1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303
/// Construct a `serde_json::Value` from a JSON literal.
///
/// ```
/// # use serde_json::json;
/// #
/// let value = json!({
/// "code": 200,
/// "success": true,
/// "payload": {
/// "features": [
/// "serde",
/// "json"
/// ],
/// "homepage": null
/// }
/// });
/// ```
///
/// 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]
macro_rules! json {
// Hide distracting implementation details from the generated rustdoc.
($($json:tt)+) => {
$crate::json_internal!($($json)+)
};
}
// Rocket relies on this because they export their own `json!` with a different
// doc comment than ours, and various Rust bugs prevent them from calling our
// `json!` from their `json!` so they call `json_internal!` directly. Check with
// @SergioBenitez before making breaking changes to this macro.
//
// Changes are fine as long as `json_internal!` does not call any new helper
// macros and can still be invoked as `json_internal!($($json)+)`.
#[macro_export]
#[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,)*]) => {
$crate::__private::vec![$($elems,)*]
};
// Done without trailing comma.
(@array [$($elems:expr),*]) => {
$crate::__private::vec![$($elems),*]
};
// Next element is `null`.
(@array [$($elems:expr,)*] null $($rest:tt)*) => {
$crate::json_internal!(@array [$($elems,)* $crate::json_internal!(null)] $($rest)*)
};
// Next element is `true`.
(@array [$($elems:expr,)*] true $($rest:tt)*) => {
$crate::json_internal!(@array [$($elems,)* $crate::json_internal!(true)] $($rest)*)
};
// Next element is `false`.
(@array [$($elems:expr,)*] false $($rest:tt)*) => {
$crate::json_internal!(@array [$($elems,)* $crate::json_internal!(false)] $($rest)*)
};
// Next element is an array.
(@array [$($elems:expr,)*] [$($array:tt)*] $($rest:tt)*) => {
$crate::json_internal!(@array [$($elems,)* $crate::json_internal!([$($array)*])] $($rest)*)
};
// Next element is a map.
(@array [$($elems:expr,)*] {$($map:tt)*} $($rest:tt)*) => {
$crate::json_internal!(@array [$($elems,)* $crate::json_internal!({$($map)*})] $($rest)*)
};
// Next element is an expression followed by comma.
(@array [$($elems:expr,)*] $next:expr, $($rest:tt)*) => {
$crate::json_internal!(@array [$($elems,)* $crate::json_internal!($next),] $($rest)*)
};
// Last element is an expression with no trailing comma.
(@array [$($elems:expr,)*] $last:expr) => {
$crate::json_internal!(@array [$($elems,)* $crate::json_internal!($last)])
};
// Comma after the most recent element.
(@array [$($elems:expr),*] , $($rest:tt)*) => {
$crate::json_internal!(@array [$($elems,)*] $($rest)*)
};
// Unexpected token after most recent element.
(@array [$($elems:expr),*] $unexpected:tt $($rest:tt)*) => {
$crate::json_unexpected!($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);
$crate::json_internal!(@object $object () ($($rest)*) ($($rest)*));
};
// Current entry followed by unexpected token.
(@object $object:ident [$($key:tt)+] ($value:expr) $unexpected:tt $($rest:tt)*) => {
$crate::json_unexpected!($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) => {
$crate::json_internal!(@object $object [$($key)+] ($crate::json_internal!(null)) $($rest)*);
};
// Next value is `true`.
(@object $object:ident ($($key:tt)+) (: true $($rest:tt)*) $copy:tt) => {
$crate::json_internal!(@object $object [$($key)+] ($crate::json_internal!(true)) $($rest)*);
};
// Next value is `false`.
(@object $object:ident ($($key:tt)+) (: false $($rest:tt)*) $copy:tt) => {
$crate::json_internal!(@object $object [$($key)+] ($crate::json_internal!(false)) $($rest)*);
};
// Next value is an array.
(@object $object:ident ($($key:tt)+) (: [$($array:tt)*] $($rest:tt)*) $copy:tt) => {
$crate::json_internal!(@object $object [$($key)+] ($crate::json_internal!([$($array)*])) $($rest)*);
};
// Next value is a map.
(@object $object:ident ($($key:tt)+) (: {$($map:tt)*} $($rest:tt)*) $copy:tt) => {
$crate::json_internal!(@object $object [$($key)+] ($crate::json_internal!({$($map)*})) $($rest)*);
};
// Next value is an expression followed by comma.
(@object $object:ident ($($key:tt)+) (: $value:expr , $($rest:tt)*) $copy:tt) => {
$crate::json_internal!(@object $object [$($key)+] ($crate::json_internal!($value)) , $($rest)*);
};
// Last value is an expression with no trailing comma.
(@object $object:ident ($($key:tt)+) (: $value:expr) $copy:tt) => {
$crate::json_internal!(@object $object [$($key)+] ($crate::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"
$crate::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"
$crate::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 `:`".
$crate::json_unexpected!($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 `,`".
$crate::json_unexpected!($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) => {
$crate::json_internal!(@object $object ($key) (: $($rest)*) (: $($rest)*));
};
// Refuse to absorb colon token into key expression.
(@object $object:ident ($($key:tt)*) (: $($unexpected:tt)+) $copy:tt) => {
$crate::json_expect_expr_comma!($($unexpected)+);
};
// Munch a token into the current key.
(@object $object:ident ($($key:tt)*) ($tt:tt $($rest:tt)*) $copy:tt) => {
$crate::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)
};
([]) => {
$crate::Value::Array($crate::__private::vec![])
};
([ $($tt:tt)+ ]) => {
$crate::Value::Array($crate::json_internal!(@array [] $($tt)+))
};
({}) => {
$crate::Value::Object($crate::Map::new())
};
({ $($tt:tt)+ }) => {
$crate::Value::Object({
let mut object = $crate::Map::new();
$crate::json_internal!(@object object () ($($tt)+) ($($tt)+));
object
})
};
// Any Serialize type: numbers, strings, struct literals, variables etc.
// Must be below every other rule.
($other:expr) => {
$crate::to_value(&$other).unwrap()
};
}
// Used by old versions of Rocket.
// Unused since https://github.com/rwf2/Rocket/commit/c74bcfd40a47b35330db6cafb88e4f3da83e0d17
#[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)*) => {};
}