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Start building out type inference.

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This commit is contained in:
Adam Wick
2023-06-21 21:56:54 -07:00
parent 3687785540
commit 1ad3d6c517
14 changed files with 1286 additions and 305 deletions
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5
build.rs
View File

@@ -68,7 +68,10 @@ fn generate_tests(f: &mut File, path_so_far: PathBuf) -> std::io::Result<()> {
" assert_eq!(errors.len(), 0, \"file should have no validation errors\");" " assert_eq!(errors.len(), 0, \"file should have no validation errors\");"
)?; )?;
writeln!(f, " let syntax_result = syntax.eval();")?; writeln!(f, " let syntax_result = syntax.eval();")?;
writeln!(f, " let ir = IR::from(syntax);")?; writeln!(
f,
" let ir = syntax.type_infer().expect(\"example is typed correctly\");"
)?;
writeln!( writeln!(
f, f,
" assert_eq!(syntax_result, ir.eval(), \"syntax equivalent to IR\");" " assert_eq!(syntax_result, ir.eval(), \"syntax equivalent to IR\");"

36
src/compiler.rs
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@@ -1,5 +1,5 @@
use crate::backend::Backend;
use crate::syntax::Program as Syntax; use crate::syntax::Program as Syntax;
use crate::{backend::Backend, ir::TypeInferenceResult};
use codespan_reporting::{ use codespan_reporting::{
diagnostic::Diagnostic, diagnostic::Diagnostic,
files::SimpleFiles, files::SimpleFiles,
@@ -99,8 +99,38 @@ impl Compiler {
return Ok(None); return Ok(None);
} }
// Now that we've validated it, turn it into IR. // Now that we've validated it, let's do type inference, potentially turning
let ir = syntax.type_infer(); // into IR while we're at it.
let ir = match syntax.type_infer() {
TypeInferenceResult::Failure {
mut errors,
mut warnings,
} => {
let messages = errors
.drain(..)
.map(Into::into)
.chain(warnings.drain(..).map(Into::into));
for message in messages {
self.emit(message);
}
return Ok(None);
}
TypeInferenceResult::Success {
result,
mut warnings,
} => {
let messages = warnings.drain(..).map(Into::into);
for message in messages {
self.emit(message);
}
result
}
};
// Finally, send all this to Cranelift for conversion into an object file. // Finally, send all this to Cranelift for conversion into an object file.
let mut backend = Backend::object_file(Triple::host())?; let mut backend = Backend::object_file(Triple::host())?;

56
src/eval/primtype.rs
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@@ -80,6 +80,62 @@ impl FromStr for PrimitiveType {
} }
impl PrimitiveType { impl PrimitiveType {
/// Return true if this type can be safely cast into the target type.
pub fn can_cast_to(&self, target: &PrimitiveType) -> bool {
match self {
PrimitiveType::U8 => match target {
PrimitiveType::U8 => true,
PrimitiveType::U16 => true,
PrimitiveType::U32 => true,
PrimitiveType::U64 => true,
PrimitiveType::I16 => true,
PrimitiveType::I32 => true,
PrimitiveType::I64 => true,
_ => false,
},
PrimitiveType::U16 => match target {
PrimitiveType::U16 => true,
PrimitiveType::U32 => true,
PrimitiveType::U64 => true,
PrimitiveType::I32 => true,
PrimitiveType::I64 => true,
_ => false,
},
PrimitiveType::U32 => match target {
PrimitiveType::U32 => true,
PrimitiveType::U64 => true,
PrimitiveType::I64 => true,
_ => false,
},
PrimitiveType::U64 => match target {
PrimitiveType::U64 => true,
_ => false,
},
PrimitiveType::I8 => match target {
PrimitiveType::I8 => true,
PrimitiveType::I16 => true,
PrimitiveType::I32 => true,
PrimitiveType::I64 => true,
_ => false,
},
PrimitiveType::I16 => match target {
PrimitiveType::I16 => true,
PrimitiveType::I32 => true,
PrimitiveType::I64 => true,
_ => false,
},
PrimitiveType::I32 => match target {
PrimitiveType::I32 => true,
PrimitiveType::I64 => true,
_ => false,
},
PrimitiveType::I64 => match target {
PrimitiveType::I64 => true,
_ => false,
},
}
}
/// Try to cast the given value to this type, returning the new value. /// Try to cast the given value to this type, returning the new value.
/// ///
/// Returns an error if the cast is not safe *in* *general*. This means that /// Returns an error if the cast is not safe *in* *general*. This means that

1
src/examples.rs
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@@ -1,5 +1,4 @@
use crate::backend::Backend; use crate::backend::Backend;
use crate::ir::Program as IR;
use crate::syntax::Program as Syntax; use crate::syntax::Program as Syntax;
use codespan_reporting::files::SimpleFiles; use codespan_reporting::files::SimpleFiles;
use cranelift_jit::JITModule; use cranelift_jit::JITModule;

1
src/ir.rs
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@@ -18,3 +18,4 @@ mod strings;
mod type_infer; mod type_infer;
pub use ast::*; pub use ast::*;
pub use type_infer::{TypeInferenceError, TypeInferenceResult, TypeInferenceWarning};

8
src/ir/ast.rs
View File

@@ -61,7 +61,10 @@ impl Arbitrary for Program {
fn arbitrary_with(args: Self::Parameters) -> Self::Strategy { fn arbitrary_with(args: Self::Parameters) -> Self::Strategy {
crate::syntax::Program::arbitrary_with(args) crate::syntax::Program::arbitrary_with(args)
.prop_map(syntax::Program::type_infer) .prop_map(|x| {
x.type_infer()
.expect("arbitrary_with should generate type-correct programs")
})
.boxed() .boxed()
} }
} }
@@ -330,7 +333,6 @@ where
#[derive(Clone, Debug, Eq, PartialEq)] #[derive(Clone, Debug, Eq, PartialEq)]
pub enum Type { pub enum Type {
Variable(Location, ArcIntern<String>),
Primitive(PrimitiveType), Primitive(PrimitiveType),
} }
@@ -341,7 +343,6 @@ where
{ {
fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> { fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
match self { match self {
Type::Variable(_, x) => allocator.text(x.to_string()),
Type::Primitive(pt) => allocator.text(format!("{}", pt)), Type::Primitive(pt) => allocator.text(format!("{}", pt)),
} }
} }
@@ -350,7 +351,6 @@ where
impl fmt::Display for Type { impl fmt::Display for Type {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self { match self {
Type::Variable(_, x) => write!(f, "{}", x),
Type::Primitive(pt) => pt.fmt(f), Type::Primitive(pt) => pt.fmt(f),
} }
} }

5
src/ir/eval.rs
View File

@@ -40,7 +40,6 @@ impl Expression {
let value = valref.eval(env)?; let value = valref.eval(env)?;
match t { match t {
Type::Variable(_, _) => unimplemented!("how to cast to a type variable?"),
Type::Primitive(pt) => Ok(pt.safe_cast(&value)?), Type::Primitive(pt) => Ok(pt.safe_cast(&value)?),
} }
} }
@@ -86,7 +85,7 @@ impl ValueOrRef {
#[test] #[test]
fn two_plus_three() { fn two_plus_three() {
let input = crate::syntax::Program::parse(0, "x = 2 + 3; print x;").expect("parse works"); let input = crate::syntax::Program::parse(0, "x = 2 + 3; print x;").expect("parse works");
let ir = input.type_infer(); let ir = input.type_infer().expect("test should be type-valid");
let output = ir.eval().expect("runs successfully"); let output = ir.eval().expect("runs successfully");
assert_eq!("x = 5u64\n", &output); assert_eq!("x = 5u64\n", &output);
} }
@@ -95,7 +94,7 @@ fn two_plus_three() {
fn lotsa_math() { fn lotsa_math() {
let input = let input =
crate::syntax::Program::parse(0, "x = 2 + 3 * 10 / 5 - 1; print x;").expect("parse works"); crate::syntax::Program::parse(0, "x = 2 + 3 * 10 / 5 - 1; print x;").expect("parse works");
let ir = input.type_infer(); let ir = input.type_infer().expect("test should be type-valid");
let output = ir.eval().expect("runs successfully"); let output = ir.eval().expect("runs successfully");
assert_eq!("x = 7u64\n", &output); assert_eq!("x = 7u64\n", &output);
} }

