cranelift_isle/ast.rs
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//! Abstract syntax tree (AST) created from parsed ISLE.
#![allow(missing_docs)]
use crate::lexer::Pos;
use crate::log;
/// One toplevel form in an ISLE file.
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum Def {
Pragma(Pragma),
Type(Type),
Rule(Rule),
Extractor(Extractor),
Decl(Decl),
Extern(Extern),
Converter(Converter),
}
/// An identifier -- a variable, term symbol, or type.
#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct Ident(pub String, pub Pos);
/// Pragmas parsed with the `(pragma <ident>)` syntax.
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum Pragma {
// currently, no pragmas are defined, but the infrastructure is useful to keep around
}
/// A declaration of a type.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct Type {
pub name: Ident,
pub is_extern: bool,
pub is_nodebug: bool,
pub ty: TypeValue,
pub pos: Pos,
}
/// The actual type-value: a primitive or an enum with variants.
///
/// TODO: add structs as well?
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum TypeValue {
Primitive(Ident, Pos),
Enum(Vec<Variant>, Pos),
}
/// One variant of an enum type.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct Variant {
pub name: Ident,
pub fields: Vec<Field>,
pub pos: Pos,
}
/// One field of an enum variant.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct Field {
pub name: Ident,
pub ty: Ident,
pub pos: Pos,
}
/// A declaration of a term with its argument and return types.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct Decl {
pub term: Ident,
pub arg_tys: Vec<Ident>,
pub ret_ty: Ident,
/// Whether this term's constructor is pure.
pub pure: bool,
/// Whether this term can exist with some multiplicity: an
/// extractor or a constructor that matches multiple times, or
/// produces multiple values.
pub multi: bool,
/// Whether this term's constructor can fail to match.
pub partial: bool,
pub pos: Pos,
}
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct Rule {
pub pattern: Pattern,
pub iflets: Vec<IfLet>,
pub expr: Expr,
pub pos: Pos,
pub prio: Option<i64>,
}
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct IfLet {
pub pattern: Pattern,
pub expr: Expr,
pub pos: Pos,
}
/// An extractor macro: (A x y) becomes (B x _ y ...). Expanded during
/// ast-to-sema pass.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct Extractor {
pub term: Ident,
pub args: Vec<Ident>,
pub template: Pattern,
pub pos: Pos,
}
/// A pattern: the left-hand side of a rule.
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum Pattern {
/// A mention of a variable.
///
/// Equivalent either to a binding (which can be emulated with
/// `BindPattern` with a `Pattern::Wildcard` subpattern), if this
/// is the first mention of the variable, in order to capture its
/// value; or else a match of the already-captured value. This
/// disambiguation happens when we lower `ast` nodes to `sema`
/// nodes as we resolve bound variable names.
Var { var: Ident, pos: Pos },
/// An operator that binds a variable to a subterm and matches the
/// subpattern.
BindPattern {
var: Ident,
subpat: Box<Pattern>,
pos: Pos,
},
/// An operator that matches a constant integer value.
ConstInt { val: i128, pos: Pos },
/// An operator that matches an external constant value.
ConstPrim { val: Ident, pos: Pos },
/// An application of a type variant or term.
Term {
sym: Ident,
args: Vec<Pattern>,
pos: Pos,
},
/// An operator that matches anything.
Wildcard { pos: Pos },
/// N sub-patterns that must all match.
And { subpats: Vec<Pattern>, pos: Pos },
/// Internal use only: macro argument in a template.
MacroArg { index: usize, pos: Pos },
}
impl Pattern {
pub fn root_term(&self) -> Option<&Ident> {
match self {
&Pattern::Term { ref sym, .. } => Some(sym),
_ => None,
}
}
/// Call `f` for each of the terms in this pattern.
pub fn terms(&self, f: &mut dyn FnMut(Pos, &Ident)) {
match self {
Pattern::Term { sym, args, pos } => {
f(*pos, sym);
for arg in args {
arg.terms(f);
}
}
Pattern::And { subpats, .. } => {
for p in subpats {
p.terms(f);
}
}
Pattern::BindPattern { subpat, .. } => {
subpat.terms(f);
}
Pattern::Var { .. }
| Pattern::ConstInt { .. }
| Pattern::ConstPrim { .. }
| Pattern::Wildcard { .. }
| Pattern::MacroArg { .. } => {}
}
}
pub fn make_macro_template(&self, macro_args: &[Ident]) -> Pattern {
log!("make_macro_template: {:?} with {:?}", self, macro_args);
match self {
&Pattern::BindPattern {
ref var,
ref subpat,
pos,
..
