Listing a String object's index names for for-in built one name per UTF-16 unit before any
limit check, so a string within the heap limit could make the loop allocate many times that
limit. The heap budget for all the names is now checked first, after a collection if needed,
and each name takes a unit of fuel. A wrapper made by ToObject stays rooted while the names
are listed.
Realm::run compiles the script with the realm's Options::strict instead of always as sloppy code, so a realm made with strict: true rejects with statements and calls functions with an undefined this. Indirect eval and Function keep their own strictness (ES5.1 10.4.2, 15.3.2.1).
Function.prototype.apply drops the temporary GC roots it holds for the argument values when an index getter throws, as it already did when reading succeeds. Before, a caught throw left them rooted until the run ended, so a loop of such calls could reach the heap limit.
Realm::run now resets the exception that bind_last_thrown binds, so a run
that completes, reaches a limit or does not parse leaves it undefined. The
script source, the text built by Function and the strings given to eval are
checked against the run's remaining max_source_units before they are encoded
or flattened, so an oversized source is rejected without being copied.
vectorcraft-js gains a Realm that runs ECMAScript 5.1 scripts. The parsed
script compiles to stack-machine bytecode, a verifier checks every jump
target, handler, constant index and stack depth before the code runs, and
the interpreter keeps JavaScript calls on its own frame stack. Closures,
this, arguments, with, direct and indirect eval, new Function,
try/catch/finally, labeled break and continue, and for-in in insertion
order follow sections 10 to 14 of ECMA-262 5.1. Variable references are
resolved before the right-hand side of an assignment runs (11.13).
Objects and environments live in an arena with a mark-and-sweep
collector and index handles. Built-ins are limited to Object and
Object.prototype's basic methods, Function with call and apply, eval
and the error constructors.
Every run is bounded by fuel, heap bytes, frames, nested host calls and
an interrupt flag another thread can set, with smaller defaults in the
wasm build. A run that reaches a limit ends with a limit error that a
script's try cannot catch. Source passed to eval and Function counts
against Options::max_source_units.
cargo xtask test262 also runs the suite's ES5 test/language tests that
need only these built-ins and prints their counts apart from the parse
counts. Nothing in the app calls the interpreter yet.
Current test262 (ECMA-262 2017 Annex B.3.6) accepts `for (var x = 1 in o)` only outside strict
mode code. The parser now rejects the initializer in strict code, with the error at `in`.
New crate vectorcraft-js reads ECMAScript 5.1 source into a syntax tree
with source positions: a UTF-16 lexer (line and column tracking, automatic
semicolon insertion, the regexp and division goals), preprocessor lines
read as directive tokens, a recursive-descent parser to an arena tree, and
the ES5 early errors, strict mode included. Nesting deeper than
Options::max_depth (200 by default) gives a SyntaxError with its line and
column rather than overflowing the stack. Nothing runs scripts yet.
cargo xtask test262 downloads test262 at a pinned commit, checks its
SHA-256, unpacks it into the gitignored corpus/ folder and runs the ES5
syntax tests. A differential test in the engine compares the lexer with
scriptcheck on line counts, directives and unterminated literals.
dotCooCoo