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https://github.com/nushell/nushell
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9c7feb2b19
For the width calculations for table layout the `strip_ansi` function
has to be called frequently. By checking for the ASCII control chars
(0x00 to 0x1f) except `\n` that are stripped by `strip_ansi_escapes` the number of
necessary allocations can be reduced significantly for the simple case
of text not containing ANSI escapes.
**Benchmark:**
```
nu -c "for i in 0..1000 { ls } | flatten | table"
```
**Allocation reduction**
Running on the nushell repo root as the directory, this change reduces the
allocation volume by approximately 400 MB
(Measured run via KDE heaptrack)
**Speed improvement to output**
Measured via `/usr/bin/time -v`
*before*
```
Command being timed: "./eager_nu -c for i in 0..1000 {ls} | flatten | table"
User time (seconds): 0.87
System time (seconds): 0.14
Percent of CPU this job got: 87%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:01.16
Average shared text size (kbytes): 0
Average unshared data size (kbytes): 0
Average stack size (kbytes): 0
Average total size (kbytes): 0
Maximum resident set size (kbytes): 18888
Average resident set size (kbytes): 0
Major (requiring I/O) page faults: 0
Minor (reclaiming a frame) page faults: 4809
Voluntary context switches: 38
Involuntary context switches: 14
Swaps: 0
File system inputs: 0
File system outputs: 0
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 0
Page size (bytes): 4096
Exit status: 0
```
*after*
```
Command being timed: "./lazy_nu -c for i in 0..1000 {ls} | flatten | table"
User time (seconds): 0.63
System time (seconds): 0.14
Percent of CPU this job got: 80%
Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.97
Average shared text size (kbytes): 0
Average unshared data size (kbytes): 0
Average stack size (kbytes): 0
Average total size (kbytes): 0
Maximum resident set size (kbytes): 18660
Average resident set size (kbytes): 0
Major (requiring I/O) page faults: 0
Minor (reclaiming a frame) page faults: 5149
Voluntary context switches: 24
Involuntary context switches: 5
Swaps: 0
File system inputs: 0
File system outputs: 0
Socket messages sent: 0
Socket messages received: 0
Signals delivered: 0
Page size (bytes): 4096
Exit status: 0
```
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| .gitignore | ||
| Cargo.toml | ||