285
src/ir/type_infer.rs
View File

@@ -1,292 +1,35 @@
use internment::ArcIntern; mod ast;
use std::collections::HashMap; mod convert;
use std::str::FromStr; mod finalize;
use std::sync::atomic::AtomicUsize; mod solve;
use crate::eval::PrimitiveType; use self::convert::convert_program;
use self::finalize::finalize_program;
use self::solve::solve_constraints;
pub use self::solve::{TypeInferenceError, TypeInferenceResult, TypeInferenceWarning};
use crate::ir::ast as ir; use crate::ir::ast as ir;
use crate::ir::ast::Type; use crate::syntax;
use crate::syntax::{self, ConstantType, Location};
enum Constraint {
/// The given type must be printable using the `print` built-in
Printable(Location, Type),
/// The provided numeric value fits in the given constant type
FitsInNumType(Location, ConstantType, u64),
/// The given primitive has the proper arguments types associated with it
ProperPrimitiveArgs(Location, ir::Primitive, Vec<Type>, Type),
/// The given type can be casted to the target type safely
CanCastTo(Location, Type, Type),
}
/// This function takes a syntactic program and converts it into the IR version of the
/// program, with appropriate type variables introduced and their constraints added to
/// the given database.
///
/// If the input function has been validated (which it should be), then this should run
/// into no error conditions. However, if you failed to validate the input, then this
/// function can panic.
fn convert_program(
mut program: syntax::Program,
constraint_db: &mut Vec<Constraint>,
) -> ir::Program {
let mut statements = Vec::new();
let mut renames = HashMap::new();
let mut bindings = HashMap::new();
for stmt in program.statements.drain(..) {
statements.append(&mut convert_statement(
stmt,
constraint_db,
&mut renames,
&mut bindings,
));
}
ir::Program { statements }
}
/// This function takes a syntactic statements and converts it into a series of
/// IR statements, adding type variables and constraints as necessary.
///
/// We generate a series of statements because we're going to flatten all
/// incoming expressions so that they are no longer recursive. This will
/// generate a bunch of new bindings for all the subexpressions, which we
/// return as a bundle.
///
/// See the safety warning on [`convert_program`]! This function assumes that
/// you have run [`Statement::validate`], and will trigger panics in error
/// conditions if you have run that and had it come back clean.
fn convert_statement(
statement: syntax::Statement,
constraint_db: &mut Vec<Constraint>,
renames: &mut HashMap<ArcIntern<String>, ArcIntern<String>>,
bindings: &mut HashMap<ArcIntern<String>, Type>,
) -> Vec<ir::Statement> {
match statement {
syntax::Statement::Print(loc, name) => {
let iname = ArcIntern::new(name);
let final_name = renames.get(&iname).map(Clone::clone).unwrap_or_else(|| iname.clone());
let varty = bindings
.get(&final_name)
.expect("print variable defined before use")
.clone();
constraint_db.push(Constraint::Printable(loc.clone(), varty.clone()));
vec![ir::Statement::Print(loc, varty, iname)]
}
syntax::Statement::Binding(loc, name, expr) => {
let (mut prereqs, expr, ty) =
convert_expression(expr, constraint_db, renames, bindings);
let iname = ArcIntern::new(name);
let final_name = if bindings.contains_key(&iname) {
let new_name = gensym(iname.as_str());
renames.insert(iname, new_name.clone());
new_name
} else {
iname
};
bindings.insert(final_name.clone(), ty.clone());
prereqs.push(ir::Statement::Binding(loc, final_name, ty, expr));
prereqs
}
}
}
/// This function takes a syntactic expression and converts it into a series
/// of IR statements, adding type variables and constraints as necessary.
///
/// We generate a series of statements because we're going to flatten all
/// incoming expressions so that they are no longer recursive. This will
/// generate a bunch of new bindings for all the subexpressions, which we
/// return as a bundle.
///
/// See the safety warning on [`convert_program`]! This function assumes that
/// you have run [`Statement::validate`], and will trigger panics in error
/// conditions if you have run that and had it come back clean.
fn convert_expression(
expression: syntax::Expression,
constraint_db: &mut Vec<Constraint>,
renames: &HashMap<ArcIntern<String>, ArcIntern<String>>,
bindings: &mut HashMap<ArcIntern<String>, Type>,
) -> (Vec<ir::Statement>, ir::Expression, Type) {
match expression {
syntax::Expression::Value(loc, val) => {
let newval = match val {
syntax::Value::Number(base, mctype, value) => {
if let Some(suggested_type) = mctype {
constraint_db.push(Constraint::FitsInNumType(loc.clone(), suggested_type, value));
}
match mctype {
None => ir::Value::U64(base, value),
Some(ConstantType::U8) => ir::Value::U8(base, value as u8),
Some(ConstantType::U16) => ir::Value::U16(base, value as u16),
Some(ConstantType::U32) => ir::Value::U32(base, value as u32),
Some(ConstantType::U64) => ir::Value::U64(base, value),
Some(ConstantType::I8) => ir::Value::I8(base, value as i8),
Some(ConstantType::I16) => ir::Value::I16(base, value as i16),
Some(ConstantType::I32) => ir::Value::I32(base, value as i32),
Some(ConstantType::I64) => ir::Value::I64(base, value as i64),
}
}
};
let valtype = newval.type_of();
(
vec![],
ir::Expression::Atomic(ir::ValueOrRef::Value(loc, valtype.clone(), newval)),
valtype,
)
}
syntax::Expression::Reference(loc, name) => {
let iname = ArcIntern::new(name);
let final_name = renames.get(&iname).cloned().unwrap_or(iname);
let rtype = bindings
.get(&final_name)
.cloned()
.expect("variable bound before use");
let refexp =
ir::Expression::Atomic(ir::ValueOrRef::Ref(loc, rtype.clone(), final_name));
(vec![], refexp, rtype)
}
syntax::Expression::Cast(loc, target, expr) => {
let (mut stmts, nexpr, etype) =
convert_expression(*expr, constraint_db, renames, bindings);
let val_or_ref = simplify_expr(nexpr, &mut stmts);
let target_prim_type = PrimitiveType::from_str(&target).expect("valid type for cast");
let target_type = Type::Primitive(target_prim_type);
let res = ir::Expression::Cast(loc.clone(), target_type.clone(), val_or_ref);
constraint_db.push(Constraint::CanCastTo(loc, etype, target_type.clone()));
(stmts, res, target_type)
}
syntax::Expression::Primitive(loc, fun, mut args) => {
let primop = ir::Primitive::from_str(&fun).expect("valid primitive");
let mut stmts = vec![];
let mut nargs = vec![];
let mut atypes = vec![];
let ret_type = gentype();
for arg in args.drain(..) {
let (mut astmts, aexp, atype) = convert_expression(arg, constraint_db, renames, bindings);
stmts.append(&mut astmts);
nargs.push(simplify_expr(aexp, &mut stmts));
atypes.push(atype);
}
constraint_db.push(Constraint::ProperPrimitiveArgs(loc.clone(), primop, atypes.clone(), ret_type.clone()));
(stmts, ir::Expression::Primitive(loc, ret_type.clone(), primop, nargs), ret_type)
}
}
}
fn simplify_expr(expr: ir::Expression, stmts: &mut Vec<ir::Statement>) -> ir::ValueOrRef {
match expr {
ir::Expression::Atomic(v_or_ref) => v_or_ref,
expr => {
let etype = expr.type_of().clone();
let loc = expr.location().clone();
let nname = gensym("g");
let nbinding = ir::Statement::Binding(loc.clone(), nname.clone(), etype.clone(), expr);
stmts.push(nbinding);
ir::ValueOrRef::Ref(loc, etype, nname)
}
}
}
impl syntax::Program { impl syntax::Program {
/// Infer the types for the syntactic AST, returning either a type-checked program in /// Infer the types for the syntactic AST, returning either a type-checked program in
/// the IR, or a series of type errors encountered during inference. /// the IR, or a series of type errors encountered during inference.
/// ///
/// You really should have made sure that this program was validated before running /// You really should have made sure that this program was validated before running
/// this method, otherwise you may experience panics during operation. /// this method, otherwise you may experience panics during operation.
pub fn type_infer(self) -> ir::Program { pub fn type_infer(self) -> TypeInferenceResult<ir::Program> {
let mut constraint_db = vec![]; let mut constraint_db = vec![];
let program = convert_program(self, &mut constraint_db); let program = convert_program(self, &mut constraint_db);
let mut changed_something = true; let inference_result = solve_constraints(constraint_db);
// We want to run this inference endlessly, until either we have solved all of our inference_result.map(|type_renames| finalize_program(program, type_renames))
// constraints or we've gotten stuck somewhere.
while constraint_db.len() > 0 && changed_something {
// Set this to false at the top of the loop. We'll set this to true if we make
// progress in any way further down, but having this here prevents us from going
// into an infinite look when we can't figure stuff out.
changed_something = false;
// This is sort of a double-buffering thing; we're going to rename constraint_db
// and then set it to a new empty vector, which we'll add to as we find new
// constraints or find ourselves unable to solve existing ones.
let mut local_constraints = constraint_db;
constraint_db = vec![];
for constraint in local_constraints.drain(..) {
match constraint {
// Currently, all of our types are printable
Constraint::Printable(_loc, _ty) => {}
Constraint::FitsInNumType(loc, ctype, val) => unimplemented!(),
Constraint::ProperPrimitiveArgs(loc, prim, args, ret) => unimplemented!(),
Constraint::CanCastTo(loc, from_type, to_type) => unimplemented!(),
}
}
}
program
} }
} }
/// Generate a fresh new name based on the given name.
///
/// The new name is guaranteed to be unique across the entirety of the
/// execution. This is achieved by using characters in the variable name
/// that would not be valid input, and by including a counter that is
/// incremented on every invocation.
fn gensym(name: &str) -> ArcIntern<String> {
static COUNTER: AtomicUsize = AtomicUsize::new(0);
let new_name = format!(
"<{}:{}>",
name,
COUNTER.fetch_add(1, std::sync::atomic::Ordering::SeqCst)
);
ArcIntern::new(new_name)
}
/// Generate a fresh new type; this will be a unique new type variable.
///
/// The new name is guaranteed to be unique across the entirety of the
/// execution. This is achieved by using characters in the variable name
/// that would not be valid input, and by including a counter that is
/// incremented on every invocation.
fn gentype() -> Type {
static COUNTER: AtomicUsize = AtomicUsize::new(0);
let new_name = ArcIntern::new(format!(
"t<{}>",
COUNTER.fetch_add(1, std::sync::atomic::Ordering::SeqCst)
));
Type::Variable(Location::manufactured(), new_name)
}
proptest::proptest! { proptest::proptest! {
#[test] #[test]
fn translation_maintains_semantics(input: syntax::Program) { fn translation_maintains_semantics(input: syntax::Program) {
let syntax_result = input.eval(); let syntax_result = input.eval();
let ir = input.type_infer(); let ir = input.type_infer().expect("arbitrary should generate type-safe programs");
let ir_result = ir.eval(); let ir_result = ir.eval();
assert_eq!(syntax_result, ir_result); assert_eq!(syntax_result, ir_result);
} }

