use std::collections::HashMap; use std::collections::hash_map::Entry; use std::rc::Rc; use std::fmt; use std::fmt::Write; use crate::ast; use crate::ast::{Meta, TypeBody, TypeSingletonName, Signature, Statement}; use crate::typechecking::TypeName; type LineNumber = u32; type SymbolTrackTable = HashMap, LineNumber>; #[derive(PartialEq, Eq, Hash, Debug)] struct PathToSymbol(Vec>); #[derive(Debug, Clone)] struct ScopeSegment { scope_name: Rc, scope_type: ScopeSegmentKind, } #[derive(Debug, Clone)] enum ScopeSegmentKind { Function, Type, } //cf. p. 150 or so of Language Implementation Patterns pub struct SymbolTable { values: HashMap, } //TODO add various types of lookups here, maybe multiple hash tables internally? impl SymbolTable { pub fn new() -> SymbolTable { SymbolTable { values: HashMap::new(), } } fn add_new_symbol(&mut self, name: &Rc, scope_path: &Vec, spec: SymbolSpec) { let mut vec: Vec> = scope_path.iter().map(|segment| segment.scope_name.clone()).collect(); vec.push(name.clone()); let symbol_path = PathToSymbol(vec); let symbol = Symbol { name: name.clone(), scopes: scope_path.to_vec(), spec }; self.values.insert(symbol_path, symbol); } pub fn lookup_by_name(&self, name: &Rc) -> Option<&Symbol> { self.lookup_by_path(name, &vec![]) } pub fn lookup_by_path(&self, name: &Rc, path: &Vec>) -> Option<&Symbol> { let mut vec = path.clone(); vec.push(name.clone()); let symbol_path = PathToSymbol(vec); self.values.get(&symbol_path) } } #[derive(Debug)] pub struct Symbol { pub name: Rc, //TODO does this need to be pub? scopes: Vec, pub spec: SymbolSpec, } impl fmt::Display for Symbol { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { write!(f, "", self.name, self.spec) } } #[derive(Debug)] pub enum SymbolSpec { Func(Vec), DataConstructor { index: usize, type_name: Rc, type_args: Vec>, }, RecordConstructor { fields: HashMap, Rc> }, Binding } impl fmt::Display for SymbolSpec { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { use self::SymbolSpec::*; match self { Func(type_names) => write!(f, "Func({:?})", type_names), DataConstructor { index, type_name, type_args } => write!(f, "DataConstructor(idx: {})({:?} -> {})", index, type_args, type_name), RecordConstructor { fields: _fields } => write!(f, "RecordConstructor( )"), Binding => write!(f, "Binding"), } } } impl SymbolTable { /* note: this adds names for *forward reference* but doesn't actually create any types. solve that problem * later */ pub fn add_top_level_symbols(&mut self, ast: &ast::AST) -> Result<(), String> { let mut scope_name_stack = Vec::new(); self.add_symbols_from_scope(&ast.0, &mut scope_name_stack) } fn add_symbols_from_scope<'a>(&'a mut self, statements: &Vec>, scope_name_stack: &mut Vec) -> Result<(), String> { use self::ast::Declaration::*; fn insert_and_check_duplicate_symbol(table: &mut SymbolTrackTable, name: &Rc) -> Result<(), String> { match table.entry(name.clone()) { Entry::Occupied(o) => { let line_number = o.get(); //TODO make this actually work Err(format!("Duplicate definition: {}. It's already defined at {}", name, line_number)) }, Entry::Vacant(v) => { let line_number = 0; //TODO should work v.insert(line_number); Ok(()) } } } let mut seen_identifiers: SymbolTrackTable = HashMap::new(); for meta in statements.iter() { let statement = meta.node(); if let Statement::Declaration(decl) = statement { match decl { FuncSig(ref signature) => { insert_and_check_duplicate_symbol(&mut seen_identifiers, &signature.name)?; self.add_function_signature(signature, scope_name_stack)? } FuncDecl(ref signature, ref body) => { insert_and_check_duplicate_symbol(&mut seen_identifiers, &signature.name)?; self.add_function_signature(signature, scope_name_stack)?; scope_name_stack.push(ScopeSegment{ scope_name: signature.name.clone(), scope_type: ScopeSegmentKind::Function, }); let output = self.add_symbols_from_scope(body, scope_name_stack); let _ = scope_name_stack.pop(); output? }, TypeDecl { name, body, mutable } => { insert_and_check_duplicate_symbol(&mut seen_identifiers, &name.name)?; self.add_type_decl(name, body, mutable, scope_name_stack)? }, Binding { name, .. } => { insert_and_check_duplicate_symbol(&mut seen_identifiers, name)?; self.add_new_symbol(name, scope_name_stack, SymbolSpec::Binding); } _ => () } } } Ok(()) } pub fn debug_symbol_table(&self) -> String { let mut output = format!("Symbol table\n"); for (name, sym) in &self.values { write!(output, "{:?} -> {}\n", name, sym).unwrap(); } output } fn add_function_signature(&mut self, signature: &Signature, scope_name_stack: &mut Vec) -> Result<(), String> { let mut local_type_context = LocalTypeContext::new(); let types = signature.params.iter().map(|param| match param { (_, Some(type_identifier)) => Rc::new(format!("{:?