ludic/tools/ludic-cli/checks.ludic

# checks.ludic — the documentation / vocabulary lint suite, in Ludic.
#
# Ports the Python guards that used to live under tools/ (check-docs.py,
# check-vocabulary.py, tools/docgen/check-impl.py) so the doc/lint tooling runs
# through `x` with no Python in the loop. Each is a plain `x` subcommand and
# reuses the prelude (read_file / shq / capture / the PASS/FAIL harness).
#
# String work is over NUL-terminated byte buffers (read_file), reached with
# plain indexing; `==` on pointers is a byte-string compare (the whole toolchain
# leans on this).

# ============================================================================
# check-docs — every ```ludic fence in the docs must parse (or be marked)
# ============================================================================
# A fence declares its intent inline (# is a Ludic comment, so the marker is
# valid code):  `# doc-check: skip` (not checked), `# doc-check: expect-error`
# (must FAIL to parse). Everything else must parse under `ludicc --fmt` (lex +
# parse, no identifier resolution), after wrapping a bare fragment.

# the declaration heads that mean "these are top-level decls, wrap in program"
function is_decl_head(h: pointer) -> bool {
  if h == "program" or h == "property" or h == "model" or h == "handler" { return true }
  if h == "enum" or h == "function" or h == "extern" or h == "const" { return true }
  if h == "var" or h == "ui" or h == "struct" or h == "import" { return true }
  return false
}

# classify a fence body: "whole" (a full program), "decls", or "stmts"
function classify_fence(body: pointer) -> pointer {
  let n = slen(body)
  var i = 0
  while i < n {
    let ln = line_at(body, i)
    let t = s_trim(ln)
    if slen(t) > 0 and t[0] != '#' {          # non-empty, not a '#' comment
      # head = first token, split on '(' or whitespace
      var e = 0
      let tn = slen(t)
      while e < tn and t[e] != '(' and not is_ws(t[e]) { e += 1 }
      let head = sslice(t, 0, e)
      if head == "program" { return "whole" }
      if is_decl_head(head) { return "decls" }
      return "stmts"
    }
    i = i + slen(ln) + 1
  }
  return "stmts"
}

# does the wrapped source at `path` parse? (ludicc --fmt = lex+parse gate)
function fence_parses(src: pointer) -> bool {
  write_file(`{tmp_dir()}/docchk.ludic`, src)
  return shq(`bin/ludicc {tmp_dir()}/docchk.ludic --fmt > /dev/null 2>&1`)
}

# try the candidate framings for a fence; true if any parses
function fence_body_parses(body: pointer, kind: pointer) -> bool {
  if kind == "whole" { return fence_parses(body) }
  let as_decls = "program DocCheck {\n" + body + "\n}\n"
  let as_stmts = "program DocCheck {\n  handler DocS phase Start {\n" + body + "\n  }\n}\n"
  if kind == "decls" {
    if fence_parses(as_decls) { return true }
    return fence_parses(as_stmts)
  }
  if fence_parses(as_stmts) { return true }
  return fence_parses(as_decls)
}

var DC_OK: int = 0
var DC_BAD: int = 0
var DC_SKIP: int = 0
var DC_FAILS: pointer = ""

# scan one markdown file's ```ludic fences
function check_docs_file(path: pointer) -> void {
  let t = read_file(path)
  if t == null { return }
  var i = 0
  while true {
    let open = s_index(t, "```ludic\n", i)
    if open < 0 { break }
    # require the fence to sit at a line start
    if open != 0 and t[open - 1] != '\n' { i = open + 1;  continue }
    let bstart = open + 9                      # past "```ludic\n"
    let close = s_index(t, "\n```", bstart)
    if close < 0 { break }
    let body = sslice(t, bstart, close + 1)    # include trailing newline
    let line = 1 + count_nl(t, open)
    i = close + 4
    if s_contains(body, "# doc-check: skip") { DC_SKIP += 1;  continue }
    let expect_err = s_contains(body, "# doc-check: expect-error")
    let kind = classify_fence(body)
    let parsed = fence_body_parses(body, kind)
    if parsed == (not expect_err) {
      DC_OK += 1
    } else {
      DC_BAD += 1
      if expect_err { DC_FAILS = DC_FAILS + "    " + path + ":" + string(line) + "  expected to be rejected\n" }
      else { DC_FAILS = DC_FAILS + "    " + path + ":" + string(line) + "  expected to parse\n" }
    }
  }
}

