rust/src/libstd/json.rs

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// Rust JSON serialization library
// Copyright (c) 2011 Google Inc.
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#[doc = "json serialization"];
import result::{result, ok, err};
import io;
import io::{reader_util, writer_util};
import map;
import map::hashmap;
export json;
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export error;
export to_writer;
export to_str;
export from_reader;
export from_str;
export eq;
export to_json;
export num;
export string;
export boolean;
export list;
export dict;
export null;
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#[doc = "Represents a json value"]
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enum json {
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num(float),
string(str),
boolean(bool),
list([json]),
dict(map::hashmap<str,json>),
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null,
}
type error = {
line: uint,
col: uint,
msg: str,
};
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#[doc = "Serializes a json value into a io::writer"]
fn to_writer(wr: io::writer, j: json) {
alt j {
num(n) { wr.write_str(float::to_str(n, 6u)); }
string(s) {
wr.write_char('"');
let mut escaped = "";
str::chars_iter(s) { |c|
alt c {
'"' { escaped += "\\\""; }
'\\' { escaped += "\\\\"; }
'\x08' { escaped += "\\b"; }
'\x0c' { escaped += "\\f"; }
'\n' { escaped += "\\n"; }
'\r' { escaped += "\\r"; }
'\t' { escaped += "\\t"; }
_ { escaped += str::from_char(c); }
}
};
wr.write_str(escaped);
wr.write_char('"');
}
boolean(b) {
wr.write_str(if b { "true" } else { "false" });
}
list(v) {
wr.write_char('[');
let mut first = true;
vec::iter(v) { |item|
if !first {
wr.write_str(", ");
}
first = false;
to_writer(wr, item);
};
wr.write_char(']');
}
dict(d) {
if d.size() == 0u {
wr.write_str("{}");
ret;
}
wr.write_str("{ ");
let mut first = true;
for d.each { |key, value|
if !first {
wr.write_str(", ");
}
first = false;
to_writer(wr, string(key));
wr.write_str(": ");
to_writer(wr, value);
};
wr.write_str(" }");
}
null {
wr.write_str("null");
}
}
}
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#[doc = "Serializes a json value into a string"]
fn to_str(j: json) -> str {
io::with_str_writer { |wr| to_writer(wr, j) }
}
type parser = {
rdr: io::reader,
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mut ch: char,
mut line: uint,
mut col: uint,
};
impl parser for parser {
fn eof() -> bool { self.ch == -1 as char }
fn bump() {
self.ch = self.rdr.read_char();
if self.ch == '\n' {
self.line += 1u;
self.col = 1u;
} else {
self.col += 1u;
}
}
fn next_char() -> char {
self.bump();
self.ch
}
fn error<T>(msg: str) -> result<T, error> {
err({ line: self.line, col: self.col, msg: msg })
}
fn parse() -> result<json, error> {
alt self.parse_value() {
ok(value) {
// Skip trailing whitespaces.
self.parse_whitespace();
// Make sure there is no trailing characters.
if self.eof() {
ok(value)
} else {
self.error("trailing characters")
}
}
e { e }
}
}
fn parse_value() -> result<json, error> {
self.parse_whitespace();
if self.eof() { ret self.error("EOF while parsing value"); }
alt self.ch {
'n' { self.parse_ident("ull", null) }
't' { self.parse_ident("rue", boolean(true)) }
'f' { self.parse_ident("alse", boolean(false)) }
'0' to '9' | '-' { self.parse_number() }
'"' {
alt self.parse_str() {
ok(s) { ok(string(s)) }
err(e) { err(e) }
}
}
'[' { self.parse_list() }
'{' { self.parse_object() }
_ { self.error("invalid syntax") }
}
}
fn parse_whitespace() {
while char::is_whitespace(self.ch) { self.bump(); }
}
fn parse_ident(ident: str, value: json) -> result<json, error> {
if str::all(ident, { |c| c == self.next_char() }) {
self.bump();
ok(value)
} else {
self.error("invalid syntax")
}
}
fn parse_number() -> result<json, error> {
let mut neg = 1f;
if self.ch == '-' {
self.bump();
neg = -1f;
}
let mut res = alt self.parse_integer() {
ok(res) { res }
err(e) { ret err(e); }
};
if self.ch == '.' {
alt self.parse_decimal(res) {
ok(r) { res = r; }
err(e) { ret err(e); }
}
}
if self.ch == 'e' || self.ch == 'E' {
alt self.parse_exponent(res) {
ok(r) { res = r; }
err(e) { ret err(e); }
}
}
ok(num(neg * res))
}
fn parse_integer() -> result<float, error> {
let mut res = 0f;
alt self.ch {
'0' {
self.bump();
// There can be only one leading '0'.