330
src/ir/type_infer/ast.rs Normal file
View File

@@ -0,0 +1,330 @@
pub use crate::ir::ast::Primitive;
/// This is largely a copy of `ir/ast`, with a couple of extensions that we're going
/// to want to use while we're doing type inference, but don't want to keep around
/// afterwards. These are:
///
/// * A notion of a type variable
/// * An unknown numeric constant form
///
use crate::{
eval::PrimitiveType,
syntax::{self, ConstantType, Location},
};
use internment::ArcIntern;
use pretty::{DocAllocator, Pretty};
use std::fmt;
use std::sync::atomic::AtomicUsize;
/// We're going to represent variables as interned strings.
///
/// These should be fast enough for comparison that it's OK, since it's going to end up
/// being pretty much the pointer to the string.
type Variable = ArcIntern<String>;
/// The representation of a program within our IR. For now, this is exactly one file.
///
/// In addition, for the moment there's not really much of interest to hold here besides
/// the list of statements read from the file. Order is important. In the future, you
/// could imagine caching analysis information in this structure.
///
/// `Program` implements both [`Pretty`] and [`Arbitrary`]. The former should be used
/// to print the structure whenever possible, especially if you value your or your
/// user's time. The latter is useful for testing that conversions of `Program` retain
/// their meaning. All `Program`s generated through [`Arbitrary`] are guaranteed to be
/// syntactically valid, although they may contain runtime issue like over- or underflow.
#[derive(Debug)]
pub struct Program {
// For now, a program is just a vector of statements. In the future, we'll probably
// extend this to include a bunch of other information, but for now: just a list.
pub(crate) statements: Vec<Statement>,
}
impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Program
where
A: 'a,
D: ?Sized + DocAllocator<'a, A>,
{
fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
let mut result = allocator.nil();
for stmt in self.statements.iter() {
// there's probably a better way to do this, rather than constantly
// adding to the end, but this works.
result = result
.append(stmt.pretty(allocator))
.append(allocator.text(";"))
.append(allocator.hardline());
}
result
}
}
/// The representation of a statement in the language.
///
/// For now, this is either a binding site (`x = 4`) or a print statement
/// (`print x`). Someday, though, more!
///
/// As with `Program`, this type implements [`Pretty`], which should
/// be used to display the structure whenever possible. It does not
/// implement [`Arbitrary`], though, mostly because it's slightly
/// complicated to do so.
///
#[derive(Debug)]
pub enum Statement {
Binding(Location, Variable, Type, Expression),
Print(Location, Type, Variable),
}
impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Statement
where
A: 'a,
D: ?Sized + DocAllocator<'a, A>,
{
fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
match self {
Statement::Binding(_, var, _, expr) => allocator
.text(var.as_ref().to_string())
.append(allocator.space())
.append(allocator.text("="))
.append(allocator.space())
.append(expr.pretty(allocator)),
Statement::Print(_, _, var) => allocator
.text("print")
.append(allocator.space())
.append(allocator.text(var.as_ref().to_string())),
}
}
}
/// The representation of an expression.
///
/// Note that expressions, like everything else in this syntax tree,
/// supports [`Pretty`], and it's strongly encouraged that you use
/// that trait/module when printing these structures.
///
/// Also, Expressions at this point in the compiler are explicitly
/// defined so that they are *not* recursive. By this point, if an
/// expression requires some other data (like, for example, invoking
/// a primitive), any subexpressions have been bound to variables so
/// that the referenced data will always either be a constant or a
/// variable reference.
#[derive(Debug)]
pub enum Expression {
Atomic(ValueOrRef),
Cast(Location, Type, ValueOrRef),
Primitive(Location, Type, Primitive, Vec<ValueOrRef>),
}
impl Expression {
/// Return a reference to the type of the expression, as inferred or recently
/// computed.
pub fn type_of(&self) -> &Type {
match self {
Expression::Atomic(ValueOrRef::Ref(_, t, _)) => t,
Expression::Atomic(ValueOrRef::Value(_, t, _)) => t,
Expression::Cast(_, t, _) => t,
Expression::Primitive(_, t, _, _) => t,
}
}
/// Return a reference to the location associated with the expression.
pub fn location(&self) -> &Location {
match self {
Expression::Atomic(ValueOrRef::Ref(l, _, _)) => l,
Expression::Atomic(ValueOrRef::Value(l, _, _)) => l,
Expression::Cast(l, _, _) => l,
Expression::Primitive(l, _, _, _) => l,
}
}
}
impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Expression
where
A: 'a,
D: ?Sized + DocAllocator<'a, A>,
{
fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
match self {
Expression::Atomic(x) => x.pretty(allocator),
Expression::Cast(_, t, e) => allocator
.text("<")
.append(t.pretty(allocator))
.append(allocator.text(">"))
.append(e.pretty(allocator)),
Expression::Primitive(_, _, op, exprs) if exprs.len() == 1 => {
op.pretty(allocator).append(exprs[0].pretty(allocator))
}
Expression::Primitive(_, _, op, exprs) if exprs.len() == 2 => {
let left = exprs[0].pretty(allocator);
let right = exprs[1].pretty(allocator);
left.append(allocator.space())
.append(op.pretty(allocator))
.append(allocator.space())
.append(right)
.parens()
}
Expression::Primitive(_, _, op, exprs) => {
allocator.text(format!("!!{:?} with {} arguments!!", op, exprs.len()))
}
}
}
}
/// An expression that is always either a value or a reference.
///
/// This is the type used to guarantee that we don't nest expressions
/// at this level. Instead, expressions that take arguments take one
/// of these, which can only be a constant or a reference.
#[derive(Clone, Debug)]
pub enum ValueOrRef {
Value(Location, Type, Value),
Ref(Location, Type, ArcIntern<String>),
}
impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b ValueOrRef
where
A: 'a,
D: ?Sized + DocAllocator<'a, A>,
{
fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
match self {
ValueOrRef::Value(_, _, v) => v.pretty(allocator),
ValueOrRef::Ref(_, _, v) => allocator.text(v.as_ref().to_string()),
}
}
}
impl From<ValueOrRef> for Expression {
fn from(value: ValueOrRef) -> Self {
Expression::Atomic(value)
}
}
/// A constant in the IR.
///
/// The optional argument in numeric types is the base that was used by the
/// user to input the number. By retaining it, we can ensure that if we need
/// to print the number back out, we can do so in the form that the user
/// entered it.
#[derive(Clone, Debug)]
pub enum Value {
Unknown(Option<u8>, u64),
I8(Option<u8>, i8),
I16(Option<u8>, i16),
I32(Option<u8>, i32),
I64(Option<u8>, i64),
U8(Option<u8>, u8),
U16(Option<u8>, u16),
U32(Option<u8>, u32),
U64(Option<u8>, u64),
}
impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Value
where
A: 'a,
D: ?Sized + DocAllocator<'a, A>,
{
fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
let pretty_internal = |opt_base: &Option<u8>, x, t| {
syntax::Value::Number(*opt_base, Some(t), x).pretty(allocator)
};
let pretty_internal_signed = |opt_base, x: i64, t| {
let base = pretty_internal(opt_base, x.unsigned_abs(), t);
allocator.text("-").append(base)
};
match self {
Value::Unknown(opt_base, value) => {
pretty_internal_signed(opt_base, *value as i64, ConstantType::U64)
}
Value::I8(opt_base, value) => {
pretty_internal_signed(opt_base, *value as i64, ConstantType::I8)
}
Value::I16(opt_base, value) => {
pretty_internal_signed(opt_base, *value as i64, ConstantType::I16)
}
Value::I32(opt_base, value) => {
pretty_internal_signed(opt_base, *value as i64, ConstantType::I32)
}
Value::I64(opt_base, value) => {
pretty_internal_signed(opt_base, *value, ConstantType::I64)
}
Value::U8(opt_base, value) => {
pretty_internal(opt_base, *value as u64, ConstantType::U8)
}
Value::U16(opt_base, value) => {
pretty_internal(opt_base, *value as u64, ConstantType::U16)
}
Value::U32(opt_base, value) => {
pretty_internal(opt_base, *value as u64, ConstantType::U32)
}
Value::U64(opt_base, value) => pretty_internal(opt_base, *value, ConstantType::U64),
}
}
}
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum Type {
Variable(Location, ArcIntern<String>),
Primitive(PrimitiveType),
}
impl<'a, 'b, D, A> Pretty<'a, D, A> for &'b Type
where
A: 'a,
D: ?Sized + DocAllocator<'a, A>,
{
fn pretty(self, allocator: &'a D) -> pretty::DocBuilder<'a, D, A> {
match self {
Type::Variable(_, x) => allocator.text(x.to_string()),
Type::Primitive(pt) => allocator.text(format!("{}", pt)),
}
}
}
impl fmt::Display for Type {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
Type::Variable(_, x) => write!(f, "{}", x),
Type::Primitive(pt) => pt.fmt(f),
}
}
}
/// Generate a fresh new name based on the given name.
///
/// The new name is guaranteed to be unique across the entirety of the
/// execution. This is achieved by using characters in the variable name
/// that would not be valid input, and by including a counter that is
/// incremented on every invocation.
pub fn gensym(name: &str) -> ArcIntern<String> {
static COUNTER: AtomicUsize = AtomicUsize::new(0);
let new_name = format!(
"<{}:{}>",
name,
COUNTER.fetch_add(1, std::sync::atomic::Ordering::SeqCst)
);
ArcIntern::new(new_name)
}
/// Generate a fresh new type; this will be a unique new type variable.
///
/// The new name is guaranteed to be unique across the entirety of the
/// execution. This is achieved by using characters in the variable name
/// that would not be valid input, and by including a counter that is
/// incremented on every invocation.
pub fn gentype() -> Type {
static COUNTER: AtomicUsize = AtomicUsize::new(0);
let new_name = ArcIntern::new(format!(
"t<{}>",
COUNTER.fetch_add(1, std::sync::atomic::Ordering::SeqCst)
));
Type::Variable(Location::manufactured(), new_name)
}