# number of '\n' in s[0 .. upto)
function count_nl(s: pointer, upto: int) -> int {
  var n = 0;  var i = 0
  while i < upto { if s[i] == '\n' { n += 1 };  i += 1 }
  return n
}

# usage: ludic-dev check-docs   (scans the user-facing docs + docs/language/**)
function cmd_check_docs() -> int {
  ensure_ludicc()
  DC_OK = 0;  DC_BAD = 0;  DC_SKIP = 0;  DC_FAILS = ""
  # the corpus: root references + every per-symbol page
  let list = capture("{ ls LANGUAGE.md COMPILING.md README.md CONTRIBUTING.md 2>/dev/null; find docs -name '*.md' 2>/dev/null; }")
  let n = slen(list)
  var i = 0
  while i < n {
    let ln = line_at(list, i)
    i = i + slen(ln) + 1
    let path = s_trim(ln)
    if slen(path) > 0 { check_docs_file(path) }
  }
  print(`  doc fences: {string(DC_OK)} as documented, {string(DC_BAD)} drifted, {string(DC_SKIP)} skipped`)
  if DC_BAD > 0 { out(DC_FAILS) }
  if DC_BAD > 0 { return 1 }
  return 0
}

# ============================================================================
# check-impl — every implemented feature has a docs/language page
# ============================================================================
# Reads the implementation (emit_ns_call dispatch + the is_<ns>_ns predicates,
# and ludic_syntax.h's keyword/type/phase tables) and the per-symbol docs, then
# asserts they agree. Replaces the former tools/docgen/check-impl.py.

# a double-quote byte as a string (the lexer has no \" escape we rely on)
function dq() -> pointer { let b = bytes(2);  b[0] = '"';  b[1] = 0;  return b }

# set-style string list
function set_has(l: []pointer, s: pointer) -> bool {
  var i = 0
  while i < len(l) { if l[i] == s { return true };  i += 1 }
  return false
}
function set_add(l: []pointer, s: pointer) -> void { if not set_has(l, s) { push(l, s) } }

# the body of `function <name>(` up to the next top-level `function ` (or EOF)
function fn_body(src: pointer, name: pointer) -> pointer {
  let needle = "function " + name + "("
  var p = -1
  if s_starts(src, needle) { p = 0 }
  else {
    let q = s_index(src, "\n" + needle, 0)
    if q >= 0 { p = q + 1 }
  }
  if p < 0 { return "" }
  let nxt = s_index(src, "\nfunction ", p + 1)
  if nxt < 0 { return sslice(src, p, slen(src)) }
  return sslice(src, p, nxt)
}

# every identifier string following each occurrence of `marker` (read to a quote)
function collect_after(src: pointer, marker: pointer) -> []pointer {
  let out = new []pointer
  let mn = slen(marker)
  var i = 0
  while true {
    let p = s_index(src, marker, i)
    if p < 0 { break }
    var e = p + mn
    while src[e] != 0 and src[e] != '"' { e += 1 }
    push(out, sslice(src, p + mn, e))
    i = e + 1
  }
  return out
}

# quoted strings inside the `NAME[] = { ... };` C table in `h`
function table_set(h: pointer, name: pointer) -> []pointer {
  let out = new []pointer
  let p = s_index(h, name + "[]", 0)
  if p < 0 { return out }
  let b = s_index(h, "{", p)
  let e = s_index(h, "};", b)
  if b < 0 or e < 0 { return out }
  var i = b
  while i < e {
    if h[i] == '"' {
      var j = i + 1
      while j < e and h[j] != '"' { j += 1 }
      set_add(out, sslice(h, i + 1, j))
      i = j + 1
    } else { i += 1 }
  }
  return out
}

