3.1 Basic Input File Processing

3.1 Basic Input File Processing

In order to read in an input file or include file, the scanner calls

a submodule called the 

mapper

 that reads a file in and creates a

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contiguous copy of it in memory. The scanner then performs

three checks on the file, the first (file termination) of which is

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performed before scanning commences, and the other two of

which take place during scanning before each line is scanned.

Reference

File Termination:

 The first check the scanner

1 Introduction

makes is whether the file is terminated properly. A

2 Interface

file is considered to be properly terminated if it

either contains no lines, or if the last line in the file

3 Scanner

is terminated by an end of line marker. If the

4 Parser

scanner detects that an input file is not properly

5 Analyser

terminated, it adds an end of line marker itself (to

6 Tangle

the copy in memory only).

7 Weave

Unprintable Characters:

 The second check the

8 Shell

scanner makes is for unprintable characters (ASCII

9 Commands

0  31 and 127  255 (except for EOL(10))) which it

10 Glossary

flags as errors and replaces by question marks.

11 References

Line Lengths:

 The third check the scanner makes

is input line length. When FunnelWeb starts up, a

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default maximum input line length of 80 is set.

This can be changed dynamically during scanning

using a @p maximum_input_line_length pragma.

If the number of characters on a line (not including

the end of line marker) exceeds this limit,

FunnelWeb generates an error.

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Copyright   Ross N. Williams 1992,1999. All rights

reserved.

http://www.ross.net/funnelweb/reference/scanner_basic.html [3/3/2000 10:47:07 PM]