How to resolve the algorithm Strip block comments step by step in the SNOBOL4 programming language
Published on 12 May 2024 09:40 PM
How to resolve the algorithm Strip block comments step by step in the SNOBOL4 programming language
Table of Contents
Problem Statement
A block comment begins with a beginning delimiter and ends with a ending delimiter, including the delimiters. These delimiters are often multi-character sequences.
Strip block comments from program text (of a programming language much like classic C).
Your demos should at least handle simple, non-nested and multi-line block comment delimiters.
The block comment delimiters are the two-character sequences:
Sample text for stripping: Ensure that the stripping code is not hard-coded to the particular delimiters described above, but instead allows the caller to specify them. (If your language supports them, optional parameters may be useful for this.)
Let's start with the solution:
Step by Step solution about How to resolve the algorithm Strip block comments step by step in the SNOBOL4 programming language
Source code in the snobol4 programming language
* Program: strip_block_comments.sbl
* To run: sbl -r extract_extension.sbl
* Description: Strip block comments.
* Can use different begin and end delimiters.
* Handles comment nesting and unmatched end delimiters.
* Unmatched begin delimiters remove text to end of file.
* Does not handle quoted delimiters.
* Most null lines are removed, which may not be
* what is desired.
* Comment: Tested using the Spitbol for Linux version of SNOBOL4
* Function strip_block_comments will read a file, or the text after
* the END statement below. Parameter bcom is the beginning comment
* string and parameter ecom is the ending comment string.
*
define('strip_block_comments(bcom,ecom)break_chars,c,newc,pre,pc,b')
pat1 = breakx(*break_chars) . pre (*bcom | *gt(b,0) *ecom) . pc
:(strip_block_comments_end)
strip_block_comments
break_chars = substr(bcom,1,1) substr(ecom,1,1)
newc = ""
b = 0
in1
c = input :f(p60)
p10
c ? pat1 = "" :f(p20)
* matches
le(b,0) :s(leb)f(gtb)
leb
b = leq(pc,bcom) b + 1 :f(leb2)
newc = newc pre :(p10)
leb2
b = leq(pc,ecom) b - 1 :f(error)
:(p10)
gtb
b = leq(pc,bcom) b + 1
b = leq(pc,ecom) b - 1
:(p10)
* nomatches
p20
newc = lt(b,1) newc c
ident(newc) :s(in1)
:(p50)
p50
output = newc
newc = "" :(in1)
p60
output = differ(newc) newc
:(return)
strip_block_comments_end
* Set "begin" comment delimiter (bcom) and "end" comment delimiter (ecom) below
bcom = "/*"
ecom = "*/"
* bcom = "{{*"
* ecom = "?/"
* Strip block comments from the text lines after the END statement
strip_block_comments(bcom,ecom)
END
/**
* Some comments
* longer comments here that we can parse.
*
* Rahoo
*/
function subroutine() {
a = /* inline comment */ b + c ;
}
/*/ <-- tricky comments */
/**
* Another comment.
*/
function something() {
}
----------------------------------------------
With nested comments/* Nested /* comment*/s*/*/!
Unmatched"/*" end delimiters simply remove
to end of file
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