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reg/xscan - Search text or byte strings

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Synopsis
Description
Error Handling
Examples
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Author

reg/xscan write, [text], [find]
reg/xscan write, [text], [find], #offset

Searches given text argument, which may be a text or byte string, for the sub-string find, returning in the write argument the offset within text where the find string was located. The returned offset will be represented as a psInteger encoded as a PSUNIT_TYPE_XVALUE where the first character position is index 0.

If the find sub-string could not be located within the given text, then a NULL pointer will be returned instead of a raw index.

If the optional offset argument is provided, this may be a raw index or a psInteger encoded as a PSUNIT_TYPE_XVALUE and indicates the starting position for the search. If omitted, the start position is the first character (index 0).

A runtime error is generated if an argument provided is of the wrong type.

The following searches the standard input for any lines containing the text "Function:", and sends matching lines to standard output:

.main   % Prepare registers reg/load P9, ![.prose.sys.io] attr/load P10, [psStreamIn], P11, [psStreamOut] reg/load P12, [Function:]       % string to search .loop   % Load next line from stdin attr/copy P0, P9, P10 reg/jmpeq &[.exit], P0, NULL % Search for text reg/xscan P1, P0, P12 % If text was found, send line to stdout reg/jmpeq &[.clr], P1, NULL attr/mod P9, P11, P0 local/jmp &[.loop] .clr   % Free string and continue loop reg/clr P0 local/jmp &[.loop] .exit   func/rtn

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