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MetaType

Enum MetaType 

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#[non_exhaustive]
pub enum MetaType { Default, Clear, Name(String), Use(String), Indirect, Offset, }
Expand description

Control-flow directive carried by TypeKind::Meta.

These are not value-reading types – they correspond to magic(5) control-flow keywords (default, clear, name, use, indirect, offset) that modify how a rule set is traversed rather than reading bytes from the buffer. All six variants are fully evaluated by the engine: default/clear manage per-level sibling-matched state; name/use implement subroutine dispatch; indirect re-applies the root rule database at a resolved offset; and offset emits the current file position as Value::Uint for printf-style formatting.

Variants (Non-exhaustive)§

This enum is marked as non-exhaustive
Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.
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Default

default directive: fires when no sibling at the same indentation level has matched at the current offset. See magic(5) for the “default” type semantics.

§Examples

use libmagic_rs::parser::ast::MetaType;
let meta = MetaType::Default;
assert_eq!(meta, MetaType::Default);
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Clear

clear directive: resets the sibling-matched flag so a later default sibling can fire even if an earlier sibling matched. See magic(5) for the “clear” type semantics.

§Examples

use libmagic_rs::parser::ast::MetaType;
let meta = MetaType::Clear;
assert_eq!(meta, MetaType::Clear);
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Name(String)

name <identifier> directive: declares a named subroutine that can be invoked later via MetaType::Use. See magic(5) for the “name” type semantics.

§Examples

use libmagic_rs::parser::ast::MetaType;
let meta = MetaType::Name("part2".to_string());
assert_eq!(meta, MetaType::Name("part2".to_string()));
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Use(String)

use <identifier> directive: invokes a named subroutine previously declared via MetaType::Name. See magic(5) for the “use” type semantics.

§Examples

use libmagic_rs::parser::ast::MetaType;
let meta = MetaType::Use("part2".to_string());
assert_eq!(meta, MetaType::Use("part2".to_string()));
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Indirect

indirect directive: re-applies the entire magic database at the resolved offset. See magic(5) for the “indirect” type semantics.

§Examples

use libmagic_rs::parser::ast::MetaType;
let meta = MetaType::Indirect;
assert_eq!(meta, MetaType::Indirect);
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Offset

offset type keyword: reports the current file offset rather than reading a typed value from the buffer. See magic(5) for the “offset” type semantics.

Evaluation: the engine resolves the rule’s offset specification to an absolute position and emits a RuleMatch whose value is Value::Uint(position). Message templates can reference that value through printf-style format specifiers (e.g. %lld), which are substituted by crate::output::format::format_magic_message at description- assembly time. The only supported operator is x (AnyValue); any other operator is debug!-logged and skipped.

§Examples

use libmagic_rs::parser::ast::MetaType;
let meta = MetaType::Offset;
assert_eq!(meta, MetaType::Offset);

Trait Implementations§

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impl Clone for MetaType

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fn clone(&self) -> MetaType

Returns a duplicate of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for MetaType

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

Formats the value using the given formatter. Read more
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impl<'de> Deserialize<'de> for MetaType

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fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>
where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer. Read more
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impl PartialEq for MetaType

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

Tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
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impl Serialize for MetaType

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fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>
where __S: Serializer,

Serialize this value into the given Serde serializer. Read more
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impl Eq for MetaType

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impl StructuralPartialEq for MetaType

Auto Trait Implementations§

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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unsafe fn clone_to_uninit(&self, dest: *mut u8)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dest. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> DeserializeOwned for T
where T: for<'de> Deserialize<'de>,