Crate dynfmt[−][src]
A crate for formatting strings dynamically.
dynfmt
provides several implementations for formats that implement a subset of the
std::fmt
facilities. Parsing of the format string and arguments checks are performed at
runtime. There is also the option to implement new formats.
The public API is exposed via the Format
trait, which contains formatting helper functions
and lower-level utilities to interface with format strings. See the Features section for a list
of provided implementations.
Usage
use dynfmt::{Format, NoopFormat}; let formatted = NoopFormat.format("hello, world", &["unused"]); assert_eq!("hello, world", formatted.expect("formatting failed"));
See the Format
trait for more methods.
Features
This crate ships with a set of features that either activate formatting capabilities or new format implementations:
json
(default): Implements the serialization of complex structures via JSON. Certain formats, such as Python, also have a representation format (%r
) that makes use of this feature, if enabled. Without this feature, such values will cause an error.python
: Implements theprintf
-like format that python 2 used for formatting strings. SeePythonFormat
for more information.curly
: A simple format string syntax using curly braces for arguments. Similar to .NET and Rust, but much less capable. SeeSimpleCurlyFormat
for mor information.
Extensibility
Implement the Format
trait to create a new format. The only required method is iter_args
,
which must return an iterator over ArgumentSpec
structs. Based on the capabilities of the
format, the specs can be parameterized with formatting parameters.
use std::str::MatchIndices; use dynfmt::{ArgumentSpec, Format, Error}; struct HashFormat; impl<'f> Format<'f> for HashFormat { type Iter = HashIter<'f>; fn iter_args(&self, format: &'f str) -> Result<Self::Iter, Error<'f>> { Ok(HashIter(format.match_indices('#'))) } } struct HashIter<'f>(MatchIndices<'f, char>); impl<'f> Iterator for HashIter<'f> { type Item = Result<ArgumentSpec<'f>, Error<'f>>; fn next(&mut self) -> Option<Self::Item> { self.0.next().map(|(index, _)| Ok(ArgumentSpec::new(index, index + 1))) } } let formatted = HashFormat.format("hello, #", &["world"]); assert_eq!("hello, world", formatted.expect("formatting failed"));
Re-exports
pub use crate::python::PythonFormat; |
pub use crate::curly::SimpleCurlyFormat; |
Modules
curly | Implementation for simple format strings using curly braces. |
python | Implementation for old-style Python format strings. |
Structs
ArgumentSpec | The format specification for a single argument in the format string, created by
|
NoopFormat | A format implementation that does not format anything. |
Enums
Alignment | Specifies the alignment of an argument when formatted with a specific width. |
Count | The value of a formatting parameter, used within |
Error | An error returned during formatting. |
FormatType | Formatting types for arguments. |
Position | Refers to an argument within an argument list. |
Traits
Format | A format for string formatting. |
FormatArgs | A container that provides access to indexed or named arguments. |
Type Definitions
Argument | A serializable argument. |
ArgumentResult | The result returned for each element of |