Add async statements
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README.md
23
README.md
@ -11,8 +11,10 @@ A basic dust program:
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Dust can do two (or more) things at the same time with effortless concurrency:
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```dust
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async (output 'will this one finish first?')
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async (output 'or will this one?')
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async {
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(output 'will this one finish first?')
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(output 'or will this one?')
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}
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```
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Dust is an interpreted, general purpose language with first class functions. It is *data-oriented*, with extensive tools to manage structured and relational data. Dust also includes built-in tooling to import and export data in a variety of formats, including JSON, TOML, YAML and CSV.
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@ -28,6 +30,7 @@ Dust is an interpreted, general purpose language with first class functions. It
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- [Maps](#maps)
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- [Tables](#tables)
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- [Functions](#functions)
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- [Concurrency](#concurrency)
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- [Implementation](#implementation)
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<!--toc:end-->
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@ -176,12 +179,20 @@ print = function <input> {
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As a language written in Rust, Dust features effortless concurrency anywhere in your code.
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```dust
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if (random_integer) % 2 == 0 {
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run {
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(output 1 + 1)
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(output 1 + 1 == 2)
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async {
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await 1 + 1
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}
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```
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The **await** keyword can be used in an asnyc block to indicate what value the async block should evaluate to. In this case, we want "data" to be read from a file.
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```dust
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data = async {
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(output "Reading a file...")
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(read "examples/assets/faithful.csv")
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}
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(output data)
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```
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## Implementation
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@ -1,23 +1,60 @@
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use rayon::prelude::*;
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use serde::{Deserialize, Serialize};
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use tree_sitter::Node;
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use crate::{AbstractTree, Item};
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use crate::{AbstractTree, Error, Result, Statement, Value, VariableMap};
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#[derive(Debug, Clone, Serialize, Deserialize, Eq, PartialEq, PartialOrd, Ord)]
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pub struct Async {
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item: Item,
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statements: Vec<Statement>,
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}
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impl AbstractTree for Async {
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fn from_syntax_node(source: &str, node: tree_sitter::Node) -> crate::Result<Self> {
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fn from_syntax_node(source: &str, node: Node) -> Result<Self> {
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debug_assert_eq!("async", node.kind());
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let item_node = node.child(2).unwrap();
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let item = Item::from_syntax_node(source, item_node)?;
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let child_count = node.child_count();
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let mut statements = Vec::with_capacity(child_count);
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Ok(Async { item })
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for index in 2..child_count - 1 {
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let child = node.child(index).unwrap();
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let statement = match child.kind() {
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"statement" => Statement::from_syntax_node(source, child)?,
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_ => {
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return Err(Error::UnexpectedSyntaxNode {
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expected: "comment or statement",
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actual: child.kind(),
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location: child.start_position(),
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relevant_source: source[child.byte_range()].to_string(),
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})
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}
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};
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statements.push(statement);
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}
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fn run(&self, source: &str, context: &mut crate::VariableMap) -> crate::Result<crate::Value> {
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self.item.run_parallel(source, context)
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Ok(Async { statements })
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}
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fn run(&self, source: &str, context: &mut VariableMap) -> Result<Value> {
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let statements = &self.statements;
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statements
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.into_par_iter()
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.enumerate()
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.find_map_last(|(index, statement)| {
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let mut context = context.clone();
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let result = statement.run(source, &mut context).unwrap_or_default();
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if index == statements.len() - 1 {
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Some(result)
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} else {
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None
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}
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})
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.ok_or(Error::CustomMessage(
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"Async block has nothing to run.".to_string(),
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))
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}
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}
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@ -22,13 +22,16 @@ impl Item {
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}
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pub fn run_parallel(&self, source: &str, context: &mut VariableMap) -> Result<Value> {
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self.statements.par_iter().for_each(|statement| {
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let statements = &self.statements;
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let run_result = statements.into_par_iter().try_for_each(|statement| {
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let mut context = context.clone();
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statement.run(source, &mut context);
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statement.run(source, &mut context).map(|_| ())
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});
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Ok(Value::Empty)
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match run_result {
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Ok(()) => Ok(Value::Empty),
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Err(error) => Err(error),
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}
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}
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}
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@ -1 +1 @@
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Subproject commit 0f58ea5a7a05d49d99bbe24b9da03eea5249cbd7
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Subproject commit cf22950b7ee6f40c7840b6af4d7b2dda69f4965b
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