pub fn serde_json_from_zcstring<T>(json: ZCString) -> Result<T, Box<dyn Error>>where
T: for<'de> Deserialize<'de>,Expand description
Parses a JSON string into type T while using the provided ZCString as
the context for any zero-copy deserialization.
Requires the serde feature.
Examples found in repository?
examples/simple_example.rs (line 80)
48fn main() -> Result<(), Box<dyn Error>> {
49 // ZCString creation
50 println!("From str: {:?}", ZCString::from("str"));
51 #[cfg(feature = "std")]
52 println!("From String: {:?}", ZCString::from(String::from("str")));
53 println!("New ZCString: {:?}", ZCString::new());
54
55 // how big is a ZCString member in a structure as compared &str?
56
57 // we expect the same size. Why? &str is a fat pointer and
58 // ZString is a Substr which is a thin pointer to an ArcStr plus
59 // a range consisting of two u32s
60 println!("size_of &str: {}", size_of::<&str>());
61 println!("size_of ZCString: {}", size_of::<ZCString>());
62
63 #[cfg(feature = "serde")]
64 {
65 // example JSON data feed
66 let input = [
67 literal!(r#"{"level": "error", "message": "Connection lost"}"#),
68 literal!(r#"{"level": "warning", "message": "Cat on keyboard"}"#),
69 literal!(r#"{"level": "info", "message": "Crow pecked camera"}"#),
70 literal!(r#"{"level": "error", "message": "Raven pecked camera, now offline"}"#),
71 // in this case the address of message should not fall within
72 // the memory address range of the raw json
73 literal!(r#"{"level": "error", "message": "Escaped \" "}"#),
74 ];
75
76 let items = input
77 .into_iter()
78 .map(|line| -> Result<LogEntry, Box<dyn Error>> {
79 // our special wrapper for JSON parsing
80 let entry = serde_json_from_zcstring::<LogEntry>(ZCString::from(line.clone()))?;
81
82 // show values and memory layout
83 println!("------");
84
85 println!("Log Line: {}", line);
86 println!(
87 " Log Line Location: 0x{:x} - 0x{:x}",
88 line.as_ptr() as usize,
89 line.as_ptr() as usize + line.len(),
90 );
91
92 show("level", &line, &entry.level);
93 show("message", &line, &entry.message);
94
95 // now serialize - Ok we could do a zero-alloc deserialize but
96 // not right now...
97 println!(" Serialized: {}", serde_json::to_string(&entry)?);
98 println!("");
99
100 Ok(entry)
101 })
102 .collect::<Result<Vec<LogEntry>, _>>()?;
103
104 println!("items size: {}\n", items.len());
105 }
106
107 Ok(())
108}