alt self.ch {
'0' to '9' { ret self.error("invalid number"); }
_ {}
}
}
'1' to '9' {
while !self.eof() {
alt self.ch {
'0' to '9' {
res *= 10f;
res += ((self.ch as int) - ('0' as int)) as float;
self.bump();
}
_ { break; }
}
}
}
_ { ret self.error("invalid number"); }
}
ok(res)
}
fn parse_decimal(res: float) -> result<float, error> {
self.bump();
// Make sure a digit follows the decimal place.
alt self.ch {
'0' to '9' {}
_ { ret self.error("invalid number"); }
}
let mut res = res;
let mut dec = 1f;
while !self.eof() {
alt self.ch {
'0' to '9' {
dec /= 10f;
res += (((self.ch as int) - ('0' as int)) as float) * dec;
self.bump();
}
_ { break; }
}
}
ok(res)
}
fn parse_exponent(res: float) -> result<float, error> {
self.bump();
let mut res = res;
let mut exp = 0u;
let mut neg_exp = false;
alt self.ch {
'+' { self.bump(); }
'-' { self.bump(); neg_exp = true; }
_ {}
}
// Make sure a digit follows the exponent place.
alt self.ch {
'0' to '9' {}
_ { ret self.error("invalid number"); }
}
while !self.eof() {
alt self.ch {
'0' to '9' {
exp *= 10u;
exp += (self.ch as uint) - ('0' as uint);
self.bump();
}
_ { break; }
}
}
let exp = float::pow_with_uint(10u, exp);
if neg_exp {
res /= exp;
} else {
res *= exp;
}
ok(res)
}
fn parse_str() -> result<str, error> {
let mut escape = false;
let mut res = "";
while !self.eof() {
self.bump();
if (escape) {
alt self.ch {
'"' { str::push_char(res, '"'); }
'\\' { str::push_char(res, '\\'); }
'/' { str::push_char(res, '/'); }
'b' { str::push_char(res, '\x08'); }
'f' { str::push_char(res, '\x0c'); }
'n' { str::push_char(res, '\n'); }
'r' { str::push_char(res, '\r'); }
't' { str::push_char(res, '\t'); }
'u' {
// Parse \u1234.
let mut i = 0u;
let mut n = 0u;
while i < 4u {
alt self.next_char() {
'0' to '9' {
n = n * 10u +
(self.ch as uint) - ('0' as uint);
}
_ { ret self.error("invalid \\u escape"); }
}
i += 1u;
}
// Error out if we didn't parse 4 digits.
if i != 4u {
ret self.error("invalid \\u escape");
}
str::push_char(res, n as char);
}
_ { ret self.error("invalid escape"); }
}
escape = false;
} else if self.ch == '\\' {
escape = true;
} else {
if self.ch == '"' {
self.bump();
ret ok(res);
}
str::push_char(res, self.ch);
}
}
self.error("EOF while parsing string")
}
fn parse_list() -> result<json, error> {
self.bump();
self.parse_whitespace();
let mut values = [];
if self.ch == ']' {
self.bump();
ret ok(list(values));
}
loop {
alt self.parse_value() {
ok(v) { vec::push(values, v); }
e { ret e; }
}
self.parse_whitespace();
if self.eof() {
ret self.error("EOF while parsing list");
}
alt self.ch {
',' { self.bump(); }
']' { self.bump(); ret ok(list(values)); }
_ { ret self.error("expecting ',' or ']'"); }
}
};
}
fn parse_object() -> result<json, error> {
self.bump();
self.parse_whitespace();
let values = map::str_hash();
if self.ch == '}' {
self.bump();
ret ok(dict(values));
}
while !self.eof() {
self.parse_whitespace();
if self.ch != '"' {
ret self.error("key must be a string");
}
let key = alt self.parse_str() {
ok(key) { key }
err(e) { ret err(e); }
};
self.parse_whitespace();
if self.ch != ':' {
if self.eof() { break; }
ret self.error("expecting ':'");
}
self.bump();
alt self.parse_value() {
ok(value) { values.insert(key, value); }
e { ret e; }
}
self.parse_whitespace();
alt self.ch {
',' { self.bump(); }
'}' { self.bump(); ret ok(dict(values)); }
_ {
if self.eof() { break; }
ret self.error("expecting ',' or '}'");
}
}
}
ret self.error("EOF while parsing object");
