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Diffstat (limited to 'vendor/serde_json/src/value/mod.rs')
| -rw-r--r-- | vendor/serde_json/src/value/mod.rs | 1009 |
1 files changed, 1009 insertions, 0 deletions
diff --git a/vendor/serde_json/src/value/mod.rs b/vendor/serde_json/src/value/mod.rs new file mode 100644 index 0000000..b3f51ea --- /dev/null +++ b/vendor/serde_json/src/value/mod.rs @@ -0,0 +1,1009 @@ +//! The Value enum, a loosely typed way of representing any valid JSON value. +//! +//! # Constructing JSON +//! +//! Serde JSON provides a [`json!` macro][macro] to build `serde_json::Value` +//! objects with very natural JSON syntax. +//! +//! ``` +//! use serde_json::json; +//! +//! fn main() { +//! // The type of `john` is `serde_json::Value` +//! let john = json!({ +//! "name": "John Doe", +//! "age": 43, +//! "phones": [ +//! "+44 1234567", +//! "+44 2345678" +//! ] +//! }); +//! +//! println!("first phone number: {}", john["phones"][0]); +//! +//! // Convert to a string of JSON and print it out +//! println!("{}", john.to_string()); +//! } +//! ``` +//! +//! The `Value::to_string()` function converts a `serde_json::Value` into a +//! `String` of JSON text. +//! +//! One neat thing about the `json!` macro is that variables and expressions can +//! be interpolated directly into the JSON value as you are building it. Serde +//! will check at compile time that the value you are interpolating is able to +//! be represented as JSON. +//! +//! ``` +//! # use serde_json::json; +//! # +//! # fn random_phone() -> u16 { 0 } +//! # +//! let full_name = "John Doe"; +//! let age_last_year = 42; +//! +//! // The type of `john` is `serde_json::Value` +//! let john = json!({ +//! "name": full_name, +//! "age": age_last_year + 1, +//! "phones": [ +//! format!("+44 {}", random_phone()) +//! ] +//! }); +//! ``` +//! +//! A string of JSON data can be parsed into a `serde_json::Value` by the +//! [`serde_json::from_str`][from_str] function. There is also +//! [`from_slice`][from_slice] for parsing from a byte slice `&[u8]` and +//! [`from_reader`][from_reader] for parsing from any `io::Read` like a File or +//! a TCP stream. +//! +//! ``` +//! use serde_json::{json, Value, Error}; +//! +//! fn untyped_example() -> Result<(), Error> { +//! // Some JSON input data as a &str. Maybe this comes from the user. +//! let data = r#" +//! { +//! "name": "John Doe", +//! "age": 43, +//! "phones": [ +//! "+44 1234567", +//! "+44 2345678" +//! ] +//! }"#; +//! +//! // Parse the string of data into serde_json::Value. +//! let v: Value = serde_json::from_str(data)?; +//! +//! // Access parts of the data by indexing with square brackets. +//! println!("Please call {} at the number {}", v["name"], v["phones"][0]); +//! +//! Ok(()) +//! } +//! # +//! # untyped_example().unwrap(); +//! ``` +//! +//! [macro]: crate::json +//! [from_str]: crate::de::from_str +//! [from_slice]: crate::de::from_slice +//! [from_reader]: crate::de::from_reader + +use crate::error::Error; +use crate::io; +use alloc::string::String; +use alloc::vec::Vec; +use core::fmt::{self, Debug, Display}; +use core::mem; +use core::str; +use serde::de::DeserializeOwned; +use serde::ser::Serialize; + +pub use self::index::Index; +pub use self::ser::Serializer; +pub use crate::map::Map; +pub use crate::number::Number; + +#[cfg(feature = "raw_value")] +#[cfg_attr(docsrs, doc(cfg(feature = "raw_value")))] +pub use crate::raw::{to_raw_value, RawValue}; + +/// Represents any valid JSON value. +/// +/// See the [`serde_json::value` module documentation](self) for usage examples. +#[derive(Clone, Eq, PartialEq)] +pub enum Value { + /// Represents a JSON null value. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!(null); + /// ``` + Null, + + /// Represents a JSON boolean. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!