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use super::ast as ir;
use super::ast::Type;
use crate::eval::PrimitiveType;
use crate::ir::type_infer::solve::Constraint;
use crate::syntax::{self, ConstantType};
use internment::ArcIntern;
use std::collections::HashMap;
use std::str::FromStr;
/// This function takes a syntactic program and converts it into the IR version of the
/// program, with appropriate type variables introduced and their constraints added to
/// the given database.
///
/// If the input function has been validated (which it should be), then this should run
/// into no error conditions. However, if you failed to validate the input, then this
/// function can panic.
pub fn convert_program(
mut program: syntax::Program,
constraint_db: &mut Vec<Constraint>,
) -> ir::Program {
let mut statements = Vec::new();
let mut renames = HashMap::new();
let mut bindings = HashMap::new();
for stmt in program.statements.drain(..) {
statements.append(&mut convert_statement(
stmt,
constraint_db,
&mut renames,
&mut bindings,
));
}
ir::Program { statements }
}
/// This function takes a syntactic statements and converts it into a series of
/// IR statements, adding type variables and constraints as necessary.
///
/// We generate a series of statements because we're going to flatten all
/// incoming expressions so that they are no longer recursive. This will
/// generate a bunch of new bindings for all the subexpressions, which we
/// return as a bundle.
///
/// See the safety warning on [`convert_program`]! This function assumes that
/// you have run [`Statement::validate`], and will trigger panics in error
/// conditions if you have run that and had it come back clean.
fn convert_statement(
statement: syntax::Statement,
constraint_db: &mut Vec<Constraint>,
renames: &mut HashMap<ArcIntern<String>, ArcIntern<String>>,
bindings: &mut HashMap<ArcIntern<String>, Type>,
) -> Vec<ir::Statement> {
match statement {
syntax::Statement::Print(loc, name) => {
let iname = ArcIntern::new(name);
let final_name = renames
.get(&iname)
.map(Clone::clone)
.unwrap_or_else(|| iname.clone());
let varty = bindings
.get(&final_name)
.expect("print variable defined before use")
.clone();
constraint_db.push(Constraint::Printable(loc.clone(), varty.clone()));
vec![ir::Statement::Print(loc, varty, iname)]
}
syntax::Statement::Binding(loc, name, expr) => {
let (mut prereqs, expr, ty) =
convert_expression(expr, constraint_db, renames, bindings);
let iname = ArcIntern::new(name);
let final_name = if bindings.contains_key(&iname) {
let new_name = ir::gensym(iname.as_str());
renames.insert(iname, new_name.clone());
new_name
} else {
iname
};
bindings.insert(final_name.clone(), ty.clone());
prereqs.push(ir::Statement::Binding(loc, final_name, ty, expr));
prereqs
}
}
}
/// This function takes a syntactic expression and converts it into a series
/// of IR statements, adding type variables and constraints as necessary.
///
/// We generate a series of statements because we're going to flatten all
/// incoming expressions so that they are no longer recursive. This will
/// generate a bunch of new bindings for all the subexpressions, which we
/// return as a bundle.
///
/// See the safety warning on [`convert_program`]! This function assumes that
/// you have run [`Statement::validate`], and will trigger panics in error
/// conditions if you have run that and had it come back clean.
fn convert_expression(
expression: syntax::Expression,
constraint_db: &mut Vec<Constraint>,
renames: &HashMap<ArcIntern<String>, ArcIntern<String>>,
bindings: &mut HashMap<ArcIntern<String>, Type>,
) -> (Vec<ir::Statement>, ir::Expression, Type) {
match expression {
syntax::Expression::Value(loc, val) => match val {
syntax::Value::Number(base, mctype, value) => {
let (newval, newtype) = match mctype {
None => {
let newtype = ir::gentype();
let newval = ir::Value::Unknown(base, value);
constraint_db.push(Constraint::NumericType(loc.clone(), newtype.clone()));
(newval, newtype)
}
Some(ConstantType::U8) => (
ir::Value::U8(base, value as u8),
ir::Type::Primitive(PrimitiveType::U8),
),
Some(ConstantType::U16) => (
ir::Value::U16(base, value as u16),
ir::Type::Primitive(PrimitiveType::U16),
),
Some(ConstantType::U32) => (
ir::Value::U32(base, value as u32),
ir::Type::Primitive(PrimitiveType::U32),
),
Some(ConstantType::U64) => (
ir::Value::U64(base, value),
ir::Type::Primitive(PrimitiveType::U64),
),
Some(ConstantType::I8) => (
ir::Value::I8(base, value as i8),
ir::Type::Primitive(PrimitiveType::I8),
),
Some(ConstantType::I16) => (
ir::Value::I16(base, value as i16),
ir::Type::Primitive(PrimitiveType::I16),
),
Some(ConstantType::I32) => (
ir::Value::I32(base, value as i32),
ir::Type::Primitive(PrimitiveType::I32),
),
Some(ConstantType::I64) => (
ir::Value::I64(base, value as i64),
ir::Type::Primitive(PrimitiveType::I64),
),
};
constraint_db.push(Constraint::FitsInNumType(loc.clone(), newtype.clone(), value));
(
vec![],
ir::Expression::Atomic(ir::ValueOrRef::Value(loc, newtype.clone(), newval)),
newtype,
)
}
},
syntax::Expression::Reference(loc, name) => {
let iname = ArcIntern::new(name);
let final_name = renames.get(&iname).cloned().unwrap_or(iname);
let rtype = bindings
.get(&final_name)
.cloned()
.expect("variable bound before use");
let refexp =
ir::Expression::Atomic(ir::ValueOrRef::Ref(loc, rtype.clone(), final_name));
(vec![], refexp, rtype)
}
syntax::Expression::Cast(loc, target, expr) => {
let (mut stmts, nexpr, etype) =
convert_expression(*expr, constraint_db, renames, bindings);
let val_or_ref = simplify_expr(nexpr, &mut stmts);
let target_prim_type = PrimitiveType::from_str(&target).expect("valid type for cast");
let target_type = Type::Primitive(target_prim_type);
let res = ir::Expression::Cast(loc.clone(), target_type.clone(), val_or_ref);
constraint_db.push(Constraint::CanCastTo(loc, etype, target_type.clone()));
(stmts, res, target_type)
}
syntax::Expression::Primitive(loc, fun, mut args) => {
let primop = ir::Primitive::from_str(&fun).expect("valid primitive");
let mut stmts = vec![];
let mut nargs = vec![];
let mut atypes = vec![];
let ret_type = ir::gentype();
for arg in args.drain(..) {
let (mut astmts, aexp, atype) =
convert_expression(arg, constraint_db, renames, bindings);
stmts.append(&mut astmts);
nargs.push(simplify_expr(aexp, &mut stmts));
atypes.push(atype);
}
constraint_db.push(Constraint::ProperPrimitiveArgs(
loc.clone(),
primop,
atypes.clone(),
ret_type.clone(),
));
(
stmts,
ir::Expression::Primitive(loc, ret_type.clone(), primop, nargs),
ret_type,
)
}
}
}
fn simplify_expr(expr: ir::Expression, stmts: &mut Vec<ir::Statement>) -> ir::ValueOrRef {
match expr {
ir::Expression::Atomic(v_or_ref) => v_or_ref,
expr => {
let etype = expr.type_of().clone();
let loc = expr.location().clone();
let nname = ir::gensym("g");
let nbinding = ir::Statement::Binding(loc.clone(), nname.clone(), etype.clone(), expr);
stmts.push(nbinding);
ir::ValueOrRef::Ref(loc, etype, nname)
}
}
}

