nom-trace

This crate provides a way to trace a parser execution, storing positions in the input data, positions in the parser tree and parser results.

As an example, if you run the following code:

```rust

[macro_use] extern crate nom;

[macro_use] extern crate nom-trace;

//adds a thread local storage object to store the trace declare_trace!();

pub fn main() { named!(parser

println!("parsed: {:?}", parser(&b"data: (1,2,3)"[..]));

// prints the last parser trace print_trace!();

// the list of trace events can be cleared reset_trace!(); } ```

You would get the following result ``` parsed: Ok(("", ["1", "2", "3"])) preceded "data: (1,2,3)"

    tag     "data: (1,2,3)"

    -> Ok("data: ")
    delimited       "(1,2,3)"

            digit   "1,2,3)"

            -> Ok("1")
            tag     ",2,3)"

            -> Ok(",")
            digit   "2,3)"

            -> Ok("2")
            tag     ",3)"

            -> Ok(",")
            digit   "3)"

            -> Ok("3")
            tag     ")"

            -> Error(Code(")", Tag))
            tag     ")"

            -> Ok(")")
    -> Ok(["1", "2", "3"])

-> Ok(["1", "2", "3"]) ```

Parser level is indicated through indentation. For each trace point, we have:

• indent level, then parser or combinator name, then input position
• traces for sub parsers
• -> followed by the parser's result

You can add intermediate names instead of combinator names for the trace, like this: tr!(PARENS, delimited!( ... )) this would replace the name delimited in the trace print, with PARENS

This tracer works with parsers based on &[u8] and &str input types. For &[u8], input positions will be displayed as a hexdump.