347 lines
12 KiB
Text
347 lines
12 KiB
Text
# ============================================================================
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# xml.ludic — a minimal pure-Ludic XML reader (`Xml.*`), for the TMX/TSX/TX
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# subset Tiled emits (Tiled design §0.1, issue #67). It handles exactly what the
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# native Tiled formats use: elements, single/double-quoted attributes, nested
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# children, text/CDATA content, comments, the `<?xml?>` prolog and `<!DOCTYPE>`,
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# and the five predefined entities plus numeric character references. It is NOT
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# a validating or namespace-aware parser — best-effort, deterministic, allocation
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# the only cost, the same contract as the JSON reader (value.ludic).
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#
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# ludicc splices this file when a program mentions `Xml.*` (parse.ludic), exactly
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# like `Regex.*`/`Value.*`. The tree is plain Ludic over heap records.
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#
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# A node is one element: its `tag`, parallel attribute `akeys`/`avals`, ordered
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# child elements `kids`, and the concatenated character data `text` (the CSV in a
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# `<data encoding="csv">` element, or a `<property>` string, lands here).
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# ============================================================================
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property Xml {
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tag: pointer = null # element name ("" for the synthetic empty node)
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text: pointer = null # concatenated character data of this element
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akeys: []pointer # attribute names
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avals: []pointer # attribute values (entity-decoded)
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kids: []Xml # child elements, in document order
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at: int = 0 # where its '<' is in the text, for an error that names a line
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mixed: []Xml # its elements and its runs of text ("#text"), in document order
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}
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function xml_new(tag: pointer) -> Xml {
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let n = new Xml
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n.tag = tag
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n.text = ""
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n.akeys = new []pointer
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n.avals = new []pointer
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n.kids = new []Xml
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n.mixed = new []Xml
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return n
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}
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# --- accessors --------------------------------------------------------------
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function xml_tag(n: Xml) -> string { if n.tag == null { return "" }; return n.tag }
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function xml_text(n: Xml) -> string { if n.text == null { return "" }; return n.text }
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function xml_child_count(n: Xml) -> int { return len(n.kids) }
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function xml_child(n: Xml, i: int) -> Xml {
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if i < 0 or i >= len(n.kids) { return xml_new("") }
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return n.kids[i]
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}
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function xml_attr_count(n: Xml) -> int { return len(n.akeys) }
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function xml_has(n: Xml, key: pointer) -> int {
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var i = 0
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while i < len(n.akeys) { if n.akeys[i] == key { return 1 }; i += 1 }
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return 0
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}
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function xml_attr(n: Xml, key: pointer) -> string {
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var i = 0
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while i < len(n.akeys) { if n.akeys[i] == key { return n.avals[i] }; i += 1 }
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return ""
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}
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# attribute as an integer (decimal, optional leading '-'); `dflt` when absent.
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function xml_attr_int(n: Xml, key: pointer, dflt: int) -> int {
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if xml_has(n, key) == 0 { return dflt }
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return xml_atoi(xml_attr(n, key))
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}
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# the first direct child named `tag`, or the synthetic empty node if none.
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function xml_find(n: Xml, tag: pointer) -> Xml {
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var i = 0
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while i < len(n.kids) { if n.kids[i].tag == tag { return n.kids[i] }; i += 1 }
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return xml_new("")
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}
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# count direct children named `tag`.
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function xml_count(n: Xml, tag: pointer) -> int {
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var c = 0
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var i = 0
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while i < len(n.kids) { if n.kids[i].tag == tag { c += 1 }; i += 1 }
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return c
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}
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# parse a signed decimal integer prefix of `s` (stops at the first non-digit).
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function xml_atoi(s: pointer) -> int {
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var i = 0
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let n = len(s)
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var neg = 0
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if i < n and s[i] == '-' { neg = 1; i += 1 } # '-'
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var v = 0
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while i < n and s[i] >= '0' and s[i] <= '9' {
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v = v * 10 + (s[i] - 48)
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i += 1
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}
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if neg != 0 { return -v }
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return v
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}
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# --- entity decoding --------------------------------------------------------
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# expand the five predefined entities and &#NN; / &#xHH; numeric references in a
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# raw run. Only bytes 0..255 of a character reference are emitted (Ludic strings
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# are byte strings); a code point above that is written as its low byte, which is
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# ample for the ASCII/Latin-1 text Tiled attributes carry.