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use super::ast as input;
use crate::{eval::PrimitiveType, ir as output};
use internment::ArcIntern;
use std::collections::HashMap;
pub fn finalize_program(
mut program: input::Program,
type_renames: HashMap<ArcIntern<String>, input::Type>,
) -> output::Program {
output::Program {
statements: program
.statements
.drain(..)
.map(|x| finalize_statement(x, &type_renames))
.collect(),
}
}
fn finalize_statement(
statement: input::Statement,
type_renames: &HashMap<ArcIntern<String>, input::Type>,
) -> output::Statement {
match statement {
input::Statement::Binding(loc, var, ty, expr) => output::Statement::Binding(
loc,
var,
finalize_type(ty, type_renames),
finalize_expression(expr, type_renames),
),
input::Statement::Print(loc, ty, var) => {
output::Statement::Print(loc, finalize_type(ty, type_renames), var)
}
}
}
fn finalize_expression(
expression: input::Expression,
type_renames: &HashMap<ArcIntern<String>, input::Type>,
) -> output::Expression {
match expression {
input::Expression::Atomic(val_or_ref) => {
output::Expression::Atomic(finalize_val_or_ref(val_or_ref, type_renames))
}
input::Expression::Cast(loc, target, val_or_ref) => output::Expression::Cast(
loc,
finalize_type(target, type_renames),
finalize_val_or_ref(val_or_ref, type_renames),
),
input::Expression::Primitive(loc, ty, prim, mut args) => output::Expression::Primitive(
loc,
finalize_type(ty, type_renames),
prim,
args.drain(..)
.map(|x| finalize_val_or_ref(x, type_renames))
.collect(),
),
}
}
fn finalize_type(
ty: input::Type,
type_renames: &HashMap<ArcIntern<String>, input::Type>,
) -> output::Type {
match ty {
input::Type::Primitive(x) => output::Type::Primitive(x),
input::Type::Variable(loc, name) => match type_renames.get(&name) {
Some(input::Type::Primitive(x)) => output::Type::Primitive(*x),
res => panic!(
"ACK! Internal error cleaning up temporary type name at {:?}: got {:?}",
loc, res
),
},
}
}
fn finalize_val_or_ref(
valref: input::ValueOrRef,
type_renames: &HashMap<ArcIntern<String>, input::Type>,
) -> output::ValueOrRef {
match valref {
input::ValueOrRef::Ref(loc, ty, var) => {
output::ValueOrRef::Ref(loc, finalize_type(ty, type_renames), var)
}
input::ValueOrRef::Value(loc, ty, val) => {
let new_type = finalize_type(ty, type_renames);
match val {
input::Value::Unknown(base, value) => match new_type {
output::Type::Primitive(PrimitiveType::U8) => output::ValueOrRef::Value(
loc,
new_type,
output::Value::U8(base, value as u8),
),
output::Type::Primitive(PrimitiveType::U16) => output::ValueOrRef::Value(
loc,
new_type,
output::Value::U16(base, value as u16),
),
output::Type::Primitive(PrimitiveType::U32) => output::ValueOrRef::Value(
loc,
new_type,
output::Value::U32(base, value as u32),
),
output::Type::Primitive(PrimitiveType::U64) => output::ValueOrRef::Value(
loc,
new_type,
output::Value::U64(base, value),
),
output::Type::Primitive(PrimitiveType::I8) => output::ValueOrRef::Value(
loc,
new_type,
output::Value::I8(base, value as i8),
),
output::Type::Primitive(PrimitiveType::I16) => output::ValueOrRef::Value(
loc,
new_type,
output::Value::I16(base, value as i16),
),
output::Type::Primitive(PrimitiveType::I32) => output::ValueOrRef::Value(
loc,
new_type,
output::Value::I32(base, value as i32),
),
output::Type::Primitive(PrimitiveType::I64) => output::ValueOrRef::Value(
loc,
new_type,
output::Value::I64(base, value as i64),
),
},
input::Value::U8(base, value) => {
assert!(matches!(
new_type,
output::Type::Primitive(PrimitiveType::U8)
));
output::ValueOrRef::Value(loc, new_type, output::Value::U8(base, value))
}
input::Value::U16(base, value) => {
assert!(matches!(
new_type,
output::Type::Primitive(PrimitiveType::U16)
));
output::ValueOrRef::Value(loc, new_type, output::Value::U16(base, value))
}
input::Value::U32(base, value) => {
assert!(matches!(
new_type,
output::Type::Primitive(PrimitiveType::U32)
));
output::ValueOrRef::Value(loc, new_type, output::Value::U32(base, value))
}
input::Value::U64(base, value) => {
assert!(matches!(
new_type,
output::Type::Primitive(PrimitiveType::U64)
));
output::ValueOrRef::Value(loc, new_type, output::Value::U64(base, value))
}
input::Value::I8(base, value) => {
assert!(matches!(
new_type,
output::Type::Primitive(PrimitiveType::I8)
));
output::ValueOrRef::Value(loc, new_type, output::Value::I8(base, value))
}
input::Value::I16(base, value) => {
assert!(matches!(
new_type,
output::Type::Primitive(PrimitiveType::I16)
));
output::ValueOrRef::Value(loc, new_type, output::Value::I16(base, value))
}
input::Value::I32(base, value) => {
assert!(matches!(
new_type,
output::Type::Primitive(PrimitiveType::I32)
));
output::ValueOrRef::Value(loc, new_type, output::Value::I32(base, value))
}
input::Value::I64(base, value) => {
assert!(matches!(
new_type,
output::Type::Primitive(PrimitiveType::I64)
));
output::ValueOrRef::Value(loc, new_type, output::Value::I64(base, value))
}
}
}
}
}