}", type_identifier)), (_, None) => local_type_context.new_universal_type() }).collect(); self.add_new_symbol(&signature.name, scope_name_stack, SymbolSpec::Func(types)); Ok(()) } fn add_type_decl(&mut self, type_name: &TypeSingletonName, body: &TypeBody, _mutable: &bool, scope_name_stack: &mut Vec) -> Result<(), String> { use crate::ast::{TypeIdentifier, Variant}; let TypeBody(variants) = body; let TypeSingletonName { name, .. } = type_name; //scope_name_stack.push(name.clone()); //TODO adding this makes variants scoped under their //type name and breaks a lot of things - don't add it until importing names works //TODO figure out why _params isn't being used here for (index, var) in variants.iter().enumerate() { match var { Variant::UnitStruct(variant_name) => { let spec = SymbolSpec::DataConstructor { index, type_name: name.clone(), type_args: vec![], }; self.add_new_symbol(variant_name, scope_name_stack, spec); }, Variant::TupleStruct(variant_name, tuple_members) => { let type_args = tuple_members.iter().map(|type_name| match type_name { TypeIdentifier::Singleton(TypeSingletonName { name, ..}) => name.clone(), TypeIdentifier::Tuple(_) => unimplemented!(), }).collect(); let spec = SymbolSpec::DataConstructor { index, type_name: name.clone(), type_args }; self.add_new_symbol(variant_name, scope_name_stack, spec); }, //TODO if there is only one variant, and it is a record, it doesn't need to have an //explicit name Variant::Record { name, members: _members } => { let fields = HashMap::new(); let spec = SymbolSpec::RecordConstructor { fields }; self.add_new_symbol(name, scope_name_stack, spec); }, } } //scope_name_stack.pop(); Ok(()) } } struct LocalTypeContext { state: u8 } impl LocalTypeContext { fn new() -> LocalTypeContext { LocalTypeContext { state: 0 } } fn new_universal_type(&mut self) -> TypeName { let n = self.state; self.state += 1; Rc::new(format!("{}", (('a' as u8) + n) as char)) } } #[cfg(test)] mod symbol_table_tests { use super::*; use crate::util::quick_ast; macro_rules! values_in_table { //TODO multiple values ($source:expr, $single_value:expr) => { { let mut symbol_table = SymbolTable::new(); let ast = quick_ast($source); symbol_table.add_top_level_symbols(&ast).unwrap(); match symbol_table.lookup_by_name($single_value) { Some(_spec) => (), None => panic!(), }; } } } #[test] fn basic_symbol_table() { values_in_table! { "let a = 10; fn b() { 20 }", &rc!(b) }; } #[test] fn no_duplicates() { let source = r#" fn a() { 1 } fn b() { 2 } fn a() { 3 } "#; let mut symbol_table = SymbolTable::new(); let ast = quick_ast(source); let output = symbol_table.add_top_level_symbols(&ast).unwrap_err(); assert!(output.contains("Duplicate")) } #[test] fn no_duplicates_2() { let source = r#" let a = 20; let q = 39; let a = 30; "#; let mut symbol_table = SymbolTable::new(); let ast = quick_ast(source); let output = symbol_table.add_top_level_symbols(&ast).unwrap_err(); assert!(output.contains("Duplicate")) } #[test] fn no_duplicates_3() { let source = r#" fn a() { let a = 20 let b = 40 a + b } fn q() { let x = 30 let x = 33 } "#; let mut symbol_table = SymbolTable::new(); let ast = quick_ast(source); let output = symbol_table.add_top_level_symbols(&ast).unwrap_err(); assert!(output.contains("Duplicate")) } #[test] fn dont_falsely_detect_duplicates() { let source = r#" let a = 20; fn some_func() { let a = 40; 77 } let q = 39; "#; let mut symbol_table = SymbolTable::new(); let ast = quick_ast(source); symbol_table.add_top_level_symbols(&ast).unwrap(); assert!(symbol_table.lookup_by_path(&rc!(a), &vec![]).is_some()); assert!(symbol_table.lookup_by_path(&rc!(a), &vec![rc!(some_func)]).is_some()); } #[test] fn enclosing_scopes() { let source = r#" fn outer_func(x) { fn inner_func(arg) { arg } x + inner_func(x) }"#; let mut symbol_table = SymbolTable::new(); let ast = quick_ast(source); symbol_table.add_top_level_symbols(&ast).unwrap(); assert!(symbol_table.lookup_by_path(&rc!(outer_func), &vec![]).is_some()); assert!(symbol_table.lookup_by_path(&rc!(inner_func), &vec![rc!(outer_func)]).is_some()); } #[test] fn enclosing_scopes_2() { let source = r#" fn outer_func(x) { fn inner_func(arg) { arg } fn second_inner_func() { fn another_inner_func() { } } inner_func(x) }"#; let mut symbol_table = SymbolTable::new(); let ast = quick_ast(source); symbol_table.add_top_level_symbols(&ast).unwrap(); println!("{}", symbol_table.debug_symbol_table()); assert!(symbol_table.lookup_by_path(&rc!(outer_func), &vec![]).is_some()); assert!(symbol_table.lookup_by_path(&rc!(inner_func), &vec![rc!(outer_func)]).is_some()); assert!(symbol_table.lookup_by_path(&rc!(second_inner_func), &vec![rc!(outer_func)]).is_some()); assert!(symbol_table.lookup_by_path(&rc!(another_inner_func), &vec![rc!(outer_func), rc!(second_inner_func)]).is_some()); } #[test] fn enclosing_scopes_3() { let source = r#" fn outer_func(x) { fn inner_func(arg) { arg } fn second_inner_func() { fn another_inner_func() { } fn another_inner_func() { } } inner_func(x) }"#; let mut symbol_table = SymbolTable::new(); let ast = quick_ast(source); let output = symbol_table.add_top_level_symbols(&ast).unwrap_err(); assert!(output.contains("Duplicate")) } }