diff options
Diffstat (limited to 'third_party/rust/serde_json/src/macros.rs')
| -rw-r--r-- | third_party/rust/serde_json/src/macros.rs | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/third_party/rust/serde_json/src/macros.rs b/third_party/rust/serde_json/src/macros.rs new file mode 100644 index 0000000000..5287998b46 --- /dev/null +++ b/third_party/rust/serde_json/src/macros.rs @@ -0,0 +1,303 @@ +/// Construct a `serde_json::Value` from a JSON literal. +/// +/// ``` +/// # use serde_json::json; +/// # +/// let value = json!({ +/// "code": 200, +/// "success": true, +/// "payload": { +/// "features": [ +/// "serde", +/// "json" +/// ] +/// } +/// }); +/// ``` +/// +/// Variables or expressions can be interpolated into the JSON literal. Any type +/// interpolated into an array element or object value must implement Serde's +/// `Serialize` trait, while any type interpolated into a object key must +/// implement `Into<String>`. If the `Serialize` implementation of the +/// interpolated type decides to fail, or if the interpolated type contains a +/// map with non-string keys, the `json!` macro will panic. +/// +/// ``` +/// # use serde_json::json; +/// # +/// let code = 200; +/// let features = vec!["serde", "json"]; +/// +/// let value = json!({ +/// "code": code, +/// "success": code == 200, +/// "payload": { +/// features[0]: features[1] +/// } +/// }); +/// ``` +/// +/// Trailing commas are allowed inside both arrays and objects. +/// +/// ``` +/// # use serde_json::json; +/// # +/// let value = json!([ +/// "notice", +/// "the", +/// "trailing", +/// "comma -->", +/// ]); +/// ``` +#[macro_export(local_inner_macros)] +macro_rules! json { + // Hide distracting implementation details from the generated rustdoc. + ($($json:tt)+) => { + json_internal!($($json)+) + }; +} + +// Rocket relies on this because they export their own `json!` with a different +// doc comment than ours, and various Rust bugs prevent them from calling our +// `json!` from their `json!` so they call `json_internal!` directly. Check with +// @SergioBenitez before making breaking changes to this macro. +// +// Changes are fine as long as `json_internal!` does not call any new helper +// macros and can still be invoked as `json_internal!($($json)+)`. +#[macro_export(local_inner_macros)] +#[doc(hidden)] +macro_rules! json_internal { + ////////////////////////////////////////////////////////////////////////// + // TT muncher for parsing the inside of an array [...]. Produces a vec![...] + // of the elements. + // + // Must be invoked as: json_internal!(@array [] $($tt)*) + ////////////////////////////////////////////////////////////////////////// + + // Done with trailing comma. + (@array [$($elems:expr,)*]) => { + json_internal_vec![$($elems,)*] + }; + + // Done without trailing comma. + (@array [$($elems:expr),*]) => { + json_internal_vec![$($elems),*] + }; + + // Next element is `null`. + (@array [$($elems:expr,)*] null $($rest:tt)*) => { + json_internal!(@array [$($elems,)* json_internal!(null)] $($rest)*) + }; + + // Next element is `true`. + (@array [$($elems:expr,)*] true $($rest:tt)*) => { + json_internal!(@array [$($elems,)* json_internal!(true)] $($rest)*) + }; + + // Next element is `false`. + (@array [$($elems:expr,)*] false $($rest:tt)*) => { + json_internal!(@array [$($elems,)* json_internal!(false)] $($rest)*) + }; + + // Next element is an array. + (@array [$($elems:expr,)*] [$($array:tt)*] $($rest:tt)*) => { + json_internal!(@array [$($elems,)* json_internal!([$($array)*])] $($rest)*) + }; + + // Next element is a map. + (@array [$($elems:expr,)*] {$($map:tt)*} $($rest:tt)*) => { + json_internal!(@array [$($elems,)* json_internal!({$($map)*})] $($rest)*) + }; + + // Next element is an expression followed by comma. + (@array [$($elems:expr,)*] $next:expr, $($rest:tt)*) => { + json_internal!(@array [$($elems,)* json_internal!($next),] $($rest)*) + }; + + // Last element is an expression with no trailing comma. + (@array [$($elems:expr,)*] $last:expr) => { + json_internal!(@array [$($elems,)* json_internal!($last)]) + }; + + // Comma after the most recent element. + (@array [$($elems:expr),*] , $($rest:tt)*) => { + json_internal!(@array [$($elems,)*] $($rest)*) + }; + + // Unexpected token after most recent element. + (@array [$($elems:expr),*] $unexpected:tt $($rest:tt)*) => { + json_unexpected!($unexpected) + }; + + ////////////////////////////////////////////////////////////////////////// + // TT muncher for parsing the inside of an object {...}. Each entry is + // inserted into the given map variable. + // + // Must be invoked as: json_internal!(@object $map () ($($tt)*) ($($tt)*)) + // + // We require two copies of the input tokens so that we can match on one + // copy and trigger errors on the other copy. + ////////////////////////////////////////////////////////////////////////// + + // Done. + (@object $object:ident () () ()) => {}; + + // Insert the current entry followed by trailing comma. + (@object $object:ident [$($key:tt)+] ($value:expr) , $($rest:tt)*) => { + let _ = $object.insert(($($key)+).into(), $value); + json_internal!