1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
//! Runtime implementation of [`format!`].
//!
//! # `std::fmt` compatible formatting
//!
//! All options but the fill character for alignment is supported
//! (due to [rust-lang/rfcs#3394](https://github.com/rust-lang/rfcs/pull/3394)).
//!
//! Though the non [`Display`] traits need to be enabled through
//! [features](#features).
//!
//! ```
//! use interpolator::{format, Formattable};
//!
//! let formatted = format(
//!     "{value:+05}", // could be dynamic
//!     &[("value", Formattable::display(&12))].into_iter().collect(),
//! )?;
//!
//! assert_eq!(formatted, format!("{:+05}", 12));
//! # return Ok::<(), interpolator::Error>(())
//! ```

#![cfg_attr(
    feature = "iter",
    doc = r#"
# `i` iter format

The feature `iter` enables an additional format trait `i`, it allows to
format a list of values with a format string and an optional join
expression.

The syntax is `{list:i(the format string, '{}' is the array element)(the
join)}`, an empty join can also be omitted `{list:i({})}`. If join is omitted
the format string `{}` can be omitted as well `{list:i}`.

Should you need to use `)` inside your format string or join, you can add `#`
similar to rust's [raw string](https://doc.rust-lang.org/reference/tokens.html#raw-string-literals)
(i.e. `#(({}))#`).

It is also possible to only iterate a sub-slice specified through a range
before the format string, i.e. `{list:i1..4}`. For open ranges range
bounds can also be omitted. To index from the end, you can use negative
range bounds.

It is also possible to index a single value by only specifying an [`isize`]
`{list:i1}`.

A [`Formattable`] implementing iter is created using [`Formattable::iter`]:

```
// HashMap macro
use collection_literals::hash;
use interpolator::{format, Formattable};
// Needs to be a slice of references because `Formattable::display` expects a
// reference
let items = [&"hello", &"hi", &"hey"].map(Formattable::display);
let items = Formattable::iter(&items);
let format_str = "Greetings: {items:i..-1(`{}`)(, )} and `{items:i-1}`";
assert_eq!(
    format(format_str, &hash!("items" => items))?,
    "Greetings: `hello`, `hi` and `hey`"
);
# return Ok::<(), interpolator::Error>(())
```"#
)]

//! See [`format`](format()) and [`write`](write()) for details.
//!
//! # Features
//! By default only [`Display`] is supported, the rest of the
//! [formatting traits](https://doc.rust-lang.org/std/fmt/index.html#formatting-traits)
//! can be enabled through the following features.
//!
//! - `debug` enables `?`, `x?` and `X?` trait specifiers
//! - `number` enables `x`, `X`, `b`, `o`, `e` and `E` trait specifiers
//! - `pointer` enables `p` trait specifiers
//! - `iter` enables [`i`](#i-iter-format) trait specifier
#![warn(clippy::pedantic, missing_docs)]
#![allow(
    clippy::wildcard_imports,
    clippy::implicit_hasher,
    clippy::enum_glob_use,
    clippy::module_name_repetitions
)]
#![cfg_attr(docsrs, feature(doc_auto_cfg))]
use std::borrow::Borrow;
use std::collections::HashMap;
use std::error::Error as StdError;
#[cfg(feature = "pointer")]
use std::fmt::Pointer;
#[cfg(feature = "number")]
use std::fmt::{Binary, LowerExp, LowerHex, Octal, UpperExp, UpperHex};
use std::fmt::{Debug, Display, Error as FmtError, Write};
use std::hash::Hash;
use std::num::ParseIntError;

#[macro_use]
mod error;
pub use error::*;
mod hard_coded;
use hard_coded::format_value;
mod formattable;
pub use formattable::*;
mod parser;
use parser::*;

type Result<T = (), E = Error> = std::result::Result<T, E>;

/// Runtime version of [`format!`].
///
/// Takes a string and a context, containing [`Formattable`] values, returns a
/// string.
///
/// ```
/// use interpolator::{format, Formattable};
///
/// let formatted = format(
///     "{value:+05}", // could be dynamic
///     &[("value", Formattable::display(&12))].into_iter().collect(),
/// )
/// .unwrap();
///
/// assert_eq!(formatted, format!("{:+05}", 12));
/// ```
///
/// # Errors
///
/// It will return an error if the specified format string has invalid syntax,
/// the type doesn't implement the expected trait, or the formatting itself
/// failed.
///
/// For more details have a look at [`Error`] and [`ParseError`].
pub fn format<K: Borrow<str> + Eq + Hash>(
    format: &str,
    context: &HashMap<K, Formattable>,
) -> Result<String> {
    let mut out = String::with_capacity(format.len());
    write(&mut out, format, context)?;
    Ok(out)
}

/// Runtime version of [`write!`].
///
/// Takes a mutable [`Write`] e.g. `&mut String`, a format string and a context,
/// containing [`Formattable`] values.
///
/// ```
/// use interpolator::{write, Formattable};
///
/// let mut buf = String::new();
/// write(
///     &mut buf,
///     "{value:+05}", // could be dynamic
///     &[("value", Formattable::display(&12))].into_iter().collect(),
/// )
/// .unwrap();
///
/// assert_eq!(buf, format!("{:+05}", 12));
/// ```
///
/// # Errors
///
/// It will return an error if the specified format string has invalid syntax,
/// the type doesn't implement the expected trait, or the formatting itself
/// failed.
///
/// For more details have a look at [`Error`] and [`ParseError`].
pub fn write<'a, K: Borrow<str> + Eq + Hash, F: Borrow<Formattable<'a>>>(
    out: &mut impl Write,
    mut format: &str,
    context: &'a HashMap<K, F>,
) -> Result {
    let format = &mut format;
    let idx = &mut 0;
    while !format.is_empty() {
        if format.starts_with("{{") || format.starts_with("}}") {
            out.write_str(&format[..1])
                .map_err(|e| Error::Fmt(e, *idx))?;
            step(2, format, idx);
            continue;
        }
        if format.starts_with('{') {
            step(1, format, idx);
            let start = *idx;
            let FormatArgument {
                ident,
                alignment,
                sign,
                hash,
                zero,
                width,
                precision,
                trait_,
            } = FormatArgument::from_str(format, idx)?;
            let value = context
                .get(ident)
                .ok_or(Error::MissingValue(ident.to_string(), start))?;
            format_value(
                out,
                value.borrow(),
                width,
                precision,
                alignment,
                sign,
                hash,
                zero,
                trait_,
                *idx,
            )?;
            ensure!(format.starts_with('}'), ParseError::Expected("}", *idx));
            step(1, format, idx);
            continue;
        }
        let next = format
            .chars()
            .next()
            .expect("should contain a char if not empty");
        out.write_char(next).map_err(|e| Error::Fmt(e, *idx))?;
        step(next.len_utf8(), format, idx);
    }
    Ok(())
}