ASTBinaryFormat class

Constants describing the ApolloVM binary AST container format.

A binary AST file — .avma, for Apollo Virtual Machine Archive — stores an already-parsed ASTRoot so that a code unit can be loaded without running a parser. The layout is:

offset  size  field
 0       4    magic             \0AVM
 4       2    formatVersion     uint16 BE — the container revision that wrote this file
 6       2    minReaderVersion  uint16 BE — oldest reader that can decode it correctly
 8       4    flags             uint32 BE — see [ASTBinaryFlags]
12       4    sectionsSize      uint32 BE — byte length of the section stream
16      ..    sections          repeated: leb128 id, leb128 size, size bytes
 T+0     4    crc32             uint32 BE — over bytes [0, T)
 T+4     2    signatureLength   uint16 BE — 0 when unsigned
 T+6    ..    signature         signatureLength bytes
 ..      4    trailerMagic      AVM\0

where T = headerSize + sectionsSize. The total file length is always headerSize + sectionsSize + minTrailerSize + signatureLength, which lets a reader detect truncation and trailing garbage structurally, before doing any integrity arithmetic.

Every fixed-width field is big-endian. Sections are length-prefixed, so a reader skips any section id it does not recognize — that is what lets a file written by a newer ApolloVM keep loading in an older one.

Properties

hashCode → int

The hash code for this object.

no setter, inherited

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

Methods

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

toString() → String

A string representation of this object.

inherited

Operators

operator ==(Object other) → bool

The equality operator.

inherited

Static Methods

constantTimeEquals(List<int> a, List<int> b) → bool

Compares a and b without an early exit on the first differing byte.

isASTBinary(Uint8List bytes) → bool

Whether bytes begins with the binary AST magic.

Constants

fileExtension → const String

The conventional file extension, without a leading dot.

headerSize → const int

Size of the fixed header, in bytes.

magic → const List<int>

File magic: \0AVM. The leading NUL marks the file as binary so no tool mistakes it for text, in the spirit of WebAssembly's \0asm.

maxSectionsSize → const int

The largest section stream this format can address (sectionsSize is a uint32).

maxSignatureLength → const int

The largest signature this format can hold (signatureLength is a uint16).

minSupportedVersion → const int

The oldest container revision this build can still read.

minTrailerSize → const int

Size of the trailer excluding the signature: crc32 + signatureLength + trailerMagic.

trailerMagic → const List<int>

Trailer magic: AVM\0 (the magic reversed).

version → const int

The container revision this build writes, and the newest it fully understands.