Enum Value 

pub enum Value {
    Bool(bool),
    Integer(i32),
    Integer64(i64),
    Float(f64),
    String(String),
    Array(Vec<Value>),
    List(Vec<Value>),
    Group(Map),
}

A dynamically-typed value that can represent any libconfig data

Examples

use libconfig::Value;

let config = r#"
    name = "My App";
    version = 1;
    enabled = true;
    ports = [8080, 8081, 8082];
"#;

let v = Value::from_str(config).unwrap();

assert_eq!(v["name"], "My App");
assert_eq!(v["version"], 1);
assert_eq!(v["enabled"], true);
assert_eq!(v["ports"][0], 8080);

Variants

Bool(bool)

Represents a boolean value

Integer(i32)

Represents a 32-bit integer

Integer64(i64)

Represents a 64-bit integer

Float(f64)

Represents a floating point number

String(String)

Represents a string

Array(Vec<Value>)

Represents an array (homogeneous sequence)

List(Vec<Value>)

Represents a list (heterogeneous sequence)

Group(Map)

Represents a group (object/map)

Implementations

impl Value

pub fn is_bool(&self) -> bool

Returns true if the value is a boolean

pub fn is_integer(&self) -> bool

Returns true if the value is an integer (32-bit or 64-bit)

pub fn is_i32(&self) -> bool

Returns true if the value is a 32-bit integer

pub fn is_i64(&self) -> bool

Returns true if the value is a 64-bit integer

pub fn is_float(&self) -> bool

Returns true if the value is a float

pub fn is_number(&self) -> bool

Returns true if the value is a number (integer or float)

pub fn is_string(&self) -> bool

Returns true if the value is a string

pub fn is_array(&self) -> bool

Returns true if the value is an array

pub fn is_list(&self) -> bool

Returns true if the value is a list

pub fn is_group(&self) -> bool

Returns true if the value is a group (object)

pub fn as_bool(&self) -> Option<bool>

If the value is a boolean, returns it. Returns None otherwise.

pub fn as_i32(&self) -> Option<i32>

If the value is an integer, returns it as i32. Returns None otherwise.

pub fn as_i64(&self) -> Option<i64>

If the value is an integer, returns it as i64. Returns None otherwise.

pub fn as_f64(&self) -> Option<f64>

If the value is a float, returns it. Integers are converted to their float value (a lossless promotion for Integer; Integer64 values beyond 2^53 lose precision). Returns None for non-numeric values.

pub fn as_str(&self) -> Option<&str>

If the value is a string, returns a reference to it. Returns None otherwise.

pub fn as_array(&self) -> Option<&Vec<Value>>

If the value is an array or a list, returns a reference to its elements. Use Value::is_array/Value::is_list to distinguish the two aggregate kinds. Returns None otherwise.

pub fn as_array_mut(&mut self) -> Option<&mut Vec<Value>>

If the value is an array or a list, returns a mutable reference to its elements. Returns None otherwise.

pub fn as_group(&self) -> Option<&Map>

If the value is a group, returns a reference to the map. Returns None otherwise.

pub fn as_group_mut(&mut self) -> Option<&mut Map>

If the value is a group, returns a mutable reference to the map. Returns None otherwise.

Note: keys inserted directly into the map are not validated; keys that are not grammar-valid setting names will fail at serialization time. Prefer Value::set, which validates.

pub fn get<S: AsRef<str>>(&self, key: S) -> Option<&Value>

Gets a reference to a value in a group by key

Returns None if the value is not a group or the key doesn’t exist.

pub fn get_mut<S: AsRef<str>>(&mut self, key: S) -> Option<&mut Value>

Gets a mutable reference to a value in a group by key

Returns None if the value is not a group or the key doesn’t exist.

pub fn get_index(&self, index: usize) -> Option<&Value>

Gets a reference to a value in an array/list by index

Returns None if the value is not an array/list or the index is out of bounds.

pub fn get_index_mut(&mut self, index: usize) -> Option<&mut Value>

Gets a mutable reference to a value in an array/list by index

Returns None if the value is not an array/list or the index is out of bounds.

pub fn lookup(&self, path: &str) -> Option<&Value>

Looks up a value by a dotted path like “application.window.title”

Returns None if any part of the path doesn’t exist.

