Extract operation-related code to a new module

2 files changed, 9 insertions, 295 deletions

diff --git a/dhall/src/semantics/nze/nir.rs b/dhall/src/semantics/nze/nir.rs
index 88123d8..5c67c02 100644
--- a/dhall/src/semantics/nze/nir.rs
+++ b/dhall/src/semantics/nze/nir.rs
@@ -1,6 +1,7 @@
 use std::collections::HashMap;
 use std::rc::Rc;
 
+use crate::operations::OpKind;
 use crate::semantics::nze::lazy;
 use crate::semantics::{
     apply_any, normalize_hir, normalize_one_layer, squash_textlit, Binder,
@@ -8,7 +9,7 @@ use crate::semantics::{
 };
 use crate::syntax::{
     BinOp, Builtin, Const, Expr, ExprKind, InterpolatedTextContents, Label,
-    NumKind, OpKind, Span,
+    NumKind, Span,
 };
 use crate::ToExprOptions;
 
diff --git a/dhall/src/semantics/nze/normalize.rs b/dhall/src/semantics/nze/normalize.rs
index c0e41cb..d042f3f 100644
--- a/dhall/src/semantics/nze/normalize.rs
+++ b/dhall/src/semantics/nze/normalize.rs
@@ -1,11 +1,9 @@
-use itertools::Itertools;
 use std::collections::HashMap;
 
+use crate::operations::{normalize_operation, OpKind};
 use crate::semantics::NzEnv;
 use crate::semantics::{Binder, Closure, Hir, HirKind, Nir, NirKind, TextLit};
-use crate::syntax::{
-    BinOp, ExprKind, InterpolatedTextContents, Label, NumKind, OpKind,
-};
+use crate::syntax::{ExprKind, InterpolatedTextContents};
 
 pub fn apply_any(f: &Nir, a: Nir) -> NirKind {
     match f.kind() {
@@ -83,306 +81,21 @@ where
     kvs
 }
 
-type Ret = NirKind;
+pub type Ret = NirKind;
 
-fn ret_nir(x: Nir) -> Ret {
+pub fn ret_nir(x: Nir) -> Ret {
     ret_ref(&x)
 }
-fn ret_kind(x: NirKind) -> Ret {
+pub fn ret_kind(x: NirKind) -> Ret {
     x
 }
-fn ret_ref(x: &Nir) -> Ret {
+pub fn ret_ref(x: &Nir) -> Ret {
     x.kind().clone()
 }
-fn ret_op(x: OpKind<Nir>) -> Ret {
+pub fn ret_op(x: OpKind<Nir>) -> Ret {
     NirKind::Op(x)
 }
 