341
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use super::ast as ir;
use super::ast::Type;
use crate::{eval::PrimitiveType, syntax::Location};
use codespan_reporting::diagnostic::Diagnostic;
use internment::ArcIntern;
use std::collections::HashMap;
pub enum Constraint {
/// The given type must be printable using the `print` built-in
Printable(Location, Type),
/// The provided numeric value fits in the given constant type
FitsInNumType(Location, Type, u64),
/// The given primitive has the proper arguments types associated with it
ProperPrimitiveArgs(Location, ir::Primitive, Vec<Type>, Type),
/// The given type can be casted to the target type safely
CanCastTo(Location, Type, Type),
/// The given type must be some numeric type
NumericType(Location, Type),
/// The two types should be equivalent
Equivalent(Location, Type, Type),
}
pub enum TypeInferenceResult<Result> {
Success {
result: Result,
warnings: Vec<TypeInferenceWarning>,
},
Failure {
errors: Vec<TypeInferenceError>,
warnings: Vec<TypeInferenceWarning>,
},
}
impl<R> TypeInferenceResult<R> {
// If this was a successful type inference, run the function over the result to
// create a new result.
pub fn map<U, F>(self, f: F) -> TypeInferenceResult<U>
where
F: FnOnce(R) -> U,
{
match self {
TypeInferenceResult::Success { result, warnings } => TypeInferenceResult::Success {
result: f(result),
warnings,
},
TypeInferenceResult::Failure { errors, warnings } => {
TypeInferenceResult::Failure { errors, warnings }
}
}
}
// Return the final result, or panic if it's not a success
pub fn expect(self, msg: &str) -> R {
match self {
TypeInferenceResult::Success { result, .. } => result,
TypeInferenceResult::Failure { .. } => {
panic!("tried to get value from failed type inference: {}", msg)
}
}
}
}
pub enum TypeInferenceError {
ConstantTooLarge(Location, PrimitiveType, u64),
NotEquivalent(Location, PrimitiveType, PrimitiveType),
CannotSafelyCast(Location, PrimitiveType, PrimitiveType),
WrongPrimitiveArity(Location, ir::Primitive, usize, usize, usize),
CouldNotSolve(Constraint),
}
impl From<TypeInferenceError> for Diagnostic<usize> {
fn from(value: TypeInferenceError) -> Self {
unimplemented!()
}
}
pub enum TypeInferenceWarning {
DefaultedTo(Location, Type),
}
impl From<TypeInferenceWarning> for Diagnostic<usize> {
fn from(value: TypeInferenceWarning) -> Self {
unimplemented!()
}
}
pub fn solve_constraints(
mut constraint_db: Vec<Constraint>,
) -> TypeInferenceResult<HashMap<ArcIntern<String>, Type>> {
let mut type_renames = HashMap::new();
let mut errors = vec![];
let mut warnings = vec![];
let mut changed_something = true;
// We want to run this inference endlessly, until either we have solved all of our
// constraints. Internal to the loop, we have a check that will make sure that we
// do (eventually) stop.
while changed_something && !constraint_db.is_empty() {
// Set this to false at the top of the loop. We'll set this to true if we make
// progress in any way further down, but having this here prevents us from going
// into an infinite look when we can't figure stuff out.
changed_something = false;
// This is sort of a double-buffering thing; we're going to rename constraint_db
// and then set it to a new empty vector, which we'll add to as we find new
// constraints or find ourselves unable to solve existing ones.
let mut local_constraints = constraint_db;
constraint_db = vec![];
// OK. First thing we're going to do is run through all of our constraints,
// and see if we can solve any, or reduce them to theoretically more simple
// constraints.
for constraint in local_constraints.drain(..) {
match constraint {
// Currently, all of our types are printable
Constraint::Printable(_loc, _ty) => changed_something = true,
// If the first type is a variable, then we rename it to the second.
Constraint::Equivalent(_, Type::Variable(_, n), second) => {
type_renames.insert(n, second);
changed_something = true;
}
// If the second type is a variable (I guess the first wasn't, then rename it to the first)
Constraint::Equivalent(_, first, Type::Variable(_, n)) => {
type_renames.insert(n, first);
changed_something = true;
}
// Otherwise, we ar testing if two concrete types are equivalent, and just need to see
// if they're the same.
Constraint::Equivalent(loc, Type::Primitive(a), Type::Primitive(b)) => {
if a != b {
errors.push(TypeInferenceError::NotEquivalent(loc, a, b));
}
changed_something = true;
}
// Make sure that the provided number fits within the provided constant type. For the
// moment, we're going to call an error here a failure, although this could be a
// warning in the future.
Constraint::FitsInNumType(loc, Type::Primitive(ctype), val) => {
let is_too_big = match ctype {
PrimitiveType::U8 => (u8::MAX as u64) < val,
PrimitiveType::U16 => (u16::MAX as u64) < val,
PrimitiveType::U32 => (u32::MAX as u64) < val,
PrimitiveType::U64 => false,
PrimitiveType::I8 => (i8::MAX as u64) < val,
PrimitiveType::I16 => (i16::MAX as u64) < val,
PrimitiveType::I32 => (i32::MAX as u64) < val,
PrimitiveType::I64 => (i64::MAX as u64) < val,
};
if is_too_big {
errors.push(TypeInferenceError::ConstantTooLarge(loc, ctype, val));
}
changed_something = true;
}
// If we have a non-constant type, then let's see if we can advance this to a constant
// type
Constraint::FitsInNumType(loc, Type::Variable(vloc, var), val) => {
match type_renames.get(&var) {
None => constraint_db.push(Constraint::FitsInNumType(loc, Type::Variable(vloc, var), val)),
Some(nt) => {
constraint_db.push(Constraint::FitsInNumType(loc, nt.clone(), val));
changed_something = true;
}
}
}
