parse_string scanned for `"` and `\` but accepted every other byte,
including raw control characters. RFC 8259 §7 requires those bytes to be
escaped inside a string; an unescaped one is invalid JSON and must surface
a parse error, not be silently accepted.
Add `BadControlChar` to JsonParseError and reject any unescaped byte < 0x20
in the string body scan (which gates the decode path too, so escaped forms
like \t/\n/ still decode correctly; 0x20 and 0x7F are not over-rejected).
Regression test in examples/0714: raw 0x09/0x0A/0x00 each raise
BadControlChar via `?`/`!`; a positive case proves the escaped forms still
decode to the right bytes. All prior assertions kept.
Issue 0078 (string == as an and/or operand emitting an invalid PHI) is
resolved on this branch, so the example no longer needs the split that
worked around it. Restore the natural combined assertion
sub.items[0].key == "k" and sub.items[0].val.str == "v"
(one nested-pair report), and the in_range containment helper to
return x >= lo and x < hi;
Drop the now-stale issues/0078 references. Re-captured expected stdout
(nested-key/nested-val -> nested-pair). json.sx and src/ untouched.
Add the JSON reader (parser) to library/modules/std/json.sx, the inverse
of the F2.1 writer over the same value model: insertion-ordered objects,
arrays, strings (full unescaping incl. \uXXXX + surrogate pairs), s64
integers, bool, null.
Heap discipline (binding): exactly two allocation kinds, both through the
EXPLICIT `alloc` parameter, never the implicit context allocator —
composite backing stores (Array/Object.items via add/put) and decoded
escaped-string buffers (bounded by the raw span). Un-escaped string
values are zero-copy VIEWS into the input buffer (valid only while it
lives); scalars carry no heap.
Failure surfacing (hard contract): malformed input raises a meaningful
JsonParseError variant (UnexpectedToken / UnexpectedEnd / BadEscape /
BadNumber / TrailingGarbage) on the error channel, never a bogus value.
Trailing non-whitespace is TrailingGarbage; fractions/exponents,
out-of-s64 magnitudes, and leading zeros are BadNumber. Number
accumulation runs in negative space so s64 MIN parses exactly.
examples/0714-modules-json-reader.sx asserts the parsed structure
(insertion order, every kind), proves the view-vs-decoded heap split by
pointer containment, round-trips back through the writer byte-for-byte,
decodes a surrogate-pair into 4 UTF-8 bytes, and checks every malformed
variant.
Filed issues/0078: a string `==` (or any sub-CFG operand) used in a
short-circuit `and`/`or` emits invalid LLVM IR (stale PHI predecessor),
hit while writing the example's assertions and worked around there by not
combining comparisons with `and`/`or`. src/ untouched.
