Enum ExceptionClause 

pub enum ExceptionClause {
    Catch {
        try_offset: u32,
        try_length: u32,
        handler_offset: u32,
        handler_length: u32,
        catch_type: Token,
    },
    Filter {
        try_offset: u32,
        try_length: u32,
        handler_offset: u32,
        handler_length: u32,
        filter_offset: u32,
    },
    Finally {
        try_offset: u32,
        try_length: u32,
        handler_offset: u32,
        handler_length: u32,
    },
    Fault {
        try_offset: u32,
        try_length: u32,
        handler_offset: u32,
        handler_length: u32,
    },
}

An exception handling clause from .NET method metadata.

Exception clauses define protected regions (try blocks) and their associated handlers within a method. Each clause specifies the IL offset ranges for both the try block and the handler block.

Clause Types

• Catch - Type-based exception handling
• Filter - Condition-based exception handling
• Finally - Guaranteed cleanup code
• Fault - Exception-only cleanup code

IL Offset Ranges

All offsets are relative to the start of the method body’s IL code:

• try_offset to try_offset + try_length defines the protected region
• handler_offset to handler_offset + handler_length defines the handler

Example

// For C# code:
// try { /* IL 0x00-0x10 */ }
// catch (Exception) { /* IL 0x10-0x20 */ }

let clause = ExceptionClause::Catch {
    try_offset: 0x00,
    try_length: 0x10,
    handler_offset: 0x10,
    handler_length: 0x10,
    catch_type: exception_type_token,
};

Variants

Catch

A catch clause that handles exceptions of a specific type.

Corresponds to try { } catch (ExceptionType) { } in C#. The handler is entered if the thrown exception’s type is assignable to catch_type.

Fields

try_offset: u32

IL offset where the try block begins.

try_length: u32

Length in bytes of the try block.

handler_offset: u32

IL offset where the catch handler begins.

handler_length: u32

Length in bytes of the catch handler.

catch_type: Token

Metadata token of the exception type to catch.

The exception is caught if its type is this type or a derived type.

Filter

A filter clause that handles exceptions based on a runtime condition.

Corresponds to try { } catch (Exception e) when (condition) { } in C#. The filter code is evaluated first; if it returns true (non-zero on the evaluation stack), the handler is entered.

Fields

try_offset: u32

IL offset where the try block begins.

try_length: u32

Length in bytes of the try block.

handler_offset: u32

IL offset where the catch handler begins (entered if filter passes).

handler_length: u32

Length in bytes of the catch handler.

filter_offset: u32

IL offset where the filter code begins.

The filter code must push an integer onto the stack:

• Non-zero (typically 1): Enter the handler
• Zero: Continue searching for other handlers

Finally

A finally clause that runs regardless of whether an exception occurred.

Corresponds to try { } finally { } in C#. The handler runs on both normal exit (via leave instruction) and exception exit (during unwinding).

Fields

try_offset: u32

IL offset where the try block begins.

try_length: u32

Length in bytes of the try block.

handler_offset: u32

IL offset where the finally handler begins.

handler_length: u32

Length in bytes of the finally handler.

Fault

A fault clause that runs only when an exception is thrown.

Similar to finally, but only executes on the exception path. Not commonly used in C# but supported by the CLR.

Fields

try_offset: u32

IL offset where the try block begins.

try_length: u32

Length in bytes of the try block.

handler_offset: u32

IL offset where the fault handler begins.

handler_length: u32

Length in bytes of the fault handler.

Implementations

impl ExceptionClause

pub fn try_offset(&self) -> u32

Gets the IL offset where the try block begins.

Returns

The starting IL offset of the protected region.

pub fn try_length(&self) -> u32

Gets the length of the try block in bytes.

Returns

The length of the protected region.

pub fn try_end(&self) -> u32

Gets the IL offset where the try block ends.

This is the first offset after the try block (exclusive end).

Returns

The ending IL offset of the protected region.

pub fn handler_offset(&self) -> u32

Gets the IL offset where the handler block begins.

Returns

The starting IL offset of the handler code.

pub fn handler_length(&self) -> u32

Gets the length of the handler block in bytes.

Returns

The length of the handler code.

pub fn handler_end(&self) -> u32

Gets the IL offset where the handler block ends.

This is the first offset after the handler block (exclusive end).

Returns

The ending IL offset of the handler code.

pub fn is_in_try(&self, offset: u32) -> bool

Checks if an IL offset is within the try block.

An offset is considered “in the try block” if it is greater than or equal to the try offset and less than the try end (half-open range).

Arguments

• offset - The IL offset to check

Returns

true if the offset is within the protected region.

pub fn is_in_handler(&self, offset: u32) -> bool

Checks if an IL offset is within the handler block.

An offset is considered “in the handler” if it is greater than or equal to the handler offset and less than the handler end.

Arguments

• offset - The IL offset to check

Returns

true if the offset is within the handler code.

pub fn is_catch(&self) -> bool

Checks if this is a catch clause.

Returns

true if this is a Catch variant.

pub fn is_filter(&self) -> bool

Checks if this is a filter clause.

Returns

true if this is a Filter variant.

pub fn is_finally(&self) -> bool

Checks if this is a finally clause.

Returns

true if this is a Finally variant.

pub fn is_fault(&self) -> bool

Checks if this is a fault clause.

Returns

true if this is a Fault variant.

pub fn catch_type(&self) -> Option<Token>

Gets the catch type token for catch clauses.

Returns

• Some(token) if this is a Catch clause
• None for other clause types

pub fn filter_offset(&self) -> Option<u32>

Gets the filter offset for filter clauses.

Returns

• Some(offset) if this is a Filter clause
• None for other clause types

impl ExceptionClause

pub fn from_metadata_handler(handler: &MetadataExceptionHandler) -> Self

Converts a metadata exception handler to an exception clause.

This method bridges the metadata representation (MetadataExceptionHandler) used during assembly loading with the emulation representation (ExceptionClause) used during runtime exception handling.

Arguments

• handler - The metadata exception handler to convert

Returns

An ExceptionClause with the appropriate variant based on the handler’s flags:

• FILTER flag -> Filter
• FINALLY flag -> Finally
• FAULT flag -> Fault
• No flags (default) -> Catch

pub fn from_metadata_handlers( handlers: &[MetadataExceptionHandler], ) -> Vec<Self>

Converts a slice of metadata exception handlers to exception clauses.

Convenience method for converting all exception handlers from a method’s metadata into the emulation representation.

Arguments

• handlers - Slice of metadata exception handlers from a method body

Returns

A vector of exception clauses in the same order as the input handlers. The order is significant: clauses are processed innermost-first during handler search.

Trait Implementations

impl Clone for ExceptionClause

fn clone(&self) -> ExceptionClause

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ExceptionClause

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

Formats the value using the given formatter.

impl Eq for ExceptionClause

impl PartialEq for ExceptionClause

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ExceptionClause