// If the left type in a "can cast to" check is a variable, let's see if we can advance
// it into something more tangible
Constraint::CanCastTo(loc, Type::Variable(vloc, var), to_type) => {
match type_renames.get(&var) {
None => constraint_db.push(Constraint::CanCastTo(loc, Type::Variable(vloc, var), to_type)),
Some(nt) => {
constraint_db.push(Constraint::CanCastTo(loc, nt.clone(), to_type));
changed_something = true;
}
}
}
// If the right type in a "can cast to" check is a variable, same deal
Constraint::CanCastTo(loc, from_type, Type::Variable(vloc, var)) => {
match type_renames.get(&var) {
None => constraint_db.push(Constraint::CanCastTo(loc, from_type, Type::Variable(vloc, var))),
Some(nt) => {
constraint_db.push(Constraint::CanCastTo(loc, from_type, nt.clone()));
changed_something = true;
}
}
}
// If both of them are types, then we can actually do the test. yay!
Constraint::CanCastTo(
loc,
Type::Primitive(from_type),
Type::Primitive(to_type),
) => {
if !from_type.can_cast_to(&to_type) {
errors.push(TypeInferenceError::CannotSafelyCast(
loc, from_type, to_type,
));
}
changed_something = true;
}
// As per usual, if we're trying to test if a type variable is numeric, first
// we try to advance it to a primitive
Constraint::NumericType(loc, Type::Variable(vloc, var)) => {
match type_renames.get(&var) {
None => constraint_db.push(Constraint::NumericType(loc, Type::Variable(vloc, var))),
Some(nt) => {
constraint_db.push(Constraint::NumericType(loc, nt.clone()));
changed_something = true;
}
}
}
// Of course, if we get to a primitive type, then it's true, because all of our
// primitive types are numbers
Constraint::NumericType(_, Type::Primitive(_)) => {
changed_something = true;
}
// OK, this one could be a little tricky if we tried to do it all at once, but
// instead what we're going to do here is just use this constraint to generate
// a bunch more constraints, and then go have the engine solve those. The only
// real errors we're going to come up with here are "arity errors"; errors we
// find by discovering that the number of arguments provided doesn't make sense
// given the primitive being used.
Constraint::ProperPrimitiveArgs(loc, prim, mut args, ret) => match prim {
ir::Primitive::Plus | ir::Primitive::Times | ir::Primitive::Divide
if args.len() != 2 =>
{
errors.push(TypeInferenceError::WrongPrimitiveArity(
loc,
prim,
2,
2,
args.len(),
));
changed_something = true;
}
ir::Primitive::Plus | ir::Primitive::Times | ir::Primitive::Divide => {
let right = args.pop().expect("2 > 0");
let left = args.pop().expect("2 > 1");
// technically testing that both are numeric is redundant, but it might give
// a slightly helpful type error if we do both.
constraint_db.push(Constraint::NumericType(loc.clone(), left.clone()));
constraint_db.push(Constraint::NumericType(loc.clone(), right.clone()));
constraint_db.push(Constraint::NumericType(loc.clone(), ret.clone()));
constraint_db.push(Constraint::Equivalent(loc.clone(), left.clone(), right));
constraint_db.push(Constraint::Equivalent(loc, left, ret));
changed_something = true;
}
ir::Primitive::Minus if args.is_empty() || args.len() > 2 => {
errors.push(TypeInferenceError::WrongPrimitiveArity(
loc,
prim,
1,
2,
args.len(),
));
changed_something = true;
}
ir::Primitive::Minus if args.len() == 1 => {
let arg = args.pop().expect("1 > 0");
constraint_db.push(Constraint::NumericType(loc.clone(), arg.clone()));
constraint_db.push(Constraint::NumericType(loc.clone(), ret.clone()));
constraint_db.push(Constraint::Equivalent(loc, arg, ret));
changed_something = true;
}
ir::Primitive::Minus => {
let right = args.pop().expect("2 > 0");
let left = args.pop().expect("2 > 1");
// technically testing that both are numeric is redundant, but it might give
// a slightly helpful type error if we do both.
constraint_db.push(Constraint::NumericType(loc.clone(), left.clone()));
constraint_db.push(Constraint::NumericType(loc.clone(), right.clone()));
constraint_db.push(Constraint::NumericType(loc.clone(), ret.clone()));
constraint_db.push(Constraint::Equivalent(loc.clone(), left.clone(), right));
constraint_db.push(Constraint::Equivalent(loc.clone(), left, ret));
changed_something = true;
}
},
}
}
// If that didn't actually come up with anything, and we just recycled all the constraints
// back into the database unchanged, then let's take a look for cases in which we just
// wanted something we didn't know to be a number. Basically, those are cases where the
// user just wrote a number, but didn't tell us what type it was, and there isn't enough
// information in the context to tell us. If that happens, we'll just set that type to
// be u64, and warn the user that we did so.
if !changed_something && !constraint_db.is_empty() {
local_constraints = constraint_db;
constraint_db = vec![];
for constraint in local_constraints.drain(..) {
match constraint {
Constraint::NumericType(loc, Type::Variable(_, name)) => {
let resty = Type::Primitive(PrimitiveType::U64);
type_renames.insert(name, resty.clone());
warnings.push(TypeInferenceWarning::DefaultedTo(loc, resty));
changed_something = true;
}
_ => constraint_db.push(constraint),
}
}
}
}
// OK, we left our loop. Which means that either we solved everything, or we didn't.
// If we didn't, turn the unsolved constraints into type inference errors, and add
// them to our error list.
let mut unsolved_constraint_errors = constraint_db
.drain(..)
.map(TypeInferenceError::CouldNotSolve)
.collect();
errors.append(&mut unsolved_constraint_errors);
// How'd we do?
if errors.is_empty() {
TypeInferenceResult::Success {
result: type_renames,
warnings,
}
} else {
TypeInferenceResult::Failure { errors, warnings }
}
}

