cgrep

cgrep is an npm package for writing project checks with regex.

It includes

• A command, yarn cgrep, which runs all project checks against all project files.
• An extended regex grammar for finding code patterns.

yarn add -D cgrep

command

> yarn cgrep -h
Usage: cgrep [options]

Checks project files against cgrep rules.

Options:
  -V, --version         output the version number
  -s, --staged          only check git staged files
  -d, --debug           print debug information
  -p, --project <path>  path to tsconfig.json
  -g, --glob <pattern>  only check files matching glob pattern
  --cwd <path>          set the current working directory
  -h, --help            display help for command

On run, cgrep will

1. Load all checks from cgrep.config.[ts,js] in the project root.
   • All publicly exported functions will be registered as a check. For example,

     import { cgrep, CGrepCheckArgs } from 'cgrep';
     export function avoidFooModule({ underline }: CGrepCheckArgs) {
         underline(
             cgrep`import $$ from 'foo'`,
             "Do not use foo module, prefer bar.",
             "warn");
     }

2. Each check will be run against all project files. .gitignore is respected. If a check returns boolean false or the string fail, the cgrep command will have a failure exit code.
   • Each check is passed the following args as an object:

     /** Eg 'src/components/foo.js'. Relative posix path format. */
     filePath: string;
     
     /** Eg 'example.js' */
     fileName: string;
     
     /** Eg '.js' */
     fileExtension: string;
     
     /** Eg 'console.log("hello world");' */
     fileContents: string;
     
     /** Function to underline a string or regexp in `fileContents` and log it to console. */
     underline: (
         regexOrText: RegExp | string,
         message: string,
         alert?: 'error' | 'warn' | 'info'
     ) => void;

cgrep can be plugged in as part of a lint step in CI:CD or as a git commit hook.

module

cgrep exports typings and one string interpolation function, cgrep.

cgrep returns a standard RegExp object with two extra functions, matchFirst and matchAll. You can think of it as regex specifically for JavaScript code.

$a: match any variable.
$1: match any literal.
$@: match any operator.
$#: match any keyword.
$$: match any block (non-greedy).
$$$: match any block (greedy).
REGEX(): match any regex.

Let's look at some examples.

cgrep`if ($a == $b) { return $c; }`
    matches:
        1. if (foo == bar) {
            return baz;
        }
        2. if (apple==orange){return banana;}
cgrep`$1 + $2 + $3`
    matches:
        1. 44 + "hello world" + 3.14159
        2. 1 + 2 + 3
        3. 1 + 1 + 1
cgrep`if (a $@ b)`
    matches:
        1. if (a + b)
        2. if(a-b)
        3. if(a   <  b)
cgrep`$# (true)`
    matches:
        1. while (true)
        2. if ( true )
cgrep`do { $$ } while(true)`
    matches
        1. do {
            console.log(foo);
            log("cool");
        }   while  (true)
        2. do {} while(true)
cgrep`REGEX(3+9+2*) 5 + 5`
    matches
        1. 392225+5

There is a live cgrep expression playground here.
You can also view the test suite for more examples.