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#![no_std] #![feature(array_value_iter)] pub struct JsonCompound { data: [u8; 4096], index: usize } impl JsonCompound { pub fn new() -> Self { let mut this = JsonCompound { data: [0; 4096], index: 1 }; this.data[0] = b'{'; this } #[inline] fn write_str(&mut self, s: &str) { self.write_bytes(s.as_bytes()); } #[inline] fn write_bytes(&mut self, b: &[u8]) { self.data[self.index..][..b.len()].copy_from_slice(b); self.index += b.len(); } #[inline] fn write_char(&mut self, c: u8) { self.data[self.index] = c; self.index += 1; } fn key(&mut self, key: &str) { if self.index > 1 {self.write_char(b',')} self.write_char(b'"'); self.write_str(key); self.write_bytes(b"\":"); } pub fn literal(mut self, key: impl AsRef<str>, value: impl AsRef<str>) -> Self { self.key(key.as_ref()); self.write_str(value.as_ref()); self } pub fn string(mut self, key: impl AsRef<str>, value: impl AsRef<str>) -> Self { self.key(key.as_ref()); self.write_char(b'"'); self.write_str(value.as_ref()); self.write_char(b'"'); self } pub fn json(mut self, key: impl AsRef<str>, json: JsonResult) -> Self { self.key(key.as_ref()); self.write_bytes(json.as_bytes()); self } pub fn build(mut self) -> JsonResult { self.write_char(b'}'); JsonResult { data: self.data, len: self.index } } } pub struct JsonList { data: [u8; 4096], index: usize } impl JsonList { pub fn new() -> Self { let mut this = JsonList { data: [0; 4096], index: 1 }; this.data[0] = b'['; this } #[inline] fn write_str(&mut self, s: &str) { self.write_bytes(s.as_bytes()); } #[inline] fn write_bytes(&mut self, b: &[u8]) { self.data[self.index..][..b.len()].copy_from_slice(b); self.index += b.len(); } #[inline] fn write_char(&mut self, c: u8) { self.data[self.index] = c; self.index += 1; } #[inline] fn item(&mut self) { if self.index > 1 {self.write_char(b',')} } pub fn literal<S: AsRef<str>>(mut self, values: impl IntoIterator<Item=S>) -> Self { for value in values { self.item(); self.write_str(value.as_ref()); } self } pub fn string<S: AsRef<str>>(mut self, values: impl IntoIterator<Item=S>) -> Self { for value in values { self.item(); self.write_char(b'"'); self.write_str(value.as_ref()); self.write_char(b'"'); } self } pub fn json(mut self, json: impl IntoIterator<Item=JsonResult>) -> Self { for j in json { self.item(); self.write_bytes(j.as_bytes()); } self } pub fn build(mut self) -> JsonResult { self.write_char(b']'); JsonResult { data: self.data, len: self.index } } } pub struct JsonResult { data: [u8; 4096], len: usize } impl JsonResult { pub fn as_bytes(&self) -> &[u8] { &self.data[..self.len] } } #[cfg(test)] mod tests { use crate::{JsonCompound, JsonList}; #[test] fn test() { let json = JsonCompound::new() .literal("foo", "3") .string("bar", "bart") .json( "object", JsonCompound::new() .literal("quux", "5") .build() ) .json( "list", JsonList::new().json( core::array::IntoIter::new([ JsonCompound::new() .literal("hello", "5") .string("world", "!") .build(), JsonCompound::new() .literal("world", "5") .string("hello", "!") .build() ]) ).build() ) .build(); assert_eq!(core::str::from_utf8(json.as_bytes()).unwrap(), r#"{"foo":3,"bar":"bart","object":{"quux":5},"list":[{"hello":5,"world":"!"},{"world":5,"hello":"!"}]}"#); } }