294 lines
7.8 KiB
Rust
294 lines
7.8 KiB
Rust
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#[link(name = "json",
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vers = "0.1",
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uuid = "09d7f2fc-1fad-48b2-9f9d-a65512342f16",
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url = "http://www.leptoquark.net/~elly/rust/")];
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#[copyright = "Google Inc. 2011"];
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#[comment = "JSON serialization format library"];
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#[license = "BSD"];
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import float;
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import map;
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import option;
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import option::{some, none};
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import str;
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import vec;
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export json;
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export tostr;
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export fromstr;
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tag json {
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num(float);
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string(str);
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boolean(bool);
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list(@[json]);
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dict(map::hashmap<str,json>);
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}
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fn tostr(j: json) -> str {
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alt j {
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num(f) { float::to_str(f, 6u) }
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string(s) { #fmt["\"%s\"", s] } // XXX: escape
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boolean(true) { "true" }
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boolean(false) { "false" }
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list(@js) {
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str::concat(["[",
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str::connect(
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vec::map::<json,str>({ |e| tostr(e) }, js),
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", "),
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"]"])
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}
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dict(m) {
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let parts = [];
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m.items({ |k, v|
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vec::grow(parts, 1u,
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str::concat(["\"", k, "\": ", tostr(v)])
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)
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});
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str::concat(["{ ", str::connect(parts, ", "), " }"])
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}
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}
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}
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fn rest(s: str) -> str {
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str::char_slice(s, 1u, str::char_len(s))
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}
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fn fromstr_str(s: str) -> (option::t<json>, str) {
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let pos = 0u;
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let len = str::byte_len(s);
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let escape = false;
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let res = "";
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alt str::char_at(s, 0u) {
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'"' { pos = 1u; }
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_ { ret (none, s); }
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}
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while (pos < len) {
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let chr = str::char_range_at(s, pos);
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let c = chr.ch;
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pos = chr.next;
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if (escape) {
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res = res + str::from_char(c);
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escape = false;
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cont;
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}
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if (c == '\\') {
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escape = true;
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cont;
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} else if (c == '"') {
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ret (some(string(res)), str::char_slice(s, pos, str::char_len(s)));
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}
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res = res + str::from_char(c);
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}
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ret (none, s);
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}
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fn fromstr_list(s: str) -> (option::t<json>, str) {
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if str::char_at(s, 0u) != '[' { ret (none, s); }
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let s0 = str::trim_left(rest(s));
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let vals = [];
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if str::is_empty(s0) { ret (none, s0); }
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if str::char_at(s0, 0u) == ']' { ret (some(list(@[])), rest(s0)); }
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while str::is_not_empty(s0) {
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s0 = str::trim_left(s0);
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let (next, s1) = fromstr_helper(s0);
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s0 = s1;
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alt next {
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some(j) { vec::grow(vals, 1u, j); }
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none { ret (none, s0); }
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}
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s0 = str::trim_left(s0);
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if str::is_empty(s0) { ret (none, s0); }
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alt str::char_at(s0, 0u) {
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',' { }
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']' { ret (some(list(@vals)), rest(s0)); }
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_ { ret (none, s0); }
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}
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s0 = rest(s0);
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}
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ret (none, s0);
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}
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fn fromstr_dict(s: str) -> (option::t<json>, str) {
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if str::char_at(s, 0u) != '{' { ret (none, s); }
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let s0 = str::trim_left(rest(s));
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let vals = map::new_str_hash::<json>();
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if str::is_empty(s0) { ret (none, s0); }
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if str::char_at(s0, 0u) == '}' { ret (some(dict(vals)), rest(s0)); }
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while str::is_not_empty(s0) {
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s0 = str::trim_left(s0);
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let (next, s1) = fromstr_helper(s0); // key
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let key = "";
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s0 = s1;
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alt next {
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some(string(k)) { key = k; }
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_ { ret (none, s0); }
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}
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s0 = str::trim_left(s0);
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if str::is_empty(s0) { ret (none, s0); }
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if str::char_at(s0, 0u) != ':' { ret (none, s0); }
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s0 = str::trim_left(rest(s0));
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let (next, s1) = fromstr_helper(s0); // value
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s0 = s1;
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alt next {
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some(j) { vals.insert(key, j); }
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_ { ret (none, s0); }
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}
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s0 = str::trim_left(s0);
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if str::is_empty(s0) { ret (none, s0); }
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alt str::char_at(s0, 0u) {
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',' { }
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'}' { ret (some(dict(vals)), rest(s0)); }
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_ { ret (none, s0); }