76
src/repl.rs
View File

@@ -1,4 +1,5 @@
use crate::backend::{Backend, BackendError}; use crate::backend::{Backend, BackendError};
use crate::ir::TypeInferenceResult;
use crate::syntax::{ConstantType, Location, ParserError, Statement}; use crate::syntax::{ConstantType, Location, ParserError, Statement};
use codespan_reporting::diagnostic::Diagnostic; use codespan_reporting::diagnostic::Diagnostic;
use codespan_reporting::files::SimpleFiles; use codespan_reporting::files::SimpleFiles;
@@ -128,18 +129,32 @@ impl REPL {
.source(); .source();
let syntax = Statement::parse(entry, source)?; let syntax = Statement::parse(entry, source)?;
// if this is a variable binding, and we've never defined this variable before, let program = match syntax {
// we should tell cranelift about it. this is optimistic; if we fail to compile, Statement::Binding(loc, name, expr) => {
// then we won't use this definition until someone tries again. // if this is a variable binding, and we've never defined this variable before,
if let Statement::Binding(_, ref name, _) = syntax { // we should tell cranelift about it. this is optimistic; if we fail to compile,
if !self.variable_binding_sites.contains_key(name.as_str()) { // then we won't use this definition until someone tries again.
self.jitter.define_string(name)?; if !self.variable_binding_sites.contains_key(&name) {
self.jitter self.jitter.define_string(&name)?;
.define_variable(name.clone(), ConstantType::U64)?; self.jitter
.define_variable(name.clone(), ConstantType::U64)?;
}
crate::syntax::Program {
statements: vec![
Statement::Binding(loc.clone(), name.clone(), expr),
Statement::Print(loc, name),
],
}
} }
nonbinding => crate::syntax::Program {
statements: vec![nonbinding],
},
}; };
let (mut errors, mut warnings) = syntax.validate(&mut self.variable_binding_sites); let (mut errors, mut warnings) =
program.validate_with_bindings(&mut self.variable_binding_sites);
let stop = !errors.is_empty(); let stop = !errors.is_empty();
let messages = errors let messages = errors
.drain(..) .drain(..)
@@ -154,16 +169,39 @@ impl REPL {
return Ok(()); return Ok(());
} }
let ir = crate::syntax::Program { match program.type_infer() {
statements: vec![syntax], TypeInferenceResult::Failure {
mut errors,
mut warnings,
} => {
let messages = errors
.drain(..)
.map(Into::into)
.chain(warnings.drain(..).map(Into::into));
for message in messages {
self.emit_diagnostic(message)?;
}
Ok(())
}
TypeInferenceResult::Success {
result,
mut warnings,
} => {
for message in warnings.drain(..).map(Into::into) {
self.emit_diagnostic(message)?;
}
let name = format!("line{}", line_no);
let function_id = self.jitter.compile_function(&name, result)?;
self.jitter.module.finalize_definitions()?;
let compiled_bytes = self.jitter.bytes(function_id);
let compiled_function =
unsafe { std::mem::transmute::<_, fn() -> ()>(compiled_bytes) };
compiled_function();
Ok(())
}
} }
.type_infer();
let name = format!("line{}", line_no);
let function_id = self.jitter.compile_function(&name, ir)?;
self.jitter.module.finalize_definitions()?;
let compiled_bytes = self.jitter.bytes(function_id);
let compiled_function = unsafe { std::mem::transmute::<_, fn() -> ()>(compiled_bytes) };
compiled_function();
Ok(())
} }
} }

18
src/syntax/validate.rs
View File

@@ -65,12 +65,24 @@ impl Program {
/// example, and generates warnings for things that are inadvisable but not /// example, and generates warnings for things that are inadvisable but not
/// actually a problem. /// actually a problem.
pub fn validate(&self) -> (Vec<Error>, Vec<Warning>) { pub fn validate(&self) -> (Vec<Error>, Vec<Warning>) {
let mut bound_variables = HashMap::new();
self.validate_with_bindings(&mut bound_variables)
}
/// Validate that the program makes semantic sense, not just syntactic sense.
///
/// This checks for things like references to variables that don't exist, for
/// example, and generates warnings for things that are inadvisable but not
/// actually a problem.
pub fn validate_with_bindings(
&self,
bound_variables: &mut HashMap<String, Location>,
) -> (Vec<Error>, Vec<Warning>) {
let mut errors = vec![]; let mut errors = vec![];
let mut warnings = vec![]; let mut warnings = vec![];
let mut bound_variables = HashMap::new();
for stmt in self.statements.iter() { for stmt in self.statements.iter() {
let (mut new_errors, mut new_warnings) = stmt.validate(&mut bound_variables); let (mut new_errors, mut new_warnings) = stmt.validate(bound_variables);
errors.append(&mut new_errors); errors.append(&mut new_errors);
warnings.append(&mut new_warnings); warnings.append(&mut new_warnings);
} }
@@ -89,7 +101,7 @@ impl Statement {
/// occurs. We use a `HashMap` to map these bound locations to the locations /// occurs. We use a `HashMap` to map these bound locations to the locations
/// where their bound, because these locations are handy when generating errors /// where their bound, because these locations are handy when generating errors
/// and warnings. /// and warnings.
pub fn validate( fn validate(
&self, &self,
bound_variables: &mut HashMap<String, Location>, bound_variables: &mut HashMap<String, Location>,
) -> (Vec<Error>, Vec<Warning>) { ) -> (Vec<Error>, Vec<Warning>) {