311 lines
9.3 KiB
Rust
311 lines
9.3 KiB
Rust
use std::collections::HashMap;
|
|
|
|
use winnow::prelude::*;
|
|
use winnow::{
|
|
ascii::{alphanumeric1 as alphanumeric, float, take_escaped},
|
|
combinator::alt,
|
|
combinator::cut_err,
|
|
combinator::separated,
|
|
combinator::{preceded, separated_pair, terminated},
|
|
error::ParserError,
|
|
error::StrContext,
|
|
stream::Offset,
|
|
token::one_of,
|
|
token::{literal, take_while},
|
|
};
|
|
|
|
use std::cell::Cell;
|
|
use std::str;
|
|
|
|
#[derive(Clone, Debug)]
|
|
pub struct JsonValue<'a, 'b> {
|
|
input: &'a str,
|
|
pub offset: &'b Cell<usize>,
|
|
}
|
|
|
|
impl<'a, 'b: 'a> JsonValue<'a, 'b> {
|
|
pub fn new(input: &'a str, offset: &'b Cell<usize>) -> JsonValue<'a, 'b> {
|
|
JsonValue { input, offset }
|
|
}
|
|
|
|
pub fn offset(&self, input: &'a str) {
|
|
let offset = input.offset_from(&self.input);
|
|
self.offset.set(offset);
|
|
}
|
|
|
|
pub fn data(&self) -> &'a str {
|
|
&self.input[self.offset.get()..]
|
|
}
|
|
|
|
pub fn string(&self) -> Option<&'a str> {
|
|
println!("string()");
|
|
let mut data = self.data();
|
|
match string(&mut data) {
|
|
Ok(s) => {
|
|
self.offset(data);
|
|
println!("-> {s}");
|
|
Some(s)
|
|
}
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
pub fn boolean(&self) -> Option<bool> {
|
|
println!("boolean()");
|
|
let mut data = self.data();
|
|
match boolean(&mut data) {
|
|
Ok(o) => {
|
|
self.offset(data);
|
|
println!("-> {o}");
|
|
Some(o)
|
|
}
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
pub fn number(&self) -> Option<f64> {
|
|
println!("number()");
|
|
let mut data = self.data();
|
|
match float::<_, _, ()>.parse_next(&mut data) {
|
|
Ok(o) => {
|
|
self.offset(data);
|
|
println!("-> {o}");
|
|
Some(o)
|
|
}
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
pub fn array(&self) -> Option<impl Iterator<Item = JsonValue<'a, 'b>>> {
|
|
println!("array()");
|
|
|
|
let mut data = self.data();
|
|
match literal::<_, _, ()>("[").parse_next(&mut data) {
|
|
Err(_) => None,
|
|
Ok(_) => {
|
|
println!("[");
|
|
self.offset(data);
|
|
let mut first = true;
|
|
let mut done = false;
|
|
let mut previous = usize::MAX;
|
|
|
|
let v = self.clone();
|
|
|
|
Some(std::iter::from_fn(move || {
|
|
if done {
|
|
return None;
|
|
}
|
|
|
|
// if we ignored one of the items, skip over the value
|
|
if v.offset.get() == previous {
|
|
println!("skipping value");
|
|
if value(&mut data).is_ok() {
|
|
v.offset(data);
|
|
}
|
|
}
|
|
|
|
if literal::<_, _, ()>("]").parse_next(&mut data).is_ok() {
|
|
println!("]");
|
|
v.offset(data);
|
|
done = true;
|
|
return None;
|
|
}
|
|
|
|
if first {
|
|
first = false;
|
|
} else {
|
|
match literal::<_, _, ()>(",").parse_next(&mut data) {
|
|
Ok(_) => {
|
|
println!(",");
|
|
v.offset(data);
|
|
}
|
|
Err(_) => {
|
|
done = true;
|
|
return None;
|
|
}
|
|
}
|
|
}
|
|
|
|
println!("-> {}", v.data());
|
|
previous = v.offset.get();
|
|
Some(v.clone())
|
|
}))
|
|
}
|
|
}
|
|
}
|
|
|
|
pub fn object(&self) -> Option<impl Iterator<Item = (&'a str, JsonValue<'a, 'b>)>> {
|
|
println!("object()");
|
|
let mut data = self.data();
|
|
match literal::<_, _, ()>("{").parse_next(&mut data) {
|
|
Err(_) => None,
|
|
Ok(_) => {
|
|
self.offset(data);
|
|
|
|
println!("{{");
|
|
|
|
let mut first = true;
|
|
let mut done = false;
|
|
let mut previous = usize::MAX;
|
|
|
|
let v = self.clone();
|
|
|
|
Some(std::iter::from_fn(move || {
|
|
if done {
|
|
return None;
|
|
}
|
|
|
|
// if we ignored one of the items, skip over the value
|
|
if v.offset.get() == previous {
|
|
println!("skipping value");
|
|
if value(&mut data).is_ok() {
|
|
v.offset(data);
|
|
}
|
|
}
|
|
|
|
if literal::<_, _, ()>("}").parse_next(&mut data).is_ok() {
|
|
println!("}}");
