12.6 Reading From the Source

Chapter 12
PLVio: Reading and Writing PL/SQL Source Code

 

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The PLVio.get_line procedure is the core program for reading from the source. This header for this program is:

PROCEDURE get_line    (line_inout IN OUT line_type,     curr_line#_in IN INTEGER := NULL);

The first argument, line_inout, is a record of type line_type (defined in the PLVio specification). The second argument, curr_line#, provides a current line number; if that number is not NULL, it will be used to increment the line# value found in the line_inout record.

The record contains all the information about a line necessary either for PLVio activity or other actions on a line of text. The definition of the record TYPE is:

TYPE line_type IS RECORD    (text VARCHAR2(2000) := NULL,     len INTEGER := NULL,     pos INTEGER := 1,     line INTEGER := 0, /* line # in original */     line# INTEGER := 0, /* line # for new */     is_blank BOOLEAN := FALSE,     eof BOOLEAN := FALSE);

The following table explains the different fields of a line_type record:

text	The line of text.
len	The length of the line of text.
pos	The current position of a scan through this line.
line	The line number associated with this text in the source.
line#	The line number associated with this text in the target.
is_blank	TRUE if the text RTRIMS to NULL.
eof	TRUE if no line was placed into the record.

12.6.1 Main Steps of get_line

The get_line procedure has two main steps:

1. Read a line from the source repository. If reading from a database table, get_line uses the DBMS_SQL builtin package to fetch the next row and read the text and line number from the retrieved data. If reading from a file, get_line calls the PLVfile.get_line procedure. If reading from a string, get_line finds the next newline character and uses SUBSTR to extract the desired characters.

2. Massage the data retrieved from the repository so that the values of all record fields are set properly. Assuming that data was found (the eof field is not set to TRUE), then the following actions are taken: replace newline characters with single spaces, replace tab characters with three spaces, increment the line number (using the second argument in the call to get_line, if provided), set the pos field to 1, set is_blank to TRUE if the string is composed solely of blanks, and compute the length of the line of text.

When these two steps are completed, the newly populated record is returned to the calling program.