(@object $object () ($($rest)*) ($($rest)*)); + }; + + // Current entry followed by unexpected token. + (@object $object:ident [$($key:tt)+] ($value:expr) $unexpected:tt $($rest:tt)*) => { + json_unexpected!($unexpected); + }; + + // Insert the last entry without trailing comma. + (@object $object:ident [$($key:tt)+] ($value:expr)) => { + let _ = $object.insert(($($key)+).into(), $value); + }; + + // Next value is `null`. + (@object $object:ident ($($key:tt)+) (: null $($rest:tt)*) $copy:tt) => { + json_internal!(@object $object [$($key)+] (json_internal!(null)) $($rest)*); + }; + + // Next value is `true`. + (@object $object:ident ($($key:tt)+) (: true $($rest:tt)*) $copy:tt) => { + json_internal!(@object $object [$($key)+] (json_internal!(true)) $($rest)*); + }; + + // Next value is `false`. + (@object $object:ident ($($key:tt)+) (: false $($rest:tt)*) $copy:tt) => { + json_internal!(@object $object [$($key)+] (json_internal!(false)) $($rest)*); + }; + + // Next value is an array. + (@object $object:ident ($($key:tt)+) (: [$($array:tt)*] $($rest:tt)*) $copy:tt) => { + json_internal!(@object $object [$($key)+] (json_internal!([$($array)*])) $($rest)*); + }; + + // Next value is a map. + (@object $object:ident ($($key:tt)+) (: {$($map:tt)*} $($rest:tt)*) $copy:tt) => { + json_internal!(@object $object [$($key)+] (json_internal!({$($map)*})) $($rest)*); + }; + + // Next value is an expression followed by comma. + (@object $object:ident ($($key:tt)+) (: $value:expr , $($rest:tt)*) $copy:tt) => { + json_internal!(@object $object [$($key)+] (json_internal!($value)) , $($rest)*); + }; + + // Last value is an expression with no trailing comma. + (@object $object:ident ($($key:tt)+) (: $value:expr) $copy:tt) => { + json_internal!(@object $object [$($key)+] (json_internal!($value))); + }; + + // Missing value for last entry. Trigger a reasonable error message. + (@object $object:ident ($($key:tt)+) (:) $copy:tt) => { + // "unexpected end of macro invocation" + json_internal!(); + }; + + // Missing colon and value for last entry. Trigger a reasonable error + // message. + (@object $object:ident ($($key:tt)+) () $copy:tt) => { + // "unexpected end of macro invocation" + json_internal!(); + }; + + // Misplaced colon. Trigger a reasonable error message. + (@object $object:ident () (: $($rest:tt)*) ($colon:tt $($copy:tt)*)) => { + // Takes no arguments so "no rules expected the token `:`". + json_unexpected!($colon); + }; + + // Found a comma inside a key. Trigger a reasonable error message. + (@object $object:ident ($($key:tt)*) (, $($rest:tt)*) ($comma:tt $($copy:tt)*)) => { + // Takes no arguments so "no rules expected the token `,`". + json_unexpected!($comma); + }; + + // Key is fully parenthesized. This avoids clippy double_parens false + // positives because the parenthesization may be necessary here. + (@object $object:ident () (($key:expr) : $($rest:tt)*) $copy:tt) => { + json_internal!(@object $object ($key) (: $($rest)*) (: $($rest)*)); + }; + + // Refuse to absorb colon token into key expression. + (@object $object:ident ($($key:tt)*) (: $($unexpected:tt)+) $copy:tt) => { + json_expect_expr_comma!($($unexpected)+); + }; + + // Munch a token into the current key. + (@object $object:ident ($($key:tt)*) ($tt:tt $($rest:tt)*) $copy:tt) => { + json_internal!(@object $object ($($key)* $tt) ($($rest)*) ($($rest)*)); + }; + + ////////////////////////////////////////////////////////////////////////// + // The main implementation. + // + // Must be invoked as: json_internal!($($json)+) + ////////////////////////////////////////////////////////////////////////// + + (null) => { + $crate::Value::Null + }; + + (true) => { + $crate::Value::Bool(true) + }; + + (false) => { + $crate::Value::Bool(false) + }; + + ([]) => { + $crate::Value::Array(json_internal_vec![]) + }; + + ([ $($tt:tt)+ ]) => { + $crate::Value::Array(json_internal!(@array [] $($tt)+)) + }; + + ({}) => { + $crate::Value::Object($crate::Map::new()) + }; + + ({ $($tt:tt)+ }) => { + $crate::Value::Object({ + let mut object = $crate::Map::new(); + json_internal!(@object object () ($($tt)+) ($($tt)+)); + object + }) + }; + + // Any Serialize type: numbers, strings, struct literals, variables etc. + // Must be below every other rule. + ($other:expr) => { + $crate::to_value(&$other).unwrap() + }; +} + +// The json_internal macro above cannot invoke vec directly because it uses +// local_inner_macros. A vec invocation there would resolve to $crate::vec. +// Instead invoke vec here outside of local_inner_macros. +#[macro_export] +#[doc(hidden)] +macro_rules! json_internal_vec { + ($($content:tt)*) => { + vec![$($content)*] + }; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! json_unexpected { + () => {}; +} + +#[macro_export] +#[doc(hidden)] +macro_rules! json_expect_expr_comma { + ($e:expr , $($tt:tt)*) => {}; +} |