From 605081b7590426135758ab4bf364f085e20c2cab Mon Sep 17 00:00:00 2001
From: Chris Pressey <cpressey@catseye.tc>
Date: Sun, 13 Feb 2022 21:21:27 +0000
Subject: [PATCH] Deep struct equality, and union equality, in JavaScript
 backend.

---
 TODO.md                            |  2 --
 src/castile/backends/javascript.py | 19 ++++++++++++++++---
 test.sh                            |  2 +-
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/TODO.md b/TODO.md
index 4c4cdde..632ee88 100644
--- a/TODO.md
+++ b/TODO.md
@@ -11,8 +11,6 @@ Figure out a way to do `input`, `read`, and `write` with node.js backend.
 
 Implement `int`, `chr`, `ord` for Ruby, JavaScript, stackmac, C.
 
-Struct equality is not properly deep in JavaScript or C.
-
 Better indentation in the JavaScript backend.
 
 TaggedValue -> just a tuple.
diff --git a/src/castile/backends/javascript.py b/src/castile/backends/javascript.py
index d1e33fd..af789ae 100644
--- a/src/castile/backends/javascript.py
+++ b/src/castile/backends/javascript.py
@@ -1,4 +1,4 @@
-from castile.types import Struct
+from castile.types import Struct, Union
 
 OPS = {
     'and': '&&',
@@ -56,6 +56,10 @@ def compile(self, ast):
   }
 };
 
+var equal_tagged_value = function(tv1, tv2)
+{
+    return (tv1.tag === tv2.tag) && (tv1.value === tv2.value);
+}
 """)
             for child in ast.children:
                 self.compile(child)
@@ -75,8 +79,11 @@ def compile(self, ast):
             self.out.write('function equal_%s(a, b) {\n' % ast.value)
             for child in ast.children:
                 assert child.tag == 'FieldDefn'
-                # TODO does not handle structs within structs
-                self.out.write('if (a.%s !== b.%s) return false;\n' % (child.value, child.value))
+                struct_type = child.children[0].value if child.children[0].tag == 'StructType' else None
+                if struct_type:
+                    self.out.write('if (!equal_%s(a.%s, b.%s)) return false;\n' % (struct_type, child.value, child.value))
+                else:
+                    self.out.write('if (a.%s !== b.%s) return false;\n' % (child.value, child.value))
             self.out.write('return true;\n')
             self.out.write('}\n\n')
         elif ast.tag == 'FunLit':
@@ -120,6 +127,12 @@ def compile(self, ast):
                 self.out.write(', ')
                 self.compile(ast.children[1])
                 self.out.write(')')
+            elif ast.value == '==' and isinstance(ast.children[0].type, Union):
+                self.out.write('equal_tagged_value(')
+                self.compile(ast.children[0])
+                self.out.write(', ')
+                self.compile(ast.children[1])
+                self.out.write(')')
             else:
                 self.out.write('(')
                 self.compile(ast.children[0])
diff --git a/test.sh b/test.sh
index d40b040..adbefc0 100755
--- a/test.sh
+++ b/test.sh
@@ -24,7 +24,7 @@ if [ ! x`command -v gcc` = x ]; then
     APPLIANCES="$APPLIANCES tests/appliances/castile-c-c.md"
 fi
 
-#APPLIANCES="tests/appliances/castile-c-c.md"
+#APPLIANCES="tests/appliances/castile-c-javascript.md"
 
 falderal $APPLIANCES tests/Castile.md
 RESULT=$?