feat: infer types of show rule transformers (#1045)

* feat: infer types of show rule transformers

* test: add test for show rules

* feat: more selector cases

* test: update snapshot

crates/tinymist-query/src/analysis/tyck/syntax.rs

@@ -1,5 +1,7 @@
 //! Type checking on source file
 
+use typst::foundations::{Element, Type};
+
 use super::*;
 use crate::analysis::ParamAttrs;
 use crate::docs::{SignatureDocsT, TypelessParamDocs, UntypedDefDocs};
@@ -434,13 +436,66 @@ impl TypeChecker<'_> {
     }
 
     fn check_show(&mut self, show: &Interned<ShowExpr>) -> Ty {
-        let _selector = show.selector.as_ref().map(|sel| self.check(sel));
-        // todo: infer it type by selector
-        let _transform = self.check(&show.edit);
+        let selector = show.selector.as_ref().map(|sel| self.check(sel));
+        let transform = self.check(&show.edit);
 
+        self.constraint_show(selector, transform);
         Ty::Builtin(BuiltinTy::None)
     }
 
+    fn constraint_show(&mut self, selector: Option<Ty>, transform: Ty) -> Option<()> {
+        crate::log_debug_ct!("show on {selector:?}, transform {transform:?}");
+
+        let selected = match selector {
+            Some(selector) => Self::content_by_selector(selector)?,
+            None => Ty::Builtin(BuiltinTy::Content),
+        };
+
+        let show_fact = Ty::Func(SigTy::unary(selected, Ty::Any));
+        crate::log_debug_ct!("check show_fact type {show_fact:?} value: {transform:?}");
+        self.constrain(&transform, &show_fact);
+
+        Some(())
+    }
+
+    fn content_by_selector(selector: Ty) -> Option<Ty> {
+        crate::log_debug_ct!("check selector {selector:?}");
+
+        Some(match selector {
+            Ty::With(with) => return Self::content_by_selector(with.sig.as_ref().clone()),
+            Ty::Builtin(BuiltinTy::Type(ty)) => {
+                if ty == Type::of::<typst::foundations::Regex>() {
+                    Ty::Builtin(BuiltinTy::Element(Element::of::<typst::text::TextElem>()))
+                } else {
+                    return None;
+                }
+            }
+            Ty::Builtin(BuiltinTy::Element(..)) => selector,
+            Ty::Value(ins_ty) => match &ins_ty.val {
+                Value::Str(..) => {
+                    Ty::Builtin(BuiltinTy::Element(Element::of::<typst::text::TextElem>()))
+                }
+                Value::Content(c) => Ty::Builtin(BuiltinTy::Element(c.elem())),
+                Value::Func(f) => {
+                    if let Some(elem) = f.element() {
+                        Ty::Builtin(BuiltinTy::Element(elem))
+                    } else {
+                        return None;
+                    }
+                }
+                Value::Dyn(value) => {
+                    if value.ty() == Type::of::<typst::foundations::Regex>() {
+                        Ty::Builtin(BuiltinTy::Element(Element::of::<typst::text::TextElem>()))
+                    } else {
+                        return None;
+                    }
+                }
+                _ => return None,
+            },
+            _ => return None,
+        })
+    }
+
     // todo: merge with func call, and regard difference (may be here)
     fn check_set(&mut self, set: &Interned<SetExpr>) -> Ty {
         let callee = self.check(&set.target);

crates/tinymist-query/src/fixtures/completion/snaps/test@set_in_show.typ.snap

@@ -15,7 +15,7 @@ snapshot_kind: text
     "labelDetails": {
      "description": "(str, align: alignment, block: bool, lang: none | str, syntaxes: [syntax], tab-size: int, theme: [theme]) => raw"
     },
-    "sortText": "052",
+    "sortText": "053",
     "textEdit": {
      "newText": "raw(${1:})",
      "range": {

crates/tinymist-query/src/fixtures/type_check/show.typ

@@ -0,0 +1,5 @@
+/// contains: text
+
+#show regex(":\S+:"): it => it./* range 0..1 */
+
+:test:

crates/tinymist-query/src/fixtures/type_check/show_raw.typ

@@ -0,0 +1,5 @@
+/// contains: text
+
+#show raw: it => it./* range 0..1 */
+
+:test:

crates/tinymist-query/src/fixtures/type_check/show_raw_where.typ

@@ -0,0 +1,5 @@
+/// contains: text
+
+#show raw.where(block: false): it => it./* range 0..1 */
+
+:test:

crates/tinymist-query/src/fixtures/type_check/snaps/test@show.typ.snap

@@ -0,0 +1,15 @@
+---
+source: crates/tinymist-query/src/analysis.rs
+expression: result
+input_file: crates/tinymist-query/src/fixtures/type_check/show.typ
+snapshot_kind: text
+---
+"" = (Any) => Any.it
+"it" = Element(text)
+=====
+26..31 -> Type(regex)
+26..40 -> Type(regex)
+42..44 -> @it
+42..51 -> @
+48..50 -> @it
+48..51 -> @v"it".it

crates/tinymist-query/src/fixtures/type_check/snaps/test@show_raw.typ.snap

@@ -0,0 +1,14 @@
+---
+source: crates/tinymist-query/src/analysis.rs
+expression: result
+input_file: crates/tinymist-query/src/fixtures/type_check/show_raw.typ
+snapshot_kind: text
+---
+"" = (Any) => Any.it
+"it" = Element(raw)
+=====
+26..29 -> Func(raw)
+31..33 -> @it
+31..40 -> @
+37..39 -> @it
+37..40 -> @v"it".it

crates/tinymist-query/src/fixtures/type_check/snaps/test@show_raw_where.typ.snap

@@ -0,0 +1,16 @@
+---
+source: crates/tinymist-query/src/analysis.rs
+expression: result
+input_file: crates/tinymist-query/src/fixtures/type_check/show_raw_where.typ
+snapshot_kind: text
+---
+"" = (Any) => Any.it
+"it" = Element(raw)
+=====
+26..29 -> Func(raw)
+26..35 -> (Func(raw) | Func(raw).where)
+26..49 -> (Func(raw)).with(..("block": false) => any)
+51..53 -> @it
+51..60 -> @
+57..59 -> @it
+57..60 -> @v"it".it