# concatenate every selfhost/*.ludic into one buffer (via cat, then read)
function read_all_selfhost() -> pointer {
  shell(`find selfhost -name '*.ludic' | sort | xargs cat > {tmp_dir()}/allsh.txt 2>/dev/null`)
  let s = read_file(`{tmp_dir()}/allsh.txt`)
  if s == null { return "" }
  return s
}

# {ns}.{method} pairs the compiler actually dispatches on -> into `pairs`
function collect_impl_pairs(allsrc: pointer, pairs: []pointer) -> void {
  let body = fn_body(allsrc, "emit_ns_call")
  let mns = "if (ns == " + dq()
  let mmeth = "meth == " + dq()
  let mnslen = slen(mns)
  var i = 0
  while true {
    let p = s_index(body, mns, i)
    if p < 0 { break }
    var ne = p + mnslen
    while body[ne] != 0 and body[ne] != '"' { ne += 1 }
    let nsname = sslice(body, p + mnslen, ne)
    let nxt = s_index(body, mns, ne)
    var chunkEnd = slen(body)
    if nxt >= 0 { chunkEnd = nxt }
    let chunk = sslice(body, p, chunkEnd)
    var methods = collect_after(chunk, mmeth)
    if len(methods) == 0 {
      let dp = s_index(chunk, "is_", 0)
      if dp >= 0 {
        var pe = dp
        while chunk[pe] != 0 and chunk[pe] != '(' { pe += 1 }
        let predname = sslice(chunk, dp, pe)
        methods = collect_after(fn_body(allsrc, predname), mmeth)
      }
    }
    var k = 0
    while k < len(methods) { set_add(pairs, nsname + "." + methods[k]);  k += 1 }
    if nxt < 0 { break }
    i = nxt
  }
}

# {ns}.{method} pairs a namespace declares with `alias` (L6) - the engine's in
# runtime/native/namespaces.ludic - which the compiler dispatches as surely as its own
function collect_alias_pairs(pairs: []pointer) -> void {
  let src = read_file("runtime/native/namespaces.ludic")
  if src == null { return }
  var ns = ""
  let n = slen(src)
  var i = 0
  while i < n {
    let ln = s_trim(line_at(src, i))
    i = i + slen(line_at(src, i)) + 1
    if s_starts(ln, "namespace ") {
      var e = 10
      while e < slen(ln) and ln[e] != ' ' and ln[e] != '{' { e += 1 }
      ns = sslice(ln, 10, e)
    }
    if s_starts(ln, "alias ") and slen(ns) > 0 {
      var e = 6
      while e < slen(ln) and ln[e] != '(' and ln[e] != ' ' and ln[e] != '=' { e += 1 }
      set_add(pairs, ns + "." + sslice(ln, 6, e))
    }
  }
}

# gather the docs facts: token set, and the (ns.member) pairs of ns-method pages
function collect_docs(tokens: []pointer, docpairs: []pointer) -> void {
  let list = capture("find docs/language -name '*.md' ! -name '_section.md' 2>/dev/null")
  let n = slen(list)
  var i = 0
  while i < n {
    let ln = line_at(list, i)
    i = i + slen(ln) + 1
    let path = s_trim(ln)
    if slen(path) == 0 { continue }
    let t = read_file(path)
    if t == null { continue }
    if not s_starts(t, "---") { continue }
    let end = s_index(t, "\n---", 3)
    if end < 0 { continue }
    let fm = sslice(t, 3, end)
    # walk front-matter lines
    var kind = "";  var ns = "";  var member = ""
    let fn2 = slen(fm)
    var j = 0
    while j < fn2 {
      let fl = line_at(fm, j)
      j = j + slen(fl) + 1
      let c = s_index(fl, ":", 0)
      if c < 0 { continue }
      let key = s_trim(sslice(fl, 0, c))
      let val = s_trim(sslice(fl, c + 1, slen(fl)))
      if key == "tokens" {
        # split val on spaces
        var a = 0
        let vn = slen(val)
        while a < vn {
          while a < vn and val[a] == ' ' { a += 1 }
          var e = a
          while e < vn and val[e] != ' ' { e += 1 }
          if e > a { set_add(tokens, sslice(val, a, e)) }
          a = e
        }
      }
      if key == "kind" { kind = val }
      if key == "ns" { ns = val }
      if key == "member" { member = val }
    }
    if kind == "namespace-method" and slen(ns) > 0 and slen(member) > 0 {
      set_add(docpairs, ns + "." + member)
    }
  }
}