} if matches!(&**subpat, &Pattern::Wildcard { .. }) => {
if let Some(i) = macro_args.iter().position(|arg| arg.0 == var.0) {
Pattern::MacroArg { index: i, pos }
} else {
self.clone()
}
}
&Pattern::BindPattern {
ref var,
ref subpat,
pos,
} => Pattern::BindPattern {
var: var.clone(),
subpat: Box::new(subpat.make_macro_template(macro_args)),
pos,
},
&Pattern::Var { ref var, pos } => {
if let Some(i) = macro_args.iter().position(|arg| arg.0 == var.0) {
Pattern::MacroArg { index: i, pos }
} else {
self.clone()
}
}
&Pattern::And { ref subpats, pos } => {
let subpats = subpats
.iter()
.map(|subpat| subpat.make_macro_template(macro_args))
.collect::<Vec<_>>();
Pattern::And { subpats, pos }
}
&Pattern::Term {
ref sym,
ref args,
pos,
} => {
let args = args
.iter()
.map(|arg| arg.make_macro_template(macro_args))
.collect::<Vec<_>>();
Pattern::Term {
sym: sym.clone(),
args,
pos,
}
}
&Pattern::Wildcard { .. } | &Pattern::ConstInt { .. } | &Pattern::ConstPrim { .. } => {
self.clone()
}
&Pattern::MacroArg { .. } => unreachable!(),
}
}
pub fn subst_macro_args(&self, macro_args: &[Pattern]) -> Option<Pattern> {
log!("subst_macro_args: {:?} with {:?}", self, macro_args);
match self {
&Pattern::BindPattern {
ref var,
ref subpat,
pos,
} => Some(Pattern::BindPattern {
var: var.clone(),
subpat: Box::new(subpat.subst_macro_args(macro_args)?),
pos,
}),
&Pattern::And { ref subpats, pos } => {
let subpats = subpats
.iter()
.map(|subpat| subpat.subst_macro_args(macro_args))
.collect::<Option<Vec<_>>>()?;
Some(Pattern::And { subpats, pos })
}
&Pattern::Term {
ref sym,
ref args,
pos,
} => {
let args = args
.iter()
.map(|arg| arg.subst_macro_args(macro_args))
.collect::<Option<Vec<_>>>()?;
Some(Pattern::Term {
sym: sym.clone(),
args,
pos,
})
}
&Pattern::Var { .. }
| &Pattern::Wildcard { .. }
| &Pattern::ConstInt { .. }
| &Pattern::ConstPrim { .. } => Some(self.clone()),
&Pattern::MacroArg { index, .. } => macro_args.get(index).cloned(),
}
}
pub fn pos(&self) -> Pos {
match self {
&Pattern::ConstInt { pos, .. }
| &Pattern::ConstPrim { pos, .. }
| &Pattern::And { pos, .. }
| &Pattern::Term { pos, .. }
| &Pattern::BindPattern { pos, .. }
| &Pattern::Var { pos, .. }
| &Pattern::Wildcard { pos, .. }
| &Pattern::MacroArg { pos, .. } => pos,
}
}
}
/// An expression: the right-hand side of a rule.
///
/// Note that this *almost* looks like a core Lisp or lambda calculus,
/// except that there is no abstraction (lambda). This first-order
/// limit is what makes it analyzable.
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum Expr {
/// A term: `(sym args...)`.
Term {
sym: Ident,
args: Vec<Expr>,
pos: Pos,
},
/// A variable use.
Var { name: Ident, pos: Pos },
/// A constant integer.
ConstInt { val: i128, pos: Pos },
/// A constant of some other primitive type.
ConstPrim { val: Ident, pos: Pos },
/// The `(let ((var ty val)*) body)` form.
Let {
defs: Vec<LetDef>,
body: Box<Expr>,
pos: Pos,
},
}
impl Expr {
pub fn pos(&self) -> Pos {
match self {
&Expr::Term { pos, .. }
| &Expr::Var { pos, .. }
| &Expr::ConstInt { pos, .. }
| &Expr::ConstPrim { pos, .. }
| &Expr::Let { pos, .. } => pos,
}
}
/// Call `f` for each of the terms in this expression.
pub fn terms(&self, f: &mut dyn FnMut(Pos, &Ident)) {
match self {
Expr::Term { sym, args, pos } => {
f(*pos, sym);
for arg in args {
arg.terms(f);
}
}
Expr::Let { defs, body, .. } => {
for def in defs {
def.val.terms(f);
}
body.terms(f);
}
Expr::Var { .. } | Expr::ConstInt { .. } | Expr::ConstPrim { .. } => {}
}
}
}
/// One variable locally bound in a `(let ...)` expression.
#[derive(Clone, PartialEq, Eq, Debug)]
pub struct LetDef {
pub var: Ident,
pub ty: Ident,
pub val: Box<Expr>,
pub pos: Pos,
}
/// An external binding: an extractor or constructor function attached
/// to a term.
#[derive(Clone, PartialEq, Eq, Debug)]
pub enum Extern {
/// An external extractor: `(extractor Term rustfunc)` form.
Extractor {
/// The term to which this external extractor is attached.
term: Ident,
/// The Rust function name.
func: Ident,
/// The position of this decl.
pos: Pos,
/// Infallibility: if an external extractor returns `(T1, T2,
/// ...)` rather than `Option<(T1, T2, ...)>`, and hence can
/// never fail, it is declared as such and allows for slightly
/// better code to be generated.
infallible: bool,
},
/// An external constructor: `(constructor Term rustfunc)` form.
Constructor {
/// The term to which this external constructor is attached.
term: Ident,
/// The Rust function name.
func: Ident,
/// The position of this decl.
pos: Pos,
},
/// An external constant: `(const $IDENT type)` form.
Const { name: Ident, ty: Ident, pos: Pos },
}
/// An implicit converter: the given term, which must have type
/// (inner_ty) -> outer_ty, is used either in extractor or constructor
/// position as appropriate when a type mismatch with the given pair
/// of types would otherwise occur.
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Converter {
/// The term name.
pub term: Ident,
/// The "inner type": the type to convert *from*, on the
/// right-hand side, or *to*, on the left-hand side. Must match
/// the singular argument type of the term.
pub inner_ty: Ident,
/// The "outer type": the type to convert *to*, on the right-hand
/// side, or *from*, on the left-hand side. Must match the ret_ty
/// of the term.
pub outer_ty: Ident,
/// The position of this converter decl.
pub pos: Pos,
}