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85 строки
3.1 KiB
Markdown
85 строки
3.1 KiB
Markdown
# Decimal   [![Build Status]][actions] [![Latest Version]][crates.io]
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[Build Status]: https://img.shields.io/endpoint.svg?url=https%3A%2F%2Factions-badge.atrox.dev%2Fpaupino%2Frust-decimal%2Fbadge&label=build&logo=none
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[actions]: https://actions-badge.atrox.dev/paupino/rust-decimal/goto
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[Latest Version]: https://img.shields.io/crates/v/rust-decimal.svg
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[crates.io]: https://crates.io/crates/rust-decimal
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A Decimal implementation written in pure Rust suitable for financial calculations that require significant integral and fractional digits with no round-off errors.
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The binary representation consists of a 96 bit integer number, a scaling factor used to specify the decimal fraction and a 1 bit sign. Because of this representation, trailing zeros are preserved and may be exposed when in string form. These can be truncated using the `normalize` or `round_dp` functions.
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[Documentation](https://docs.rs/rust_decimal/)
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## Usage
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Decimal numbers can be created in a few distinct ways. The easiest and most optimal method of creating a Decimal is to use the procedural macro within the `rust_decimal_macros` crate:
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```rust
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// Procedural macros need importing directly
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use rust_decimal_macros::*;
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let number = dec!(-1.23);
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```
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Alternatively you can also use one of the Decimal number convenience functions:
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```rust
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use rust_decimal::prelude::*;
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// Using an integer followed by the decimal points
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let scaled = Decimal::new(202, 2); // 2.02
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// From a string representation
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let from_string = Decimal::from_str("2.02").unwrap(); // 2.02
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// Using the `Into` trait
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let my_int : Decimal = 3i32.into();
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// Using the raw decimal representation
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// 3.1415926535897932384626433832
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let pi = Decimal::from_parts(1102470952, 185874565, 1703060790, false, 28);
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```
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## Features
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* [db-postgres](#db-postgres)
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* [db-tokio-postgres](#db-tokio-postgres)
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* [db-diesel-postgres](#db-diesel-postgres)
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* [serde-float](#serde-float)
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* [serde-bincode](#serde-bincode)
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## `db-postgres`
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This feature enables a PostgreSQL communication module. It allows for reading and writing the `Decimal`
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type by transparently serializing/deserializing into the `NUMERIC` data type within PostgreSQL.
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## `db-tokio-postgres`
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Enables the tokio postgres module allowing for async communication with PostgreSQL.
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## `db-diesel-postgres`
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Enable `diesel` PostgreSQL support.
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## `serde-float`
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Enable this so that JSON serialization of Decimal types are sent as a float instead of a string (default).
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e.g. with this turned on, JSON serialization would output:
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```
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{
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"value": 1.234
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}
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```
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## `serde-bincode`
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Since `bincode` does not specify type information, we need to ensure that a type hint is provided in order to
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correctly be able to deserialize. Enabling this feature on it's own will force deserialization to use `deserialize_str`
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instead of `deserialize_any`.
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If, for some reason, you also have `serde-float` enabled then this will use `deserialize_f64` as a type hint. Because
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converting to `f64` _loses_ precision, it's highly recommended that you do NOT enable this feature when working with
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`bincode`. That being said, this will only use 8 bytes so is slightly more efficient in regards to storage size.
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