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}
}
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#[doc = "Deserializes a json value from an io::reader"]
fn from_reader(rdr: io::reader) -> result<json, error> {
let parser = {
rdr: rdr,
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mut ch: rdr.read_char(),
mut line: 1u,
mut col: 1u,
};
parser.parse()
}
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#[doc = "Deserializes a json value from a string"]
fn from_str(s: str) -> result<json, error> {
io::with_str_reader(s, from_reader)
}
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#[doc = "Test if two json values are equal"]
fn eq(value0: json, value1: json) -> bool {
alt (value0, value1) {
(num(f0), num(f1)) { f0 == f1 }
(string(s0), string(s1)) { s0 == s1 }
(boolean(b0), boolean(b1)) { b0 == b1 }
(list(l0), list(l1)) { vec::all2(l0, l1, eq) }
(dict(d0), dict(d1)) {
if d0.size() == d1.size() {
let mut equal = true;
for d0.each { |k, v0|
alt d1.find(k) {
some(v1) {
if !eq(v0, v1) { equal = false; } }
none { equal = false; }
}
};
equal
} else {
false
}
}
(null, null) { true }
_ { false }
}
}
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iface to_json { fn to_json() -> json; }
impl of to_json for json {
fn to_json() -> json { self }
}
impl of to_json for i8 {
fn to_json() -> json { num(self as float) }
}
impl of to_json for i16 {
fn to_json() -> json { num(self as float) }
}
impl of to_json for i32 {
fn to_json() -> json { num(self as float) }
}
impl of to_json for i64 {
fn to_json() -> json { num(self as float) }
}
impl of to_json for u8 {
fn to_json() -> json { num(self as float) }
}
impl of to_json for u16 {
fn to_json() -> json { num(self as float) }
}
impl of to_json for u32 {
fn to_json() -> json { num(self as float) }
}
impl of to_json for u64 {
fn to_json() -> json { num(self as float) }
}
impl of to_json for float {
fn to_json() -> json { num(self) }
}
impl of to_json for f32 {
fn to_json() -> json { num(self as float) }
}
impl of to_json for f64 {
fn to_json() -> json { num(self as float) }
}
impl of to_json for () {
fn to_json() -> json { null }
}
impl of to_json for bool {
fn to_json() -> json { boolean(self) }
}
impl of to_json for str {
fn to_json() -> json { string(self) }
}
impl <A: to_json copy, B: to_json copy> of to_json for (A, B) {
fn to_json() -> json {
let (a, b) = self;
list([a.to_json(), b.to_json()])
}
}
impl <A: to_json copy, B: to_json copy, C: to_json copy>
of to_json for (A, B, C) {
fn to_json() -> json {
let (a, b, c) = self;
list([a.to_json(), b.to_json(), c.to_json()])
}
}
impl <A: to_json> of to_json for [A] {
fn to_json() -> json { list(self.map { |elt| elt.to_json() }) }
}
impl <A: to_json copy> of to_json for hashmap<str, A> {
fn to_json() -> json {
let d = map::str_hash();
for self.each() { |key, value|
d.insert(key, value.to_json());
}
dict(d)
}
}
impl <A: to_json> of to_json for option<A> {
fn to_json() -> json {
alt self {
none { null }
some(value) { value.to_json() }
}
}
}
impl of to_str::to_str for json {
fn to_str() -> str { to_str(self) }
}
impl of to_str::to_str for error {
fn to_str() -> str {
#fmt("%u:%u: %s", self.line, self.col, self.msg)
}
}
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#[cfg(test)]
mod tests {
fn mk_dict(items: [(str, json)]) -> json {
let d = map::str_hash();
vec::iter(items) { |item|
let (key, value) = item;
d.insert(key, value);
};
dict(d)
}
#[test]
fn test_write_null() {
assert to_str(null) == "null";
