commit-slab.h: code split

The struct declaration and implementation macros are moved to
commit-slab-hdr.h and commit-slab-impl.h respectively.

This right now is not needed for current users but if we make a public
commit-slab type, we may want to avoid including the slab
implementation in a header file which gets replicated in every c file
that includes it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 127 insertions, 109 deletions

diff --git a/commit-slab-decl.h b/commit-slab-decl.h
new file mode 100644
index 0000000000..fb5220fb7d
--- /dev/null
+++ b/commit-slab-decl.h
@@ -0,0 +1,30 @@
+#ifndef COMMIT_SLAB_HDR_H
+#define COMMIT_SLAB_HDR_H
+
+/* allocate ~512kB at once, allowing for malloc overhead */
+#ifndef COMMIT_SLAB_SIZE
+#define COMMIT_SLAB_SIZE (512*1024-32)
+#endif
+
+#define declare_commit_slab(slabname, elemtype) 			\
+									\
+struct slabname {							\
+	unsigned slab_size;						\
+	unsigned stride;						\
+	unsigned slab_count;						\
+	elemtype **slab;						\
+}
+
+/*
+ * Statically initialize a commit slab named "var". Note that this
+ * evaluates "stride" multiple times! Example:
+ *
+ *   struct indegree indegrees = COMMIT_SLAB_INIT(1, indegrees);
+ *
+ */
+#define COMMIT_SLAB_INIT(stride, var) { \
+	COMMIT_SLAB_SIZE / sizeof(**((var).slab)) / (stride), \
+	(stride), 0, NULL \
+}
+
+#endif /* COMMIT_SLAB_HDR_H */
diff --git a/commit-slab-impl.h b/commit-slab-impl.h
new file mode 100644
index 0000000000..234d9ee5f0
--- /dev/null
+++ b/commit-slab-impl.h
@@ -0,0 +1,91 @@
+#ifndef COMMIT_SLAB_IMPL_H
+#define COMMIT_SLAB_IMPL_H
+
+#define MAYBE_UNUSED __attribute__((__unused__))
+
+#define implement_commit_slab(slabname, elemtype) 			\
+									\
+static int stat_ ##slabname## realloc;					\
+									\
+static MAYBE_UNUSED void init_ ##slabname## _with_stride(struct slabname *s, \
+						   unsigned stride)	\
+{									\
+	unsigned int elem_size;						\
+	if (!stride)							\
+		stride = 1;						\
+	s->stride = stride;						\
+	elem_size = sizeof(elemtype) * stride;				\
+	s->slab_size = COMMIT_SLAB_SIZE / elem_size;			\
+	s->slab_count = 0;						\
+	s->slab = NULL;							\
+}									\
+									\
+static MAYBE_UNUSED void init_ ##slabname(struct slabname *s)		\
+{									\
+	init_ ##slabname## _with_stride(s, 1);				\
+}									\
+									\
+static MAYBE_UNUSED void clear_ ##slabname(struct slabname *s)		\
+{									\
+	unsigned int i;							\
+	for (i = 0; i < s->slab_count; i++)				\
+		free(s->slab[i]);					\
+	s->slab_count = 0;						\
+	FREE_AND_NULL(s->slab);						\
+}									\
+									\
+static MAYBE_UNUSED elemtype *slabname## _at_peek(struct slabname *s,	\
+						  const struct commit *c, \
+						  int add_if_missing)   \
+{									\
+	unsigned int nth_slab, nth_slot;				\
+									\
+	nth_slab = c->index / s->slab_size;				\
+	nth_slot = c->index % s->slab_size;				\
+									\
+	if (s->slab_count <= nth_slab) {				\
+		unsigned int i;						\
+		if (!add_if_missing)					\
+			return NULL;					\
+		REALLOC_ARRAY(s->slab, nth_slab + 1);			\
+		stat_ ##slabname## realloc++;				\
+		for (i = s->slab_count; i <= nth_slab; i++)		\
+			s->slab[i] = NULL;				\
+		s->slab_count = nth_slab + 1;				\
+	}								\
+	if (!s->slab[nth_slab]) {					\
+		if (!add_if_missing)					\
+			return NULL;					\
+		s->slab[nth_slab] = xcalloc(s->slab_size,		\
+					    sizeof(**s->slab) * s->stride);		\
+	}								\
+	return &s->slab[nth_slab][nth_slot * s->stride];		\
+}									\
+									\
+static MAYBE_UNUSED elemtype *slabname## _at(struct slabname *s,	\
+					     const struct commit *c)	\
+{									\
+	return slabname##_at_peek(s, c, 1);				\
+}									\
+									\
+static MAYBE_UNUSED elemtype *slabname## _peek(struct slabname *s,	\
+					     const struct commit *c)	\
+{									\
+	return slabname##_at_peek(s, c, 0);				\
+}									\
+									\
+struct slabname
+
+/*
+ * Note that this redundant forward declaration is required
+ * to allow a terminating semicolon, which makes instantiations look
+ * like function declarations.  I.e., the expansion of
+ *
+ *    implement_commit_slab(indegree, int);
+ *
+ * ends in 'struct indegree;'.  This would otherwise
+ * be a syntax error according (at least) to ISO C.  It's hard to
+ * catch because GCC silently parses it by default.
+ */
+
+#endif	/* COMMIT_SLAB_IMPL_H */
diff --git a/commit-slab.h b/commit-slab.h
index dcaab8ca04..32aa2c0e46 100644
--- a/commit-slab.h
+++ b/commit-slab.h
@@ -1,6 +1,9 @@
 #ifndef COMMIT_SLAB_H
 #define COMMIT_SLAB_H
 
