In most programming languages, the compiler carries a preprocessing step to dete
ID: 3607077 • Letter: I
Question
In most programming languages, the compiler carries a preprocessing step to determine if certain statements will compile. For instance it may check to see if parentheses match.
Write a Java program that simulates the actions of a preprocessor, to detect if certain Java constructs are syntactically correct. Table 1 shows the types of Java statement formats under consideration, and also example of each statement.
Table 1
Format Example
Statement data_type = expression int x = 3 + (10 – 4) * ( 10 + 4)
Method <attrib> rt name(<parameter>) public void display(int n)
{ {
<stetament> int arr[ ] = new int[n];
} System.out.println( x[2] );
}
Class <attrib> class Name public class MyParser
{ {
dt fields; public static void main(String [ ] arg)
<attrib> Name(<parameter>) {
{ display (10);
method(<parameter>); }
} static void display(int x)
{
{ /*
} My pre-processor
*/
}
}
Table 2 shows the delimiters under consideration.
Table 2
Delimiters Symbol
Left parenthesis (
Right parenthesis )
Left curly braces {
Right curly braces }
Left square brackets [
Right square brackets ]
Forward slash /
Star (multiplication symbol) *
Note: In your implementation, design a class called Preprocessor that accepts a file that represents the program to be analyzed. The class will contain, among other possible methods, a method that determines whether or not the statement in the file are valid, with respect to the delimiters of Table 2. Do not be concerned with other symbols.
1. You will need a test class. You may want to name it MyPreprocessor.
2. You may have to enter all statements on a single line, unless you will be reading the input from a file, in which case the file would be read using presumable the class BufferedReader or LineNumberReader.
3. Your output would echo the input, and say whether or not the input passed the preprocessing stage.
4. You are to use the concept of stack to determine if the constructs are syntactically correct.
Explanation / Answer
package com.company; import java.io.IOException; import java.nio.file.Files; import java.nio.file.Paths; import java.util.Stack; /* * A program which reads input from given text filename and prints * whether it passed the pre-processing stage or not * Sample input * int A = (a + b);static void display(int x) * { * //A sample input file * } * */ public class MyPreprocessor { /* * Reads input from filename and returns a string * containing whole text * */ public String readInput(String filename) { String content = ""; try { content = new String(Files.readAllBytes(Paths.get(filename))); } catch (IOException e) { e.printStackTrace(); } return content; } /** * Filters input since we are only concerned with * a subset of input = '{}[]()/*' */ public String filterText(String text) { String output = ""; for(int i = 0;iRelated Questions
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