to avoid unncessary error message generation, check the first some
characters before parsing it. It makes parsing process faster and
is also helpful to generate more accurate error messages.
all the parsers generate error messages and error message generation is
not a lightweight task. It concatenates a lot of strings, it formats
many values, etc. To avoid useless error-message generation, first check
which prefix is used and then parse special integers. Additionally, by
checking that, the quality of the error message can be improved (later).
`location::line_num()` function used to be implemented by using
`std::count`, so each time the parser encounters a type mismatch,
`std::count` was called with almost whole file. It decelerates the
parsing process too much, so I decided to add `line_number_` member
variable to `location` and add `advance/retrace/reset` to `location`
in order to modify the position that is pointed.
in 2.0.x and 2.1.0, README says "it shows warning" for invalid unicode
codepoints. So far, this library just show an error message in stderr
for this case. It is not good to change the behavior fatal in the next
minor release, 2.1.1, that includes patches and improved error msgs.
I will make it throw syntax_error after 2.2.0 for invalid unicode
codepoints. For now, I will keep it to be "warning".
Error messages related to dotted keys looks weird. like:
1 | a.b.c = 42
| ~~ in this table
The underlined token is not a table. This should be like the following.
1 | a.b.c = 42
| ~~~ in this table
To implement this, the region information is needed when the keys are
read. This commit add this functionality, though currently the region
information is not used yet.
like, with the following (invalid) toml file
> a.b = "value"
> a.b.c = 42
The error message becomes
> terminate called after throwing an instance of 'toml::syntax_error'
> what(): [error] toml::insert_value: target (a.b) is neither table nor
> an array of tables
> --> example.toml
> 1 | a.b = "value"
> | ~~~~~~~ actual type is string
> ...
> 2 | a.b.c = 42
> | ~~ inserting this
it is convenient to have get_region function that can access region_info
in toml::value. get_region is placed in toml::detail and made friend of
toml::value because I don't want to make toml::value::region_info public
and keep it internal use only.
before this, it recommends the range that can be represented by utf-8
but the range of valid unicode codepoint is narrower than that. for
error message, it is good to recommend valid unicode codepoint.
location constructed from token string does not has correct line number
information. to show an informative error message about UTF-8 and escape
sequences, parse_(ml_)basic_string requires those information that can
only be given from root location<Container>.