(true); + /// ``` + Bool(bool), + + /// Represents a JSON number, whether integer or floating point. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!(12.5); + /// ``` + Number(Number), + + /// Represents a JSON string. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!("a string"); + /// ``` + String(String), + + /// Represents a JSON array. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!(["an", "array"]); + /// ``` + Array(Vec<Value>), + + /// Represents a JSON object. + /// + /// By default the map is backed by a BTreeMap. Enable the `preserve_order` + /// feature of serde_json to use IndexMap instead, which preserves + /// entries in the order they are inserted into the map. In particular, this + /// allows JSON data to be deserialized into a Value and serialized to a + /// string while retaining the order of map keys in the input. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "an": "object" }); + /// ``` + Object(Map<String, Value>), +} + +impl Debug for Value { + fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + match self { + Value::Null => formatter.write_str("Null"), + Value::Bool(boolean) => write!(formatter, "Bool({})", boolean), + Value::Number(number) => Debug::fmt(number, formatter), + Value::String(string) => write!(formatter, "String({:?})", string), + Value::Array(vec) => { + tri!(formatter.write_str("Array ")); + Debug::fmt(vec, formatter) + } + Value::Object(map) => { + tri!(formatter.write_str("Object ")); + Debug::fmt(map, formatter) + } + } + } +} + +impl Display for Value { + /// Display a JSON value as a string. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let json = json!({ "city": "London", "street": "10 Downing Street" }); + /// + /// // Compact format: + /// // + /// // {"city":"London","street":"10 Downing Street"} + /// let compact = format!("{}", json); + /// assert_eq!(compact, + /// "{\"city\":\"London\",\"street\":\"10 Downing Street\"}"); + /// + /// // Pretty format: + /// // + /// // { + /// // "city": "London", + /// // "street": "10 Downing Street" + /// // } + /// let pretty = format!("{:#}", json); + /// assert_eq!(pretty, + /// "{\n \"city\": \"London\",\n \"street\": \"10 Downing Street\"\n}"); + /// ``` + fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { + struct WriterFormatter<'a, 'b: 'a> { + inner: &'a mut fmt::Formatter<'b>, + } + + impl<'a, 'b> io::Write for WriterFormatter<'a, 'b> { + fn write(&mut self, buf: &[u8]) -> io::Result<usize> { + // Safety: the serializer below only emits valid utf8 when using + // the default formatter. + let s = unsafe { str::from_utf8_unchecked(buf) }; + tri!(self.inner.write_str(s).map_err(io_error)); + Ok(buf.len()) + } + + fn flush(&mut self) -> io::Result<()> { + Ok(()) + } + } + + fn io_error(_: fmt::Error) -> io::Error { + // Error value does not matter because Display impl just maps it + // back to fmt::Error. + io::Error::new(io::ErrorKind::Other, "fmt error") + } + + let alternate = f.alternate(); + let mut wr = WriterFormatter { inner: f }; + if alternate { + // {:#} + super::ser::to_writer_pretty(&mut wr, self).map_err(|_| fmt::Error) + } else { + // {} + super::ser::to_writer(&mut wr, self).map_err(|_| fmt::Error) + } + } +} + +fn parse_index(s: &str) -> Option<usize> { + if s.starts_with('+') || (s.starts_with('0') && s.len() != 1) { + return None; + } + s.parse().ok() +} + +impl Value { + /// Index into a JSON array or map. A string index can be used to access a + /// value in a map, and a usize index can be used to access an element of an + /// array. + /// + /// Returns `None` if the type of `self` does not match the type of the + /// index, for example if the index is a string and `self` is an array or a + /// number. Also returns `None` if the given key does not exist in the map + /// or the given index is not within the bounds of the array. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let object = json!