docs (and not std's), it will be a broken link. There is precedent for this e.g. in core::hint::spin_loop which links to std::thread::yield_now using a url-based link and thus is a dead link when only building core's docs.

ACP: rust-lang/libs-team#506

[rustbot]

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[tgross35]

I don't think I see any libs-api feedback on the other thread, and that is from a while back anyway. Could you file an ACP for this at https://github.com/rust-lang/libs-team/issues?

[tgross35]

These methods would be convenient but I feel like they should probably come with an in-place replace alternative.

[zachs18]

ACP opened: rust-lang/libs-team#506

@rustbot label S-waiting-on-ACP

I added String::replace_in_place (doing str::replace in-place) as a possible alternative/addition in the ACP, but I'll hold off on adding it if/until the ACP is approved with it.

[bors]

☔ The latest upstream changes (presumably #135286) made this pull request unmergeable. Please resolve the merge conflicts.

[alex-semenyuk]

@zachs18
Thanks for your contribution
Could you please rebase

[tgross35]

@zachs18 Thanks for your contribution Could you please rebase

This is still waiting on the ACP

[joshtriplett]

@bors r+ rollup

ACP approved, PR approved.

Might be interested in the proposed replace_in_place in the future, but these seem clearly valuable and worth adding.

[bors]

📌 Commit 0243f5c has been approved by joshtriplett

It is now in the queue for this repository.

[joshtriplett]

@bors r-

r=me when the conflicts are fixed.

[tgross35]

I think the wording here can be softened a bit to say this can (not should) be preferred over replacen if you don't need to retain the original. At least while this is unstable.

[zachs18]

Updated in latest push. Also updated to say string = string.replacen(..., 1); instead of String::replacen(..., 1) as replacen isn't from String, but str, and also to show that this is only a replacement for replacen if it was used to immediately replace the original String.

[tgross35]

Please also squash when you rebase, this PR has fixup commits

[rustbot]

This PR was rebased onto a different master commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[zachs18]

@rustbot ready

[tgross35]

Fwiw I think you may as well drop the cfg_attr and enable the feature unconditionally, usually we don't gate these too strictly. And we'll wind up using it elsewhere anyway.

I'll merge after PR CI finishes, with or without this (just ping me once it does if I miss it)

[rust-log-analyzer]

The job x86_64-gnu-gcc failed! Check out the build log: (web) (plain enhanced) (plain)

Click to see the possible cause of the failure (guessed by this bot)

