Grit is a query language for searching and modifying codebases.
| Syntax | Explanation |
|---|---|
`console.log($_)` | The root of a Grit query is a pattern. |
`console.log` | A pattern can be a code snippet surrounded in backticks. |
`console.log($message)` | Code snippets can contain metavariables prefixed with $. |
$_ | The anonymous metavariable can be bound to without a name. |
$... | $... is a spread metavariable that matches 0 or more nodes. |
call_expression() | AST nodes can also be used as patterns. |
call_expression(callee=$callee) | AST nodes can specify fields, where each field value is bound to a pattern or metavariable. |
`console.log($message)` => `console.warn($message)` | A rewrite is a pattern followed by a => followed by a pattern. Rewrites are usable as patterns. |
$x => . | The |
r"console\.(log\|warn)"($method) | Regular expressions can be used as patterns, prefixed with r" and followed by capture variables. |
$list = [1, 2, 3] $one = $list[0] $three = $list[-1] | Lists can be accessed via index, where negative indices count from the end of the list. |
$map = { a: 1, b: 2, c: 3 }
$c = $map.c | Maps can be accessed via dot notation. Map keys must be strings. |
or {`console.log`, `console.warn`} | Compound patterns can be combined with and, or, and any clauses. |
not `console.log` | not clauses can be used to negate a pattern. |
maybe `console.log` | maybe clauses can be used to optionally match against a pattern, without failing the query. |
contains `console` | contains clauses can be used to match any node that contains a specific pattern by traversing downwards through the syntax tree. |
within `function() { $_ }` | within clauses search up the syntax tree for a matching node. |
after `console.warn($_)` |
|
`console.log($message)` as $log | as clauses can assign a pattern to a metavariable. |
$statements <: some `console.log($_)` | some matches lists where at least one element matches a pattern. |
`console.log($message)` where { ... } | A where clause can be added after a pattern to introduce conditions that restrict when the pattern matches. |
`console.log($message)` where {
$message <: "Hello world"
} | Inside the where clause, the <: operator is used to match metavariables against a pattern. |
`console.log($_)` where {
$new = "Hello world"
} => `console.log($new)` | The where block can also assign values to metavariables using =. Variables can be lists, code snippets, or strings. |
`console.log($message)` where {
$new = "Hello",
$new += "world"
} => $new | Strings and lists can be appended to using +=. (ex. ) |
`function() { $body }` where {
$body <: contains bubble {
`console.log($body)` =>
`console.warn($body)`
}
} | The default scope of a GritQL pattern is global. The bubble clause can be used to create a new scope within which all metavariables are isolated from surrounding code. |
`function $name() { $body }` where {
$body <: contains bubble($name) {
`console.log($message)` =>
`console.warn($message, $name)`
}
} | The bubble clause optionally accepts arguments, which can be used to "pierce" the bubble by allowing metavariables to preserve the values they had outside the bubble scope. |
`console.log` limit 10 | The limit clause can be used to limit the number of files returned by a query. |
// this is a comment | Comments in GritQL start with // and are ignored by the parser. |
sequential {
`console.log` => `console.error`,
`console.warn` => `console.info`
} | sequential clauses can be used to contain multiple patterns that are applied to the same file in order. |
function custom_example($name) {
return `name: $name`
} | Custom functions can be used to define reusable right-side values. |
function mod($value) js {
return $value % 2
} | Custom functions be written in JavaScript by adding the js keyword parameters. |