DEQUOTE

Name

dequote

Purpose (one Line Only)

Reconvert a string processed by QUOTE, or from the result of a MySQL query.

Description

In its simplest form this routine will take a string output from QUOTE
and convert it back to its input. This means removing leading and trailing
single quotes, and converting "\\" and "\'" to "\" and "'", respectively.
If the input string has embedded "\n" strings it will be broken into a
string array on the "\n" boundaries, with the '\n" themselves removed.
In this case, the output is a string vector- otherwise, it is a scalar.
Please note that because QUOTE is a many to one mapping in general,
the sequence dequote(quote(x)) returns a string that may not be
identical to x. (Eg, if x had leading blanks.) However, it should
be possible to use the output of DEQUOTE with QUOTE again and obtain
the same results with MySQl.
Using the /SELECTSQL flag allows quote to be used with the output of
mysql queries, particularly in processing TEXT and BLOB fields. The
main difference with SELECTSQL set is that embedded "\" and "'" fields are
left alone, except for \n which is again assumed to be a line boundary
and used to break the string into substring elements.

Calling Sequence

result = dequote(string)

Inputs

string - String to be processed

Optional Input Parameters

Keyword Input Parameters

SELECTSQL- Flag, if set some of the processing of dequote is not done,
specifically removal of backlash characters as escapes.

Outputs

return value is a scalar string, or a string array if the input contained
the "\n" escape sequence. Back to back "\n" (corresponding to empty lines)
in the input will result in empty substrings in the array returned.

Keyword Output Parameters

Common Blocks

Side Effects

Restrictions

Newlines are currently quoted with two characters: '\n' where the
n is a literal lower case n. DEQUOTE will not do anything with embedded
actual newline (012') characters, whether or not they are preceded by '\'.
Dequote has no equivalent of the LITERAL keyword for quote.
Dequote does not remove any empty lines- for example,
dequote('\n\n\string\n\n')
returns an array of 4 elements, 3 of which are empty strings.

Procedure

Modification History

Written by Peter L. Collins, 2006/10/27, Lowell Observatory
2006/12/11, PLC, small bug fix- to return scalar if 1 element.
2016/10/25, MWB, added support for quoted semi-colon