---- [run-make] tests/run-make/alloc-no-oom-handling stdout ----

error: rmake recipe failed to complete
status: exit status: 1
command: cd "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-make/alloc-no-oom-handling/rmake_out" && env -u RUSTFLAGS -u __RUSTC_DEBUG_ASSERTIONS_ENABLED -u __STD_DEBUG_ASSERTIONS_ENABLED AR="ar" BUILD_ROOT="/checkout/obj/build/x86_64-unknown-linux-gnu" CC="cc" CC_DEFAULT_FLAGS="-ffunction-sections -fdata-sections -fPIC -m64" CXX="c++" CXX_DEFAULT_FLAGS="-ffunction-sections -fdata-sections -fPIC -m64" HOST_RUSTC_DYLIB_PATH="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" LD_LIBRARY_PATH="/checkout/obj/build/x86_64-unknown-linux-gnu/bootstrap-tools/x86_64-unknown-linux-gnu/release/deps:/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/lib/rustlib/x86_64-unknown-linux-gnu/lib" LD_LIB_PATH_ENVVAR="LD_LIBRARY_PATH" LLVM_BIN_DIR="/checkout/obj/build/x86_64-unknown-linux-gnu/ci-llvm/bin" LLVM_COMPONENTS="aarch64 aarch64asmparser aarch64codegen aarch64desc aarch64disassembler aarch64info aarch64utils aggressiveinstcombine all all-targets amdgpu amdgpuasmparser amdgpucodegen amdgpudesc amdgpudisassembler amdgpuinfo amdgputargetmca amdgpuutils analysis arm armasmparser armcodegen armdesc armdisassembler arminfo armutils asmparser asmprinter avr avrasmparser avrcodegen avrdesc avrdisassembler avrinfo binaryformat bitreader bitstreamreader bitwriter bpf bpfasmparser bpfcodegen bpfdesc bpfdisassembler bpfinfo cfguard cgdata codegen codegentypes core coroutines coverage csky cskyasmparser cskycodegen cskydesc cskydisassembler cskyinfo debuginfobtf debuginfocodeview debuginfodwarf debuginfodwarflowlevel debuginfogsym debuginfologicalview debuginfomsf debuginfopdb demangle dlltooldriver dwarfcfichecker dwarflinker dwarflinkerclassic dwarflinkerparallel dwp engine executionengine extensions filecheck frontendatomic frontenddirective frontenddriver frontendhlsl frontendoffloading frontendopenacc frontendopenmp fuzzercli fuzzmutate globalisel hexagon hexagonasmparser hexagoncodegen hexagondesc hexagondisassembler hexagoninfo hipstdpar instcombine instrumentation interfacestub interpreter ipo irprinter irreader jitlink libdriver lineeditor linker loongarch loongarchasmparser loongarchcodegen loongarchdesc loongarchdisassembler loongarchinfo lto m68k m68kasmparser m68kcodegen m68kdesc m68kdisassembler m68kinfo mc mca mcdisassembler mcjit mcparser mips mipsasmparser mipscodegen mipsdesc mipsdisassembler mipsinfo mirparser msp430 msp430asmparser msp430codegen msp430desc msp430disassembler msp430info native nativecodegen nvptx nvptxcodegen nvptxdesc nvptxinfo objcarcopts objcopy object objectyaml option orcdebugging orcjit orcshared orctargetprocess passes powerpc powerpcasmparser powerpccodegen powerpcdesc powerpcdisassembler powerpcinfo profiledata remarks riscv riscvasmparser riscvcodegen riscvdesc riscvdisassembler riscvinfo riscvtargetmca runtimedyld sandboxir scalaropts selectiondag sparc sparcasmparser sparccodegen sparcdesc sparcdisassembler sparcinfo support symbolize systemz systemzasmparser systemzcodegen systemzdesc systemzdisassembler systemzinfo tablegen target targetparser telemetry textapi textapibinaryreader transformutils vectorize webassembly webassemblyasmparser webassemblycodegen webassemblydesc webassemblydisassembler webassemblyinfo webassemblyutils windowsdriver windowsmanifest x86 x86asmparser x86codegen x86desc x86disassembler x86info x86targetmca xray xtensa xtensaasmparser xtensacodegen xtensadesc xtensadisassembler xtensainfo" LLVM_FILECHECK="/checkout/obj/build/x86_64-unknown-linux-gnu/ci-llvm/bin/FileCheck" PYTHON="/usr/bin/python3" RUSTC="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" RUSTDOC="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustdoc" SOURCE_ROOT="/checkout" TARGET="x86_64-unknown-linux-gnu" TARGET_EXE_DYLIB_PATH="/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-make/alloc-no-oom-handling/rmake"
stdout: none
--- stderr -------------------------------
command failed at line 14
Command { cmd: LD_LIBRARY_PATH="/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-make/alloc-no-oom-handling/rmake_out:/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib:/checkout/obj/build/x86_64-unknown-linux-gnu/bootstrap-tools/x86_64-unknown-linux-gnu/release/deps:/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/lib/rustlib/x86_64-unknown-linux-gnu/lib" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/run-make/alloc-no-oom-handling/rmake_out" "--edition" "2021" "-Dwarnings" "--crate-type" "rlib" "/checkout/library/alloc/src/lib.rs" "--cfg" "no_global_oom_handling" "--target=x86_64-unknown-linux-gnu", stdin_buf: None, stdin: None, stdout: None, stderr: None, drop_bomb: DropBomb { command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc", defused: true, armed_location: Location { file: "/checkout/tests/run-make/alloc-no-oom-handling/rmake.rs", line: 8, column: 5 } }, already_executed: true }
output status: `exit status: 1`
=== STDOUT ===



=== STDERR ===
error[E0635]: unknown feature `string_replace_in_place`

For more information how to resolve CI failures of this job, visit this link.

[tgross35]

Thanks! I assume the GCC failure is spurious

@bors r=joshtriplett ,tgross35

[bors]

📌 Commit 271b10c has been approved by joshtriplett

It is now in the queue for this repository.

[tgross35]

@bors rollup