var CI_PROB: pointer = ""
var CI_NPROB: int = 0
function ci_problem(msg: pointer) -> void { CI_PROB = CI_PROB + "  - " + msg + "\n";  CI_NPROB += 1 }

# usage: ludic-dev check-impl
function cmd_check_impl() -> int {
  CI_PROB = "";  CI_NPROB = 0
  let allsrc = read_all_selfhost()
  let impl = new []pointer
  collect_impl_pairs(allsrc, impl)
  collect_alias_pairs(impl)
  let tokens = new []pointer
  let docpairs = new []pointer
  collect_docs(tokens, docpairs)

  # 1) every implemented ns-method has a page with the right token
  var i = 0
  while i < len(impl) {
    let pair = impl[i]
    if not set_has(docpairs, pair) { ci_problem("undocumented " + pair + " — add a docs/language page (tokens: " + pair + ")") }
    else { if not set_has(tokens, pair) { ci_problem(pair + " documented but its page lacks that tokens entry") } }
    i += 1
  }
  # 2) every documented ns-method corresponds to real dispatch
  i = 0
  while i < len(docpairs) {
    if not set_has(impl, docpairs[i]) { ci_problem("stale doc: " + docpairs[i] + " is not dispatched by the compiler") }
    i += 1
  }
  # 3) every implemented keyword / type / phase is documented
  let h = read_file("tools/ludic-tools/ludic_syntax.h")
  let reserved = table_set(h, "LUDIC_KW_RESERVED")
  let kws = new []pointer
  add_all_except(kws, table_set(h, "LUDIC_KW_DECL"), reserved)
  add_all_except(kws, table_set(h, "LUDIC_KW_CLAUSE"), reserved)
  add_all_except(kws, table_set(h, "LUDIC_KW_STMT"), reserved)
  let types = table_set(h, "LUDIC_TYPES")
  let phases = table_set(h, "LUDIC_PHASES")
  check_all_documented(kws, tokens, "keyword")
  check_all_documented(types, tokens, "type")
  check_all_documented(phases, tokens, "phase")

  if CI_NPROB > 0 {
    err("docs-vs-implementation drift:\n")
    err(CI_PROB)
    return 1
  }
  print("docs cover the implementation: " + string(len(impl)) + " namespace methods, " + string(len(kws)) + " keywords, " + string(len(types)) + " types, " + string(len(phases)) + " phases")
  return 0
}

# add every element of `src` not in `deny` to `dst` (set semantics)
function add_all_except(dst: []pointer, src: []pointer, deny: []pointer) -> void {
  var i = 0
  while i < len(src) { if not set_has(deny, src[i]) { set_add(dst, src[i]) };  i += 1 }
}
# every name must appear in the token set, else a problem
function check_all_documented(names: []pointer, tokens: []pointer, label: pointer) -> void {
  var i = 0
  while i < len(names) {
    if not set_has(tokens, names[i]) { ci_problem("undocumented " + label + ": " + names[i] + " (no docs/language page lists it in tokens)") }
    i += 1
  }
}

# ============================================================================
# check-vocabulary — the language vocabulary is written down in several places
# that cannot include each other (ludic_syntax.h, the JetBrains Kotlin lexer,
# the TextMate grammar, the self-host parser); drift between them is silent, so
# it is checked. Replaces the former tools/check-vocabulary.py.
# ============================================================================

