Generate a visitor trait to ast_gen.rs

ast/asdl_rs.py

@@ -543,6 +543,153 @@ class FoldModuleVisitor(EmitVisitor):
         self.emit("}", depth)
 
 
+class VisitorStructsDefVisitor(StructVisitor):
+    def visitModule(self, mod, depth):
+        for dfn in mod.dfns:
+            self.visit(dfn, depth)
+
+    def visitProduct(self, product, name, depth):
+        pass
+
+    def visitSum(self, sum, name, depth):
+        if not is_simple(sum):
+            typeinfo = self.typeinfo[name]
+            if not sum.attributes:
+                return
+            for t in sum.types:
+                typename = t.name + "Node"
+
+                has_userdata = any(
+                    getattr(self.typeinfo.get(f.type), "has_userdata", False)
+                    for f in t.fields
+                )
+                self.emit(
+                    f"pub struct {typename}Data<{'U=()' if has_userdata else ''}> {{",
+                    depth,
+                )
+                for f in t.fields:
+                    self.visit(f, typeinfo, "pub ", depth + 1, t.name)
+                self.emit("}", depth)
+                self.emit(
+                    f"pub type {typename}<U = ()> = Located<{typename}Data<{'U' if has_userdata else ''}>, U>;",
+                    depth,
+                )
+                self.emit("", depth)
+
+
+class VisitorTraitDefVisitor(StructVisitor):
+    def visitModule(self, mod, depth):
+        self.emit("pub trait Visitor<U=()> {", depth)
+        for dfn in mod.dfns:
+            self.visit(dfn, depth + 1)
+        self.emit("}", depth)
+
+    def visitType(self, type, depth=0):
+        self.visit(type.value, type.name, depth)
+
+    def emit_visitor(self, nodename, rusttype, depth):
+        self.emit(f"fn visit_{nodename}(&mut self, node: {rusttype}) {{", depth)
+        self.emit(f"self.generic_visit_{nodename}(node);", depth + 1)
+        self.emit("}", depth)
+
+    def emit_generic_visitor_signature(self, nodename, rusttype, depth):
+        self.emit(f"fn generic_visit_{nodename}(&mut self, node: {rusttype}) {{", depth)
+
+    def emit_empty_generic_visitor(self, nodename, rusttype, depth):
+        self.emit_generic_visitor_signature(nodename, rusttype, depth)
+        self.emit("}", depth)
+
+    def simple_sum(self, sum, name, depth):
+        rustname = get_rust_type(name)
+        self.emit_visitor(name, rustname, depth)
+        self.emit_empty_generic_visitor(name, rustname, depth)
+
+    def visit_match_for_type(self, enumname, type_, depth):
+        self.emit(f"{enumname}::{type_.name} {{", depth)
+        for field in type_.fields:
+            self.emit(f"{rust_field(field.name)},", depth + 1)
+        self.emit(f"}} => self.visit_{type_.name}(", depth)
+        self.emit(f"{type_.name}Node {{", depth + 2)
+        self.emit("location: node.location,", depth + 2)
+        self.emit("end_location: node.end_location,", depth + 2)
+        self.emit("custom: node.custom,", depth + 2)
+        self.emit(f"node: {type_.name}NodeData {{", depth + 2)
+        for field in type_.fields:
+            self.emit(f"{rust_field(field.name)},", depth + 3)
+        self.emit("},", depth + 2)
+        self.emit("}", depth + 1)
+        self.emit("),", depth)
+
+    def visit_sumtype(self, type_, depth):
+        rustname = get_rust_type(type_.name) + "Node"
+        self.emit_visitor(type_.name, rustname, depth)
+        self.emit_generic_visitor_signature(type_.name, rustname, depth)
+        for f in type_.fields:
+            fieldname = rust_field(f.name)
+            fieldtype = self.typeinfo.get(f.type)
+            if not (fieldtype and fieldtype.has_userdata):
+                continue
+
+            if f.opt:
+                self.emit(f"if let Some(value) = node.node.{fieldname} {{", depth + 1)
+            elif f.seq:
+                iterable = f"node.node.{fieldname}"
+                if type_.name == "Dict" and f.name == "keys":
+                    iterable = f"{iterable}.into_iter().flatten()"
+                self.emit(f"for value in {iterable} {{", depth + 1)
+            else:
+                self.emit("{", depth + 1)
+                self.emit(f"let value = node.node.{fieldname};", depth + 2)
+
+            variable = "value"
+            if fieldtype.boxed and (not f.seq or f.opt):
+                variable = "*" + variable
+            self.emit(f"self.visit_{fieldtype.name}({variable});", depth + 2)
+
+            self.emit("}", depth + 1)
+
+        self.emit("}", depth)
+
+    def sum_with_constructors(self, sum, name, depth):
+        if not sum.attributes:
+            return
+
+        rustname = enumname = get_rust_type(name)
+        if sum.attributes:
+            enumname += "Kind"
+        self.emit_visitor(name, rustname, depth)
+        self.emit_generic_visitor_signature(name, rustname, depth)
+        depth += 1
+        self.emit("match node.node {", depth)
+        for t in sum.types:
+            self.visit_match_for_type(enumname, t, depth + 1)
+        self.emit("}", depth)
+        depth -= 1
+        self.emit("}", depth)
+
+        # Now for the visitors for the types
+        for t in sum.types:
+            self.visit_sumtype(t, depth)
+
+    def visitProduct(self, product, name, depth):
+        rusttype = get_rust_type(name)
+        self.emit_visitor(name, rusttype, depth)
+        self.emit_empty_generic_visitor(name, rusttype, depth)
+
+
+class VisitorModuleVisitor(EmitVisitor):
+    def visitModule(self, mod):
+        depth = 0
+        self.emit('#[cfg(feature = "visitor")]', depth)
+        self.emit("#[allow(unused_variables, non_snake_case)]", depth)
+        self.emit("pub mod visitor {", depth)
+        self.emit("use super::*;", depth + 1)
+        VisitorStructsDefVisitor(self.file, self.typeinfo).visit(mod, depth + 1)
+        VisitorTraitDefVisitor(self.file, self.typeinfo).visit(mod, depth + 1)
+        self.emit("}", depth)
+        self.emit("", depth)
+
+
 class ClassDefVisitor(EmitVisitor):
     def visitModule(self, mod):
         for dfn in mod.dfns:
@@ -811,7 +958,11 @@ def write_generic_def(mod, typeinfo, f):
         )
     )
 
-    c = ChainOfVisitors(StructVisitor(f, typeinfo), FoldModuleVisitor(f, typeinfo))
+    c = ChainOfVisitors(
+        StructVisitor(f, typeinfo),
+        FoldModuleVisitor(f, typeinfo),
+        VisitorModuleVisitor(f, typeinfo),
+    )
     c.visit(mod)