+#include "commit-slab-decl.h"
+#include "commit-slab-impl.h"
+
 /*
  * define_commit_slab(slabname, elemtype) creates boilerplate code to define
  * a new struct (struct slabname) that is used to associate a piece of data
@@ -41,114 +44,8 @@
  *   leaking memory.
  */
 
-/* allocate ~512kB at once, allowing for malloc overhead */
-#ifndef COMMIT_SLAB_SIZE
-#define COMMIT_SLAB_SIZE (512*1024-32)
-#endif
-
-#define MAYBE_UNUSED __attribute__((__unused__))
-
-#define define_commit_slab(slabname, elemtype) 				\
-									\
-struct slabname {							\
-	unsigned slab_size;						\
-	unsigned stride;						\
-	unsigned slab_count;						\
-	elemtype **slab;						\
-};									\
-static int stat_ ##slabname## realloc;					\
-									\
-static MAYBE_UNUSED void init_ ##slabname## _with_stride(struct slabname *s, \
-						   unsigned stride)	\
-{									\
-	unsigned int elem_size;						\
-	if (!stride)							\
-		stride = 1;						\
-	s->stride = stride;						\
-	elem_size = sizeof(elemtype) * stride;				\
-	s->slab_size = COMMIT_SLAB_SIZE / elem_size;			\
-	s->slab_count = 0;						\
-	s->slab = NULL;							\
-}									\
-									\
-static MAYBE_UNUSED void init_ ##slabname(struct slabname *s)		\
-{									\
-	init_ ##slabname## _with_stride(s, 1);				\
-}									\
-									\
-static MAYBE_UNUSED void clear_ ##slabname(struct slabname *s)		\
-{									\
-	unsigned int i;							\
-	for (i = 0; i < s->slab_count; i++)				\
-		free(s->slab[i]);					\
-	s->slab_count = 0;						\
-	FREE_AND_NULL(s->slab);						\
-}									\
-									\
-static MAYBE_UNUSED elemtype *slabname## _at_peek(struct slabname *s,	\
-						  const struct commit *c, \
-						  int add_if_missing)   \
-{									\
-	unsigned int nth_slab, nth_slot;				\
-									\
-	nth_slab = c->index / s->slab_size;				\
-	nth_slot = c->index % s->slab_size;				\
-									\
-	if (s->slab_count <= nth_slab) {				\
-		unsigned int i;						\
-		if (!add_if_missing)					\
-			return NULL;					\
-		REALLOC_ARRAY(s->slab, nth_slab + 1);			\
-		stat_ ##slabname## realloc++;				\
-		for (i = s->slab_count; i <= nth_slab; i++)		\
-			s->slab[i] = NULL;				\
-		s->slab_count = nth_slab + 1;				\
-	}								\
-	if (!s->slab[nth_slab]) {					\
-		if (!add_if_missing)					\
-			return NULL;					\
-		s->slab[nth_slab] = xcalloc(s->slab_size,		\
-					    sizeof(**s->slab) * s->stride);		\
-	}								\
-	return &s->slab[nth_slab][nth_slot * s->stride];		\
-}									\
-									\
-static MAYBE_UNUSED elemtype *slabname## _at(struct slabname *s,	\
-					     const struct commit *c)	\
-{									\
-	return slabname##_at_peek(s, c, 1);				\
-}									\
-									\
-static MAYBE_UNUSED elemtype *slabname## _peek(struct slabname *s,	\
-					     const struct commit *c)	\
-{									\
-	return slabname##_at_peek(s, c, 0);				\
-}									\
-									\
-struct slabname
-
-/*
- * Note that this redundant forward declaration is required
- * to allow a terminating semicolon, which makes instantiations look
- * like function declarations.  I.e., the expansion of
- *
- *    define_commit_slab(indegree, int);
- *
- * ends in 'struct indegree;'.  This would otherwise
- * be a syntax error according (at least) to ISO C.  It's hard to
- * catch because GCC silently parses it by default.
- */
-
-/*
- * Statically initialize a commit slab named "var". Note that this
- * evaluates "stride" multiple times! Example:
- *
- *   struct indegree indegrees = COMMIT_SLAB_INIT(1, indegrees);
- *
- */
-#define COMMIT_SLAB_INIT(stride, var) { \
-	COMMIT_SLAB_SIZE / sizeof(**((var).slab)) / (stride), \
-	(stride), 0, NULL \
-}
+#define define_commit_slab(slabname, elemtype) \
+	declare_commit_slab(slabname, elemtype); \
+	implement_commit_slab(slabname, elemtype)
 
 #endif /* COMMIT_SLAB_H */