[jira] [Comment Edited] (CALCITE-5305) Support string constants with c-style escapes

["Dmitry Sysolyatin (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CALCITE-5305?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17619413#comment-17619413 ] 

Dmitry Sysolyatin edited comment on CALCITE-5305 at 10/18/22 9:52 AM:
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[~julianhyde] Sorry for late response. I used it because it merges doubled single-quotes as you wrote in your comment. C-style escaped string has the same behaviour.

Also the sequence {{\''}} will not be parsed because
{code:java}
CSTYLE_ESCAPED_STRING_LITERAL: "E" <QUOTE> ( (~["'", "\\"]) | ("\\" ~[]) | "''")* <QUOTE>{code}
Parsing {{'ab\''cd}} throws exception. I will add test case for that


was (Author: dmsysolyatin):
[~julianhyde] Sorry for late response. I used it because it merges doubled single-quotes as you wrote in your comment. C-style escaped string has the same behaviour.

Also the sequence {{\''}} will not be parsed because
{code:java}
"E" <QUOTE> ( (~["'", "\\"]) | ("\\" ~[]) | "''")* <QUOTE>{code}
Parsing {{'ab\''cd}} throws exception. I will add test case for that

> Support string constants with c-style escapes
> ---------------------------------------------
>
>                 Key: CALCITE-5305
>                 URL: https://issues.apache.org/jira/browse/CALCITE-5305
>             Project: Calcite
>          Issue Type: Improvement
>          Components: core
>            Reporter: Dmitry Sysolyatin
>            Assignee: Dmitry Sysolyatin
>            Priority: Major
>              Labels: pull-request-available
>
> Support string constants with c-style escapes. Example:
> {code:java}
> select e'\u0061\x61\141' as col1;
>  col1 
> ------
>  aaa
> (1 row)
> {code}
> From PostgreSQL documentation [4.1.2.2. String Constants With C-Style Escapes|https://www.postgresql.org/docs/14/sql-syntax-lexical.html#SQL-SYNTAX-CONSTANTS]:
> An escape string constant is specified by writing the letter {{E}} (upper or lower case) just before the opening single quote, e.g., {{{}E'foo'{}}}. (When continuing an escape string constant across lines, write {{E}} only before the first opening quote.) Within an escape string, a backslash character (\) begins a C-like _backslash escape_ sequence, in which the combination of backslash and following character(s) represent a special byte value, as shown in Table:
> ||Backslash Escape Sequence||Interpretation||
> |\b|backspace|
> |\f|form feed|
> |\n|newline|
> |\r|carriage return|
> |\t|tab|
> |\o, \oo, \ooo (o = 0–7)|octal byte value|
> |\xh, \xhh (h = 0–9, A–F)|hexadecimal byte value|
> |\uxxxx, \Uxxxxxxxx (x = 0–9, A–F)|16 or 32-bit hexadecimal Unicode character value|
> I suggest to not introduce any configuration flags for this feature because it seems like it does not contradict with any SQL dialect and it shouldn't slow down queries parsing.



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