forked from StudioInfinity/dyna3
44 lines
2.2 KiB
Rust
44 lines
2.2 KiB
Rust
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use std::num::ParseFloatError;
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// a real number described by a specification string. since the structure is
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// read-only, we can guarantee that `spec` always specifies `value` in the
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// following format
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// ┌──────────────────────────────────────────────────────┬───────────┐
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// │ `spec` │ `value` │
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// ┝━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┿━━━━━━━━━━━┥
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// │ a string that parses to the floating-point value `x` │ `Some(x)` │
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// ├──────────────────────────────────────────────────────┼───────────┤
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// │ the empty string │ `None` │
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// └──────────────────────────────────────────────────────┴───────────┘
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#[readonly::make]
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pub struct SpecifiedValue {
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pub spec: String,
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pub value: Option<f64>
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}
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impl SpecifiedValue {
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pub fn from_empty_spec() -> SpecifiedValue {
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SpecifiedValue { spec: String::new(), value: None }
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}
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pub fn is_present(&self) -> bool {
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matches!(self.value, Some(_))
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}
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}
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// a `SpecifiedValue` can be constructed from a specification string, formatted
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// as described in the comment on the structure definition. the result is `Ok`
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// if the specification is properly formatted, and `Error` if not
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impl TryFrom<String> for SpecifiedValue {
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type Error = ParseFloatError;
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fn try_from(spec: String) -> Result<Self, Self::Error> {
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if spec.is_empty() {
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Ok(SpecifiedValue::from_empty_spec())
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} else {
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spec.parse::<f64>().map(
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|value| SpecifiedValue { spec: spec, value: Some(value) }
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)
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}
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}
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}
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