With `Options::e4x` set, vectorcraft-js runs ECMA-357 (2nd edition):
XML and XMLList literals with embedded expressions, the `..`, `.@`,
`.*`, `.()` and `::` selectors, assignment and `delete` on selected
nodes, `for each`, `default xml namespace`, and the four objects with
their methods and settings. The option is off by default, and without
it the syntax and globals do not exist.
Parsing, serializing, comparing and copying trees use no native stack,
and each takes fuel and counts against the heap limit. Inserting a node
into itself or its descendants throws a TypeError before the tree
changes. A literal or XML string nested past `Options::max_depth` gives
a SyntaxError, and a tree built past that depth stops at the heap limit.
`XML.prototype.xpath` is not provided.
is_id_start accepts the letter categories (Lu, Ll, Lt, Lm, Lo, Nl) and
is_id_part adds Mn, Mc, Nd and Pc, read with unicode-general-category.
A superscript digit (No) inside an identifier and a mark such as U+09BE
at its start are now SyntaxErrors, and identifiers with marks outside
the old list, such as the Bengali and Tamil viramas, now parse.
Labels in scope are kept in a map, and duplicate labels in a chain and
duplicate parameters of a strict function are found with a hash set, so
long chains, many labeled statements and long parameter lists are
checked in linear time.
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.
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