({ "A": 65, "B": 66, "C": 67 }); + /// assert_eq!(*object.get("A").unwrap(), json!(65)); + /// + /// let array = json!([ "A", "B", "C" ]); + /// assert_eq!(*array.get(2).unwrap(), json!("C")); + /// + /// assert_eq!(array.get("A"), None); + /// ``` + /// + /// Square brackets can also be used to index into a value in a more concise + /// way. This returns `Value::Null` in cases where `get` would have returned + /// `None`. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let object = json!({ + /// "A": ["a", "á", "à"], + /// "B": ["b", "b́"], + /// "C": ["c", "ć", "ć̣", "ḉ"], + /// }); + /// assert_eq!(object["B"][0], json!("b")); + /// + /// assert_eq!(object["D"], json!(null)); + /// assert_eq!(object[0]["x"]["y"]["z"], json!(null)); + /// ``` + pub fn get<I: Index>(&self, index: I) -> Option<&Value> { + index.index_into(self) + } + + /// Mutably index into a JSON array or map. A string index can be used to + /// access a value in a map, and a usize index can be used to access an + /// element of an array. + /// + /// Returns `None` if the type of `self` does not match the type of the + /// index, for example if the index is a string and `self` is an array or a + /// number. Also returns `None` if the given key does not exist in the map + /// or the given index is not within the bounds of the array. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let mut object = json!({ "A": 65, "B": 66, "C": 67 }); + /// *object.get_mut("A").unwrap() = json!(69); + /// + /// let mut array = json!([ "A", "B", "C" ]); + /// *array.get_mut(2).unwrap() = json!("D"); + /// ``` + pub fn get_mut<I: Index>(&mut self, index: I) -> Option<&mut Value> { + index.index_into_mut(self) + } + + /// Returns true if the `Value` is an Object. Returns false otherwise. + /// + /// For any Value on which `is_object` returns true, `as_object` and + /// `as_object_mut` are guaranteed to return the map representation of the + /// object. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let obj = json!({ "a": { "nested": true }, "b": ["an", "array"] }); + /// + /// assert!(obj.is_object()); + /// assert!(obj["a"].is_object()); + /// + /// // array, not an object + /// assert!(!obj["b"].is_object()); + /// ``` + pub fn is_object(&self) -> bool { + self.as_object().is_some() + } + + /// If the `Value` is an Object, returns the associated Map. Returns None + /// otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": { "nested": true }, "b": ["an", "array"] }); + /// + /// // The length of `{"nested": true}` is 1 entry. + /// assert_eq!(v["a"].as_object().unwrap().len(), 1); + /// + /// // The array `["an", "array"]` is not an object. + /// assert_eq!(v["b"].as_object(), None); + /// ``` + pub fn as_object(&self) -> Option<&Map<String, Value>> { + match self { + Value::Object(map) => Some(map), + _ => None, + } + } + + /// If the `Value` is an Object, returns the associated mutable Map. + /// Returns None otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let mut v = json!({ "a": { "nested": true } }); + /// + /// v["a"].as_object_mut().unwrap().clear(); + /// assert_eq!(v, json!({ "a": {} })); + /// ``` + pub fn as_object_mut(&mut self) -> Option<&mut Map<String, Value>> { + match self { + Value::Object(map) => Some(map), + _ => None, + } + } + + /// Returns true if the `Value` is an Array. Returns false otherwise. + /// + /// For any Value on which `is_array` returns true, `as_array` and + /// `as_array_mut` are guaranteed to return the vector representing the + /// array. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let obj = json!({ "a": ["an", "array"], "b": { "an": "object" } }); + /// + /// assert!(obj["a"].is_array()); + /// + /// // an object, not an array + /// assert!