QUILT - Little Quilt

no tags 

Little Quilt is a small language introduced by Ravi Sethi in his book ‘Programming Languages’.

Here, a restricted version of Little Quilt is presented. The language is defined by the following BNF grammar:

< QUILT > ::= A | B | turn(< QUILT >) | sew(< QUILT >,< QUILT >)

A and B represent the two primitive quilts. Each primitive quilt corresponds to a matricial arrangement of 2 × 2 characters. turn() and sew() are operations over quilts.

The instruction turn(x) turns the quilt x 90 degrees clockwise. The following table illustrates the primitive quilts as well as examples of the effect of the turn() operation:

subir imagenes

Accordingly, the instruction sew(x,y) sews quilt x to the left of quilt y. Both x and y must have the same height, otherwise an error will be generated. The following figure represents the result of sew(A,turn(B)):

subir imagenes

while the sew(turn(sew(B,turn(B))),A) generates an error message.

Your job is to build an interpreter of the Little Quilt language.


The input file will be a text file containing different Little Quilt expressions, each one ended by a semicolon character (;). Space and new line characters must be ignored; this means that an expression may span several lines.


The output file contains the quilts produced as a result of interpreting the input expressions.

Each quilt must be preceded by a line, left aligned, with the format

Quilt i:
where i is the quilt number, starting at 1. If the expression interpretation generates and error, the word

must be printed.


turn(sew(turn(B),B))) ;

sew(turn(sew(B,turn(B))),A); sew(turn(sew(A,turn(A))), turn(turn(
turn(sew(A,turn(A)))))) ; Output: Quilt 1: ||-- ||-- --|| --|| Quilt 2: error Quilt 3: \\// +\/+ +/\+ //\\

hide comments
niabbf: 2016-11-05 02:38:28

What is the data's range? What size will the final graph be ?

Benito: 2013-12-03 04:27:24

Hi I need the solve of this problem :( I dont have time for solve, its for school, please send me the code in Java, send me to produccionesbenito@hotmail.com

Santiago Palacio: 2011-06-27 03:55:38

Can we assume the input is valid? i mean, there will be no expressions like sew(a); ?

abhijith reddy d: 2009-10-10 02:43:19

A Tedious one !!

Added by:Camilo Andrés Varela León
Time limit:0.200s-0.400s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ERL JS-RHINO NODEJS PERL6 VB.NET
Resource:XX Colombian National Programming ACM 2006