How can I find if and for statements without brace

问题:

I'm looking at a project in which some if and for statements do not have their associated brackets, like so:

if(condition)
  single_line_statement;
for(int i=0;i<10;i++)
  single_line_statement;

I want to find these statements!

However, this is made challenging by the existence of code with two different bracketing styles:

if(condition){
   stuff;
}

and

if(condition(a) && condition(b))
{
  stuff;
}

as well as by complex statements such as (note the nested brackets):

for (auto const &x : y)
{
    for (auto const &m : ted.bob())
    {
        if (m.n(o) != 0)
        {
            p[q] = true;
        }
        r["s"].push_back(rn.t(u));
    }
}

How can I find the if and for statements without brackets?

回答1:

To solve this problem, I created a handy dandy script:

#!/bin/bash
find . -name '*.h' -o -name '*.cpp' | #Find all C++ files
  xargs pcregrep -A 1 -nHM '\b(?:if|for)\s*(\(([^()]++|(?1))*\))(?!.*{|.*\n.*{)'

This finds all the C++ files and then examines the contents of each file as a single, long line using a Perl Compatible Regular Expression. This expression uses recursion (?1) to extract the (condition) following the if and for statements and the . character to match characters which are not newlines and the \n constant to match new lines. Negative-lookahead (?!...) is used to find the lines without braces.

The regular expression can be tested online here.

The output looks like this:

./dir1/file1.cpp:845:        if (!a)
./dir1/file1.cpp-846-            std::cout << "a not found!" << std::endl;
--
./dir2/file2.cpp:20:    if (b == NULL)
./dir2/file2.cpp-21-        throw std::runtime_error("b was NULL");

Since the script does not, in fact, parse C++, there are situations where it will misbehave. For instance, it will miss this:

if (condition) // An example {
  statement;

This answer leverages clang-tidy to provide a complete check, at the cost of having to incorporate clang-tidy into one's build system.

回答2:

I use vera++ to validate that code in my project conforms to specific style rules.

Vera: https://bitbucket.org/verateam/vera/wiki/Rules  
Rule: T019 Control structures should have complete curly-braced block of code