(!obj["b"].is_array()); + /// ``` + pub fn is_array(&self) -> bool { + self.as_array().is_some() + } + + /// If the `Value` is an Array, returns the associated vector. Returns None + /// otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": ["an", "array"], "b": { "an": "object" } }); + /// + /// // The length of `["an", "array"]` is 2 elements. + /// assert_eq!(v["a"].as_array().unwrap().len(), 2); + /// + /// // The object `{"an": "object"}` is not an array. + /// assert_eq!(v["b"].as_array(), None); + /// ``` + pub fn as_array(&self) -> Option<&Vec<Value>> { + match self { + Value::Array(array) => Some(array), + _ => None, + } + } + + /// If the `Value` is an Array, returns the associated mutable vector. + /// Returns None otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let mut v = json!({ "a": ["an", "array"] }); + /// + /// v["a"].as_array_mut().unwrap().clear(); + /// assert_eq!(v, json!({ "a": [] })); + /// ``` + pub fn as_array_mut(&mut self) -> Option<&mut Vec<Value>> { + match self { + Value::Array(list) => Some(list), + _ => None, + } + } + + /// Returns true if the `Value` is a String. Returns false otherwise. + /// + /// For any Value on which `is_string` returns true, `as_str` is guaranteed + /// to return the string slice. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": "some string", "b": false }); + /// + /// assert!(v["a"].is_string()); + /// + /// // The boolean `false` is not a string. + /// assert!(!v["b"].is_string()); + /// ``` + pub fn is_string(&self) -> bool { + self.as_str().is_some() + } + + /// If the `Value` is a String, returns the associated str. Returns None + /// otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": "some string", "b": false }); + /// + /// assert_eq!(v["a"].as_str(), Some("some string")); + /// + /// // The boolean `false` is not a string. + /// assert_eq!(v["b"].as_str(), None); + /// + /// // JSON values are printed in JSON representation, so strings are in quotes. + /// // + /// // The value is: "some string" + /// println!("The value is: {}", v["a"]); + /// + /// // Rust strings are printed without quotes. + /// // + /// // The value is: some string + /// println!("The value is: {}", v["a"].as_str().unwrap()); + /// ``` + pub fn as_str(&self) -> Option<&str> { + match self { + Value::String(s) => Some(s), + _ => None, + } + } + + /// Returns true if the `Value` is a Number. Returns false otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": 1, "b": "2" }); + /// + /// assert!(v["a"].is_number()); + /// + /// // The string `"2"` is a string, not a number. + /// assert!(!v["b"].is_number()); + /// ``` + pub fn is_number(&self) -> bool { + match *self { + Value::Number(_) => true, + _ => false, + } + } + + /// If the `Value` is a Number, returns the associated [`Number`]. Returns + /// None otherwise. + /// + /// ``` + /// # use serde_json::{json, Number}; + /// # + /// let v = json!({ "a": 1, "b": 2.2, "c": -3, "d": "4" }); + /// + /// assert_eq!(v["a"].as_number(), Some(&Number::from(1u64))); + /// assert_eq!(v["b"].as_number(), Some(&Number::from_f64(2.2).unwrap())); + /// assert_eq!(v["c"].as_number(), Some(&Number::from(-3i64))); + /// + /// // The string `"4"` is not a number. + /// assert_eq!(v["d"].as_number(), None); + /// ``` + pub fn as_number(&self) -> Option<&Number> { + match self { + Value::Number(number) => Some(number), + _ => None, + } + } + + /// Returns true if the `Value` is an integer between `i64::MIN` and + /// `i64::MAX`. + /// + /// For any Value on which `is_i64` returns true, `as_i64` is guaranteed to + /// return the integer value. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let big = i64::max_value() as u64 + 10; + /// let v = json!({ "a": 64, "b": big, "c": 256.0 }); + /// + /// assert!(v["a"].is_i64()); + /// + /// // Greater than i64::MAX. + /// assert!(!v["b"].is_i64()); + /// + /// // Numbers with a decimal point are not considered integers. + /// assert!