nx_js_eval.nx

nx_js_eval.nx -- R-JS-EVAL (WB-JS-001 rung 2): the ECMAScript tree-walking EVALUATOR with a variable ENVIRONMENT (scope chain) + USER FUNCTIONS, riding the gated parser (nx_js_parse) per the no-floating law. Shape = recursive tree-walk over the parser's flat node arena. Founds R-JS-RUNTIME (objects/builtins) and the DOM bindings that render JS-walled pages (google image results are JS-walled). VALUE = 2 i64 slots [type, payload]: VAL_UNDEF / VAL_NULL ; VAL_BOOL: 0|1 ; VAL_NUM: integer ; VAL_STR: pointer (as i64) to a string-heap RECORD [len:i64][bytes...] -- so '+' can produce real, comparable byte strings (concat) ; VAL_FUNC: function-decl node index (params+body live in the AST; the call frame parents the global env). ERROR is signalled by an eval return code of 1 (NOT a tag): a ReferenceError -- reading or assigning an UNDECLARED name -- is an ERROR, never a silent undefined (`y+1` with y undeclared yields an error result, matching real JS "y is not defined"). RUNG-2 (ALL gated): expressions: literals (number/string/bool/null), identifier lookup with ReferenceError, unary ! - + typeof, binary + - * / % (integer; + does STRING CONCAT when either operand is a string, coercing the other), comparison < <= > >= (numeric; AND byte-lexicographic when BOTH operands are strings: 'a'<'b', 'apple'<'banana', 'ab'<'abc'), equality == != === !== (strings compared by bytes), logical && || SHORT-CIRCUIT (returns the deciding OPERAND value = real JS), assignment (incl chained a=b=c -- updates the DECLARING scope, never auto-creates a global). statements: var/let/const decl, assignment, expr stmt, { blocks }, if/else, while (iteration cap), return. FUNCTIONS: `function f(params){body}` is a VAL_FUNC; CALL f(args) opens a fresh call env (parent = global env -> globals + recursion resolve), binds params (a param SHADOWS an outer same-named var), runs the body, and RETURN unwinds (completion status 2) out of any nested if/while to the call boundary. Recursion works (fact(5)=120, fib(10)=55). Function declarations are HOISTED both at the TOP LEVEL (js_run_source) and INTRA-BODY (js_call_core pre-pass over the body block's DIRECT children) -- so a nested `function inner(){}` is callable BEFORE its textual position within the same function body (rung 7). Decls inside inner blocks (if/for) are bound when reached, not hoisted across block boundaries (real-JS `var`- style function hoisting to the enclosing function scope is a NAMED OPEN -- only the body's DIRECT children are pre-bound). RUNG-6 (R-JS-CLOSURE, NOW DONE + gated): FIRST-CLASS FUNCTIONS with PROPER LEXICAL