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Doc/libimagutil
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Matthias Beyer 2016-03-07 17:18:50 +01:00
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doc/src/03000-lib-util.md
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@ -9,11 +9,63 @@ used by all other libraries and/or binaries.
It is explicitely not intended for module-use only, but for all other libraries.
## Datatypes {#sec:libutil:datatypes}
## Key-Value split {#sec:libutil:kvsplit}
_Nothing here yet_
This helper implements functionality to split key-value string into two parts.
It was introduced to simplify commandline specification for header fields (see
@lst:kvsplit:headerspec).
## Functions {#sec:libutil:functions}
```{#lst:kvsplit:headerspec .bash .numberLines caption="Headerfield spec"}
imag store create --path /some.entry entry --header field=foo
# ^^^^^^^^^
```
_Nothing here yet_
It is implemented by introducing a `KeyValue` type which is generic over Key
and Value. This type gets implemented `KeyValue<String, String> for String` to
be able to split a `String` into two `String` objects, key and value
respectively. The implementation is realized via Regex.
The `KeyValue` type implementes `Into<(K, V)>` for convenience.
## Error tracing {#sec:libutil:errortrace}
The error tracing functions are functions which help printing an error chain
to the user.
It allows to trace nested errors like @lst:errtrace:exampleerror to the user
in a backtrace-ish way (@lst:errtrace:exampletrace).
```{#lst:errtrace:exampleerror.rust .numberLines caption="Error chain"}
ErrA::new(a_errorkind,
Some(Box::new(ErrB::new(b_errorkind,
Some(Box::new(ErrC::new(c_errorkind,
None)))
)))
)
```
The variants of the function allow limiting the trace to a certain depth or
printing the error trace to the debug output stream.
```{#lst:errtrace:exampletrace .numberLines caption="Error trace"}
[Error][c_errorkind]: Some C-error text -- caused:
[Error][b_errorkind]: Some B-error text -- caused:
[Error][a_errorkind]: Some A-error text
```
## Variant generator {#sec:libutil:vargen}
The `generate_variants()` function can be used to generate variants of a base
vector value.
```{#lst:vargen:exampleuse .rust .numberLines caption="Variant generation"}
let base = 1;
let vars = vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
let res = generate_variants(base, vars, &|base, var| base + var);
assert!(res == vec![1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
```
As shown in @lst:vargen:exampleuse (from the tests), can this function
be used to generate values from a base value.