(!v["c"].is_i64()); + /// ``` + pub fn is_i64(&self) -> bool { + match self { + Value::Number(n) => n.is_i64(), + _ => false, + } + } + + /// Returns true if the `Value` is an integer between zero and `u64::MAX`. + /// + /// For any Value on which `is_u64` returns true, `as_u64` is guaranteed to + /// return the integer value. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": 64, "b": -64, "c": 256.0 }); + /// + /// assert!(v["a"].is_u64()); + /// + /// // Negative integer. + /// assert!(!v["b"].is_u64()); + /// + /// // Numbers with a decimal point are not considered integers. + /// assert!(!v["c"].is_u64()); + /// ``` + pub fn is_u64(&self) -> bool { + match self { + Value::Number(n) => n.is_u64(), + _ => false, + } + } + + /// Returns true if the `Value` is a number that can be represented by f64. + /// + /// For any Value on which `is_f64` returns true, `as_f64` is guaranteed to + /// return the floating point value. + /// + /// Currently this function returns true if and only if both `is_i64` and + /// `is_u64` return false but this is not a guarantee in the future. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": 256.0, "b": 64, "c": -64 }); + /// + /// assert!(v["a"].is_f64()); + /// + /// // Integers. + /// assert!(!v["b"].is_f64()); + /// assert!(!v["c"].is_f64()); + /// ``` + pub fn is_f64(&self) -> bool { + match self { + Value::Number(n) => n.is_f64(), + _ => false, + } + } + + /// If the `Value` is an integer, represent it as i64 if possible. Returns + /// None otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let big = i64::max_value() as u64 + 10; + /// let v = json!({ "a": 64, "b": big, "c": 256.0 }); + /// + /// assert_eq!(v["a"].as_i64(), Some(64)); + /// assert_eq!(v["b"].as_i64(), None); + /// assert_eq!(v["c"].as_i64(), None); + /// ``` + pub fn as_i64(&self) -> Option<i64> { + match self { + Value::Number(n) => n.as_i64(), + _ => None, + } + } + + /// If the `Value` is an integer, represent it as u64 if possible. Returns + /// None otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": 64, "b": -64, "c": 256.0 }); + /// + /// assert_eq!(v["a"].as_u64(), Some(64)); + /// assert_eq!(v["b"].as_u64(), None); + /// assert_eq!(v["c"].as_u64(), None); + /// ``` + pub fn as_u64(&self) -> Option<u64> { + match self { + Value::Number(n) => n.as_u64(), + _ => None, + } + } + + /// If the `Value` is a number, represent it as f64 if possible. Returns + /// None otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": 256.0, "b": 64, "c": -64 }); + /// + /// assert_eq!(v["a"].as_f64(), Some(256.0)); + /// assert_eq!(v["b"].as_f64(), Some(64.0)); + /// assert_eq!(v["c"].as_f64(), Some(-64.0)); + /// ``` + pub fn as_f64(&self) -> Option<f64> { + match self { + Value::Number(n) => n.as_f64(), + _ => None, + } + } + + /// Returns true if the `Value` is a Boolean. Returns false otherwise. + /// + /// For any Value on which `is_boolean` returns true, `as_bool` is + /// guaranteed to return the boolean value. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": false, "b": "false" }); + /// + /// assert!(v["a"].is_boolean()); + /// + /// // The string `"false"` is a string, not a boolean. + /// assert!(!v["b"].is_boolean()); + /// ``` + pub fn is_boolean(&self) -> bool { + self.as_bool().is_some() + } + + /// If the `Value` is a Boolean, returns the associated bool. Returns None + /// otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": false, "b": "false" }); + /// + /// assert_eq!(v["a"].as_bool(), Some(false)); + /// + /// // The string `"false"` is a string, not a boolean. + /// assert_eq!(v["b"].as_bool(), None); + /// ``` + pub fn as_bool(&self) -> Option<bool> { + match *self { + Value::Bool(b) => Some(b), + _ => None, + } + } + + /// Returns true if the `Value` is a Null. Returns false otherwise. + /// + /// For any Value on which `is_null` returns true, `as_null` is guaranteed + /// to return `Some(())`. