66 lines
1.6 KiB
Rust
66 lines
1.6 KiB
Rust
use crate::data_result::DataResult;
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use crate::dynamic_ops::DynamicOps;
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/// A trait for building lists.
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#[must_use]
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pub trait ListBuilder {
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type Value;
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/// Builds the final list and returns the result.
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fn build(self, prefix: Self::Value) -> DataResult<Self::Value>;
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/// Adds a direct value to this [`ListBuilder`].
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#[must_use]
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fn add(self, value: Self::Value) -> Self;
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/// Adds a [`DataResult`] to this [`ListBuilder`].
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#[must_use]
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fn add_data_result(self, value: DataResult<Self::Value>) -> Self;
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}
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/// An implementation of [`ListBuilder`].
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pub struct ListBuilderImpl<T, O: 'static> {
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elements: DataResult<Vec<T>>,
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ops: &'static O,
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}
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pub fn new_list_builder_impl<T>(
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ops: &'static impl DynamicOps<Value = T>,
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) -> impl ListBuilder<Value = T> {
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ListBuilderImpl {
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elements: DataResult::new_success(vec![]),
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ops,
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}
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}
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impl<T, O> ListBuilder for ListBuilderImpl<T, O>
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where
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O: DynamicOps<Value = T>,
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{
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type Value = T;
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fn build(self, prefix: Self::Value) -> DataResult<Self::Value> {
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self.elements
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.flat_map(|e| self.ops.merge_values_into_list(prefix, e))
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}
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fn add(mut self, value: Self::Value) -> Self {
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self.elements = self.elements.map(|mut e: Vec<T>| {
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e.push(value);
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e
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});
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self
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}
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fn add_data_result(mut self, value: DataResult<T>) -> Self {
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self.elements = self.elements.apply_2_and_make_stable(
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|mut e, v| {
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e.push(v);
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e
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},
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value,
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);
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self
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}
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}
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