Re: Ltree syntax improvement

Dear Thomas,

Thank you for your proofreading!

Please find the updated patch attached. It also contains the missing
escaping.

On Mon, Jul 8, 2019 at 10:39 AM Thomas Munro <thomas.munro@gmail.com> wrote:

> On Wed, Apr 17, 2019 at 5:29 AM Dmitry Belyavsky <beldmit@gmail.com>
> wrote:
> > I've applied your patch.
> > From my point of view, there is no major difference between case and
> chain if here.
> > Neither case nor ifs allow extracting the common code to separate
> function - just because there seem to be no identical pieces of code.
>
> Hi Dmitry,
>
> The documentation doesn't build[1], due to invalid XML.  Since I'm
> here, here is some proof-reading of the English in the documentation:
>
>    <para>
> -   A <firstterm>label</firstterm> is a sequence of alphanumeric characters
> -   and underscores (for example, in C locale the characters
> -   <literal>A-Za-z0-9_</literal> are allowed).  Labels must be less
> than 256 bytes
> -   long.
> +   A <firstterm>label</firstterm> is a sequence of characters. Labels
> must be
> +   less than 256 symbols long. Label may contain any character
> supported by Postgres
>
> "fewer than 256 characters in length", and
> "<productname>PostgreSQL</productname>"
>
> +   except <literal>\0</literal>. If label contains spaces, dots,
> lquery modifiers,
>
> "spaces, dots or lquery modifiers,"
>
> +   they may be <firstterm>escaped</firstterm>. Escaping can be done
> either by preceeding
> +   backslash (<literal>\\</literal>) symbol, or by wrapping the label
> in whole in double
> +   quotes (<literal>"</literal>). Initial and final unescaped
> whitespace is stripped.
>
> "Escaping can be done with either a preceding backslash [...] or by
> wrapping the whole label in double quotes [...]."
>
>    </para>
>
> +    During converting text into internal representations, wrapping
> double quotes
>
> "During conversion to internal representation, "
>
> +    and escaping backslashes are removed. During converting internal
> +    representations into text, if the label does not contain any special
>
> "During conversion from internal representation to text, "
>
> +    symbols, it is printed as is. Otherwise, it is wrapped in quotes and,
> if
> +    there are internal quotes, they are escaped with backslash. The
> list of special
>
> "escaped with backslashes."
>
> +  <para>
> +    Examples: <literal>42</literal>, <literal>"\\42"</literal>,
> +    <literal>\\4\\2</literal>, <literal> 42 </literal> and <literal> "42"
> +    </literal> will have the similar internal representation and, being
>
> "will all have the same internal representation and,"
>
> +    converted from internal representation, will become
> <literal>42</literal>.
> +    Literal <literal>abc def</literal> will turn into <literal>"abc
> +    def"</literal>.
>    </para>
>
> [1] https://travis-ci.org/postgresql-cfbot/postgresql/builds/555571856
>
> --
> Thomas Munro
> https://enterprisedb.com
>


-- 
SY, Dmitry Belyavsky