schala/schala-lang/language/src/schala.rs

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Rust
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use stopwatch::Stopwatch;
use std::cell::RefCell;
use std::rc::Rc;
use schala_repl::{ProgrammingLanguageInterface,
ComputationRequest, ComputationResponse,
LangMetaRequest, LangMetaResponse, GlobalOutputStats};
use crate::{reduced_ast, tokenizing, parsing, eval, typechecking, symbol_table};
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use crate::error::SchalaError;
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pub type SymbolTableHandle = Rc<RefCell<symbol_table::SymbolTable>>;
/// All the state necessary to parse and execute a Schala program are stored in this struct.
/// `state` represents the execution state for the AST-walking interpreter, the other fields
/// should be self-explanatory.
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#[allow(dead_code)]
pub struct Schala {
source_reference: SourceReference,
state: eval::State<'static>,
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symbol_table: SymbolTableHandle,
resolver: crate::scope_resolution::ScopeResolver<'static>,
type_context: typechecking::TypeContext<'static>,
active_parser: parsing::Parser,
}
impl Schala {
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//TODO implement documentation for language items
/*
fn handle_docs(&self, source: String) -> LangMetaResponse {
LangMetaResponse::Docs {
doc_string: format!("Schala item `{}` : <<Schala-lang documentation not yet implemented>>", source)
}
}
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*/
}
impl Schala {
/// Creates a new Schala environment *without* any prelude.
fn new_blank_env() -> Schala {
let symbols = Rc::new(RefCell::new(symbol_table::SymbolTable::new()));
Schala {
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//TODO maybe these can be the same structure
source_reference: SourceReference::new(),
symbol_table: symbols.clone(),
resolver: crate::scope_resolution::ScopeResolver::new(symbols.clone()),
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state: eval::State::new(),
type_context: typechecking::TypeContext::new(),
active_parser: parsing::Parser::new()
}
}
/// Creates a new Schala environment with the standard prelude, which is defined as ordinary
/// Schala code in the file `prelude.schala`
pub fn new() -> Schala {
let prelude = include_str!("prelude.schala");
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let mut env = Schala::new_blank_env();
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let response = env.run_pipeline(prelude);
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if let Err(err) = response {
panic!("Error in prelude, panicking: {}", err.display());
}
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env
}
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/// This is where the actual action of interpreting/compilation happens.
/// Note: this should eventually use a query-based system for parallelization, cf.
/// https://rustc-dev-guide.rust-lang.org/overview.html
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fn run_pipeline(&mut self, source: &str) -> Result<String, SchalaError> {
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// 1st stage - tokenization
// TODO tokenize should return its own error type
let tokens = tokenizing::tokenize(source);
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if let Some(err) = SchalaError::from_tokens(&tokens) {
return Err(err)
}
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//2nd stage - parsing
self.active_parser.add_new_tokens(tokens);
let mut ast = self.active_parser.parse()
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.map_err(|err| SchalaError::from_parse_error(err, &self.source_reference))?;
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// Symbol table
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self.symbol_table.borrow_mut().add_top_level_symbols(&ast)
.map_err(|err| SchalaError::from_string(err, Stage::Symbols))?;
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// Scope resolution - requires mutating AST
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self.resolver.resolve(&mut ast)
.map_err(|err| SchalaError::from_string(err, Stage::ScopeResolution))?;
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// Typechecking
// TODO typechecking not working
let _overall_type = self.type_context.typecheck(&ast)
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.map_err(|err| SchalaError::from_type_error(err));
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// Reduce AST - TODO this doesn't produce an error yet, but probably should
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let symbol_table = self.symbol_table.borrow();
let reduced_ast = reduced_ast::reduce(&ast, &symbol_table);
// Tree-walking evaluator. TODO fix this
let evaluation_outputs = self.state.evaluate(reduced_ast, true);
let text_output: Result<Vec<String>, String> = evaluation_outputs
.into_iter()
.collect();
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let text_output: Result<Vec<String>, SchalaError> = text_output
.map_err(|err| SchalaError::from_string(err, Stage::Evaluation));
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let eval_output: String = text_output
.map(|v| { Iterator::intersperse(v.into_iter(), "\n".to_owned()).collect() })?;
Ok(eval_output)
}
}
/// Represents lines of source code
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pub(crate) struct SourceReference {
lines: Option<Vec<String>>
}
impl SourceReference {
fn new() -> SourceReference {
SourceReference { lines: None }
}
fn load_new_source(&mut self, source: &str) {
//TODO this is a lot of heap allocations - maybe there's a way to make it more efficient?
self.lines = Some(source.lines().map(|s| s.to_string()).collect()); }
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pub fn get_line(&self, line: usize) -> String {
self.lines.as_ref().and_then(|x| x.get(line).map(|s| s.to_string())).unwrap_or(format!("NO LINE FOUND"))
}
}
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#[allow(dead_code)]
#[derive(Clone, Copy, Debug)]
pub(crate) enum Stage {
Tokenizing,
Parsing,
Symbols,
ScopeResolution,
Typechecking,
AstReduction,
Evaluation,
}
fn stage_names() -> Vec<&'static str> {
vec![
"tokenizing",
"parsing",
"symbol-table",
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"scope-resolution",
"typechecking",
"ast-reduction",
"ast-walking-evaluation"
]
}
impl ProgrammingLanguageInterface for Schala {
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type Config = ();
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fn language_name() -> String {
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"Schala".to_owned()
}
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fn source_file_suffix() -> String {
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"schala".to_owned()
}
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fn run_computation(&mut self, request: ComputationRequest<Self::Config>) -> ComputationResponse {
let ComputationRequest { source, debug_requests: _, config: _ } = request;
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self.source_reference.load_new_source(source);
let sw = Stopwatch::start_new();
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let main_output = self.run_pipeline(source)
.map_err(|schala_err| schala_err.display());
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let global_output_stats = GlobalOutputStats {
total_duration: sw.elapsed(),
stage_durations: vec![]
};
ComputationResponse {
main_output,
global_output_stats,
debug_responses: vec![]
}
}
fn request_meta(&mut self, request: LangMetaRequest) -> LangMetaResponse {
match request {
LangMetaRequest::StageNames => LangMetaResponse::StageNames(stage_names().iter().map(|s| s.to_string()).collect()),
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_ => LangMetaResponse::Custom { kind: format!("not-implemented"), value: format!("") }
}
}
}