Task A. Removing indentation

Before we make a program that indents source code files, lets make a program that unindents them.

Start by writing a function

string removeLeadingSpaces(string line); 

that takes one line of code as input and returns its copy without leading spaces and tabs:

removeLeadingSpaces(" int x = 1; ") == "int x = 1; " 

Make use of the function isspace defined in to check if a character is a whitespace. Your function should probably iterate over the input string, skip all spaces, and after it finds the first non-space character, start accumulating the characters into a new string, which will be returned.

Write a program unindent.cpp that reads input from cin and prints out each input line with leading spaces removed.

Example:

To test, create a badly indented file, for instance, called bad-code.cpp:

 int main(){ // Hi, I'm a program! int x = 1; for(int i = 0; i < 10; i++) { cout << i; cout << endl; } } 

Since our unindent program reads its input from cin, the badly indented text can be fed into it using standard input redirection:

$ ./unindent < bad-code.cpp int main(){ // Hi, I'm a program! int x = 1; for(int i = 0; i < 10; i++) { cout << i; cout << endl; } } 

Task B. Counting blocks opened and closed by { and }, and adding real indentation

To count open blocks, we need to count how many curly braces get opened and closed on each line, so we need to count { and }

Write a function

int countChar(string line, char c); 

that scans the line and returns the number of occurrences of the character c.

Write a new program indent.cpp that enhances the program from the previous task. As it reads the input line by line, it should also count the number of open and closed { } in it, and keep track of how many blocks is currently open at the beginning of each line.

In the listing below, the number of open blocks is shown on the left:

0 int main(){ 1 // Hi, I'm a program! 1 int x = 1; 1 for(int i = 0; i < 10; i++) { 2 cout << i; 2 cout << endl; 2 } 1 } 

Then instead of printing the number of open blocks, add that number of tabs '\t' at the beginning of each line, and you will get:

int main(){ // Hi, I'm a program!  int x = 1; for(int i = 0; i < 10; i++) { cout << i; cout << endl; } // <-- closing for loop  } // <-- closing main 

Notice that the closing curly braces are indented one level further than what they should be.

To fix that, when indenting the line, check its very first character. If it is a closing curly brace }, its indentation level should be reduced by one:

int main(){ // Hi, I'm a program!  int x = 1; for(int i = 0; i < 10; i++) { cout << i; cout << endl; } } 

Shortcomings of our program:

No support for loops and if statements that dont have curly braces. For example,

if (c == 'A') s = s + c; 

will be incorrectly indented as

if (c == 'A') s = s + c; 

No support for // and /* */. Commented out curly braces should not affect indentation

Symbols {, } inside string and char literals are misinterpreted as blocks

if (true) { s = "\{\{"; t = "ABC"; } 

will be incorrectly indented as

if (true) { s = "\{\{"; t = "ABC"; } 

7A code:

#include #include using namespace std; string removeLeadingSpaces(string line); int main() { string line; while(getline(cin, line)) { cout << removeLeadingSpaces(line) << endl; } return 0; } string removeLeadingSpaces(string line) { string result = ""; bool check = true; for(int i = 0; i < line.size(); ++i) { if(!(check && isspace(line[i]))) { result += line[i]; check = false; } } return result; }