# a 3-byte needle as a string
function bx3(a: int, b: int, c: int) -> pointer { let z = bytes(4);  z[0] = a;  z[1] = b;  z[2] = c;  z[3] = 0;  return z }

function all_lower(s: pointer) -> bool {
  let n = slen(s)
  if n == 0 { return false }
  var i = 0
  while i < n { if s[i] < 'a' or s[i] > 'z' { return false };  i += 1 }
  return true
}

# split `s` on '|' into a set
function split_pipe(s: pointer) -> []pointer {
  let out = new []pointer
  let n = slen(s)
  var a = 0
  while a <= n {
    var e = a
    while e < n and s[e] != '|' { e += 1 }
    set_add(out, sslice(s, a, e))
    a = e + 1
  }
  return out
}

# first quoted string after each row-opening '{' in the `name[]` C table
function c_table_names(h: pointer, name: pointer) -> []pointer {
  let out = new []pointer
  let p = s_index(h, name + "[]", 0)
  if p < 0 { return out }
  let b = s_index(h, "{", p)
  let e = s_index(h, "};", b)
  if b < 0 or e < 0 { return out }
  var i = b + 1
  while i < e {
    if h[i] == '{' {                              # '{' opens a row
      var j = i + 1
      while j < e and (h[j] == ' ' or h[j] == '\t' or h[j] == '\n') { j += 1 }
      if h[j] == '"' {
        var k = j + 1
        while k < e and h[k] != '"' { k += 1 }
        set_add(out, sslice(h, j + 1, k))
      }
    }
    i += 1
  }
  return out
}

# names in a Kotlin `val NAME = setOf( ... )` (parens matched, // comments cut)
function kotlin_set(text: pointer, name: pointer) -> []pointer {
  let out = new []pointer
  let marker = "val " + name + " = setOf("
  let p = s_index(text, marker, 0)
  if p < 0 { return out }
  var i = p + slen(marker)
  var depth = 1
  let region_start = i
  let tn = slen(text)
  while i < tn and depth > 0 {
    if text[i] == '(' { depth += 1 }
    if text[i] == ')' { depth -= 1 }
    if depth == 0 { break }
    i += 1
  }
  # collect quoted strings in [region_start, i), skipping //-comments
  var k = region_start
  while k < i {
    if text[k] == '/' and text[k + 1] == '/' {      # '//'
      while k < i and text[k] != '\n' { k += 1 }
    } else { if text[k] == '"' {
      var e = k + 1
      while e < i and text[e] != '"' { e += 1 }
      set_add(out, sslice(text, k + 1, e))
      k = e + 1
    } else { k += 1 } }
  }
  return out
}

# the alternation inside repository.<node>.patterns' first match containing marker
function grammar_alt(root: JVal, node: pointer, marker: pointer) -> []pointer {
  let out = new []pointer
  let pats = j_get(j_get(j_get(root, "repository"), node), "patterns")
  if pats.t != JV_ARR { return out }
  var i = 0
  while i < len(pats.kids) {
    let m = j_get(pats.kids[i], "match")
    if m.t == JV_STR and s_contains(m.s, marker) {
      let op = s_index(m.s, bx3('\\', 'b', '('), 0)    # \b(
      if op >= 0 {
        let cl = s_index(m.s, bx3(')', '\\', 'b'), op)  # )\b
        if cl >= 0 { return split_pipe(sslice(m.s, op + 3, cl)) }
      }
    }
    i += 1
  }
  return out
}

# the lower-case names among `src` into `out` (a set)
function add_lower(out: []pointer, src: []pointer) -> void {
  var i = 0
  while i < len(src) { if all_lower(src[i]) { set_add(out, src[i]) };  i += 1 }
}

var CV_PROB: pointer = ""
var CV_N: int = 0
function cv_problem(msg: pointer) -> void { CV_PROB = CV_PROB + "  - " + msg + "\n";  CV_N += 1 }