Examples

use libconfig::Value;

let config = r#"
    application = {
        window = {
            title = "My App";
        };
    };
"#;

let v = Value::from_str(config).unwrap();
assert_eq!(v.lookup("application.window.title").and_then(|v| v.as_str()), Some("My App"));

pub fn lookup_mut(&mut self, path: &str) -> Option<&mut Value>

Looks up a mutable reference to a value by a dotted path like “application.window.title”

Returns None if any part of the path doesn’t exist. Supports both bracket notation (items.[0]) and bare numeric (items.0).

Examples

use libconfig::Value;

let config = r#"
    ports = [80, 443];
"#;

let mut v = Value::from_str(config).unwrap();
*v.lookup_mut("ports.[0]").unwrap() = Value::Integer(8080);
assert_eq!(v["ports.0"], 8080);

pub fn set(&mut self, path: &str, value: impl Into<Value>) -> Result<()>

Sets a value at the given path, creating intermediate Group nodes as needed.

The value may be anything convertible into a Value (integers, floats, booleans, strings, or a Value itself). Array/list indices must refer to existing elements (no auto-extension).

Errors

• ErrorKind::InvalidPath if the path is malformed
• ErrorKind::InvalidSettingName if a key segment is not a valid setting name ([A-Za-z*][-A-Za-z0-9_*]*)
• ErrorKind::PathTraversal if an intermediate value has the wrong type or an index is out of bounds

Examples

use libconfig::{Map, Value};

let mut v = Value::Group(Map::new());
v.set("a.b.c", 42).unwrap();
assert_eq!(v.lookup("a.b.c").unwrap().as_i32(), Some(42));

pub fn remove(&mut self, path: &str) -> Option<Value>

Removes a value at the given path and returns it.

For group members, the key-value pair is removed. For array/list elements, the element is removed and subsequent elements shift down.

Returns None if the path is invalid or the target doesn’t exist.

Examples

use libconfig::Value;

let mut v = Value::from_str(r#"a = 1; b = 2; c = 3;"#).unwrap();
let removed = v.remove("b");
assert_eq!(removed, Some(Value::Integer(2)));
assert!(v.lookup("b").is_none());

pub fn from_str(s: &str) -> Result<Value>

Parse a libconfig string into a Value.

Examples

use libconfig::Value;

let v = Value::from_str("name = \"test\"; version = 1;").unwrap();
assert_eq!(v["name"], "test");
assert_eq!(v["version"], 1);

Trait Implementations

impl Clone for Value

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Value

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Value

fn deserialize<D>(deserializer: D) -> Result<Value, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<'de> Deserializer<'de> for Value

Deserializer implementation for Value

type Error = Error

The error type that can be returned if some error occurs during deserialization.

fn deserialize_any<V>(self, visitor: V) -> Result<V::Value>

where V: Visitor<'de>,

Require the Deserializer to figure out how to drive the visitor based on what data type is in the input.

fn deserialize_option<V>(self, visitor: V) -> Result<V::Value>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an optional value.

fn deserialize_enum<V>( self, _name: &'static str, _variants: &'static [&'static str], visitor: V, ) -> Result<V::Value>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an enum value with a particular name and possible variants.

fn deserialize_bool<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a bool value.

fn deserialize_i8<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an i8 value.

fn deserialize_i16<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an i16 value.

fn deserialize_i32<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an i32 value.

fn deserialize_i64<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an i64 value.

fn deserialize_u8<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a u8 value.

fn deserialize_u16<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a u16 value.

fn deserialize_u32<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a u32 value.

fn deserialize_u64<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a u64 value.

fn deserialize_f32<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a f32 value.

fn deserialize_f64<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a f64 value.

fn deserialize_char<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a char value.

fn deserialize_str<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a string value and does not benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_string<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a string value and would benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_bytes<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a byte array and does not benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_byte_buf<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a byte array and would benefit from taking ownership of buffered data owned by the Deserializer.

fn deserialize_unit<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a unit value.

fn deserialize_unit_struct<V>( self, name: &'static str, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a unit struct with a particular name.

fn deserialize_newtype_struct<V>( self, name: &'static str, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a newtype struct with a particular name.

fn deserialize_seq<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a sequence of values.

fn deserialize_tuple<V>( self, len: usize, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a sequence of values and knows how many values there are without looking at the serialized data.

