3.5 Inserting Arbitrary Characters into the Text

3.5 Inserting Arbitrary Characters into the

Text

While FunnelWeb does not tolerate unprintable characters in the input file

Tutorial

(except for the end of line character), it does allow the user to specify that

unprintable characters appear in the product file. The @^ sequence inserts a

Developer

single character of the user s choosing into the text. The character can be

specified by giving its ASCII number in one of four bases: binary, octal,

Reference

decimal, and hexadecimal. Here is the syntax:

1 Introduction

2 Interface

control_sequence = "@^" char_spec

3 Scanner

char_spec        = binary  | octal |

4 Parser

                   decimal | hexadecimal

5 Analyser

binary           = ("b" | "B")

6 Tangle

                   "(" {binary_digit}8  ")"

7 Weave

octal            = ("o" | "O" | "q" | "Q")

                   "(" {octal_digit}3   ")"

8 Shell

decimal          = ("d" | "D")

9 Commands

                   "(" {decimal_digit}3 ")"

10 Glossary

hexadecimal      = ("h" | "H" | "x" | "X")

11 References

                   "(" {hex_digit}2     ")"

binary_digit     = "0" | "1"

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octal_digit      = binary_digit | "2" | "3" |

                   "4" | "5" | "6" | "7"

decimal_digit    = octal_digit | "8" | "9"

hex_digit        = decimal_digit |

                   "A" | "B" | "C" | "D" | "E" | "F" |

                   "a" | "b" | "c" | "d" | "e" | "f"

Example:

@! Unix Make requires that productions

@! commence with tab characters.

@^D(009)prog.o <  prog.c

Note that the decimal "

9

" is expressed with leading zeros as "

009

". FunnelWeb

requires a fixed number of digits for each base. Eight digits for base two, three

digits for base ten, three digits for base eight and two digits for base sixteen.

FunnelWeb treats the character resulting from a @^ sequence as ordinary text in

every sense. If your input file contains many instances of a particular control

character, you can package it up in a macro like any other text. In particular,

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