# report names in `ref` missing from `other`, and names in `other` not in `ref`
function cmp_sets(label: pointer, ref: []pointer, other: []pointer, other_label: pointer) -> void {
  var i = 0
  while i < len(ref) { if not set_has(other, ref[i]) { cv_problem(other_label + " is missing " + label + ": " + ref[i]) };  i += 1 }
  i = 0
  while i < len(other) { if not set_has(ref, other[i]) { cv_problem(other_label + " has unknown " + label + ": " + other[i]) };  i += 1 }
}

# union of two sets
function set_union(a: []pointer, b: []pointer) -> []pointer {
  let out = new []pointer
  var i = 0
  while i < len(a) { set_add(out, a[i]);  i += 1 }
  i = 0
  while i < len(b) { set_add(out, b[i]);  i += 1 }
  return out
}

# usage: ludic-dev check-vocabulary
function cmd_check_vocab() -> int {
  CV_PROB = "";  CV_N = 0
  let h = read_file("tools/ludic-tools/ludic_syntax.h")
  if h == null { err("check-vocabulary: ludic_syntax.h missing\n");  return 2 }
  let h_decl = table_set(h, "LUDIC_KW_DECL")
  let h_clause = table_set(h, "LUDIC_KW_CLAUSE")
  let h_stmt = table_set(h, "LUDIC_KW_STMT")
  let h_types = table_set(h, "LUDIC_TYPES")
  let h_phases = table_set(h, "LUDIC_PHASES")
  let h_widgets = table_set(h, "LUDIC_WIDGETS")
  let h_builtins = c_table_names(h, "LUDIC_BUILTINS")
  let h_intrinsics = c_table_names(h, "LUDIC_INTRINSICS")

  # --- against the JetBrains lexer ---
  let kt = read_file("tools/editors/jetbrains/src/main/kotlin/io/ludic/ide/LudicTokens.kt")
  if kt != null {
    cmp_sets("declaration keywords", h_decl, kotlin_set(kt, "DECL"), "LudicTokens.kt")
    cmp_sets("clause keywords", h_clause, kotlin_set(kt, "CLAUSE"), "LudicTokens.kt")
    cmp_sets("statement keywords", h_stmt, kotlin_set(kt, "STMT"), "LudicTokens.kt")
    cmp_sets("primitive types", h_types, kotlin_set(kt, "PRIMITIVES"), "LudicTokens.kt")
    cmp_sets("phases", h_phases, kotlin_set(kt, "PHASES"), "LudicTokens.kt")
    cmp_sets("widgets", h_widgets, kotlin_set(kt, "WIDGETS"), "LudicTokens.kt")
    cmp_sets("builtins", set_union(h_builtins, h_intrinsics), kotlin_set(kt, "BUILTINS"), "LudicTokens.kt")
  }

  # --- against the TextMate grammar ---
  let gt = read_file("tools/editors/shared/ludic.tmLanguage.json")
  if gt != null {
    let g = json_parse(gt)
    cmp_sets("builtins", h_builtins, grammar_alt(g, "builtin", "rng_chance"), "ludic.tmLanguage.json")
    cmp_sets("intrinsics", h_intrinsics, grammar_alt(g, "builtin", "as_fixed"), "ludic.tmLanguage.json")
    cmp_sets("phases", h_phases, grammar_alt(g, "keyword", "FixedUpdate"), "ludic.tmLanguage.json")
    cmp_sets("primitive types", h_types, grammar_alt(g, "keyword", "fixed"), "ludic.tmLanguage.json")
  }