|
|
v.offset(data);
|
|
done = true;
|
|
return None;
|
|
}
|
|
|
|
if first {
|
|
first = false;
|
|
} else {
|
|
match literal::<_, _, ()>(",").parse_next(&mut data) {
|
|
Ok(_) => {
|
|
println!(",");
|
|
v.offset(data);
|
|
}
|
|
Err(_) => {
|
|
done = true;
|
|
return None;
|
|
}
|
|
}
|
|
}
|
|
|
|
match string(&mut data) {
|
|
Ok(key) => {
|
|
v.offset(data);
|
|
|
|
match literal::<_, _, ()>(":").parse_next(&mut data) {
|
|
Err(_) => None,
|
|
Ok(_) => {
|
|
v.offset(data);
|
|
|
|
previous = v.offset.get();
|
|
|
|
println!("-> {} => {}", key, v.data());
|
|
Some((key, v.clone()))
|
|
}
|
|
}
|
|
}
|
|
_ => None,
|
|
}
|
|
}))
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn sp<'a, E: ParserError<&'a str>>(i: &mut &'a str) -> ModalResult<&'a str, E> {
|
|
let chars = " \t\r\n";
|
|
|
|
take_while(0.., move |c| chars.contains(c)).parse_next(i)
|
|
}
|
|
|
|
fn parse_str<'a, E: ParserError<&'a str>>(i: &mut &'a str) -> ModalResult<&'a str, E> {
|
|
take_escaped(alphanumeric, '\\', one_of(['"', 'n', '\\'])).parse_next(i)
|
|
}
|
|
|
|
fn string<'s>(i: &mut &'s str) -> ModalResult<&'s str> {
|
|
preceded('\"', cut_err(terminated(parse_str, '\"')))
|
|
.context(StrContext::Label("string"))
|
|
.parse_next(i)
|
|
}
|
|
|
|
fn boolean(input: &mut &str) -> ModalResult<bool> {
|
|
alt(("false".map(|_| false), "true".map(|_| true))).parse_next(input)
|
|
}
|
|
|
|
fn array(i: &mut &str) -> ModalResult<()> {
|
|
preceded(
|
|
'[',
|
|
cut_err(terminated(
|
|
separated(0.., value, preceded(sp, ',')),
|
|
preceded(sp, ']'),
|
|
)),
|
|
)
|
|
.context(StrContext::Label("array"))
|
|
.parse_next(i)
|
|
}
|
|
|
|
fn key_value<'s>(i: &mut &'s str) -> ModalResult<(&'s str, ())> {
|
|
separated_pair(preceded(sp, string), cut_err(preceded(sp, ':')), value).parse_next(i)
|
|
}
|
|
|
|
fn hash(i: &mut &str) -> ModalResult<()> {
|
|
preceded(
|
|
'{',
|
|
cut_err(terminated(
|
|
separated(0.., key_value, preceded(sp, ',')),
|
|
preceded(sp, '}'),
|
|
)),
|
|
)
|
|
.context(StrContext::Label("map"))
|
|
.parse_next(i)
|
|
}
|
|
|
|
fn value(i: &mut &str) -> ModalResult<()> {
|
|
preceded(
|
|
sp,
|
|
alt((
|
|
hash,
|
|
array,
|
|
string.map(|_| ()),
|
|
float::<_, f64, _>.map(|_| ()),
|
|
boolean.map(|_| ()),
|
|
)),
|
|
)
|
|
.parse_next(i)
|
|
}
|
|
|
|
/// object(input) -> iterator over (key, `JsonValue`)
|
|
/// array(input) -> iterator over `JsonValue`
|
|
///
|
|
/// JsonValue.string -> iterator over String (returns None after first successful call)
|
|
///
|
|
/// object(input).filter(|(k, _)| k == "users").flatten(|(_, v)| v.object()).filter(|(k, _)| k == "city").flatten(|(_,v)| `v.string()`)
|
|
fn main() {
|
|
/*let data = "{
|
|
\"users\": {
|
|
\"user1\" : { \"city\": \"Nantes\", \"country\": \"France\" },
|
|
\"user2\" : { \"city\": \"Bruxelles\", \"country\": \"Belgium\" },
|
|
\"user3\": { \"city\": \"Paris\", \"country\": \"France\", \"age\": 30 }
|
|
},
|
|
\"countries\": [\"France\", \"Belgium\"]
|
|
}";
|
|
*/
|
|
let data = "{\"users\":{\"user1\":{\"city\":\"Nantes\",\"country\":\"France\"},\"user2\":{\"city\":\"Bruxelles\",\"country\":\"Belgium\"},\"user3\":{\"city\":\"Paris\",\"country\":\"France\",\"age\":30}},\"countries\":[\"France\",\"Belgium\"]}";
|
|
|
|
let offset = Cell::new(0);
|
|
{
|
|
let parser = JsonValue::new(data, &offset);
|
|
|
|
if let Some(o) = parser.object() {
|
|
let s: HashMap<&str, &str> = o
|
|
.filter(|(k, _)| *k == "users")
|
|
.filter_map(|(_, v)| v.object())
|
|
.flatten()
|
|
.filter_map(|(user, v)| v.object().map(|o| (user, o)))
|
|
.flat_map(|(user, o)| {
|
|
o.filter(|(k, _)| *k == "city")
|
|
.filter_map(move |(_, v)| v.string().map(|s| (user, s)))
|
|
})
|
|
.collect();
|
|
|
|
println!("res = {s:?}");
|
|
}
|
|
};
|
|
}
|