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function xml_unescape(rt_xml_st: mut RtXmlState, s: pointer) -> string {
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# fast path: no '&' means nothing to expand
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var k = 0
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let m = len(s)
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var amp = 0
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while k < m { if s[k] == '&' { amp = 1; k = m } else { k += 1 } }
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if amp == 0 { return s }
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var out = ""
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var i = 0
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while i < m {
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let c = s[i]
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if c != '&' { # not '&'
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# copy the run up to the next '&' in one slice
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var j = i
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while j < m and s[j] != '&' { j += 1 }
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out += s[i..j]
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i = j
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} else {
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# find the ';'
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var j = i + 1
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while j < m and s[j] != ';' { j += 1 } # ';'
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if j >= m { out += s[i..m]; i = m }
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else {
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let ent = s[i + 1..j]
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if ent == "amp" { out += "&" }
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else { if ent == "lt" { out += "<" }
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else { if ent == "gt" { out += ">" }
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else { if ent == "quot" { out += "\"" }
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else { if ent == "apos" { out += "'" }
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else {
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if len(ent) >= 2 and ent[0] == '#' { # '#' numeric reference
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var code = 0
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if ent[1] == 'x' or ent[1] == 'X' { # '#x' hex
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var h = 2
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while h < len(ent) { code = code * 16 + xml_hexval(ent[h]); h += 1 }
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} else {
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var d = 1
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while d < len(ent) { code = code * 10 + (ent[d] - 48); d += 1 }
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}
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out += xml_byte(rt_xml_st, code & 255)
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} else {
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out = out + "&" + ent + ";" # unknown entity, keep literal
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}
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} } } } }
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i = j + 1
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}
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}
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}
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return out
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}
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function xml_hexval(c: int) -> int {
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if c >= '0' and c <= '9' { return c - 48 }
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if c >= 'a' and c <= 'f' { return c - 87 }
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if c >= 'A' and c <= 'F' { return c - 55 }
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return 0
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}
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# a one-byte string holding byte value `b` (1..255); "" for 0 (a NUL can't sit in
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# a Ludic string). Built by slicing a 256-byte table of every byte value.
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export state RtXmlState {
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xml_bytetab: pointer = null
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}
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function xml_byte(rt_xml_st: mut RtXmlState, b: int) -> string {
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if b <= 0 { return "" }
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if rt_xml_st.xml_bytetab == null {
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let t = bytes(257)
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var i = 0
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while i < 256 { t[i] = i + 1; i += 1 } # table[i] = byte (i+1), so 0 never appears
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t[256] = 0
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rt_xml_st.xml_bytetab = t
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}
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return rt_xml_st.xml_bytetab[b - 1..b]
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}
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# --- parser -----------------------------------------------------------------
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property XP { s: pointer = null, i: int = 0, n: int = 0 }
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function xp_ws(c: int) -> bool { return c == ' ' or c == '\t' or c == '\n' or c == '\r' }
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function xp_skip_ws(p: XP) -> void {
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while p.i < p.n and xp_ws(p.s[p.i]) { p.i += 1 }
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}
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# skip a `<?...?>`, `<!-- ... -->` or `<!DOCTYPE ...>` at the cursor. Returns true
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# if it consumed one (cursor on '<').
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function xp_skip_misc(p: XP) -> bool {
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if p.i + 1 >= p.n or p.s[p.i] != '<' { return false } # '<'
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let c = p.s[p.i + 1]
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if c == '?' { # '<?' ... '?>'
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p.i += 2
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while p.i + 1 < p.n and not (p.s[p.i] == '?' and p.s[p.i + 1] == '>') { p.i += 1 }
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p.i += 2
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return true
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}
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if c == '!' { # '<!'
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if p.i + 3 < p.n and p.s[p.i + 2] == '-' and p.s[p.i + 3] == '-' { # '<!--' comment
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p.i += 4
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while p.i + 2 < p.n and not (p.s[p.i] == '-' and p.s[p.i + 1] == '-' and p.s[p.i + 2] == '>') { p.i += 1 }
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p.i += 3
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return true
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}
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# '<!DOCTYPE ...>' or other declaration — skip to the matching '>'
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p.i += 2
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while p.i < p.n and p.s[p.i] != '>' { p.i += 1 }
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p.i += 1
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return true
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}
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return false
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}
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# read a name (element or attribute): letters, digits, '_', '-', ':', '.'
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function xp_name(p: XP) -> string {
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let start = p.i
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while p.i < p.n {
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let c = p.s[p.i]
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let ok = (c >= 'A' and c <= 'Z') or (c >= 'a' and c <= 'z') or (c >= '0' and c <= '9')
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if ok or c == '_' or c == '-' or c == ':' or c == '.' { p.i += 1 }
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else { break }
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}
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return p.s[start..p.i]
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}
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# parse `key="value"` / `key='value'` attributes into the element node.
