refactor(codegen): split emission by responsibility

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/lib/CodeGen/Builtins.h b/lib/CodeGen/Builtins.h
new file mode 100644
index 0000000..34e36a9
--- /dev/null
+++ b/lib/CodeGen/Builtins.h
@@ -0,0 +1,37 @@
+#pragma once
+#include <string>
+
+namespace cps::detail {
+
+// Single source of truth for the built-in functions: name, arity and return
+// type. emitExpr checks arity against this table before dispatching, and
+// getExprTypeInfo reads the return type from it.
+struct BuiltinInfo {
+    const char *Name;
+    unsigned Arity;
+    const char *ReturnTypeName;
+};
+
+inline constexpr BuiltinInfo Builtins[] = {
+    {"LENGTH",     1, "INTEGER"},
+    {"MID",        3, "STRING"},
+    {"RIGHT",      2, "STRING"},
+    {"LEFT",       2, "STRING"},
+    {"LCASE",      1, "STRING"},
+    {"UCASE",      1, "STRING"},
+    {"ASC",        1, "INTEGER"},
+    {"CHR",        1, "STRING"},
+    {"IS_NUM",     1, "BOOLEAN"},
+    {"NUM_TO_STR", 1, "STRING"},
+    {"STR_TO_NUM", 1, "REAL"},
+    {"EOF",        1, "BOOLEAN"},
+};
+
+inline const BuiltinInfo *findBuiltin(const std::string &Name) {
+    for (const auto &B : Builtins) {
+        if (Name == B.Name) return &B;
+    }
+    return nullptr;
+}
+
+} // namespace cps::detail