-fn normalize_binop(o: BinOp, x: &Nir, y: &Nir) -> Ret {
-    use BinOp::*;
-    use NirKind::{EmptyListLit, NEListLit, Num, RecordLit, RecordType};
-    use NumKind::{Bool, Natural};
-
-    match (o, x.kind(), y.kind()) {
-        (BoolAnd, Num(Bool(true)), _) => ret_ref(y),
-        (BoolAnd, _, Num(Bool(true))) => ret_ref(x),
-        (BoolAnd, Num(Bool(false)), _) => ret_kind(Num(Bool(false))),
-        (BoolAnd, _, Num(Bool(false))) => ret_kind(Num(Bool(false))),
-        (BoolAnd, _, _) if x == y => ret_ref(x),
-        (BoolOr, Num(Bool(true)), _) => ret_kind(Num(Bool(true))),
-        (BoolOr, _, Num(Bool(true))) => ret_kind(Num(Bool(true))),
-        (BoolOr, Num(Bool(false)), _) => ret_ref(y),
-        (BoolOr, _, Num(Bool(false))) => ret_ref(x),
-        (BoolOr, _, _) if x == y => ret_ref(x),
-        (BoolEQ, Num(Bool(true)), _) => ret_ref(y),
-        (BoolEQ, _, Num(Bool(true))) => ret_ref(x),
-        (BoolEQ, Num(Bool(x)), Num(Bool(y))) => ret_kind(Num(Bool(x == y))),
-        (BoolEQ, _, _) if x == y => ret_kind(Num(Bool(true))),
-        (BoolNE, Num(Bool(false)), _) => ret_ref(y),
-        (BoolNE, _, Num(Bool(false))) => ret_ref(x),
-        (BoolNE, Num(Bool(x)), Num(Bool(y))) => ret_kind(Num(Bool(x != y))),
-        (BoolNE, _, _) if x == y => ret_kind(Num(Bool(false))),
-
-        (NaturalPlus, Num(Natural(0)), _) => ret_ref(y),
-        (NaturalPlus, _, Num(Natural(0))) => ret_ref(x),
-        (NaturalPlus, Num(Natural(x)), Num(Natural(y))) => {
-            ret_kind(Num(Natural(x + y)))
-        }
-        (NaturalTimes, Num(Natural(0)), _) => ret_kind(Num(Natural(0))),
-        (NaturalTimes, _, Num(Natural(0))) => ret_kind(Num(Natural(0))),
-        (NaturalTimes, Num(Natural(1)), _) => ret_ref(y),
-        (NaturalTimes, _, Num(Natural(1))) => ret_ref(x),
-        (NaturalTimes, Num(Natural(x)), Num(Natural(y))) => {
-            ret_kind(Num(Natural(x * y)))
-        }
-
-        (ListAppend, EmptyListLit(_), _) => ret_ref(y),
-        (ListAppend, _, EmptyListLit(_)) => ret_ref(x),
-        (ListAppend, NEListLit(xs), NEListLit(ys)) => {
-            ret_kind(NEListLit(xs.iter().chain(ys.iter()).cloned().collect()))
-        }
-
-        (TextAppend, NirKind::TextLit(x), _) if x.is_empty() => ret_ref(y),
-        (TextAppend, _, NirKind::TextLit(y)) if y.is_empty() => ret_ref(x),
-        (TextAppend, NirKind::TextLit(x), NirKind::TextLit(y)) => {
-            ret_kind(NirKind::TextLit(x.concat(y)))
-        }
-        (TextAppend, NirKind::TextLit(x), _) => ret_kind(NirKind::TextLit(
-            x.concat(&TextLit::interpolate(y.clone())),
-        )),
-        (TextAppend, _, NirKind::TextLit(y)) => ret_kind(NirKind::TextLit(
-            TextLit::interpolate(x.clone()).concat(y),
-        )),
-
-        (RightBiasedRecordMerge, _, RecordLit(kvs)) if kvs.is_empty() => {
-            ret_ref(x)
-        }
-        (RightBiasedRecordMerge, RecordLit(kvs), _) if kvs.is_empty() => {
-            ret_ref(y)
-        }
-        (RightBiasedRecordMerge, RecordLit(kvs1), RecordLit(kvs2)) => {
-            let mut kvs = kvs2.clone();
-            for (x, v) in kvs1 {
-                // Insert only if key not already present
-                kvs.entry(x.clone()).or_insert_with(|| v.clone());
-            }
-            ret_kind(RecordLit(kvs))
-        }
-        (RightBiasedRecordMerge, _, _) if x == y => ret_ref(y),
-
-        (RecursiveRecordMerge, _, RecordLit(kvs)) if kvs.is_empty() => {
-            ret_ref(x)
-        }
-        (RecursiveRecordMerge, RecordLit(kvs), _) if kvs.is_empty() => {
-            ret_ref(y)
-        }
-        (RecursiveRecordMerge, RecordLit(kvs1), RecordLit(kvs2)) => {
-            let kvs = merge_maps(kvs1, kvs2, |_, v1, v2| {
-                Nir::from_partial_expr(ExprKind::Op(OpKind::BinOp(
-                    RecursiveRecordMerge,
-                    v1.clone(),
-                    v2.clone(),
