feat(classes): support explicit NEW constructor method calls

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

10 files changed, 40 insertions, 11 deletions

diff --git a/include/cps/Lexer.h b/include/cps/Lexer.h
index 749ae0b..716dc4a 100644
--- a/include/cps/Lexer.h
+++ b/include/cps/Lexer.h
@@ -99,6 +99,7 @@ enum Token {
     tok_c_char = -610,
     tok_c_string = -611,
     tok_c_double = -612,
+    tok_new = -613,
 
     tok_try = -700,
     tok_catch = -701,
diff --git a/lib/CodeGen/Designator.cc b/lib/CodeGen/Designator.cc
index adf08f1..13eb25f 100644
--- a/lib/CodeGen/Designator.cc
+++ b/lib/CodeGen/Designator.cc
@@ -56,9 +56,7 @@ void CodeGen::runTypePrePass(const std::vector<std::unique_ptr<StmtAST>> &Statem
         for (const auto &Method : Class->getMethods()) {
             SaveAndRestore<int> Location(DiagnosticLine, Method->getLine());
             const std::string &Name = Method->getProto()->getName();
-            if (sameIdentifier(Name, "NEW")) {
-                reportError("NEW constructors are not implemented");
-            } else if (sameIdentifier(Name, "this")) {
+            if (sameIdentifier(Name, "this")) {
                 reportError("A method cannot be named this");
             } else if (!Names.insert(Name).second) {
                 reportError("Duplicate member %s in class %s", Name.c_str(), Class->getName().c_str());
diff --git a/lib/Lexer/Lexer.cc b/lib/Lexer/Lexer.cc
index 9203db1..8f86ced 100644
--- a/lib/Lexer/Lexer.cc
+++ b/lib/Lexer/Lexer.cc
@@ -150,6 +150,7 @@ int Lexer::readToken() {
         if (IdentifierStr == "ENDTYPE") return tok_endtype;
         if (IdentifierStr == "SET") return tok_set;
         if (IdentifierStr == "DEFINE") return tok_define;
+        if (IdentifierStr == "NEW") return tok_new;
         if (IdentifierStr == "CLASS") return tok_class;
         if (IdentifierStr == "ENDCLASS") return tok_endclass;
         if (IdentifierStr == "PUBLIC") return tok_public;
diff --git a/lib/Parser/ParserExpression.cc b/lib/Parser/ParserExpression.cc
index e9b0dcc..f4e074e 100644
--- a/lib/Parser/ParserExpression.cc
+++ b/lib/Parser/ParserExpression.cc
@@ -109,13 +109,13 @@ bool Parser::ParseDesignatorSuffix(std::vector<DesignatorAccess> &Out) {
             Out.push_back(std::move(A));
         } else if (CurTok == '.') {
             getNextToken();
-            if (CurTok != tok_identifier) {
+            if (CurTok != tok_identifier && CurTok != tok_new) {
                 fprintf(stderr, "error: Expected field name after '.' at line %d\n", Lex.getLine());
                 return false;
             }
             DesignatorAccess A;
             A.Kind = AccessKind::Field;
-            A.FieldName = Lex.IdentifierStr;
+            A.FieldName = CurTok == tok_new ? "NEW" : Lex.IdentifierStr;
             Out.push_back(std::move(A));
             getNextToken();
         } else if (CurTok == '^') {
diff --git a/lib/Parser/ParserFunction.cc b/lib/Parser/ParserFunction.cc
index ad187c8..1b8b470 100644
--- a/lib/Parser/ParserFunction.cc
+++ b/lib/Parser/ParserFunction.cc
@@ -132,6 +132,10 @@ std::optional<std::vector<ParamDecl>> Parser::ParsePrototypeArgs(bool AllowByRef
 std::unique_ptr<FunctionDefAST> Parser::ParseFunction(const std::string &OwnerClass, bool IsPublic) {
     int Line = Lex.getLine();
     getNextToken();
+    if (CurTok == tok_new || (CurTok == tok_identifier && sameIdentifier(Lex.IdentifierStr, "NEW"))) {
+        fprintf(stderr, "error: constructor NEW must be a PROCEDURE at line %d\n", Line);
+        return nullptr;
+    }
     if (CurTok != tok_identifier) {
         fprintf(stderr, "error: Expected function name\n");
         return nullptr;
@@ -176,12 +180,16 @@ std::unique_ptr<FunctionDefAST> Parser::ParseFunction(const std::string &OwnerCl
 std::unique_ptr<FunctionDefAST> Parser::ParseProcedure(const std::string &OwnerClass, bool IsPublic) {
     int Line = Lex.getLine();
     getNextToken();
-    if (CurTok != tok_identifier) {
+    if (CurTok != tok_identifier && CurTok != tok_new) {
         fprintf(stderr, "error: Expected procedure name\n");
         return nullptr;
     }
 
-    std::string Name = Lex.IdentifierStr;
+    std::string Name = CurTok == tok_new ? "NEW" : Lex.IdentifierStr;
+    if (OwnerClass.empty() && sameIdentifier(Name, "NEW")) {
+        fprintf(stderr, "error: constructor NEW is only allowed in a CLASS at line %d\n", Line);
+        return nullptr;
+    }
     getNextToken();
 
     auto Args = ParsePrototypeArgs(/*AllowByRef=*/true);
diff --git a/tests/i/class-new-methods/case.json b/tests/i/class-new-methods/case.json
new file mode 100644
index 0000000..0967ef4
--- /dev/null
+++ b/tests/i/class-new-methods/case.json
@@ -0,0 +1 @@
+{}
diff --git a/tests/i/class-new-methods/expected.txt b/tests/i/class-new-methods/expected.txt
new file mode 100644
index 0000000..426f8ca
--- /dev/null
+++ b/tests/i/class-new-methods/expected.txt
@@ -0,0 +1,3 @@
+x
+call
+again
diff --git a/tests/i/class-new-methods/notes.md b/tests/i/class-new-methods/notes.md
new file mode 100644
index 0000000..53192fb
--- /dev/null
+++ b/tests/i/class-new-methods/notes.md
@@ -0,0 +1,5 @@
+# Explicit NEW calls
+
+Human review: pending. Expected output was independently traced by AI.
+
+NEW is an ordinary procedure: the bare member call stores x, CALL with mixed case stores call, and Reset calls this.NEW to store again. DECLARE is extended with arguments in the next implementation step.
diff --git a/tests/i/class-new-methods/program.cps b/tests/i/class-new-methods/program.cps
new file mode 100644
index 0000000..573fe0f
--- /dev/null
+++ b/tests/i/class-new-methods/program.cps
@@ -0,0 +1,16 @@
+CLASS Box
+    Value : STRING
+    PROCEDURE NEW(Text : STRING)
+        Value <- Text
+    ENDPROCEDURE
+    PROCEDURE Reset()
+        this.NEW("again")
+    ENDPROCEDURE
+ENDCLASS
+DECLARE Obj : Box
+Obj.NEW("x")
+OUTPUT Obj.Value
+CALL Obj.new("call")
+OUTPUT Obj.Value
+Obj.Reset()
+OUTPUT Obj.Value
diff --git a/tests/iii/class-method-errors/case.json b/tests/iii/class-method-errors/case.json
index 655296d..e871f28 100644
--- a/tests/iii/class-method-errors/case.json
+++ b/tests/iii/class-method-errors/case.json
@@ -9,10 +9,6 @@
       "line": 13
     },
     {
-      "reason": "NEW constructors are not implemented",
-      "line": 15
-    },
-    {
       "reason": "Duplicate member set in class Box",
       "line": 17
     },