  # --- the keyword, type and phase tables, the docs and the parser, against the compiler's own
  # vocabulary (ludicc --emit-syntax; syntax_gen.ludic) ---
  if sx_vocab() == null { cv_problem("bin/ludicc has no --emit-syntax: rebuild it (ludic-dev build)") }
  else {
    g_sx_prob = new []pointer
    let ts = sx_targets()
    var ti = 0
    while ti < len(ts) {
      let text = read_file(ts[ti])
      if text != null {
        let want = sx_regenerate(ts[ti], text)
        if want != null and not (want == text) { cv_problem(ts[ti] + " is behind the vocabulary - run ludic-dev syntax") }
      }
      sx_carries(ts[ti])
      ti += 1
    }
    sx_docs()
    sx_parser()
    var pi2 = 0
    while pi2 < len(g_sx_prob) { cv_problem(g_sx_prob[pi2]);  pi2 += 1 }
  }

  if CV_N > 0 {
    err("vocabulary drift:\n")
    err(CV_PROB)
    return 1
  }
  return 0
}


# ============================================================================
# json/xml asset validation — replaces the python3 json.load / xml.dom checks
# the editor-toolchain suite used on the shared grammar + plugin assets.
# ============================================================================

# minimal XML well-formedness: tags balance and nest, quotes respected.
function xml_valid(text: pointer) -> bool {
  let n = slen(text)
  let stack = new []pointer
  var sp = 0
  var i = 0
  while i < n {
    if text[i] != '<' { i += 1;  continue }     # seek '<'
    if text[i + 1] == '?' {                         # <? ... ?>
      let e = s_index(text, "?>", i)
      if e < 0 { return false }
      i = e + 2;  continue
    }
    if text[i + 1] == '!' {                         # <! comment / cdata / doctype
      if text[i + 2] == '-' and text[i + 3] == '-' {  # <!-- ... -->
        let e = s_index(text, "-->", i)
        if e < 0 { return false }
        i = e + 3;  continue
      }
      if s_starts_at(text, i, "<![CDATA[") {        # <![CDATA[ ... ]]>
        let e = s_index(text, "]]>", i)
        if e < 0 { return false }
        i = e + 3;  continue
      }
      let e = s_index(text, ">", i)
      if e < 0 { return false }
      i = e + 1;  continue
    }
    if text[i + 1] == '/' {                         # closing </name>
      var j = i + 2
      while j < n and text[j] != '>' and text[j] != ' ' and text[j] != '\t' and text[j] != '\n' { j += 1 }
      let name = sslice(text, i + 2, j)
      let e = s_index(text, ">", j)
      if e < 0 { return false }
      if sp == 0 { return false }
      if stack[sp - 1] != name { return false }
      sp -= 1
      i = e + 1;  continue
    }
    # opening tag: read the name
    var j = i + 1
    while j < n and text[j] != '>' and text[j] != ' ' and text[j] != '\t' and text[j] != '\n' and text[j] != '/' { j += 1 }
    let name = sslice(text, i + 1, j)
    if slen(name) == 0 { return false }
    # advance to '>', skipping quoted attribute values
    var k = j
    while k < n and text[k] != '>' {
      if text[k] == '"' { k += 1;  while k < n and text[k] != '"' { k += 1 } }
      else { if text[k] == '\'' { k += 1;  while k < n and text[k] != '\'' { k += 1 } } }
      k += 1
    }
    if k >= n { return false }
    if text[k - 1] != '/' {                         # not self-closing -> push
      if sp < len(stack) { stack[sp] = name } else { push(stack, name) }
      sp += 1
    }
    i = k + 1
  }
  return sp == 0
}

# usage: ludic-dev lint-asset <file>   (validates one .json or .xml editor asset)
function cmd_lint_asset() -> int {
  if arg_count() < 3 { err("usage: ludic-dev lint-asset <file.json|file.xml>\n");  return 2 }
  let path = arg(2)
  let t = read_file(path)
  if t == null { err("lint-asset: cannot read " + path + "\n");  return 1 }
  if s_index(path, ".json", 0) >= 0 {
    if json_valid(t) { return 0 }
    return 1
  }
  if s_index(path, ".xml", 0) >= 0 {
    if xml_valid(t) { return 0 }
    return 1
  }
  err("lint-asset: unknown asset type " + path + "\n")
  return 2
}