}
#[test]
fn test_write_num() {
assert to_str(num(3f)) == "3";
assert to_str(num(3.1f)) == "3.1";
assert to_str(num(-1.5f)) == "-1.5";
assert to_str(num(0.5f)) == "0.5";
}
#[test]
fn test_write_str() {
assert to_str(string("")) == "\"\"";
assert to_str(string("foo")) == "\"foo\"";
}
#[test]
fn test_write_bool() {
assert to_str(boolean(true)) == "true";
assert to_str(boolean(false)) == "false";
}
#[test]
fn test_write_list() {
assert to_str(list([])) == "[]";
assert to_str(list([boolean(true)])) == "[true]";
assert to_str(list([
boolean(false),
null,
list([string("foo\nbar"), num(3.5f)])
])) == "[false, null, [\"foo\\nbar\", 3.5]]";
}
#[test]
fn test_write_dict() {
assert to_str(mk_dict([])) == "{}";
assert to_str(mk_dict([("a", boolean(true))])) == "{ \"a\": true }";
assert to_str(mk_dict([
("a", boolean(true)),
("b", list([
mk_dict([("c", string("\x0c\r"))]),
mk_dict([("d", string(""))])
]))
])) ==
"{ " +
"\"a\": true, " +
"\"b\": [" +
"{ \"c\": \"\\f\\r\" }, " +
"{ \"d\": \"\" }" +
"]" +
" }";
}
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#[test]
fn test_trailing_characters() {
assert from_str("nulla") ==
err({line: 1u, col: 5u, msg: "trailing characters"});
assert from_str("truea") ==
err({line: 1u, col: 5u, msg: "trailing characters"});
assert from_str("falsea") ==
err({line: 1u, col: 6u, msg: "trailing characters"});
assert from_str("1a") ==
err({line: 1u, col: 2u, msg: "trailing characters"});
assert from_str("[]a") ==
err({line: 1u, col: 3u, msg: "trailing characters"});
assert from_str("{}a") ==
err({line: 1u, col: 3u, msg: "trailing characters"});
}
#[test]
fn test_read_identifiers() {
assert from_str("n") ==
err({line: 1u, col: 2u, msg: "invalid syntax"});
assert from_str("nul") ==
err({line: 1u, col: 4u, msg: "invalid syntax"});
assert from_str("t") ==
err({line: 1u, col: 2u, msg: "invalid syntax"});
assert from_str("truz") ==
err({line: 1u, col: 4u, msg: "invalid syntax"});
assert from_str("f") ==
err({line: 1u, col: 2u, msg: "invalid syntax"});
assert from_str("faz") ==
err({line: 1u, col: 3u, msg: "invalid syntax"});
assert from_str("null") == ok(null);
assert from_str("true") == ok(boolean(true));
assert from_str("false") == ok(boolean(false));
assert from_str(" null ") == ok(null);
assert from_str(" true ") == ok(boolean(true));
assert from_str(" false ") == ok(boolean(false));
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}
#[test]
fn test_read_num() {
assert from_str("+") ==
err({line: 1u, col: 1u, msg: "invalid syntax"});
assert from_str(".") ==
err({line: 1u, col: 1u, msg: "invalid syntax"});
assert from_str("-") ==
err({line: 1u, col: 2u, msg: "invalid number"});
assert from_str("00") ==
err({line: 1u, col: 2u, msg: "invalid number"});
assert from_str("1.") ==
err({line: 1u, col: 3u, msg: "invalid number"});
assert from_str("1e") ==
err({line: 1u, col: 3u, msg: "invalid number"});
assert from_str("1e+") ==
err({line: 1u, col: 4u, msg: "invalid number"});
assert from_str("3") == ok(num(3f));
assert from_str("3.1") == ok(num(3.1f));
assert from_str("-1.2") == ok(num(-1.2f));
assert from_str("0.4") == ok(num(0.4f));
assert from_str("0.4e5") == ok(num(0.4e5f));
assert from_str("0.4e+15") == ok(num(0.4e15f));
assert from_str("0.4e-01") == ok(num(0.4e-01f));
assert from_str(" 3 ") == ok(num(3f));
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}
#[test]
fn test_read_str() {
assert from_str("\"") ==
err({line: 1u, col: 2u, msg: "EOF while parsing string"});