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function xp_attrs(rt_xml_st: mut RtXmlState, p: XP, node: Xml) -> void {
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while true {
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xp_skip_ws(p)
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if p.i >= p.n { return }
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let c = p.s[p.i]
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if c == '>' or c == '/' or c == '?' { return } # '>' '/' '?'
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let key = xp_name(p)
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if len(key) == 0 { p.i += 1; continue } # stray char, don't stall
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xp_skip_ws(p)
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var val = ""
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if p.i < p.n and p.s[p.i] == '=' { # '='
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p.i += 1
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xp_skip_ws(p)
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if p.i < p.n and (p.s[p.i] == '"' or p.s[p.i] == '\'') {
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let q = p.s[p.i]
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p.i += 1
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let start = p.i
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while p.i < p.n and p.s[p.i] != q { p.i += 1 }
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val = xml_unescape(rt_xml_st, p.s[start..p.i])
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p.i += 1 # skip closing quote
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}
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}
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push(node.akeys, key)
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push(node.avals, val)
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}
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}
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# parse one element (cursor on its opening '<'). Recurses for children.
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function xp_element(rt_xml_st: mut RtXmlState, p: XP) -> Xml {
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let at = p.i
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p.i += 1 # skip '<'
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let name = xp_name(p)
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let node = xml_new(name)
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node.at = at
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xp_attrs(rt_xml_st, p, node)
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# self-closing '/>'
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if p.i < p.n and p.s[p.i] == '/' { # '/'
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p.i += 1
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if p.i < p.n and p.s[p.i] == '>' { p.i += 1 } # '>'
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return node
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}
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if p.i < p.n and p.s[p.i] == '>' { p.i += 1 } # '>'
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# content until the matching close tag
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while p.i < p.n {
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if p.s[p.i] == '<' { # '<'
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if p.i + 1 < p.n and p.s[p.i + 1] == '/' { # '</' close
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p.i += 2
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let cn = xp_name(p)
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while p.i < p.n and p.s[p.i] != '>' { p.i += 1 }
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p.i += 1 # skip '>'
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return node
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}
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if p.i + 3 < p.n and p.s[p.i + 1] == '!' and p.s[p.i + 2] == '[' { # '<![' CDATA
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# <![CDATA[ ... ]]>
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p.i += 9 # past "<![CDATA["
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let start = p.i
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while p.i + 2 < p.n and not (p.s[p.i] == ']' and p.s[p.i + 1] == ']' and p.s[p.i + 2] == '>') { p.i += 1 }
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node.text += p.s[start..p.i]
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p.i += 3 # past "]]>"
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} else {
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if xp_skip_misc(p) { } # comment / PI inside content
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else {
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let kid = xp_element(rt_xml_st, p)
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push(node.kids, kid)
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push(node.mixed, kid)
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}
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}
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} else {
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# character data run up to the next '<'
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let start = p.i
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while p.i < p.n and p.s[p.i] != '<' { p.i += 1 }
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let run = xml_unescape(rt_xml_st, p.s[start..p.i])
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node.text += run
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xp_text_run(node, run)
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}
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}
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return node
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}
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# a run of text among an element's children, kept in order unless it is only white space
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function xp_text_run(node: Xml, run: string) -> void {
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var blank = true
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var i = 0
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while i < len(run) {
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let c = run[i]
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if not (c == ' ' or c == '\t' or c == '\n' or c == '\r') { blank = false }
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i += 1
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}
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if blank { return }
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let t = xml_new("#text")
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t.text = run
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push(node.mixed, t)
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}
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# parse a whole document -> its root element (or the synthetic empty node).
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function xml_parse(rt_xml_st: mut RtXmlState, s: pointer) -> Xml {
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let p = new XP
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p.s = s; p.i = 0; p.n = len(s)
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while p.i < p.n {
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xp_skip_ws(p)
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if p.i >= p.n { break }
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if p.s[p.i] == '<' { # '<'
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if xp_skip_misc(p) { } # prolog / comment / doctype
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else {
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let root = xp_element(rt_xml_st, p)
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free(p)
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return root
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}
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} else { p.i += 1 }
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}
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free(p)
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return xml_new("")
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}
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# the tree's records and lists given back once a reader has built what it keeps from it; its
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# strings (tags, text, names, values) are not, since what was built may hold them. Every element
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# is in its parent's `mixed`, with the runs of text
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function xml_free(n: Xml) -> void {
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if n == null { return }
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for i in 0 .. len(n.mixed) { xml_free(n.mixed[i]) }
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free(n.akeys)
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free(n.avals)
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free(n.kids)
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free(n.mixed)
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free(n)
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}
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