fn deserialize_tuple_struct<V>( self, name: &'static str, len: usize, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a tuple struct with a particular name and number of fields.

fn deserialize_map<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a map of key-value pairs.

fn deserialize_struct<V>( self, name: &'static str, fields: &'static [&'static str], visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting a struct with a particular name and fields.

fn deserialize_identifier<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting the name of a struct field or the discriminant of an enum variant.

fn deserialize_ignored_any<V>( self, visitor: V, ) -> Result<V::Value, <Self as Deserializer<'de>>::Error>

where V: Visitor<'de>,

Hint that the Deserialize type needs to deserialize a value whose type doesn’t matter because it is ignored.

fn deserialize_i128<V>( self, visitor: V, ) -> Result<<V as Visitor<'de>>::Value, Self::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an i128 value.

fn deserialize_u128<V>( self, visitor: V, ) -> Result<<V as Visitor<'de>>::Value, Self::Error>

where V: Visitor<'de>,

Hint that the Deserialize type is expecting an u128 value.

fn is_human_readable(&self) -> bool

Determine whether Deserialize implementations should expect to deserialize their human-readable form.

impl Display for Value

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<&str> for Value

fn from(v: &str) -> Value

Converts to this type from the input type.

impl From<IndexMap<String, Value>> for Value

fn from(v: Map) -> Value

Converts to this type from the input type.

impl From<String> for Value

fn from(v: String) -> Value

Converts to this type from the input type.

impl From<bool> for Value

fn from(v: bool) -> Value

Converts to this type from the input type.

impl From<f32> for Value

fn from(v: f32) -> Value

Converts to this type from the input type.

impl From<f64> for Value

fn from(v: f64) -> Value

Converts to this type from the input type.

impl From<i8> for Value

fn from(v: i8) -> Value

Converts to this type from the input type.

impl From<i16> for Value

fn from(v: i16) -> Value

Converts to this type from the input type.

impl From<i32> for Value

fn from(v: i32) -> Value

Converts to this type from the input type.

impl From<i64> for Value

fn from(v: i64) -> Value

Converts to this type from the input type.

impl From<u8> for Value

fn from(v: u8) -> Value

Converts to this type from the input type.

impl From<u16> for Value

fn from(v: u16) -> Value

Converts to this type from the input type.

impl From<u32> for Value

fn from(v: u32) -> Value

Converts to this type from the input type.

impl FromStr for Value

type Err = Error

The associated error which can be returned from parsing.

fn from_str(s: &str) -> Result<Value>

Parses a string s to return a value of this type.

impl Index<&str> for Value

Indexing by dotted path (e.g. value["misc.location"]), with the same path syntax as Value::lookup.

Panics

Panics if the path does not resolve. Use Value::lookup for a non-panicking alternative.

type Output = Value

The returned type after indexing.

fn index(&self, key: &str) -> &Self::Output

Performs the indexing (container[index]) operation.

impl Index<usize> for Value

Indexing into arrays and lists by element position.

Panics

Panics if the value is not an array/list or the index is out of bounds. Use Value::get_index for a non-panicking alternative.

type Output = Value

The returned type after indexing.

fn index(&self, index: usize) -> &Self::Output

Performs the indexing (container[index]) operation.

impl PartialEq for Value

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<&str> for Value

fn eq(&self, other: &&str) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<String> for Value

fn eq(&self, other: &String) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<Value> for bool

fn eq(&self, other: &Value) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<Value> for i32

fn eq(&self, other: &Value) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<Value> for i64

fn eq(&self, other: &Value) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<Value> for f64

fn eq(&self, other: &Value) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<Value> for str

fn eq(&self, other: &Value) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<Value> for &str

fn eq(&self, other: &Value) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<Value> for String

fn eq(&self, other: &Value) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<bool> for Value

fn eq(&self, other: &bool) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<f64> for Value

fn eq(&self, other: &f64) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<i32> for Value

fn eq(&self, other: &i32) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<i64> for Value

fn eq(&self, other: &i64) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl PartialEq<str> for Value

fn eq(&self, other: &str) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for Value

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Value

impl TryFrom<Value> for Config

fn try_from(value: Value) -> Result<Config>

Wraps a Value as a configuration document.

Errors

Returns ErrorKind::ExpectedGroup if the value is not a Value::Group — a configuration document is a group of settings.

type Error = Error

The type returned in the event of a conversion error.