How to resolve the algorithm ASCII art diagram converter step by step in the Lua programming language

Published on 12 May 2024 09:40 PM
#Lua

How to resolve the algorithm ASCII art diagram converter step by step in the Lua programming language

Table of Contents

Problem Statement

Given the RFC 1035 message diagram from Section 4.1.1 (Header section format) as a string: http://www.ietf.org/rfc/rfc1035.txt Where (every column of the table is 1 bit): Write a function, member function, class or template that accepts a similar multi-line string as input to define a data structure or something else able to decode or store a header with that specified bit structure. If your language has macros, introspection, code generation, or powerful enough templates, then accept such string at compile-time to define the header data structure statically. Such "Header" function or template should accept a table with 8, 16, 32 or 64 columns, and any number of rows. For simplicity the only allowed symbols to define the table are + - | (plus, minus, pipe), and whitespace. Lines of the input string composed just of whitespace should be ignored. Leading and trailing whitespace in the input string should be ignored, as well as before and after each table row. The box for each bit of the diagram takes four chars "+--+". The code should perform a little of validation of the input string, but for brevity a full validation is not required. Bonus: perform a thoroughly validation of the input string.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm ASCII art diagram converter step by step in the Lua programming language

Source code in the lua programming language

local function validate(diagram)
  local lines = {}
  for s in diagram:gmatch("[^\r\n]+") do
    s = s:match("^%s*(.-)%s*$")
    if s~="" then lines[#lines+1]=s end
  end
  -- "a little of validation".."for brevity"
  assert(#lines>0, "FAIL:  no non-empty lines")
  assert(#lines%2==1, "FAIL:  even number of lines")
  return lines
end

local function parse(lines)
  local schema, offset = {}, 0
  for i = 2,#lines,2 do
    for part in lines[i]:gmatch("\|([^\|]+)") do
      schema[#schema+1] = { name=part:match("^%s*(.-)%s*$"), numbits=(#part+1)/3, offset=offset }
      offset = offset + (#part+1)/3
    end
  end
  return schema
end

local diagram = [[

  +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|                      ID                       |  
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|QR|   Opcode  |AA|TC|RD|RA|   Z    |   RCODE   |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|                    QDCOUNT                    |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

|                    ANCOUNT                    |    
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|                    NSCOUNT                    |

+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
|                    ARCOUNT                    |
  +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+  

]] -- extra whitespace added for testing

local schema = parse(validate(diagram))
print("NAME       NUMBITS    OFFSET")
print("--------  --------  --------")
for i = 1,#schema do
  local item = schema[i]
  print(string.format("%-8s  %8d  %8d", item.name, item.numbits, item.offset))
end

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