5360318bfc
Previously the lexer's post-fix loop was really weird, incrementing in the middle of the function. No more
61 lines
1.4 KiB
Markdown
61 lines
1.4 KiB
Markdown
calculation + conversion
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Uses Decimal Floating Point numbers instead of Binary Coded Decimals for better accuracy.
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# Dev Instructions
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## Get started
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Install [Rust](https://www.rust-lang.org). This project was built in Rust 1.40.
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## Commands
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Run cpc with a CLI argument as input:
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```
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cargo run -- '100ms to s'
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```
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Run tests:
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```
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cargo test
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```
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## Adding a unit
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### 1. Add the unit
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In `src/units.rs`, units are specified like this:
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```rs
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pub enum UnitType {
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Time,
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// etc
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}
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// ...
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create_units!(
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Nanosecond: (Time, d128!(1)),
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Microsecond: (Time, d128!(1000)),
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// etc
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)
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```
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The number associated with a unit is it's "weight". For example, if a second's weight is `1`, then a minute's weight is `1000`.
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I have found [translatorscafe.com](https://www.translatorscafe.com/unit-converter) and [calculateme.com](https://www.calculateme.com/) to be good websites for unit convertion. Wikipedia is worth looking at as well.
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### 2. Add a test for the unit
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Make sure to also add a test for each unit. The tests look like this:
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```rs
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assert_eq!(convert_test(1000.0, Meter, Kilometer), 1.0);
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```
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Basically, 1000 Meter == 1 Kilometer.
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### 3. Add the unit to the lexer
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Text is turned into tokens (some of which are units) in `lexer.rs`. Here's one example:
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```rs
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// ...
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match string {
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"h" | "hr" | "hrs" | "hour" | "hours" => tokens.push(Token::Unit(Hour)),
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// etc
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}
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// ...
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```
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