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": null, "b": false }); + /// + /// assert!(v["a"].is_null()); + /// + /// // The boolean `false` is not null. + /// assert!(!v["b"].is_null()); + /// ``` + pub fn is_null(&self) -> bool { + self.as_null().is_some() + } + + /// If the `Value` is a Null, returns (). Returns None otherwise. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let v = json!({ "a": null, "b": false }); + /// + /// assert_eq!(v["a"].as_null(), Some(())); + /// + /// // The boolean `false` is not null. + /// assert_eq!(v["b"].as_null(), None); + /// ``` + pub fn as_null(&self) -> Option<()> { + match *self { + Value::Null => Some(()), + _ => None, + } + } + + /// Looks up a value by a JSON Pointer. + /// + /// JSON Pointer defines a string syntax for identifying a specific value + /// within a JavaScript Object Notation (JSON) document. + /// + /// A Pointer is a Unicode string with the reference tokens separated by `/`. + /// Inside tokens `/` is replaced by `~1` and `~` is replaced by `~0`. The + /// addressed value is returned and if there is no such value `None` is + /// returned. + /// + /// For more information read [RFC6901](https://tools.ietf.org/html/rfc6901). + /// + /// # Examples + /// + /// ``` + /// # use serde_json::json; + /// # + /// let data = json!({ + /// "x": { + /// "y": ["z", "zz"] + /// } + /// }); + /// + /// assert_eq!(data.pointer("/x/y/1").unwrap(), &json!("zz")); + /// assert_eq!(data.pointer("/a/b/c"), None); + /// ``` + pub fn pointer(&self, pointer: &str) -> Option<&Value> { + if pointer.is_empty() { + return Some(self); + } + if !pointer.starts_with('/') { + return None; + } + pointer + .split('/') + .skip(1) + .map(|x| x.replace("~1", "/").replace("~0", "~")) + .try_fold(self, |target, token| match target { + Value::Object(map) => map.get(&token), + Value::Array(list) => parse_index(&token).and_then(|x| list.get(x)), + _ => None, + }) + } + + /// Looks up a value by a JSON Pointer and returns a mutable reference to + /// that value. + /// + /// JSON Pointer defines a string syntax for identifying a specific value + /// within a JavaScript Object Notation (JSON) document. + /// + /// A Pointer is a Unicode string with the reference tokens separated by `/`. + /// Inside tokens `/` is replaced by `~1` and `~` is replaced by `~0`. The + /// addressed value is returned and if there is no such value `None` is + /// returned. + /// + /// For more information read [RFC6901](https://tools.ietf.org/html/rfc6901). + /// + /// # Example of Use + /// + /// ``` + /// use serde_json::Value; + /// + /// fn main() { + /// let s = r#"{"x": 1.0, "y": 2.0}"#; + /// let mut value: Value = serde_json::from_str(s).unwrap(); + /// + /// // Check value using read-only pointer + /// assert_eq!(value.pointer("/x"), Some(&1.0.into())); + /// // Change value with direct assignment + /// *value.pointer_mut("/x").unwrap() = 1.5.into(); + /// // Check that new value was written + /// assert_eq!(value.pointer("/x"), Some(&1.5.into())); + /// // Or change the value only if it exists + /// value.pointer_mut("/x").map(|v| *v = 1.5.into()); + /// + /// // "Steal" ownership of a value. Can replace with any valid Value. + /// let old_x = value.pointer_mut("/x").map(Value::take).unwrap(); + /// assert_eq!(old_x, 1.5); + /// assert_eq!(value.pointer("/x").unwrap(), &Value::Null); + /// } + /// ``` + pub fn pointer_mut(&mut self, pointer: &str) -> Option<&mut Value> { + if pointer.is_empty() { + return Some(self); + } + if !pointer.starts_with('/') { + return None; + } + pointer + .split('/') + .skip(1) + .map(|x| x.replace("~1", "/").replace("~0", "~")) + .try_fold(self, |target, token| match target { + Value::Object(map) => map.get_mut(&token), + Value::Array(list) => parse_index(&token).and_then(move |x| list.get_mut(x)), + _ => None, + }) + } + + /// Takes the value out of the `Value`, leaving a `Null` in its place. + /// + /// ``` + /// # use serde_json::json; + /// # + /// let mut v = json!