Re: Ltree syntax improvement

On Wed, Apr 17, 2019 at 5:29 AM Dmitry Belyavsky <beldmit(at)gmail(dot)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