Mark Nunberg > JSON-SL > JSON::SL::EscapeTH



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unescape_settings($character, $boolean)

Inspects and modifies the preferences for unescaping JSON strings. JSON allows several forms of escape sequences, either via the \uXXXX form, or via a two- character 'common' form for specific characters.


For \uXXXX escapes, the single or multi-byte representation of the encoded character is placed into the resultant string, thus:

    \u0041 becomes A

For JSON structural tokens, the backslash is swallowed and the character following it is left as-is. JSON requires that these characters be escaped.

    \"     becomes "
    \\     becomes \

Additionally, JSON allows the / character to be escaped (though it is not a JSON structural token, and does not require escaping).

    \/     becomes /

For certain allowable control and whitespace characters, the escape is translated into its corresponding ASCII value, thus:

    \n    becomes chr(0x0A) <LF>
    \r    becomes chr(0x0D) <CR>
    \t    becomes chr(0x09) <TAB>
    \b    becomes chr(0x08) <Backspace>
    \f    becomes chr(0x0C) <Form Feed>

Any other two-character escape sequence is not allowed, and JSON::SL will croak upon encountering it.

By default, all that is allowed to be escaped is also automatically unescaped, but this behavior is configurable via the unescape_settings

Called without any arguments, unescape_settings returns a reference to a hash. Its keys are valid ASCII characters and its values are booleans indicating whether JSON::SL should treat them specially if they follow a \.

Thus, to disable special handling for newlines and tabs:

    delete @{$json->unescape_settings}{"\t","\n","\r"};

If unescape_settings is called with one or two arguments, the first argument is taken as the character, and the second argument (if present) is taken as a boolean value which the character should be set to:

Check if forward-slashes are unescaped:

    my $fwslash_is_unescaped = $json->unescape_settings("/");

Disable handling for \uXXXX sequences:

    $json->unescape_settings("u", 0);
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