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Line parsing

 

Every line input to [B/D] is parsed before being passed to the command line interpreter. The parsing consists of replacing various of the characters in the line by other characters, and of the removal of redundant spaces. In particular we use the pair of square brackets `[ ]' to enclose text that might be replaced.

All command lines have leading and trailing spaces removed. All command lines ignore other spaces (except the space separating command from arguments) and are converted to lower case. Exceptions are the PRINT: , TITLE: , PRINT: , ITITLE: , and STRING:  commands, where space and case conversions are not carried out except as necessary. Substrings are, however, parsed completely, for the STRING:  command.

The parsing of lines to replace material enclosed in square brackets takes place before any other operation. The material that might be replaced is as follows:

Priority is decided by deepest nesting. Unrecognised quantities in [ ...] are not erased from the command line.


next up previous contents index
Next: Multiple lines Up: The [B/D] input interface Previous: Command lines

David Wooff
Wed Oct 21 15:14:31 BST 1998