({ "x": "y" }); + /// assert_eq!(v["x"].take(), json!("y")); + /// assert_eq!(v, json!({ "x": null })); + /// ``` + pub fn take(&mut self) -> Value { + mem::replace(self, Value::Null) + } +} + +/// The default value is `Value::Null`. +/// +/// This is useful for handling omitted `Value` fields when deserializing. +/// +/// # Examples +/// +/// ``` +/// # use serde::Deserialize; +/// use serde_json::Value; +/// +/// #[derive(Deserialize)] +/// struct Settings { +/// level: i32, +/// #[serde(default)] +/// extras: Value, +/// } +/// +/// # fn try_main() -> Result<(), serde_json::Error> { +/// let data = r#" { "level": 42 } "#; +/// let s: Settings = serde_json::from_str(data)?; +/// +/// assert_eq!(s.level, 42); +/// assert_eq!(s.extras, Value::Null); +/// # +/// # Ok(()) +/// # } +/// # +/// # try_main().unwrap() +/// ``` +impl Default for Value { + fn default() -> Value { + Value::Null + } +} + +mod de; +mod from; +mod index; +mod partial_eq; +mod ser; + +/// Convert a `T` into `serde_json::Value` which is an enum that can represent +/// any valid JSON data. +/// +/// # Example +/// +/// ``` +/// use serde::Serialize; +/// use serde_json::json; +/// use std::error::Error; +/// +/// #[derive(Serialize)] +/// struct User { +/// fingerprint: String, +/// location: String, +/// } +/// +/// fn compare_json_values() -> Result<(), Box<dyn Error>> { +/// let u = User { +/// fingerprint: "0xF9BA143B95FF6D82".to_owned(), +/// location: "Menlo Park, CA".to_owned(), +/// }; +/// +/// // The type of `expected` is `serde_json::Value` +/// let expected = json!({ +/// "fingerprint": "0xF9BA143B95FF6D82", +/// "location": "Menlo Park, CA", +/// }); +/// +/// let v = serde_json::to_value(u).unwrap(); +/// assert_eq!(v, expected); +/// +/// Ok(()) +/// } +/// # +/// # compare_json_values().unwrap(); +/// ``` +/// +/// # Errors +/// +/// This conversion can fail if `T`'s implementation of `Serialize` decides to +/// fail, or if `T` contains a map with non-string keys. +/// +/// ``` +/// use std::collections::BTreeMap; +/// +/// fn main() { +/// // The keys in this map are vectors, not strings. +/// let mut map = BTreeMap::new(); +/// map.insert(vec![32, 64], "x86"); +/// +/// println!("{}", serde_json::to_value(map).unwrap_err()); +/// } +/// ``` +// Taking by value is more friendly to iterator adapters, option and result +// consumers, etc. See https://github.com/serde-rs/json/pull/149. +pub fn to_value<T>(value: T) -> Result<Value, Error> +where + T: Serialize, +{ + value.serialize(Serializer) +} + +/// Interpret a `serde_json::Value` as an instance of type `T`. +/// +/// # Example +/// +/// ``` +/// use serde::Deserialize; +/// use serde_json::json; +/// +/// #[derive(Deserialize, Debug)] +/// struct User { +/// fingerprint: String, +/// location: String, +/// } +/// +/// fn main() { +/// // The type of `j` is `serde_json::Value` +/// let j = json!({ +/// "fingerprint": "0xF9BA143B95FF6D82", +/// "location": "Menlo Park, CA" +/// }); +/// +/// let u: User = serde_json::from_value(j).unwrap(); +/// println!("{:#?}", u); +/// } +/// ``` +/// +/// # Errors +/// +/// This conversion can fail if the structure of the Value does not match the +/// structure expected by `T`, for example if `T` is a struct type but the Value +/// contains something other than a JSON map. It can also fail if the structure +/// is correct but `T`'s implementation of `Deserialize` decides that something +/// is wrong with the data, for example required struct fields are missing from +/// the JSON map or some number is too big to fit in the expected primitive +/// type. +pub fn from_value<T>(value: Value) -> Result<T, Error> +where + T: DeserializeOwned, +{ + T::deserialize(value) +} |