Crate lexical_core[−][src]

Expand description

Fast lexical conversion routines for a no_std environment.

lexical-core is a low-level API for number-to-string and string-to-number conversions, without requiring a system allocator. If you would like to use a convenient, high-level API, please look at lexical instead.

Getting Started

extern crate lexical_core;

// String to number using Rust slices.
// The argument is the byte string parsed.
let f: f32 = lexical_core::parse(b"3.5").unwrap();   // 3.5
let i: i32 = lexical_core::parse(b"15").unwrap();    // 15

// All lexical_core parsers are checked, they validate the
// input data is entirely correct, and stop parsing when invalid data
// is found, or upon numerical overflow.
let r = lexical_core::parse::<u8>(b"256"); // Err(ErrorCode::Overflow.into())
let r = lexical_core::parse::<u8>(b"1a5"); // Err(ErrorCode::InvalidDigit.into())

// In order to extract and parse a number from a substring of the input
// data, use `parse_partial`. These functions return the parsed value and
// the number of processed digits, allowing you to extract and parse the
// number in a single pass.
let r = lexical_core::parse_partial::<i8>(b"3a5"); // Ok((3, 1))

// If an insufficiently long buffer is passed, the serializer will panic.
// PANICS
let mut buf = [b'0'; 1];
//let slc = lexical_core::write::<i64>(15, &mut buf);

// In order to guarantee the buffer is long enough, always ensure there
// are at least `T::FORMATTED_SIZE` bytes, which requires the
// `lexical_core::Number` trait to be in scope.
use lexical_core::Number;
let mut buf = [b'0'; f64::FORMATTED_SIZE];
let slc = lexical_core::write::<f64>(15.1, &mut buf);
assert_eq!(slc, b"15.1");

// When the `radix` feature is enabled, for decimal floats, using
// `T::FORMATTED_SIZE` may significantly overestimate the space
// required to format the number. Therefore, the
// `T::FORMATTED_SIZE_DECIMAL` constants allow you to get a much
// tighter bound on the space required.
let mut buf = [b'0'; f64::FORMATTED_SIZE_DECIMAL];
let slc = lexical_core::write::<f64>(15.1, &mut buf);
assert_eq!(slc, b"15.1");