-                )))
-            });
-            ret_kind(RecordLit(kvs))
-        }
-
-        (RecursiveRecordTypeMerge, RecordType(kts_x), RecordType(kts_y)) => {
-            let kts = merge_maps(
-                kts_x,
-                kts_y,
-                // If the Label exists for both records, then we hit the recursive case.
-                |_, l: &Nir, r: &Nir| {
-                    Nir::from_partial_expr(ExprKind::Op(OpKind::BinOp(
-                        RecursiveRecordTypeMerge,
-                        l.clone(),
-                        r.clone(),
-                    )))
-                },
-            );
-            ret_kind(RecordType(kts))
-        }
-
-        (Equivalence, _, _) => {
-            ret_kind(NirKind::Equivalence(x.clone(), y.clone()))
-        }
-
-        _ => ret_op(OpKind::BinOp(o, x.clone(), y.clone())),
-    }
-}
-
-fn normalize_field(v: &Nir, field: &Label) -> Ret {
-    use self::BinOp::{RecursiveRecordMerge, RightBiasedRecordMerge};
-    use NirKind::{Op, RecordLit, UnionConstructor, UnionType};
-    use OpKind::{BinOp, Field, Projection};
-    let nothing_to_do = || ret_op(Field(v.clone(), field.clone()));
-
-    match v.kind() {
-        RecordLit(kvs) => match kvs.get(field) {
-            Some(r) => ret_ref(r),
-            None => nothing_to_do(),
-        },
-        UnionType(kts) => {
-            ret_kind(UnionConstructor(field.clone(), kts.clone()))
-        }
-        Op(Projection(x, _)) => normalize_field(x, field),
-        Op(BinOp(RightBiasedRecordMerge, x, y)) => match (x.kind(), y.kind()) {
-            (_, RecordLit(kvs)) => match kvs.get(field) {
-                Some(r) => ret_ref(r),
-                None => normalize_field(x, field),
-            },
-            (RecordLit(kvs), _) => match kvs.get(field) {
-                Some(r) => ret_op(Field(
-                    Nir::from_kind(Op(BinOp(
-                        RightBiasedRecordMerge,
-                        Nir::from_kind(RecordLit(
-                            Some((field.clone(), r.clone()))
-                                .into_iter()
-                                .collect(),
-                        )),
-                        y.clone(),
-                    ))),
-                    field.clone(),
-                )),
-                None => normalize_field(y, field),
-            },
-            _ => nothing_to_do(),
-        },
-        Op(BinOp(RecursiveRecordMerge, x, y)) => match (x.kind(), y.kind()) {
-            (RecordLit(kvs), _) => match kvs.get(field) {
-                Some(r) => ret_op(Field(
-                    Nir::from_kind(Op(BinOp(
-                        RecursiveRecordMerge,
-                        Nir::from_kind(RecordLit(
-                            Some((field.clone(), r.clone()))
-                                .into_iter()
-                                .collect(),
-                        )),
-                        y.clone(),
-                    ))),
-                    field.clone(),
-                )),
-                None => normalize_field(y, field),
-            },
-            (_, RecordLit(kvs)) => match kvs.get(field) {
-                Some(r) => ret_op(Field(
-                    Nir::from_kind(Op(BinOp(
-                        RecursiveRecordMerge,
-                        x.clone(),
-                        Nir::from_kind(RecordLit(
-                            Some((field.clone(), r.clone()))
-                                .into_iter()
-                                .collect(),
-                        )),
-                    ))),
-                    field.clone(),
-                )),
-                None => normalize_field(x, field),
-            },
-            _ => nothing_to_do(),
-        },
-        _ => nothing_to_do(),
-    }
-}
-
-fn normalize_operation(opkind: &OpKind<Nir>) -> Ret {
-    use NirKind::{
