accept pub enum, and enums used as types

Implement pub support for enums, and also anonymous enums declared
in-place.

Also give the cdr of a `pub' form the form's own location, so a
error about what follows `pub' can say where it was written

fmt-c-writer.scm

@@ -382,10 +382,17 @@ forms, and what remains."
 
 (define (walk-enum form)
   (match form
+    ;; Naming one without defining it: `(var m (enum mood))', the same
+    ;; shape walk-struct accepts for `(struct foo)'. Guarded, and
+    ;; before the anonymous case, since `(enum (red green))' is also a
+    ;; two-element form
+    (('enum (? symbol? name))
+     `(enum ,(atom-to-fmt-c name)))
     (('enum (values ...))
      `(enum ,(map atom-to-fmt-c values)))
     (('enum name (values ...))
-     `(enum ,(atom-to-fmt-c name) ,(map atom-to-fmt-c values)))))
+     `(enum ,(atom-to-fmt-c name) ,(map atom-to-fmt-c values)))
+    (else (sex-error form "malformed enum" form))))
 
 (define (walk-extern form)
   (match form
@@ -410,6 +417,7 @@ forms, and what remains."
 
          ('struct . _)
          ('union . _)
+         ('enum . _)
 
          ('typedef . _))
      ;; ignore here, used in generating public interface
@@ -423,7 +431,10 @@ forms, and what remains."
     (('fn . _) (list 'static (walk-function form)))
     (('var . _) (list 'static (walk-var form)))
     (('extern . rest) (walk-extern rest))
-    (('pub . rest) (walk-public rest))
+    ;; The cdr of a form has no location of its own, so hand it the
+    ;; `pub' form's -- otherwise a complaint about what follows `pub'
+    ;; cannot say where it was written
+    (('pub . rest) (walk-public (copy-form-source! form rest)))
     ((or ('struct . _)
          ('union . _)) (walk-struct form))
     (('enum . _) (walk-enum form))

sex-fmt-c.scm

@@ -640,16 +640,22 @@
   (define (c-union . args) (apply c-struct/aux "union" args))
   (define (c-class . args) (apply c-struct/aux "class" args))
 
+  ;; MODIFIED FROM UPSTREAM fmt-c: an enum may also be named without
+  ;; being defined -- `enum color m;' -- exactly as c-struct/aux
+  ;; already allows `struct point p;'. Upstream assumed a value list
+  ;; was always present and mapped over whatever stood in its place.
   (define (c-enum x . o)
     (define (c-enum-one x)
       (if (pair? x) (cat (car x) " = " (c-expr (cadr x))) (dsp x)))
     (let* ((name (if (null? o) (if (or (symbol? x) (string? x)) x #f) x))
-           (vals (if name (car o) x)))
+           (vals (if name (if (null? o) #f (car o)) x)))
-      (c-wrap-stmt
+      (if vals
-       (cat
+          (c-wrap-stmt
-        (c-braced-block
+           (cat
-         (if name (cat "enum " name) (dsp "enum"))
+            (c-braced-block
-         (c-in-expr (apply c-begin (map c-enum-one vals))))))))
+             (if name (cat "enum " name) (dsp "enum"))
+             (c-in-expr (apply c-begin (map c-enum-one vals))))))
+          (c-wrap-stmt (cat "enum " name)))))
 
   (define (c-attribute . args)
     (cat "__attribute__ ((" (fmt-join c-expr args ", ") "))"))
@@ -743,7 +749,13 @@
                      (if (and (pair? (cadr type)) (eq? '%array (caadr type)))
                          (c-paren name)
                          name))))
-          ((enum) (apply c-enum name (cdr type)))
+          ;; MODIFIED FROM UPSTREAM fmt-c: upstream passed the
+          ;; declarator's name to c-enum as the enum's tag, so
+          ;; `(var m (enum color))' emitted `enum m {...}' and lost the
+          ;; variable. Enums are laid out like structs: the type, then
+          ;; the name being declared.
+          ((enum)
+           (cat (apply c-enum (cdr type)) (if name (cat " " name) "")))
           ((struct union class)
            (cat (apply c-struct/aux (car type) (cdr type)) (if name (cat " " name) "")))
           (else (fmt-join/last c-expr (lambda (x) (c-type x name)) type " "))))

sex-modules.scm

@@ -83,7 +83,7 @@
        ;; A variable becomes an `extern' declaration
        ((var)
         (cons (copy-form-source! form (cons 'extern (take (cdr form) 3))) acc))
-       ((define defmacro import include struct typedef union)
+       ((define defmacro enum import include struct typedef union)
         (cons (copy-form-source! form (cdr form)) acc))
        (else (sex-error form "pub must be followed by a definition" form))))
     (else acc)))

tests/codegen.scm

@@ -141,6 +141,28 @@ compiles."
     (test-assert "a comment in a body stays in the body"
       (emits? (in-fn "(while (< a b) ;; inside\n (g 1))")
               "while (a < b) {")))
+
+  (test-group "pub enum"
+    (test-assert "is emitted"
+      (emits? "(pub enum color (red green blue))" "enum color"))
+    (test-assert "with its values"
+      (emits? "(pub enum color (red green blue))" "red"))
+    (test-assert "and a non-pub enum still is too"
+      (emits? "(enum color (red green blue))" "enum color"))
+    ;; Naming an enum as a type, rather than defining it, had no
+    ;; walk-enum clause and died with `(match) no matching pattern'
+    (test-assert "and it can then be used as a type"
+      (emits? "(enum color (red green blue)) (fn f () void (var m (enum color) red))"
+              "enum color m = red"))
+    (test-assert "a malformed enum is rejected with its location"
+      (reports? "(enum)" "codegen.sex:1:"))
+    ;; c-type handed the declarator's name to c-enum as the enum tag,
+    ;; so this emitted `enum m { up, down }' with no variable at all
+    (test-assert "an anonymous enum keeps the variable"
+      (emits? "(fn f () void (var e (enum (up down)) up))" "} e = up"))
+    (test-assert "and a named definition keeps both"
+      (emits? "(fn f () void (var n (enum named (a b)) a))" "enum named{")))
+
   ;; `|', `||' and `|=' read as ordinary symbols -- our own reader has
   ;; no |symbol| syntax for them to collide with -- but fmt-c cannot
   ;; dispatch on a symbol whose name it cannot write in Scheme source,

tests/modules/Makefile

@@ -14,7 +14,7 @@
 
 SEXC ?= ../../sexc
 
-EXPECTED = hello, world\nhello, sex\n2 greetings\ntext times 
+EXPECTED = hello, world\nhello, sex\n2 greetings\ntext times \nmood 1
 
 check:
 	@$(SEXC) greet.sex -c -o greet.o

tests/modules/greet-app.sex

@@ -21,4 +21,6 @@
   (printf "%d greetings\n" greet-count)
   (describe-fields greeting)
   (printf "\n")
+  (var m (enum mood) grumpy)
+  (printf "mood %d\n" m)
   (return 0))

tests/modules/greet.sex

@@ -11,6 +11,8 @@
 
 (pub struct greeting ((text (* const char)) (times int)))
 
+(pub enum mood (cheerful grumpy))
+
 ;;; Compile-time reflection across the module boundary: both the macro
 ;;; and the struct it asks about are exported, and the importing unit
 ;;; has to know the struct's fields to expand this.