assert from_str("\"lol") ==
err({line: 1u, col: 5u, msg: "EOF while parsing string"});
assert from_str("\"\"") == ok(string(""));
assert from_str("\"foo\"") == ok(string("foo"));
assert from_str("\"\\\"\"") == ok(string("\""));
assert from_str("\"\\b\"") == ok(string("\x08"));
assert from_str("\"\\n\"") == ok(string("\n"));
assert from_str("\"\\r\"") == ok(string("\r"));
assert from_str("\"\\t\"") == ok(string("\t"));
assert from_str(" \"foo\" ") == ok(string("foo"));
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}
#[test]
fn test_read_list() {
assert from_str("[") ==
err({line: 1u, col: 2u, msg: "EOF while parsing value"});
assert from_str("[1") ==
err({line: 1u, col: 3u, msg: "EOF while parsing list"});
assert from_str("[1,") ==
err({line: 1u, col: 4u, msg: "EOF while parsing value"});
assert from_str("[1,]") ==
err({line: 1u, col: 4u, msg: "invalid syntax"});
assert from_str("[6 7]") ==
err({line: 1u, col: 4u, msg: "expecting ',' or ']'"});
assert from_str("[]") == ok(list([]));
assert from_str("[ ]") == ok(list([]));
assert from_str("[true]") == ok(list([boolean(true)]));
assert from_str("[ false ]") == ok(list([boolean(false)]));
assert from_str("[null]") == ok(list([null]));
assert from_str("[3, 1]") == ok(list([num(3f), num(1f)]));
assert from_str("\n[3, 2]\n") == ok(list([num(3f), num(2f)]));
assert from_str("[2, [4, 1]]") ==
ok(list([num(2f), list([num(4f), num(1f)])]));
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}
#[test]
fn test_read_dict() {
assert from_str("{") ==
err({line: 1u, col: 2u, msg: "EOF while parsing object"});
assert from_str("{ ") ==
err({line: 1u, col: 3u, msg: "EOF while parsing object"});
assert from_str("{1") ==
err({line: 1u, col: 2u, msg: "key must be a string"});
assert from_str("{ \"a\"") ==
err({line: 1u, col: 6u, msg: "EOF while parsing object"});
assert from_str("{\"a\"") ==
err({line: 1u, col: 5u, msg: "EOF while parsing object"});
assert from_str("{\"a\" ") ==
err({line: 1u, col: 6u, msg: "EOF while parsing object"});
assert from_str("{\"a\" 1") ==
err({line: 1u, col: 6u, msg: "expecting ':'"});
assert from_str("{\"a\":") ==
err({line: 1u, col: 6u, msg: "EOF while parsing value"});
assert from_str("{\"a\":1") ==
err({line: 1u, col: 7u, msg: "EOF while parsing object"});
assert from_str("{\"a\":1 1") ==
err({line: 1u, col: 8u, msg: "expecting ',' or '}'"});
assert from_str("{\"a\":1,") ==
err({line: 1u, col: 8u, msg: "EOF while parsing object"});
assert eq(result::get(from_str("{}")), mk_dict([]));
assert eq(result::get(from_str("{\"a\": 3}")),
mk_dict([("a", num(3.0f))]));
assert eq(result::get(from_str("{ \"a\": null, \"b\" : true }")),
mk_dict([("a", null), ("b", boolean(true))]));
assert eq(result::get(from_str("\n{ \"a\": null, \"b\" : true }\n")),
mk_dict([("a", null), ("b", boolean(true))]));
assert eq(result::get(from_str("{\"a\" : 1.0 ,\"b\": [ true ]}")),
mk_dict([
("a", num(1.0)),
("b", list([boolean(true)]))
]));
assert eq(result::get(from_str(
"{" +
"\"a\": 1.0, " +
"\"b\": [" +
"true," +
"\"foo\\nbar\", " +
"{ \"c\": {\"d\": null} } " +
"]" +
"}")),
mk_dict([
("a", num(1.0f)),
("b", list([
boolean(true),
string("foo\nbar"),
mk_dict([
("c", mk_dict([("d", null)]))
])
]))
]));
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}
#[test]
fn test_multiline_errors() {
assert from_str("{\n \"foo\":\n \"bar\"") ==
err({line: 3u, col: 8u, msg: "EOF while parsing object"});
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}
}