-        EmptyListLit, EmptyOptionalLit, NEListLit, NEOptionalLit, Num, Op,
-        RecordLit, RecordType, UnionConstructor, UnionLit,
-    };
-    use NumKind::Bool;
-    use OpKind::*;
-    let nothing_to_do = || ret_op(opkind.clone());
-
-    match opkind {
-        App(v, a) => ret_kind(v.app_to_kind(a.clone())),
-        BinOp(o, x, y) => normalize_binop(*o, x, y),
-        BoolIf(b, e1, e2) => {
-            match b.kind() {
-                Num(Bool(true)) => ret_ref(e1),
-                Num(Bool(false)) => ret_ref(e2),
-                _ => {
-                    match (e1.kind(), e2.kind()) {
-                        // Simplify `if b then True else False`
-                        (Num(Bool(true)), Num(Bool(false))) => ret_ref(b),
-                        _ if e1 == e2 => ret_ref(e1),
-                        _ => nothing_to_do(),
-                    }
-                }
-            }
-        }
-        Merge(handlers, variant, _) => match handlers.kind() {
-            RecordLit(kvs) => match variant.kind() {
-                UnionConstructor(l, _) => match kvs.get(l) {
-                    Some(h) => ret_ref(h),
-                    None => nothing_to_do(),
-                },
-                UnionLit(l, v, _) => match kvs.get(l) {
-                    Some(h) => ret_kind(h.app_to_kind(v.clone())),
-                    None => nothing_to_do(),
-                },
-                EmptyOptionalLit(_) => match kvs.get(&"None".into()) {
-                    Some(h) => ret_ref(h),
-                    None => nothing_to_do(),
-                },
-                NEOptionalLit(v) => match kvs.get(&"Some".into()) {
-                    Some(h) => ret_kind(h.app_to_kind(v.clone())),
-                    None => nothing_to_do(),
-                },
-                _ => nothing_to_do(),
-            },
-            _ => nothing_to_do(),
-        },
-        ToMap(v, annot) => match v.kind() {
-            RecordLit(kvs) if kvs.is_empty() => {
-                match annot.as_ref().map(|v| v.kind()) {
-                    Some(NirKind::ListType(t)) => {
-                        ret_kind(EmptyListLit(t.clone()))
-                    }
-                    _ => nothing_to_do(),
-                }
-            }
-            RecordLit(kvs) => ret_kind(NEListLit(
-                kvs.iter()
-                    .sorted_by_key(|(k, _)| *k)
-                    .map(|(k, v)| {
-                        let mut rec = HashMap::new();
-                        rec.insert("mapKey".into(), Nir::from_text(k));
-                        rec.insert("mapValue".into(), v.clone());
-                        Nir::from_kind(NirKind::RecordLit(rec))
-                    })
-                    .collect(),
-            )),
-            _ => nothing_to_do(),
-        },
-        Field(v, field) => normalize_field(v, field),
-        Projection(_, ls) if ls.is_empty() => {
-            ret_kind(RecordLit(HashMap::new()))
-        }
-        Projection(v, ls) => match v.kind() {
-            RecordLit(kvs) => ret_kind(RecordLit(
-                ls.iter()
-                    .filter_map(|l| kvs.get(l).map(|x| (l.clone(), x.clone())))
-                    .collect(),
-            )),
-            Op(Projection(v2, _)) => {
-                normalize_operation(&Projection(v2.clone(), ls.clone()))
-            }
-            _ => nothing_to_do(),
-        },
-        ProjectionByExpr(v, t) => match t.kind() {
-            RecordType(kts) => normalize_operation(&Projection(
-                v.clone(),
-                kts.keys().cloned().collect(),
-            )),
-            _ => nothing_to_do(),
-        },
-        Completion(..) => {
-            unreachable!("This case should have been handled in resolution")
-        }
-    }
-}
-
 pub fn normalize_one_layer(expr: ExprKind<Nir>, env: &NzEnv) -> NirKind {
     use NirKind::{
         Assert, Const, NEListLit, NEOptionalLit, Num, RecordLit, RecordType,