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}
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s0 = str::trim_left(rest(s0));
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}
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(none, s)
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}
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fn fromstr_float(s: str) -> (option::t<json>, str) {
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let pos = 0u;
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let len = str::byte_len(s);
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let res = 0f;
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let neg = 1.f;
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alt str::char_at(s, 0u) {
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'-' {
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neg = -1.f;
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pos = 1u;
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}
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'+' {
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pos = 1u;
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}
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'0' to '9' | '.' { }
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_ { ret (none, s); }
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}
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while (pos < len) {
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let opos = pos;
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let chr = str::char_range_at(s, pos);
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let c = chr.ch;
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pos = chr.next;
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alt c {
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'0' to '9' {
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res = res * 10f;
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res += ((c as int) - ('0' as int)) as float;
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}
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'.' { break; }
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_ { ret (some(num(neg * res)),
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str::char_slice(s, opos, str::char_len(s))); }
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}
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}
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if pos == len {
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ret (some(num(neg * res)), str::char_slice(s, pos, str::char_len(s)));
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}
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let dec = 1.f;
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while (pos < len) {
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let opos = pos;
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let chr = str::char_range_at(s, pos);
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let c = chr.ch;
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pos = chr.next;
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alt c {
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'0' to '9' {
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dec /= 10.f;
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res += (((c as int) - ('0' as int)) as float) * dec;
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}
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_ { ret (some(num(neg * res)),
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str::char_slice(s, opos, str::char_len(s))); }
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}
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}
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ret (some(num(neg * res)), str::char_slice(s, pos, str::char_len(s)));
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}
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fn fromstr_bool(s: str) -> (option::t<json>, str) {
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if (str::starts_with(s, "true")) {
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(some(boolean(true)), str::slice(s, 4u, str::byte_len(s)))
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} else if (str::starts_with(s, "false")) {
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(some(boolean(false)), str::slice(s, 5u, str::byte_len(s)))
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} else {
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(none, s)
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}
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}
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fn fromstr_helper(s: str) -> (option::t<json>, str) {
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let s = str::trim_left(s);
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if str::is_empty(s) { ret (none, s); }
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let start = str::char_at(s, 0u);
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alt start {
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'"' { fromstr_str(s) }
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'[' { fromstr_list(s) }
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'{' { fromstr_dict(s) }
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'0' to '9' | '-' | '+' | '.' { fromstr_float(s) }
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't' | 'f' { fromstr_bool(s) }
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_ { ret (none, s); }
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}
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}
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fn fromstr(s: str) -> option::t<json> {
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let (j, _) = fromstr_helper(s);
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j
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}
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fn main() {
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let j = fromstr("{ \"foo\": [ 4, 5 ], \"bar\": { \"baz\": true}}");
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alt j {
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some(j0) {
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log tostr(j0);
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}
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_ { }
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}
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}
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#[cfg(test)]
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mod tests {
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#[test]
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fn test_fromstr_num() {
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assert(fromstr("3") == some(num(3f)));
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assert(fromstr("3.1") == some(num(3.1f)));
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assert(fromstr("-1.2") == some(num(-1.2f)));
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assert(fromstr(".4") == some(num(0.4f)));
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}
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#[test]
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fn test_fromstr_str() {
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assert(fromstr("\"foo\"") == some(string("foo")));
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assert(fromstr("\"\\\"\"") == some(string("\"")));
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assert(fromstr("\"lol") == none);
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}
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#[test]
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fn test_fromstr_bool() {
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assert(fromstr("true") == some(boolean(true)));
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assert(fromstr("false") == some(boolean(false)));
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assert(fromstr("truz") == none);
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}
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#[test]
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fn test_fromstr_list() {
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assert(fromstr("[]") == some(list(@[])));
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assert(fromstr("[true]") == some(list(@[boolean(true)])));
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assert(fromstr("[3, 1]") == some(list(@[num(3f), num(1f)])));
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assert(fromstr("[2, [4, 1]]") ==
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some(list(@[num(2f), list(@[num(4f), num(1f)])])));
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assert(fromstr("[2, ]") == none);
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assert(fromstr("[5, ") == none);
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assert(fromstr("[6 7]") == none);
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assert(fromstr("[3") == none);
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}
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#[test]
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fn test_fromstr_dict() {
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assert(fromstr("{}") != none);
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assert(fromstr("{\"a\": 3}") != none);
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assert(fromstr("{\"a\": }") == none);
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assert(fromstr("{\"a\" }") == none);
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assert(fromstr("{\"a\"") == none);
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assert(fromstr("{") == none);
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}
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}
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